CURRENT Diagnosis and Treatment Pediatrics, (Current Pediatric Diagnosis & Treatment) 22nd Edition
20. Cardiovascular Diseases
Jeffrey R. Darst, MD
Kathryn K. Collins, MD
Shelley D. Miyamoto, MD
Eight in 1000 infants are born with a congenital heart defect. Advances in medical and surgical care allow more than 90% of such children to enter adulthood. Pediatric cardiac care includes not only the diagnosis and treatment of congenital heart disease but also the prevention of risk factors for adult cardiovascular disease—obesity, smoking, and hyperlipidemia. Acquired and familial heart diseases such as Kawasaki disease, viral myocarditis, cardiomyopathies, and rheumatic heart disease are also a significant cause of morbidity and mortality in children.
Symptoms related to congenital heart defects primarily vary according to the alteration in pulmonary blood flow (Table 20–1). The presence of other cardiovascular symptoms such as palpitations and chest pain should be determined by history in the older child, paying particular attention to the timing (at rest or activity-related), onset, and termination (gradual vs sudden), as well as precipitating and relieving factors.
Table 20–1. Symptoms of increased and decreased pulmonary blood flow.
The examination begins with a visual assessment of mental status, signs of distress, perfusion, and skin color. Documentation of heart rate, respiratory rate, blood pressure (in all four extremities), and oxygen saturation is essential. Many congenital cardiac defects occur as part of a genetic syndrome (Table 20–2), and complete assessment includes evaluation of dysmorphic features that may be clues to the associated cardiac defect.
Table 20–2. Cardiac defects in common syndromes.
A. Inspection and Palpation
Chest conformation should be noted in the supine position. A precordial bulge indicates cardiomegaly. Palpation may reveal increased precordial activity, right ventricular lift, or left-sided heave; a diffuse point of maximal impulse; or a precordial thrill caused by a grade IV/VI or greater murmur. The thrill of aortic stenosis is found in the suprasternal notch. In patients with severe pulmonary hypertension, a palpable pulmonary closure (P2) is frequently noted at the upper left sternal border.
1. Heart sounds—The first heart sound (S1) is the sound of atrioventricular (AV) valve closure. It is best heard at the lower left sternal border and is usually medium-pitched. Although S1 has multiple components, only one of these (M1—closure of the mitral valve) is usually audible.
The second heart sound (S2) is the sound of semilunar valve closure. It is best heard at the upper left sternal border. S2 has two component sounds, A2 and P2 (aortic and pulmonic valve closure). Splitting of S2 varies with respiration, widening with inspiration and narrowing with expiration. Abnormal splitting of S2 may be an indication of cardiac disease (Table 20–3). A prominent or loud P2 is associated with pulmonary hypertension.
Table 20–3. Abnormal splitting of S2.
The third heart sound (S3) is the sound of rapid left ventricular filling. It occurs in early diastole, after S2, and is medium- to low-pitched. In healthy children, S3 diminishes or disappears when going from supine to sitting or standing. A pathologic S3 is often heard in the presence of poor cardiac function or a large left-to-right shunt. The fourth heart sound (S4) is associated with atrial contraction and increased atrial pressure, and has a low pitch similar to that of S3. It occurs just prior to S1 and is not normally audible. It is heard in the presence of atrial contraction into a noncompliant ventricle as in hypertrophic or restrictive cardiomyopathy or from other causes of diastolic dysfunction.
Ejection clicks are usually related to dilate great vessels or valve abnormalities. They are heard during ventricular systole and are classified as early, mid, or late. Early ejection clicks at the mid left sternal border are from the pulmonic valve. Aortic clicks are typically best heard at the apex. In contrast to aortic clicks, pulmonic clicks vary with respiration, becoming louder during inspiration. A mid to late ejection click at the apex is most typically caused by mitral valve prolapse.
2. Murmurs—A heart murmur is the most common cardiovascular finding leading to a cardiology referral. Innocent or functional heart murmurs are common, and 40%–45% of children have an innocent murmur at some time during childhood.
A. CHARACTERISTICS—All murmurs should be described based on the following characteristics:
(1) Location and radiation—Where the murmur is best heard and where the sound extends.
(2) Relationship to cardiac cycle and duration—Systolic ejection (immediately following S1 with a crescendo/decrescendo change in intensity), pansystolic (occurring throughout most of systole and of constant intensity), diastolic, or continuous. The timing of the murmur provides valuable clues as to underlying pathology (Table 20–4).
Table 20–4. Pathologic murmurs.
(3) Intensity—Grade I describes a soft murmur heard with difficulty; grade II, soft but easily heard; grade III, loud but without a thrill; grade IV, loud and associated with a precordial thrill; grade V, loud, with a thrill, and audible with the edge of the stethoscope; grade VI, very loud and audible with the stethoscope off the chest.
(4) Quality—Harsh, musical, or rough; high, medium, or low in pitch.
(5) Variation with position—Audible changes in murmur when the patient is supine, sitting, standing, or squatting.
B. INNOCENT MURMURS—The six most common innocent murmurs of childhood are
(1) Newborn murmur—Heard in the first few days of life, this murmur is at the lower left sternal border, without significant radiation. It has a soft, short, vibratory grade I–II/VI quality that often subsides when mild pressure is applied to the abdomen. It usually disappears by age 2–3 weeks.
(2) Peripheral pulmonary artery stenosis (PPS)—This murmur, often heard in newborns, is caused by the normal branching of the pulmonary artery. It is heard with equal intensity at the upper left sternal border, at the back, and in one or both axillae. It is a soft, short, high-pitched, grade I–II/VI systolic ejection murmur and usually disappears by age 2. This murmur must be differentiated from true peripheral pulmonary stenosis (Williams syndrome, Alagille syndrome, or rubella syndrome), coarctation of the aorta, and valvular pulmonary stenosis. Characteristic facial features, extracardiac physical exam findings, history, and laboratory abnormalities suggestive of the syndromes listed above are the best way to differentiate true peripheral pulmonary stenosis from benign PPS of infancy as the murmurs can be similar.
(3) Still murmur—This is the most common innocent murmur of early childhood. It is typically heard between 2 and 7 years of age. It is the loudest midway between the apex and the lower left sternal border. Still murmur is a musical or vibratory, short, high-pitched, grade I–III early systolic murmur. It is loudest when the patient is supine. It diminishes or disappears with inspiration or when the patient is sitting. The Still murmur is louder in patients with fever, anemia, or sinus tachycardia from any reason.
(4) Pulmonary ejection murmur—This is the most common innocent murmur in older children and adults. It is heard from age 3 years onward. It is usually a soft systolic ejection murmur, grade I–II in intensity at the upper left sternal border. The murmur is louder when the patient is supine or when cardiac output is increased. The pulmonary ejection murmur must be differentiated from murmurs of pulmonary stenosis, coarctation of the aorta, atrial septal defect (ASD), and peripheral pulmonary artery stenosis.
(5) Venous hum—A venous hum is usually heard after age 2 years. It is located in the infraclavicular area on the right. It is a continuous musical hum of grade I–III intensity and may be accentuated in diastole and with inspiration. It is best heard in the sitting position. Turning the child’s neck, placing the child supine, and compressing the jugular vein obliterates the venous hum. Venous hum is caused by turbulence at the confluence of the subclavian and jugular veins.
(6) Innominate or carotid bruit—This murmur is more common in the older child and adolescents. It is heard in the right supraclavicular area. It is a long systolic ejection murmur, somewhat harsh and of grade II–III intensity. The bruit can be accentuated by light pressure on the carotid artery and must be differentiated from all types of aortic stenosis. The characteristic findings of aortic stenosis are outlined in more detail later in this chapter.
When innocent murmurs are found in a child, the physician should assure the parents that these are normal heart sounds of the developing child and that they do not represent heart disease.
A. Arterial Pulse Rate and Rhythm
Cardiac rate and rhythm vary greatly during infancy and childhood, so multiple determinations should be made. This is particularly important for infants (Table 20–5) whose heart rates vary with activity. The rhythm may be regular or there may be a normal phasic variation with respiration (sinus arrhythmia).
Table 20–5. Resting heart rates.
B. Arterial Pulse Quality and Amplitude
A bounding pulse is characteristic of run-off lesions, including patent ductus arteriosus (PDA), aortic regurgitation, arteriovenous malformation, or any condition with a low diastolic pressure (fever, anemia, or septic shock). Narrow or thready pulses occur in patients with conditions reducing cardiac output such as decompensated heart failure pericardial tamponade, or severe aortic stenosis. A reduction in pulse amplitude or blood pressure (> 10 mm Hg) with inspiration is referred to as pulsus paradoxus and is a telltale sign of pericardial tamponade. The pulses of the upper and lower extremities should be compared. The femoral pulse should be palpable and equal in amplitude and simultaneous with the brachial pulse. A femoral pulse that is absent or weak, or that is delayed in comparison with the brachial pulse, suggests coarctation of the aorta.
C. Arterial Blood Pressure
Blood pressures should be obtained in the upper and lower extremities. Systolic pressure in the lower extremities should be greater than or equal to that in the upper extremities. The cuff must cover the same relative area of the arm and leg. Measurements should be repeated several times. A lower blood pressure in the lower extremities suggests coarctation of the aorta.
D. Cyanosis of the Extremities
Cyanosis results from an increased concentration (> 4–5 g/dL) of reduced hemoglobin in the blood. Bluish skin color is usually, but not always, a sign. Visible cyanosis also accompanies low cardiac output, hypothermia, and systemic venous congestion, even in the presence of adequate oxygenation. Cyanosis should be judged by the color of the mucous membranes (lips). Bluish discoloration around the mouth (acrocyanosis) does not correlate with cyanosis.
E. Clubbing of the Fingers and Toes
Clubbing is often associated with severe cyanotic congenital heart disease. It usually appears after age 1 year. Hypoxemia with cyanosis is the most common cause, but clubbing also occurs in patients with endocarditis, chronic liver disease, inflammatory bowel diseases, chronic pulmonary disease, and lung abscess. Digital clubbing may be a benign genetic variant.
Edema of dependent areas (lower extremities in the older child and the face and sacrum in the younger child) is characteristic of elevated right heart pressure, which may be seen with tricuspid valve pathology or heart failure.
Hepatomegaly is the cardinal sign of right heart failure in the infant and child. Left heart failure can ultimately lead to right heart failure and therefore, hepatomegaly may also be seen in the child with pulmonary edema from lesions causing left-to-right shunting (pulmonary overcirculation) or left ventricular failure. Splenomegaly may be present in patients with long-standing heart failure (HF), and is also a characteristic of infective endocarditis. Ascites is a feature of chronic right heart failure. Examination of the abdomen may reveal shifting dullness or a fluid wave.
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Mahnke CB et al: Utility of store-and-forward pediatric telecardiology evaluation in distinguishing normal from pathologic pediatric heart sounds. Clin Pediatr (Phila) 2008;47:919–925 [PMID: 18626106].
Markel H: The stethoscope and the art of listening. N Engl J Med 2006;354:551–553 [PMID: 16467541].
The electrocardiogram (ECG) is essential in the evaluation of the cardiovascular system. The heart rate should first be determined, then the cardiac rhythm (Is the patient in a normal sinus rhythm or other rhythm as evidenced by a P wave with a consistent PR interval before every QRS complex?), and then the axis (Are the P and QRS axes normal for patient age?). Finally, assessment of chamber enlargement, cardiac intervals, and ST segments should be performed.
The ECG evolves with age. The heart rate decreases and intervals increase with age. RV dominance in the newborn changes to LV dominance in the older infant, child, and adult. The normal ECG of the 1-week-old infant is abnormal for a 1-year-old child, and the ECG of a 5-year-old child is abnormal for an adult.
Figure 20–1 defines the events recorded by the ECG.
Figure 20–1 Complexes and intervals of the electrocardiogram.
The heart rate varies markedly with age, activity, and state of emotional and physical well-being (Table 20-5).
Sinus rhythm should always be present in healthy children. Extra heart beats representing premature atrial and ventricular contractions are common during childhood, with atrial ectopy predominating in infants and ventricular ectopy during adolescence. Isolated premature beats in patients with normal heart structure and function are usually benign.
1. P-wave axis—The P wave is generated from atrial contraction beginning in the high right atrium at the site of the sinus node. The impulse proceeds leftward and inferiorly, thus leading to a positive deflection in all left-sided and inferior leads (II, III, and aVF) and negative in lead aVR.
2. QRS axis—The net voltage should be positive in leads I and aVF in children with a normal axis. In infants and young children, RV dominance may persist, leading to a negative deflection in lead I. Several congenital cardiac lesions are associated with alterations in the normal QRS axis (Table 20–6).
Table 20–6. QRS axis deviation.
D. P Wave
In the pediatric patient, the amplitude of the P wave is normally no greater than 3 mm and the duration no more than 0.08 second. The P wave is best seen in leads II and V1.
E. PR Interval
The PR is measured from the beginning of the P wave to the beginning of the QRS complex. It increases with age and with slower rates. The PR interval ranges from a minimum of 0.10 second in infants to a maximum of 0.18 second in older children with slow rates. Rheumatic heart disease, digitalis, β-blockers and calcium channel blockers can prolong the PR interval.
F. QRS Complex
This represents ventricular depolarization, and its amplitude and direction of force (axis) reveal the relative ventricular mass in hypertrophy, hypoplasia, and infarction. Abnormal ventricular conduction (eg, right or left bundle-branch block) is also revealed.
G. QT Interval
This interval is measured from the beginning of the QRS complex to the end of the T wave. The QT duration may be prolonged as a primary condition or secondarily due to drugs or electrolyte imbalances (Table 20–7). The normal QT duration is rate-related and must be corrected using the Bazett formula:
Table 20–7. Causes of QT prolongation.a
The normal QTc is less than or equal to 0.44 second.
H. ST Segment
This segment, lying between the end of the QRS complex and the beginning of the T wave, is affected by drugs, electrolyte imbalances, or myocardial injury.
I. T Wave
The T wave represents myocardial repolarization and is altered by electrolytes, myocardial hypertrophy, and ischemia.
The ultimate impression of the ECG is derived from a systematic analysis of all the features above as compared with expected normal values for the child’s age.
O’Connor M, McDaniel N, Brady WJ: The pediatric electrocardiogram. Part I: age-related interpretation. Am J Emerg Med 2008 May:26(4):506–512 [PMID: 18416018].
Evaluation of the chest radiograph for cardiac disease should focus on (1) position of the heart, (2) position of the abdominal viscera, (3) cardiac size, (4) cardiac configuration, and (5) character of the pulmonary vasculature. The standard posteroanterior and left lateral chest radiographs are used (Figure 20–2).
Figure 20–2. Position of cardiovascular structures in principal radiograph views. AO, aorta; IVC, inferior vena cava; LA, left atrium; LA APP, left atrial appendage; LV, left ventricle; PA, pulmonary artery; RA, right atrium; RV, right ventricle; SVC, superior vena cava.
Cardiac position is either levocardia (heart predominantly in the left chest), dextrocardia (heart predominantly in the right chest), or mesocardia (midline heart). The position of the liver and stomach bubble is either in the normal position (abdominal situs solitus), inverted with the stomach bubble on the right (abdominal situs inversus), or variable with midline liver (abdominal situs ambiguous). The heart appears relatively large in normal newborns at least in part due to a prominent thymic shadow. The heart size should be less than 50% of the chest diameter in children older than age 1 year. The cardiac configuration on chest radiograph may provide useful diagnostic information (Table 20–8). Some congenital cardiac lesions have a characteristic radiographic appearance that suggests the diagnosis but should not be viewed as conclusive (Table 20–9). The pulmonary vasculature should be assessed. The presence of increased or decreased pulmonary blood flow suggests a possible congenital cardiac diagnosis, particularly in the cyanotic infant (Table 20–10).
Table 20–8. Radiographic changes with cardiac chamber enlargement.
Table 20–9. Lesion-specific chest radiographic findings.
Table 20–10. Alterations in pulmonary blood flow in cyanotic cardiac lesions.
Laya BF et al: The accuracy of chest radiographs in the detection of congenital heart disease and in the diagnosis of specific congenital cardiac lesions. Pediatr Radiol 2006;36:677–681 [PMID: 16547698].
Dextrocardia is a radiographic term used when the heart is on the right side of the chest. When dextrocardia occurs with reversal of position of the other important organs of the chest and abdomen (eg, liver, lungs, and spleen), the condition is called situs inversus totalis, and the heart is usually normal. When dextrocardia occurs with the other organs normally located (situs solitus), the heart usually has severe defects.
Other situs abnormalities include situs ambiguous with the liver central and anterior in the upper abdomen and the stomach pushed posteriorly; bilateral right-sidedness (asplenia syndrome); and bilateral left-sidedness (polysplenia syndrome). In virtually all cases of situs ambiguous, congenital heart disease is present.
Echocardiography is a fundamental tool of pediatric cardiology. Using multiple ultrasound modalities (two-dimensional imaging, Doppler, and M-mode), cardiac anatomy, blood flow, intracardiac pressures, and ventricular function can be assessed. Echocardiography is based on the physical principles of sound waves. The ultrasound frequencies utilized in cardiac imaging range from 2 to 10 million cycles/s.
M-mode echocardiography uses short bursts of ultrasound sent from a transducer. At acoustic interfaces, sound waves are reflected back to the transducer. The time it takes for the sound wave to return to the transducer is measured and the distance to the interface is calculated. That calculated distance is displayed against time, and a one-dimensional image is constructed that demonstrates cardiac motion. Two-dimensional imaging extends this technique by sending a rapid series of ultrasound bursts across a 90-degree sector, which allows construction of a two-dimensional image of the heart. Doppler ultrasound measures blood flow. The ultrasound transducer sends out a known frequency of sound which reflects off moving red blood cells. The transducer receives the reflected frequency and compares it with the transmitted frequency. The blood flow velocity can be calculated from the measured frequency shift. This information is used to estimate pressure gradients by the simplified Bernouli equation, in which the pressure gradient is equal to four times the calculated velocity (Pressure gradient = 4(V2)).
A transthoracic echocardiogram is obtained by placing the transducer on areas of the chest where there is minimal lung interference. At each transducer position, the beam is swept through the heart and a two-dimensional image appears on the screen. Complex intracardiac anatomy and spatial relationships can be described, making possible the accurate diagnosis of congenital heart disease. In addition to structural details, Doppler gives information about intracardiac blood flow and pressure gradients. Commonly used Doppler techniques include color flow imaging, pulsed-wave, and continuous-wave Doppler. Color flow imaging gives general information on the direction and velocity of flow. Pulsed- and continuous-wave Doppler imagings give more precise measurements of blood velocity. The role of M-mode in the ultrasound examination has decreased as other ultrasound modalities have been developed. M-mode is still used to measure LV end-diastolic and end-systolic dimensions and permits calculation of the LV-shortening fraction, a standard estimate of LV function (SF = LV end-diastolic volume – LV systolic volume/LV end-diastolic volume). Three-dimensional echocardiography, tissue Doppler, strain, and strain rate imaging are newer modalities that provide more sophisticated assessment of systolic and diastolic function and can detect early changes in myocardial function.
A typical transthoracic echocardiogram performed by a skilled sonographer takes about 30 minutes, and patients must be still for the examination. Frequently infants and children cannot cooperate for the examination and sedation is required. Transesophageal echocardiography requires general anesthesia in infants and children and is primarily used to guide interventional procedures and surgical repair of congenital heart disease. In cases of difficult imaging windows due to patient size, air interference or when looking for evidence of vegetations on cardiac valves, transesophageal echocardiography may be necessary.
It is important to note that fetal echocardiography plays an important role in the prenatal diagnosis of congenital heart disease. A fetal echocardiogram is recommended if the fetus is considered high risk for the development of congenital heart disease or if there is suspicion for structural heart disease or fetal arrhythmias based on the obstetric fetal ultrasound. In utero management of fetal arrhythmias and post-delivery planning for the fetus with complex heart disease has resulted in improved outcomes for this challenging group of patients.
Elkiran O et al: Tissue Doppler, strain, and strain rate measurements assessed by two-dimensional speckle-tracking echocardiography in healthy newborns and infants. Cardiol Young 2013 Feb 6:1–11 [PMID: 23388082].
Friedberg MK et al: Validation of 3D echocardiographic assessment of left ventricular volumes, mass, and ejection fraction in neonates and infants with congenital heart disease: a comparison study with cardiac MRI. Circ Cardiovasc Imaging 2010;3(6):735–742 [PMID: 20855861].
Nuclear imaging is not commonly used in pediatric cardiology, but can be a useful adjunct to cardiopulmonary exercise testing in assessing both fixed and reversible areas of myocardial ischemia. It is valuable in evaluating myocardial perfusion in patients with Kawasaki disease, repaired anomalous left coronary artery or other coronary anomalies, myocardial bridging in the setting of hypertrophic cardiomyopathy (HCM), or chest pain in association with ECG changes with exercise.
MAGNETIC RESONANCE IMAGING
Magnetic resonance imaging (MRI) of the heart is valuable for evaluation and noninvasive follow-up of many congenital heart defects. It is particularly useful in imaging the thoracic vessels, which are difficult to image by transthoracic echocardiogram. Cardiac gated imaging allows dynamic evaluation of structure and blood flow of the heart and great vessels. Cardiac MRI provides unique and precise imaging in patients with newly diagnosed or repaired aortic coarctation and defines the aortic dilation in Marfan, Turner, and Loeys-Dietz syndromes. Cardiac MRI can quantify regurgitant lesions such as pulmonary insufficiency (PI) after repair of tetralogy of Fallot (ToF) and can define ventricular function, chamber size, and wall thickness in patients with inadequate echocardiographic images or cardiomyopathies. MRI is especially useful to characterize right ventricular size and function as this chamber is often difficult to image comprehensively by echocardiogram. Because it allows computer manipulation of images of the heart and great vessels, three-dimensional MRI is an ideal noninvasive way of obtaining accurate reconstructions of the heart. General anesthesia is often required to facilitate cardiac MRI performance in children less than 8 years.
Van der Hulst AE et al: Cardiac MRI in postoperative congenital heart disease patients. J Magn Reson Imaging 2012;36(3):511–528 [PMID: 2290365].
CARDIOPULMONARY STRESS TESTING
Most children with heart disease are capable of normal activity. Data on cardiac function after exercise are essential to prevent unnecessary restriction of activities. The response to exercise is helpful in determining the need for and the timing of cardiovascular surgery and is a useful objective outcome measure of the results of medical and surgical interventions.
Bicycle ergometers or treadmills can be used in children as young as age 5 years. The addition of a metabolic cart enables one to assess whether exercise impairment is secondary to cardiac limitation, pulmonary limitation, deconditioning, or lack of effort. Exercise variables include the ECG, blood pressure response to exercise, oxygen saturation, ventilation, maximal oxygen consumption, and peak workload attained. Cardiopulmonary stress testing is routine in children with congenital cardiac lesions to ascertain limitations, develop exercise programs, assess the effect of therapies, and decide on the need for cardiac transplantation. Stress testing is also employed in children with structurally normal hearts with complaints of exercise-induced symptoms in order to rule out cardiac or pulmonary pathology. Significant stress ischemia or dysrhythmias warrant physical restrictions or appropriate therapy. Children with poor performance due to suboptimal conditioning benefit from a planned exercise program.
Arvidsson D, Slinde F, Hulthén L, Sunnegårdh J: Physical activity, sports participation and aerobic fitness in children who have undergone surgery for congenital heart defects. Acta Paediatr 2009 Sep;98(9):1475–1482 [PMID: 19489769].
ARTERIAL BLOOD GASES
Quantitating the partial oxygen pressure (Po2) or O2 saturation during the administration of 100% oxygen is the most useful method of distinguishing cyanosis produced primarily by heart disease or by lung disease in sick infants. In cyanotic heart disease, the partial arterial oxygen pressure (Pao2) increases very little when 100% oxygen is administered over the values obtained while breathing room air. However, Pao2 usually increases significantly when oxygen is administered to a patient with lung disease. Table 20–11 illustrates the responses seen in patients with heart or lung disease during the hyperoxic test. Although the US Department of Health and Human Services recommended newborn screening for critical congenital heart disease in 2010, implementation of comprehensive pulse oximetry screening programs are challenged by variable infrastructure and access to expert interpretation.
Table 20–11. Examples of responses to 10 minutes of 100% oxygen in lung disease and heart disease.
Kember AR et al: Strategies for implementing screening for critical congenital heart disease. Pediatrics 2011 Nov;128(5):e1259–e1267 [PMID: 21987707].
CARDIAC CATHETERIZATION & ANGIOCARDIOGRAPHY
Cardiac catheterization is an invasive method to evaluate anatomic and physiologic conditions in congenital or acquired heart disease. Management decisions may be made based on oximetric, hemodynamic or angiographic data obtained through a catheterization. In an increasing number of cases, intervention may be performed during a catheterization that may palliate, or even cure, a congenital heart defect without open heart surgery.
Cardiac Catheterization Data
Figure 20–3 shows oxygen saturation (in percent) and pressure (in millimeters of mercury) values obtained at cardiac catheterization from the chambers and great arteries of the heart. These values represent the normal range for a school age child.
Figure 20–3 Pressures (in millimeters of mercury) and oxygen saturation (in percent) obtained by cardiac catheterization in a healthy child. 3, mean pressure of 3 mm Hg in the right atrium; 5, mean pressure of 5 mm Hg in the left atrium.
A. Oximetry, Shunts, and Cardiac Output
Measurement of oxygen levels throughout the heart and surrounding blood vessels can provide a wealth of information about a patient’s physiology. The difference between systemic saturation (in the aorta) and mixed venous saturation (usually in the superior vena cava [SVC]) is usually inversely proportional to the overall cardiac output. Cardiac output is determined by saturation difference across a vascular bed, taking into account oxygen consumption and hemoglobin. This is known as the Fick principle. Cardiac output in a healthy heart varies directly with the body’s oxygen consumption and is inversely proportional to hemoglobin. The circulatory system of patients who are anemic usually tries to generate a higher cardiac output to maintain oxygen delivery to the cells of the body.
An increase in saturation across the right side of the heart (anywhere between SVC and pulmonary arteries) represents a left-to-right shunt. If oxygenated blood can mix with venous blood, the saturation rises—the degree of which correlates with the size of the shunt. Conversely, a fall in saturation across the left heart, between the pulmonary veins and the aorta, is abnormal. This represents the addition of deoxygenated blood to oxygenated blood—a right-to-left shunt.
A commonly referenced ratio in pediatric cardiology is the Qp:Qs. In a normal heart, systemic cardiac output (Qs) and pulmonary blood flow (Qp) are equal, or Qp:Qs = 1. If a step-up in saturation is noted across the right heart, suggesting a left-to-right shunt, pulmonary blood flow will exceed systemic blood flow. This can result, in cases of large shunts, in a Qp:Qs of as high as 3:1 or more. This level of shunt is usually poorly tolerated, but small shunts (such as 1.5:1) may be well tolerated for months or years. In cases of right-to-left shunts, Qs will exceed Qp. In these cyanotic patients, the Qp:Qs may be 0.7 or 0.8.
Pressures should be determined in all chambers and major vessels entered. Systolic pressure in the right ventricle should be equal to the systolic pressure in the pulmonary artery. Likewise, the systolic pressure in the left ventricle should be equal to the systolic pressure of the aorta. The mean pressure in the atria should be nearly equal to (or a point or two lower than) the end-diastolic pressure of the ventricles. If a gradient in pressure exists, an obstruction is present, and the severity of the gradient is one criterion for the necessity of intervention.
For example, a left ventricular systolic pressure in a small child of 140 mm Hg and an aortic systolic pressure of 80 mm Hg, a gradient of 60 mm Hg, would classify as severe aortic valve stenosis. Balloon aortic valvuloplasty would be indicated at the time of the catheterization.
C. Vascular Resistance
In addition to pressure and flow, resistance completes the “concept triad” of congenital heart physiology. Resistance is related to pressure and flow as described in the below equation:
The resistance across a vascular bed can be concretely calculated. The most common clinically relevant example is pulmonary vascular resistance. Patients with congenital heart disease or pulmonary vascular disease may have elevation in pulmonary vascular resistance, which can adversely impact circulation and heart function. To calculate pulmonary vascular resistance, the pressure drop from the pulmonary arteries to the left atrium is divided by pulmonary blood flow (Qp) to obtain a value in units. For example, a patient with a mean pulmonary artery pressure of 15 mm Hg and a left atrial pressure of 9 mm Hg, with a Qp of 3 L/min/m2, has a pulmonary vascular resistance of 2 U/m2.
Normal pulmonary vascular resistance is less than 3 U/m2. Systemic vascular resistance normally covers a wider range, usually from 10 to 30 U/m2. The ratio of pulmonary to systemic vascular resistance is usually less than 0.3. High pulmonary resistance, or a high ratio of resistance, denotes abnormal pulmonary vasculature. It often represents increased risk in patients with congenital heart disease or pulmonary hypertension and results in higher risk of death in severely affected patients.
Cardiac catheterization can be performed to evaluate the effects of pharmaceutical therapy. An example of this use of catheterization is monitoring changes in pulmonary vascular resistance during the administration of nitric oxide or prostacyclin in a child with primary pulmonary hypertension.
In the past, angiography was a mainstay of the initial diagnostic methods for congenital heart disease. It is still used for diagnostic purposes in selected cases, but currently is used more frequently to plan interventions or evaluate postsurgical anatomy that is poorly seen by noninvasive methods. Injection of contrast liquid via a well-positioned catheter can illuminate detailed intracardiac and intravascular anatomy more clearly than any other method. Cardiac function can be observed, and anatomic abnormalities may be easily identified. In a growing number of centers, three-dimensional reconstruction of angiograms can provide exquisite delineation of cardiac and vascular structures.
Interventional Cardiac Catheterization
Various procedures are commonly performed in the catheterization laboratory that can improve or cure congenital malformations. Lesions that result in abnormal flow near or within the heart can be occluded, such as a patent ductus arteriosus, atrial septal defect, or ventricular septal defect. Obstruction of heart valves can be addressed through balloon valvuloplasty. Intervention may also be performed on vascular obstruction through angioplasty or stent placement in pulmonary arteries or the aorta. Systemic and pulmonary veins can be modified in a similar fashion, unfortunately with often minimal success in the latter. Devices are now available to allow patients to undergo replacement of failing heart valves without open heart surgery, and an increasing armamentarium of devices are becoming available for treatment of other defects and abnormal vasculature.
With the progression of improved noninvasive imaging, fewer diagnostic cardiac catheterization studies are performed today. The number of interventional procedures, however, is on the rise. Although the risks of cardiac catheterization are very low for elective studies in older children (< 1%), the risk of major complications in distressed or small patients is higher. Interventional procedures, particularly in unstable babies and children, increase these risks further. Increased use of registries is currently being employed to better understand efficacy rates and risks of these procedures, with the hope of optimizing the care of infants and children in the catheterization laboratory.
Backes CH et al: Low weight as an independent risk factor for adverse events during cardiac catheterization of infants. Catheter Cardiovasc Interv 2013 Feb 22 [doi: 10.1002/ccd.24726].
Berman DP et al: The use of three-dimensional rotational angiography to assess the pulmonary circulation following cavo-pulmonary connection in patients with single ventricle. Catheter Cardiovasc Interv 2012 Nov 15;80(6):922–930.
PERINATAL & NEONATAL CIRCULATION
At birth, two events affect the cardiovascular and pulmonary system: (1) the umbilical cord is clamped, removing the placenta from the maternal circulation; and (2) breathing commences. As a result, marked changes in the circulation occur. During fetal life, the placenta offers low resistance to blood flow. In contrast, the pulmonary arterioles are markedly constricted and there is high resistance to blood flow in the lungs. Therefore, the majority of blood entering the right side of the heart travels from the right atrium into the left atrium across the foramen ovale (right-to-left shunt). In addition, most of the blood that makes its way into the right ventricle and then pulmonary arteries will flow from the pulmonary artery into the aorta through the ductus arteriosus (right-to-left shunt). Subsequently, pulmonary blood flow accounts for only 7%–10% of the combined in utero ventricular output. At birth, pulmonary blood flow dramatically increases with the fall in pulmonary vascular resistance and pressure. The causes of prolonged high pulmonary vascular resistance include physical factors (lack of an adequate air-liquid interface or ventilation), low oxygen tension, and vasoactive mediators such as elevated endothelin peptide levels or leukotrienes. Clamping the umbilical cord produces an immediate increase in resistance to flow in the systemic circuit.
As breathing commences, the Po2 of the small pulmonary arterioles increases, resulting in a decrease in pulmonary vascular resistance. Increased oxygen tension, rhythmic lung distention, and production of nitric oxide as well as prostacyclin play major roles in the fall in pulmonary vascular resistance at birth. The pulmonary vascular resistance falls below that of the systemic circuit, resulting in a reversal in direction of blood flow across the ductus arteriosus and marked increase in pulmonary blood flow.
Functional closure of the ductus arteriosus begins shortly after birth. The ductus arteriosus usually remains patent for 1–5 days. During the first hour after birth, a small right-to-left shunt is present (as in the fetus). However, after 1 hour, bidirectional shunting occurs, with the left-to-right direction predominating. In most cases, right-to-left shunting disappears completely by 8 hours. In patients with severe hypoxia (eg, in the syndrome of persistent pulmonary hypertension of the newborn), pulmonary vascular resistance remains high, resulting in a continued right-to-left shunt. Although flow through the ductus arteriosus usually is gone by 5 days of life, the vessel does not close anatomically for 7–14 days.
In fetal life, the foramen ovale serves as a one-way valve shunting blood from the inferior vena cava through the right atrium into the left atrium. At birth, because of the changes in the pulmonary and systemic vascular resistance and the increase in the quantity of blood returning from the pulmonary veins to the left atrium, the left atrial pressure rises above that of the right atrium. This functionally closes the flap of the foramen ovale, preventing flow of blood across the septum. The foramen ovale remains probe patent in 10%–15% of adults.
Persistent pulmonary hypertension is a clinical syndrome of full-term infants. The neonate develops tachypnea, cyanosis, and pulmonary hypertension during the first 8 hours after delivery. These infants have massive right-to-left ductal and/or foramen shunting for 3–7 days because of high pulmonary vascular resistance. Progressive hypoxia and acidosis will cause early death unless the pulmonary resistance can be lowered. Postmortem findings include increased thickness of the pulmonary arteriolar media. Increased alveolar Po2 with hyperventilation, alkalosis, paralysis, surfactant administration, high-frequency ventilation, and cardiac inotropes can usually reverse this process. Inhaled nitric oxide selectively dilates pulmonary vasculature, produces a sustained improvement in oxygenation, and has resulted in improved outcomes.
In the normal newborn, pulmonary vascular resistance and pulmonary arterial pressure continue to fall during the first weeks of life as a result of demuscularization of the pulmonary arterioles. Adult levels of pulmonary resistance and pressure are normally achieved by 4–6 weeks of age. It is at this time typically that signs of pulmonary overcirculation associated with left-to-right shunt lesions (VSD or atrioventricular septal defect [AVSD]) appear.
Konduri GG, Kim UO: Advances in the diagnosis and management of persistent pulmonary hypertension of the newborn. Pediatr Clin North Am 2009;56:579–600, Table of Contents [PMID: 19501693].
Rudolph AM: The fetal circulation and congenital heart disease. Arch Dis Child Fetal Neonatal Ed 2010;95(2):F132–F136 [PMID: 19321508].
Heart failure (HF) is the clinical condition in which the heart fails to meet the circulatory and metabolic needs of the body. The term congestive heart failure is not always accurate, as some patients with significant cardiac dysfunction have symptoms of exercise intolerance and fatigue without evidence of congestion. Right and left heart failure can result from volume or pressure overload of the respective ventricle or an intrinsic abnormality of the ventricular myocardium. Causes of right ventricular volume overload include an ASD, pulmonary insufficiency, or anomalous pulmonary venous return. Left ventricular volume overload occurs with any left-to-right shunting lesion (eg, VSD, PDA), aortic insufficiency, or a systemic arteriovenous malformation. Causes of right ventricular failure as a result of pressure overload include pulmonary hypertension, valvar pulmonary stenosis, or severe branch pulmonary artery stenosis. Left ventricular pressure overload results from left heart obstructive lesions such as aortic stenosis (subvalvar, valvar, or supravalvar) or coarctation of the aorta. Abnormalities of the right ventricular myocardium that can result in right heart failure include Ebstein’s anomaly (atrialization of the right ventricle) and arrhythmogenic right ventricular dysplasia (a genetic disorder where the right ventricular myocardium is replaced by fat). Abnormalities of the left ventricular myocardium are more common and include dilated cardiomyopathy, myocarditis, or hypertrophic cardiomyopathy. As a result of elevated left atrial pressure and impaired relaxation of the left ventricle, left heart failure can lead to right heart failure. Other causes of HF in infants include AV septal defect, coronary artery anomalies, and chronic atrial tachyarrhythmias. Metabolic, mitochondrial, and neuromuscular disorders with associated cardiomyopathy present at various ages depending on the etiology. HF due to acquired conditions such as myocarditis can occur at any age. Children with HF may present with irritability, diaphoresis with feeds, fatigue, exercise intolerance, or evidence of pulmonary congestion (see Table 20–1).
Treatment of Heart Failure
The therapy of HF should be directed toward the underlying cause as well as the symptoms. Regardless of the etiology, neurohormonal activation occurs early when ventricular systolic dysfunction is present. Plasma catecholamine levels (eg, norepinephrine) increase causing tachycardia, diaphoresis, and, by activating the renin-angiotensin system, peripheral vasoconstriction and salt and water retention. There is no gold standard diagnostic or therapeutic approach to HF in children. Treatment must be individualized and therapies should be aimed at improving cardiac performance by targeting the three determinants of cardiac performance: (1) preload, (2) afterload, and (3) contractility.
Inpatient Management of Heart Failure
Patients with cardiac decompensation may require hospitalization for initiation or augmentation of HF therapy. Table 20–12 demonstrates intravenous inotropic agents used to augment cardiac output and their relative effect on heart rate, systemic vascular resistance, and cardiac index. The drug used will depend in part on the cause of the HF.
Table 20–12. Intravenous inotropic agents.
A. Inotropic and Mechanical Support
1. Afterload reduction
A. MILRINONE—This phosphodiesterase-3 inhibitor increases cyclic adenosine monophosphate, thereby improving the inotropic state of the heart. In addition to a dose-dependent increase in cardiac contractility, milrinone is a systemic and pulmonary vasodilator and thus an effective agent in both right and left ventricular systolic dysfunction. Milrinone reduces the incidence of low cardiac output syndrome following open-heart surgery. The usual dosage range is 0.25–0.75 mcg/kg/min.
B. NITROGLYCERIN—Nitroglycerin functions primarily as a dilator of venous capacitance vessels and causes a reduction of right and left atrial pressure. Systemic blood pressure may also fall, and reflex tachycardia may occur. Nitroglycerin is used to improve coronary blood flow and may be especially useful when cardiac output is reduced because of coronary under-perfusion following congenital heart surgery. The usual intravenous dosage range is 1–3 mcg/kg/min.
2. Enhancement of contractility
A. DOPAMINE—This naturally occurring catecholamine increases myocardial contractility primarily via cardiac β-adrenergic activation. Dopamine also directly acts on renal dopamine receptors to improve renal perfusion. The usual dose range for HF is 3–10 mcg/kg/min.
B. DOBUTAMINE—This synthetic catecholamine increases myocardial contractility secondary to cardiospecific β-adrenergic activation and produces little peripheral vasoconstriction. Dobutamine does not usually cause marked tachycardia, which is a distinct advantage. However, the drug does not selectively improve renal perfusion as does dopamine. The usual dose range is essentially the same as for dopamine.
3. Mechanical circulatory support—Mechanical support is indicated in children with severe, refractory myocardial failure secondary to cardiomyopathy, myocarditis, or following cardiac surgery. Mechanical support is used for a limited time while cardiac function improves or as a bridge to cardiac transplantation.
A. EXTRACORPOREAL MEMBRANE OXYGENATION (ECMO)—ECMO is a temporary means of providing oxygenation, carbon dioxide removal, and hemodynamic support to patients with cardiac or pulmonary failure refractory to conventional therapy. The blood removed from the patient via a catheter positioned in the venous system (eg, superior vena cava or right atrium) passes through a membrane oxygenator and then is delivered back to the patient through a catheter in the arterial system (eg, aorta or common carotid artery). Flow rates are adjusted to maintain adequate systemic perfusion, as judged by mean arterial blood pressure, acid-base status, end-organ function, and mixed venous oxygen saturation. The patient is monitored closely for improvement in cardiac contractility. Risks are significant and include severe internal and external bleeding, infection, thrombosis, and pump failure.
B. VENTRICULAR ASSIST DEVICES—Use of ventricular assist devices is increasing in children as device development has progressed. These devices allow for less invasive hemodynamic support than ECMO. A cannula is usually positioned in the apex of the ventricle and removes blood from the ventricle using a battery-operated pump. Blood is then returned to the patient through a separate cannula positioned in the aorta or pulmonary artery, depending on the ventricle being supported. Biventricular support can be done if necessary. Ventricular assist carries lower risk of pump failure than ECMO, but the risk of infection, thrombosis, and bleeding complications remains.
Outpatient Management of Heart Failure
1. Afterload-reducing agents—Oral afterload-reducing agents improve cardiac output by decreasing systemic vascular resistance. Angiotensin-converting enzyme (ACE) inhibitors (captopril, enalapril, and lisinopril) are first-line therapy in children with HF requiring long-term treatment. These agents block angiotensin II–mediated systemic vasoconstriction and are particularly useful in children with structurally normal hearts but reduced LV myocardial function (eg, myocarditis or dilated cardiomyopathies [DCMs]). They are also useful in ameliorating mitral and aortic insufficiency and have a role in controlling refractory HF in patients with large left-to-right shunts in whom systemic vascular resistance is elevated.
2. β-Blockade—Although clearly beneficial in adults with HF, a randomized, controlled study of the use of a β-blocker (carvedilol) in children with HF did not demonstrate any significant improvement compared to placebo. However, β-blockers may still be useful adjunctive therapy in some children with refractory HF already taking ACE inhibitors. In the setting of HF, excessive circulating catecholamines are present due to activation of the sympathetic nervous system. Although beneficial acutely, this compensatory response over time produces myocardial fibrosis, myocyte hypertrophy, and myocyte apoptosis that contribute to the progression of HF. β-Blockers (eg, carvedilol and metoprolol) antagonize this sympathetic activation and may offset these deleterious effects. Side effects of β-blockers are significant and include bradycardia, hypotension, and worsening HF in some patients.
3. Diuretics—Diuretic therapy may be necessary in HF to maintain the euvolemic state and control symptoms related to pulmonary or hepatic congestion.
A. FUROSEMIDE—This rapid-acting loop diuretic may be given intravenously or orally. It removes large amounts of potassium and chloride from the body, producing hypochloremic metabolic alkalosis when used chronically. Electrolytes should be monitored during long-term therapy.
B. THIAZIDES—Thiazides are distal tubular diuretics used to complement furosemide in severe cases of HF.
C. SPIRONOLACTONE—Spironolactone is a potassium-sparing aldosterone inhibitor. It is used frequently in conjunction with furosemide or thiazides for its enhanced diuretic function. Because it spares potassium, supplemental potassium may be avoided. Spironolactone has benefit in adults with HF regardless of its diuretic effect as aldosterone is associated with the development of fibrosis, sodium retention, and vascular dysfunction. This effect has not been proven in children.
4. Digitalis—Digitalis is a cardiac glycoside with a positive inotropic effect on the heart and an associated decrease in systemic vascular resistance. The preparation of digitalis used in clinical practice is digoxin. Large studies in adult patients with HF have not demonstrated decreased mortality of HF with digoxin use, but treatment is associated with reduced hospitalization rates for HF exacerbations. There are no controlled studies in children.
A. DIGITALIS TOXICITY—Any dysrhythmia that occurs during digoxin therapy should be attributed to the drug until proven otherwise. Ventricular bigeminy and first-, second-, or third-degree AV block are characteristic of digoxin toxicity. A trough level should be obtained if digoxin toxicity is suspected.
B. DIGITALIS POISONING—This acute emergency must be treated without delay. Digoxin poisoning most commonly occurs in toddlers who have taken their parents’ or grandparents’ medications. The child’s stomach should be emptied immediately by gastric lavage even if several hours have passed since ingestion. Patients who have ingested massive amounts of digoxin should receive large doses of activated charcoal. In advanced heart block, atropine or temporary ventricular pacing may be needed. Digoxin immune Fab can be used to reverse potentially life-threatening intoxication. Antiarrhythmic agents may be useful.
5. Fluid restriction—Fluid restriction is rarely necessary in children with HF due to the effectiveness of diuretics and the tendency of infants and children with HF to self-regulate intake. Ensuring adequate caloric intake to promote growth is a more important goal in children with HF.
Morales DL, Zafar F, Rossano JW et al: Use of ventricular assist devices in children across the United States: analysis of 7.5 million pediatric hospitalizations. Ann Thorac Surg 2010 Oct;90(4):1313–1318, discussion 1318–1319 [PMID: 20868835].
Rosenthal D et al: International society for heart and lung transplantation: practice guidelines for management of heart failure in children. J Heart Lung Transplant 2004;23:1313 [PMID: 15607659].
GENETIC BASIS OF CONGENITAL HEART DISEASE
Environmental factors such as maternal diabetes, alcohol consumption, progesterone use, viral infection, and other maternal teratogen exposure are associated with an increased incidence of cardiac malformations. However, the importance of genetics as a cause of congenital heart disease is becoming more evident as advances in the field occur. Microdeletion in the long arm of chromosome 22 (22q11) is associated with DiGeorge syndrome. These children often have conotruncal abnormalities such as truncus arteriosus, tetralogy of Fallot, double-outlet RV, or interrupted aortic arch. Alagille, Noonan, Holt-Oram, and Williams syndromes and the Trisomies 13, 18, and 21 are all commonly associated with congenital heart lesions. Understanding these associations as well as further targeted study investigating the genetic basis of other cardiac lesions will offer opportunities for early diagnosis, gene therapy, and recurrence risk counseling for families.
Pierpont ME et al: Genetic basis for congenital heart defects: current knowledge: a scientific statement from the American Heart Association Congenital Cardiac Defects Committee, Council on Cardiovascular Disease in the Young: endorsed by the American Academy of Pediatrics. Circulation 2007;115:3015–3038 [PMID: 17519398].
ACYANOTIC CONGENITAL HEART DISEASE
DEFECTS IN SEPTATION
1. Atrial Septal Defect
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Fixed, widely split S2, RV heave.
Grade I–III/VI systolic ejection murmur at the pulmonary area.
Large shunts cause a diastolic flow murmur at the lower left sternal border (increased flow across the tricuspid valve).
ECG shows rsR′ in lead V1.
Atrial septal defect (ASD) is an opening in the atrial septum permitting the shunting of blood between the atria. There are three major types: ostium secundum, ostium primum, and sinus venosus. Ostium secundum is the most common type and represents an embryologic deficiency in the septum secundum or too large of a central hole in the septum primum. Ostium primum defect is associated with atrioventricular septal defects. The sinus venosus defect is frequently associated with abnormal pulmonary venous return, as the location of the sinus venosus is intimately related to the right upper pulmonary vein.
Ostium secundum ASD occurs in 10% of patients with congenital heart disease and is two times more common in females than in males. The defect is most often sporadic but may be familial or have a genetic basis (Holt-Oram syndrome). After the third decade, atrial arrhythmias or pulmonary vascular disease may develop. Irreversible pulmonary hypertension resulting in cyanosis as atrial level shunting becomes right-to-left and ultimately right heart failure can occur and is a life-limiting process (Eisenmenger syndrome).
A. Symptoms and Signs
Most infants and children with an ASD have no cardiovascular symptoms. Older children and adults can present with exercise intolerance, easy fatigability, or, rarely, heart failure. The direction of flow across the ASD is determined by the compliance of the ventricles. Because the right ventricle is normally more compliant, shunting across the ASD is left-to-right as blood follows the path of least resistance. Therefore, cyanosis does not occur unless RV dysfunction occurs, usually as a result of pulmonary hypertension, leading to reversal of the shunt across the defect.
Peripheral pulses are normal and equal. The heart is usually hyperactive, with an RV heave felt best at the mid to lower left sternal border. S2 at the pulmonary area is widely split and often fixed. In the absence of associated pulmonary hypertension, the pulmonary component is normal in intensity. A grade I–III/VI ejection-type systolic murmur is heard best at the left sternal border in the second intercostal space. This murmur is caused by increased flow across the pulmonic valve, not flow across the ASD. A mid-diastolic murmur is often heard in the fourth intercostal space at the left sternal border. This murmur is caused by increased flow across the tricuspid valve during diastole. The presence of this murmur suggests high flow with a pulmonary-to-systemic blood flow ratio greater than 2:1.
Radiographs may show cardiac enlargement. The main pulmonary artery may be dilated and pulmonary vascular markings increased in large defects owing to the increased pulmonary blood flow.
The usual ECG shows right axis deviation. In the right precordial leads, an rsR ′ pattern is usually present. A mutation in the cardiac homeobox gene (NKX2-5) is associated with an ASD, and AV block would be seen on the ECG.
Echocardiography shows a dilated right atrium and RV. Direct visualization of the exact anatomic location of the ASD by two-dimensional echocardiography, and demonstration of a left-to-right shunt through the defect by color-flow Doppler, confirms the diagnosis and has eliminated the need for cardiac catheterization prior to surgical or catheter closure of the defect. Assessment of all pulmonary veins should be made to rule out associated anomalous pulmonary venous return.
E. Cardiac Catheterization
Although cardiac catheterization is rarely needed for diagnostic purposes, transcatheter closure of an ostium secundum ASD is now the preferred method of treatment.
If a catheterization is performed, oximetry shows a significant step-up in oxygen saturation from the superior vena cava to the right atrium. The pulmonary artery pressure and pulmonary vascular resistance are usually normal. The Qp: Qs may vary from 1.5:1 to 4:1.
Surgical or catheterization closure is generally recommended for symptomatic children with a large atrial level defect and associated right heart dilation. In the asymptomatic child with a large hemodynamically significant defect, closure is performed electively at age 1–3 years. Most defects are amenable to nonoperative device closure during cardiac catheterization, but the defect must have adequate tissue rims on all sides on which to anchor the device. The mortality for surgical closure is less than 1%. When closure is performed by age 3 years, late complications of RV dysfunction and dysrhythmias are avoided.
Course & Prognosis
Patients usually tolerate an ASD well in the first two decades of life, and the defect often goes unnoticed until middle or late adulthood. Pulmonary hypertension and reversal of the shunt are rare late complications. Infective endocarditis (IE) is uncommon. Spontaneous closure occurs, most frequently in children with a defect less than 4 mm in diameter, therefore outpatient follow-up is recommended. Exercise tolerance and oxygen consumption in surgically corrected children are generally normal, and restriction of physical activity is unnecessary.
Arrington CB et al: An assessment of the electrocardiogram as a screening test for large atrial septal defects in children. J Electrocardiol 2007;40:484–488 [PMID: 17673249].
Butera G et al: Treatment of isolated secundum atrial septal defects: impact of age and defect morphology in 1,013 consecutive patients. Am Heart J 2008;156:706–712 [PMID: 18926151].
2. Ventricular Septal Defect
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Holosystolic murmur at lower left sternal border with RV heave.
Presentation and course depend on size of defect and the pulmonary vascular resistance.
Clinical features are failure to thrive, tachypnea, and diaphoresis with feeds.
Left-to-right shunt with normal pulmonary vascular resistance.
Large defects may cause Eisenmenger syndrome if not repaired early.
Ventricular septal defect (VSD) is the most common congenital heart malformation, accounting for about 30% of all congenital heart disease. Defects in the ventricular septum occur both in the membranous portion of the septum (most common) and the muscular portion. VSDs follow one of four courses:
A. Small, Hemodynamically Insignificant Ventricular Septal Defects
Between 80% and 85% of VSDs are small (< 3 mm in diameter) at birth and will close spontaneously. In general, small defects in the muscular interventricular septum will close sooner than those in the membranous septum. In most cases, a small VSD never requires surgical closure. Fifty percent of small VSDs will close by age 2 years, and 90% by age 6 years, with most of the remaining closing during the school years.
B. Moderate-Sized Ventricular Septal Defects
Asymptomatic patients with moderate-sized VSDs (3–5 mm in diameter) account for 3%–5% of children with VSDs. In general, these children do not have clear indicators for surgical closure. Historically, in those who had cardiac catheterization, the ratio of pulmonary to systemic blood flow is usually less than 2:1, and serial cardiac catheterizations demonstrate that the shunts get progressively smaller. If the patient is asymptomatic and without evidence of pulmonary hypertension, these defects can be followed serially as some close spontaneously over time.
C. Large Ventricular Septal Defects with Normal Pulmonary Vascular Resistance
These defects are usually 6–10 mm in diameter. Unless they become markedly smaller within a few months after birth, they often require surgery. The timing of surgery depends on the clinical situation. Many infants with large VSDs and normal pulmonary vascular resistance develop symptoms of failure to thrive, tachypnea, diaphoresis with feeds by age 3–6 months, and require correction at that time. Surgery before age 2 years in patients with large VSDs essentially eliminates the risk of pulmonary vascular disease.
D. Large Ventricular Septal Defects with Pulmonary Vascular Obstructive Disease
The direction of flow across a VSD is determined by the resistance in the systemic and pulmonary vasculature, explaining why flow is usually left-to-right. In large VSDs, ventricular pressures are equalized, resulting in increased pulmonary artery pressure. In addition, shear stress caused by increased volume in the pulmonary circuit causes increased resistance over time. The vast majority of patients with inoperable pulmonary hypertension develop the condition progressively. The combined data of the multicenter National History Study indicate that almost all cases of irreversible pulmonary hypertension can be prevented by surgical repair of a large VSD before age 2 years.
A. Symptoms and Signs
Patients with small or moderate left-to-right shunts usually have no cardiovascular symptoms. Patients with large left-to-right shunts are usually ill early in infancy. These infants have frequent respiratory infections and gain weight slowly. Dyspnea, diaphoresis, and fatigue are common. These symptoms can develop as early as 1–6 months of age. Older children may experience exercise intolerance. Over time, in children and adolescents with persistent large left-to-right shunt, the pulmonary vascular bed undergoes structural changes, leading to increased pulmonary vascular resistance and reversal of the shunt from left-to-right to right-to-left (Eisenmenger syndrome). Cyanosis will then be present.
1. Small left-to-right shunt—No lifts, heaves, or thrills are present. The first sound at the apex is normal, and the second sound at the pulmonary area is split physiologically. A grade II–IV/VI, medium- to high-pitched, harsh pansystolic murmur is heard best at the left sternal border in the third and fourth intercostal spaces. The murmur radiates over the entire precordium. No diastolic murmurs are heard.
2. Moderate left-to-right shunt—Slight prominence of the precordium with moderate LV heave is evident. A systolic thrill may be palpable at the lower left sternal border between the third and fourth intercostal spaces. The second sound at the pulmonary area is most often split but may be single. A grade III–IV/VI, harsh pansystolic murmur is heard best at the lower left sternal border in the fourth intercostal space. A mitral diastolic flow murmur indicates that pulmonary blood flow and subsequently the pulmonary venous return are significantly increased by the large shunt.
3. Large ventricular septal defects with pulmonary hypertension—The precordium is prominent, and the sternum bulges. Both LV and RV heaves are palpable. S2 is palpable in the pulmonary area. A thrill may be present at the lower left sternal border. S2 is usually single or narrowly split, with accentuation of the pulmonary component. The murmur ranges from grade I to IV/VI and is usually harsh and pansystolic. Occasionally, when the defect is large or ventricular pressures approach equivalency, a murmur is difficult to hear. A diastolic flow murmur may be heard, depending on the size of the shunt.
In patients with small shunts, the chest radiograph may be normal. Patients with large shunts have significant cardiac enlargement involving both the left and right ventricles and the left atrium. The main pulmonary artery segment may be dilated. The pulmonary vascular markings are increased.
The ECG is normal in small left-to-right shunts. Left ventricular hypertrophy (LVH) usually occurs in patients with large left-to-right shunts and normal pulmonary vascular resistance. Combined ventricular enlargement occurs in patients with pulmonary hypertension caused by increased flow, increased resistance, or both. Pure RV hypertrophy occurs in patients with pulmonary hypertension secondary to pulmonary vascular obstruction induced by long-standing left-to-right shunt (Eisenmenger syndrome).
Two-dimensional echocardiography can reveal the size of a VSD and identify its anatomic location. Multiple defects can be detected by combining two-dimensional and color-flow imaging. Doppler can further evaluate the VSD by estimating the pressure difference between the left and right ventricles. A pressure difference greater than 50 mm Hg in the left ventricle compared to the right ventricle confirms the absence of severe pulmonary hypertension.
E. Cardiac Catheterization and Angiocardiography
The ability to describe the VSD anatomy and estimate the pulmonary artery pressures on the basis of the gradient across the VSD allows for the vast majority of isolated defects to be repaired without cardiac catheterization and angiocardiography. Catheterization is indicated in those patients with increased pulmonary vascular resistance. Angiocardiographic examination defines the number, size, and location of the defects.
A. Medical Management
Patients who develop symptoms can be managed with anticongestive treatment (see section on Heart Failure, earlier), particularly diuretics and systemic afterload reduction, prior to surgery or if it is expected that the defect will close over time.
B. Surgical Treatment
Patients with cardiomegaly, poor growth, poor exercise tolerance, or other clinical abnormalities who have a significant shunt (> 2:1) typically undergo surgical repair at age 3–6 months. A synthetic or pericardial patch is used for primary closure. In most centers, these children have surgery before age 1 year. As a result, Eisenmenger syndrome has been virtually eliminated. The surgical mortality rate for VSD closure is below 2%.
Transcatheter closure of muscular VSDs is also a possibility. Perimembranous VSDs have also been closed in children during catheterization, but a high incidence of complete heart block after placement of the occluding device has slowed the acceptance of this approach.
Course & Prognosis
Significant late dysrhythmias are uncommon. Functional exercise capacity and oxygen consumption are usually normal, and physical restrictions are unnecessary. Adults with corrected defects have normal quality of life.
Butera G et al: Transcatheter closure of perimembranous ventricular septal defects: early and long-term results. J Am Coll Cardiol 2007;50:1189–1195 [PMID: 17868812].
Sondheimer HM, Rahimi-Alangi K: Current management of ventricular septal defect. Cardiol Young 2006;16(Suppl 3):131–135 [PMID: 17378052].
3. Atrioventricular Septal Defect
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Murmur often inaudible in neonates.
Loud pulmonary component of S2.
Common in infants with Down syndrome.
ECG with extreme left axis deviation.
Atrioventricular septal defect (AVSD) results from incomplete fusion of the embryonic endocardial cushions. The endocardial cushions help to form the “crux” of the heart, which includes the lower portion of the atrial septum, the membranous portion of the ventricular septum, and the septal leaflets of the tricuspid and mitral valves. AVSD accounts for about 4% of all congenital heart disease. Sixty percent of children with Down syndrome have congenital heart disease, and of these, 35%–40% have an AVSD.
AVSDs are defined as partial or complete. The physiology of the defect is determined by the location of the AV valves. If the valves are located in the midportion of the defect (complete AVSD), both atrial and ventricular components of the septal defect are present and the left- and right-sided AV valves share a common ring or orifice. In the partial form, there is a low insertion of the AV valves, resulting in a primum ASD without a ventricular defect component. In partial AVSD, there are two separate AV valve orifices and usually a cleft in the left-sided valve.
Partial AVSD behaves like an isolated ASD with variable amounts of regurgitation through the cleft in the left AV valve. The complete form causes large left-to-right shunts at both the ventricular and atrial levels with variable degrees of AV valve regurgitation. If there is increased pulmonary vascular resistance, the shunts may be bidirectional. Bidirectional shunting is more common in Down syndrome or in older children who have not undergone repair.
A. Symptoms and Signs
The partial form may produce symptoms similar to ostium secundum ASD. Patients with complete AVSD usually have symptoms such as failure to thrive, tachypnea, diaphoresis with feeding, or recurrent bouts of pneumonia.
In the neonate with the complete form, the murmur may be inaudible due to relatively equal systemic and pulmonary vascular resistance (PVR). After 4–6 weeks, as PVR drops, a nonspecific systolic murmur develops. The murmur is usually not as harsh as that of an isolated VSD. There is both right- and left-sided cardiac enlargement. S2 is loud, and a pronounced diastolic flow murmur may be heard at the apex and the lower left sternal border.
If severe pulmonary vascular obstructive disease is present, there is usually dominant RV enlargement. S2 is palpable at the pulmonary area and no thrill is felt. A nonspecific short systolic murmur is heard at the lower left sternal border. No diastolic flow murmurs are heard. If a right-to-left shunt is present, cyanosis will be evident.
Cardiac enlargement is always present in the complete form and pulmonary vascular markings are increased. Often, only the right heart size may be increased in the partial form, although a severe mitral valve cleft can rarely lead to left heart enlargement as well.
In all forms of AVSD, there is extreme left axis deviation with a counterclockwise loop in the frontal plane. The ECG is an important diagnostic tool. Only 5% of isolated VSDs have this ECG abnormality. First-degree heart block occurs in over 50% of patients. Right, left, or combined ventricular hypertrophy is present depending on the particular defect and the presence or absence of pulmonary hypertension.
Echocardiography is the diagnostic test of choice. The anatomy can be well visualized by two-dimensional echocardiography. Both AV valves are at the same level, compared with the normal heart in which the tricuspid valve is more apically positioned. The size of the atrial and ventricular components of the defect can be measured. AV valve regurgitation can be detected. The LV outflow tract is elongated (gooseneck appearance), which produces systemic outflow obstruction in some patients.
E. Cardiac Catheterization and Angiocardiography
Cardiac catheterization is not routinely used to evaluate AVSD but may be used to assess pulmonary artery pressures and resistance in the older infant with Down syndrome, as this patient group is predisposed to early-onset pulmonary hypertension. Increased oxygen saturation in the RV or the right atrium identifies the level of the shunt. Angiocardiography reveals the characteristic gooseneck deformity of the LV outflow tract in the complete form.
Spontaneous closure of this type of defect does not occur and therefore surgery is required. In the partial form, surgery carries a low mortality rate (1%–2%), but patients require follow-up because of late-occurring LV outflow tract obstruction and mitral valve dysfunction. The complete form carries a higher mortality rate. Complete correction in the first year of life, prior to the onset of irreversible pulmonary hypertension, is obligatory.
Craig B: Atrioventricular septal defect: from fetus to adult. Heart 2006;92:1879–1885 [PMID: 17105897].
Kobayashi M, Takahashi Y, Ando M: Ideal timing of surgical repair of isolated complete atrioventricular septal defect. Interact Cardiovasc Thorac Surg 2007;6:24–26 [PMID: 17669760].
PATENT (PERSISTENT) DUCTUS ARTERIOSUS
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Continuous machinery type murmur.
Bounding peripheral pulses if large ductus present.
Presentation and course depends on size of the ductus and the pulmonary vascular resistance.
Clinical features of a large ductus are failure to thrive, tachypnea, and diaphoresis with feeds.
Left-to-right shunt with normal pulmonary vascular resistance.
PDA is the persistence of the normal fetal vessel joining the pulmonary artery to the aorta. It closes spontaneously in normal-term infants at 1–5 days of age. PDA accounts for 10% of all congenital heart disease. The incidence of PDA is higher in infants born at altitudes over 10,000 ft. It is twice as common in females as in males. The frequency of PDA in preterm infants weighing less than 1500 g ranges from 20% to 60%. The defect may occur as an isolated abnormality or with associated lesions, commonly coarctation of the aorta and VSD. Patency of the ductus arteriosus may be necessary in some patients with complex forms of congenital heart disease (eg, hypoplastic left heart syndrome [HLHS], pulmonary atresia). Prostaglandin E2 (PGE2) is a product of arachidonic acid metabolism and continuous intravenous infusion maintains ductal patency.
A. Symptoms and Signs
The clinical findings and course depend on the size of the shunt and the degree of pulmonary hypertension.
1. Moderate to large patent ductus arteriosus—Pulses are bounding, and pulse pressure is widened due to diastolic runoff through the ductus. S1 is normal and S2 is usually narrowly split. In large shunts, S2 may have a paradoxical split (eg, S2 narrows on inspiration and widens on expiration). Paradoxical splitting is caused by volume overload of the LV and prolonged ejection of blood from this chamber.
The murmur is characteristic. It is a rough machinery murmur maximal at the second left intercostal space. It begins shortly after S1, rises to a peak at S2, and passes through the S2 into diastole, where it becomes a decrescendo murmur and fades before the S1. The murmur tends to radiate well to the anterior lung fields but relatively poorly to the posterior lung fields. A diastolic flow murmur is often heard at the apex.
2. Patent ductus arteriosus with increased pulmonary vascular resistance—Flow across the ductus is diminished. S2 is single and accentuated, and no significant heart murmur is present. The pulses are normal rather than bounding.
In an isolated PDA, the appearance of the chest radiograph depends on the size of the shunt. If the shunt is small, the heart is not enlarged. If the shunt is large, both left atrial and LV enlargement may be seen. The aorta and the main pulmonary artery segment may also be prominent.
The ECG may be normal or may show LVH, depending on the size of the shunt. In patients with pulmonary hypertension caused by increased blood flow, biventricular hypertrophy usually occurs. In pulmonary vascular obstructive disease, pure right ventricular hypertrophy (RVH) occurs.
Echocardiography provides direct visualization of the ductus and confirms the direction and degree of shunting. High-velocity left-to-right flow argues against abnormally elevated pulmonary vascular resistance, and as pulmonary vascular resistance drops during the neonatal period, higher velocity left-to-right shunting is usually seen. If suprasystemic pulmonary vascular resistance is present, flow across the ductus will be seen from right to left. Associated cardiac lesions and ductal-dependent pulmonary or systemic blood flow must be recognized by echocardiography, as closure of a PDA in this setting would be contraindicated.
E. Cardiac Catheterization and Angiocardiography
PDA closure in the catheterization laboratory with a vascular plug or coils is now routine in all but the smallest of neonates and infants.
Surgical closure is indicated when the PDA is large and the patient is small. Caution must be given to closing a PDA in patients with pulmonary vascular obstructive disease and right-to-left shunting across the ductus as this could result in RV failure. Patients with large left-to-right shunts require repair by age 1 year to prevent the development of progressive pulmonary vascular obstructive disease. Symptomatic PDA with normal pulmonary artery pressure can be safely coil or device-occluded in the catheterization laboratory, ideally after the child has reached 5 kg.
Patients with nonreactive pulmonary vascular obstruction, pulmonary vascular resistance greater than 10 Wood units (normal, < 3), and a ratio of pulmonary to systemic resistance greater than 0.7 (normal, < 0.3) despite vasodilator therapy (eg, nitric oxide) should not undergo PDA closure. These patients are made worse by PDA closure because the flow through the ductus allows preserved RV function and maintains cardiac output to the systemic circulation. These patients can be managed with pulmonary vasodilator therapy, but eventually may require heart-lung transplant in severe cases.
Presence of a symptomatic PDA is common in preterm infants. Indomethacin, a prostaglandin synthesis inhibitor, is often used to close the PDA in premature infants. Indomethacin does not close the PDA of full-term infants or children. The success of indomethacin therapy is as high as 80%–90% in premature infants with a birth weight greater than 1200 g, but it is less successful in smaller infants. Indomethacin (0.1–0.3 mg/kg orally every 8–24 hours or 0.1–0.3 mg/kg parenterally every 12 hours) can be used if there is adequate renal, hematologic, and hepatic function. Because indomethacin may impair renal function, urine output, BUN, and creatinine should be monitored during therapy. If indomethacin is not effective and the ductus remains hemodynamically significant, surgical ligation should be performed. If the ductus partially closes so that the shunt is no longer hemodynamically significant, a second course of indomethacin may be tried.
Course & Prognosis
Patients with an isolated PDA and small-to-moderate shunts usually do well without surgery. However, in the third or fourth decade of life, symptoms of easy fatigability, dyspnea on exertion, and exercise intolerance appear in those patients who develop pulmonary hypertension and/or HF. Percutaneous closure can be done later in life if there has not been development of severe pulmonary vascular disease. For those with severe and irreversible pulmonary hypertension prognosis is not good and heart-lung transplant may be needed.
Spontaneous closure of a PDA may occur up to age 1 year, especially in preterm infants. After age 1 year, spontaneous closure is rare. Because endocarditis is a potential complication, some cardiologists recommend closure if the defect persists beyond age 1 year, even if it is small. Most of these patients undergo percutaneous occlusion as opposed to surgical ligation.
Cherif A, Jabnoun S, Khrouf N: Oral ibuprofen in early curative closure of patent ductus arteriosus in very premature infants. Am J Perinatol 2007;24:339–345 [PMID: 17564958].
Takata H, Higaki T, Sugiyama H et al: Long-term outcome of coil occlusion in patients with patent ductus arteriosus. Circ J 2011 Feb;75(2):407–412 [PMID: 21173496].
RIGHT-SIDED OBSTRUCTIVE LESIONS
1. Pulmonary Valve Stenosis
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
No symptoms in mild or moderate stenosis.
Cyanosis and a high incidence of right-sided HF in ductal-dependent lesions.
RV lift with systolic ejection click heard at the third left intercostal space.
S2 widely split with soft to inaudible P2; grade I–VI/VI systolic ejection murmur, maximal at the pulmonary area.
Dilated pulmonary artery on chest radiograph.
Pulmonic valve stenosis accounts for 10% of all congenital heart disease. The pulmonary valve annulus is usually small with moderate to marked poststenotic dilation of the main pulmonary artery. Obstruction to blood flow across the pulmonary valve causes an increase in RV pressure. Pressures greater than systemic are potentially life-threatening and are associated with critical obstruction. Because of the increased RV strain, severe right ventricular hypertrophy (RVH) and eventual RV failure can occur.
When obstruction is severe and the ventricular septum is intact, a right-to-left shunt will often occur at the atrial level through a patent foramen ovale (PFO). In neonates with severe obstruction and minimal antegrade pulmonary blood flow (critical PS), left-to-right flow through the ductus is essential, making prostaglandin a necessary intervention at the time of birth. These infants are cyanotic at presentation.
A. Symptoms and Signs
Patients with mild or even moderate valvular pulmonary stenosis are acyanotic and asymptomatic. Patients with severe valvular obstruction may develop cyanosis early. Patients with mild to moderate obstruction are usually well developed and well nourished. They are not prone to pulmonary infections. The pulses are normal. The precordium may be prominent, often with palpable RV heave. A systolic thrill is often present in the pulmonary area. In patients with mild to moderate stenosis, a prominent ejection click of pulmonary origin is heard at the third left intercostal space. The click varies with respiration, being more prominent during expiration than inspiration. In severe stenosis, the click tends to merge with S1. S2 varies with the degree of stenosis. In mild pulmonic stenosis, S2 is normal. In moderate pulmonic stenosis, S2 is more widely split and the pulmonary component is softer. In severe pulmonary stenosis, S2 is single because the pulmonary component cannot be heard. A rough systolic ejection murmur is best heard at the second left interspace. It radiates well to the back. With severe pulmonary valve obstruction, the murmur is usually short. No diastolic murmurs are audible.
The heart size is normal. Poststenotic dilation of the main pulmonary artery and the left pulmonary artery often occurs.
The ECG is usually normal with mild obstruction. In severe obstruction, RV hypertrophy with an RV strain pattern (deep inversion of the T wave) occurs in the right precordial leads (V3R, V1, V2). Right atrial enlargement may be present. Right axis deviation occurs in moderate to severe stenosis.
The diagnosis often is made by physical examination, but the echocardiogram confirms the diagnosis, defines the anatomy, and can identify any associated lesions. The pulmonary valve has thickened leaflets with reduced valve leaflet excursion. The transvalvular pressure gradient can be estimated accurately by Doppler, which provides an estimate of RV pressure and can assist in determining the appropriate time to intervene.
E. Cardiac Catheterization and Angiocardiography
Catheterization is reserved for therapeutic balloon valvuloplasty. In severe cases with associated RV dysfunction, a right-to-left shunt at the atrial level is indicated by a lower left atrial saturation than pulmonary vein saturation. Pulmonary artery pressure is normal. The gradient across the pulmonary valve varies from 10 to 200 mm Hg. In severe cases, the right atrial pressure is elevated, with a predominant “a” wave. Angiocardiography in the RV shows a thick pulmonary valve with a narrow opening producing a jet of contrast into the pulmonary artery. Infundibular (RV outflow tract) hypertrophy may be present and may contribute to obstruction to pulmonary blood flow.
Treatment of pulmonic stenosis is recommended for children with RV systolic pressure greater than two-thirds of systemic pressure. Immediate correction is indicated for patients with systemic or suprasystemic RV pressure. Percutaneous balloon valvuloplasty is the procedure of choice. It is as effective as surgery in relieving obstruction and causes less valve insufficiency. Surgery is needed to treat pulmonic valve stenosis when balloon pulmonic valvuloplasty is unsuccessful.
Course & Prognosis
Patients with mild pulmonary stenosis live normal lives. Even those with moderate stenosis are rarely symptomatic. Those with severe valvular obstruction may develop cyanosis in infancy as described above.
After balloon pulmonary valvuloplasty or surgery, most patients have good maximum exercise capacity unless they have significant pulmonary insufficiency (PI). Limitation of physical activity is unwarranted. The quality of life of adults with successfully treated pulmonary stenosis and minimal PI is normal. Patients with PI, a frequent side effect of intervention, may be significantly limited in exercise performance. Severe PI leads to progressive RV dilation and dysfunction, which may precipitate ventricular arrhythmias or right heart failure in adulthood. Patients with severe PI may benefit from replacement of the pulmonic valve.
Drossner DM, Mahle WT: A management strategy for mild valvar pulmonary stenosis. Pediatr Cardiol 2008;29:649–652 [PMID: 18193316].
Harrild DM, Powell AJ, Tran TX et al: Long-term pulmonary regurgitation following balloon valvuloplasty for pulmonary stenosis risk factors and relationship to exercise capacity and ventricular volume and function. J Am Coll Cardiol 2010 Mar 9;55(10):1041–1047 [PMID: 20202522].
2. Subvalvular Pulmonary Stenosis
Isolated infundibular (subvalvular) pulmonary stenosis is rare. More commonly it is found in combination with other lesions, such as in tetralogy of Fallot. Infundibular hypertrophy that is associated with a small perimembranous VSD may lead to a “double-chambered RV” characterized by obstruction between the inflow and outflow portion of the RV. One should suspect such an abnormality if there is a prominent precordial thrill, no audible pulmonary ejection click, and a murmur maximal in the third and fourth inter-costal spaces rather than in the second intercostal space. The clinical picture is otherwise identical to that of pulmonic valve stenosis. Intervention, if indicated, is always surgical because this condition does not improve with balloon catheter dilation.
3. Supravalvular Pulmonary Stenosis
Supravalvular pulmonary stenosis is a relatively rare condition defined by narrowing of the main pulmonary artery. The clinical picture may be identical to valvular pulmonary stenosis, although the murmur is maximal in the first inter-costal space at the left sternal border and in the suprasternal notch. No ejection click is audible, as the valve itself is not involved. The murmur radiates toward the neck and over the lung fields. Children with William syndrome can have supravalvular and peripheral pulmonary stenosis as well as supravalvular aortic stenosis.
4. Peripheral (Branch) Pulmonary Artery Stenosis
In peripheral pulmonary stenosis, there are multiple narrowings of the branches of the pulmonary arteries, sometimes extending into the vessels in the periphery of the lungs. Systolic murmurs may be heard over both lung fields, anteriorly and posteriorly, radiating to the axilla. Mild, nonpathologic pulmonary branch stenosis produces a murmur in infancy that resolves by 6 months of age. William syndrome, Alagille syndrome, and congenital rubella are commonly associated with severe forms of peripheral pulmonary artery stenosis. Surgery is often unsuccessful, as areas of stenoses near and beyond the hilum of the lungs are not accessible to the surgeons. Transcatheter balloon angioplasty and even stent placement are used to treat this condition, with moderate success. In some instances, the stenoses improve spontaneously with age.
5. Ebstein Malformation of the Tricuspid Valve
In Ebstein malformation of the tricuspid valve, the septal leaflet of the tricuspid valve is displaced toward the apex of the heart and is attached to the endocardium of the RV rather than at the tricuspid annulus. As a result, a large portion of the RV functions physiologically as part of the right atrium. This “atrialized” portion of the RV is thin-walled and does not contribute to RV output. The portion of the ventricle below the displaced tricuspid valve is diminished in volume and represents the functioning RV.
A. Symptoms and Signs
The clinical picture of Ebstein malformation varies with the degree of displacement of the tricuspid valve. In the most extreme form, the septal leaflet is markedly displaced into the RV outflow tract, causing obstruction of antegrade flow into the pulmonary artery and there is very little functioning RV as the majority of the ventricle is “atrialized.” The degree of tricuspid insufficiency may be so severe that forward (antegrade) flow out the RV outflow tract is further diminished leading to a right-to-left atrial level shunt and cyanosis. At the opposite extreme when antegrade pulmonary blood flow is adequate, symptoms may not develop until adulthood when tachyarrhythmias associated with right atrial dilation or reentrant electrical pathways occur. These older patients typically have less displacement of the septal leaflet of the tricuspid valve and therefore more functional RV tissue.
The chest radiograph shows cardiomegaly with prominence of the right heart border. The extent of cardiomegaly depends on the degree of tricuspid valve insufficiency and the presence and size of the atrial level shunt. Massive cardiomegaly with a “wall-to-wall heart” (the heart shadow extends across the entire chest cavity from right-to-left) occurs with severe tricuspid valve displacement and/or a restrictive atrial level defect.
ECG may be normal but usually shows right atrial enlargement and right bundle-branch block (RBBB). There is an association between Ebstein anomaly and Wolff-Parkinson-White (WPW) syndrome, in which case a delta wave is present (short PR with a slurred upstroke of the QRS).
Echocardiography is necessary to confirm the diagnosis and may aid in predicting outcome. Degree of tricuspid valve displacement, size of the right atrium, and presence of associated atrial level shunt all affect outcome.
Course & Prognosis
In cyanotic neonates, PGE2 is used to maintain pulmonary blood flow via the ductus arteriosus until pulmonary vascular resistance decreases, facilitating antegrade pulmonary artery flow. If the neonate remains significantly cyanotic, surgical intervention is required.
The type of surgical repair varies and depends on the severity of the disease. For example, in order to decrease the amount of tricuspid regurgitation surgery may involve atrial plication and tricuspid valve repair. The success of the procedure is highly variable. Late arrhythmias are common due to the preexisting atrial dilation. If a significant Ebstein malformation is not treated, atrial tachyarrhythmias frequently begin during adolescence and the enlarged atrialized RV could impede LV function. Postoperative exercise tolerance improves but remains lower than age-related norms.
6. Other Rare Right-Sided Malformations
A. Absence of a Pulmonary Artery
Absence of a pulmonary artery (left or right) may be an isolated malformation or may occur in association with other congenital heart lesions. It occurs occasionally in patients with tetralogy of Fallot.
B. Absence of the Pulmonary Valve
Absence of the pulmonary valve is rare and usually associated with a VSD. In about 50% of cases, infundibular pulmonary stenosis is also present (ToF with absent pulmonary valve).
Alsoufi B et al: Surgical outcomes in the treatment of patients with tetralogy of Fallot and absent pulmonary valve. Eur J Cardiothorac Surg 2007;31:354–359; discussion 359 [PMID: 17215132].
Knott-Craig CJ et al: Repair of neonates and young infants with Ebstein’s anomaly and related disorders. Ann Thorac Surg 2007;84:587–592; discussion 592–593 [PMID: 17643640].
1. Coarctation of the Aorta
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Absent or diminished femoral pulses.
Upper to lower extremity systolic blood pressure gradient of > 20 mm Hg.
Blowing systolic murmur in the back or left axilla.
Coarctation of the aorta is a narrowing in the aortic arch that usually occurs in the proximal descending aorta near the takeoff of the left subclavian artery near the ductus arteriosus. The abdominal aorta is rarely involved. Coarctation accounts for about 6% of all congenital heart disease. Three times as many males as females are affected. Many affected females have Turner syndrome (45, XO). The incidence of associated bicuspid aortic valve with coarctation is 80%–85%.
A. Symptoms and Signs
The cardinal physical finding is decreased or absent femoral pulses. Infants with severe coarctation have equal upper and lower extremity pulses from birth until the ductus arteriosus closes (ductal patency ensures flow to the descending aorta distal to the level of obstruction). Approximately 40% of children with coarctation will present as young infants. Coarctation alone, or in combination with VSD, ASD, or other congenital cardiac anomalies, is the leading cause of HF in the first month of life.
Coarctation presents insidiously in the 60% of children with no symptoms in infancy. Coarctation is usually diagnosed by a pulse and blood pressure (> 15 mm Hg) discrepancy between the arms and legs on physical examination. The pulses in the legs are diminished or absent. The left subclavian artery is occasionally involved in the coarctation, in which case the left brachial pulse is also weak. The pathognomonic murmur of coarctation is heard in the left axilla and the left back. The murmur is usually systolic but may spill into diastole, as forward flow continues across the narrow coarctation site throughout the cardiac cycle. A systolic ejection murmur is often heard at the aortic area and the lower left sternal border along with an apical ejection click if there is an associated bicuspid aortic valve.
In the older child, radiographs may show a normal-sized heart, or more often some degree of LV enlargement. The aorta proximal to the coarctation is prominent. The aortic outline may indent at the level of the coarctation. The poststenotic segment is often dilated. This combination of abnormalities results in the “figure 3” sign on chest radiograph. Notching of the ribs caused by marked enlargement of the intercostal collaterals can be seen. In patients with severe coarctation and associated HF, marked cardiac enlargement and pulmonary venous congestion occur.
ECGs in older children may be normal or may show LVH. ECG usually shows RVH in infants with severe coarctation because the RV serves as the systemic ventricle during fetal life.
Two-dimensional echocardiography and color-flow Doppler are used to visualize the coarctation directly, and continuous-wave Doppler estimates the degree of obstruction. Diastolic runoff flow is detected by continuous-wave Doppler if the obstruction is significant. In neonates with a PDA, a coarctation cannot be ruled out, as stenosis of the arch may evolve as the PDA closes. Identification of lesions such as a bicuspid aortic valve or mitral abnormalities may suggest the presence of a coarctation. In the face of poor LV systolic function, the gradient across the coarctation will be low, as the failing LV is unable to generate very much pressure proximal to the narrowing.
E. Cardiac Catheterization and Angiocardiography
Cardiac catheterization and angiocardiography are rarely performed for diagnosis in infants or children with coarctation, but are used if transcatheter intervention is planned.
Infants with coarctation of the aorta and HF may present in extremis secondary to LV dysfunction and low cardiac output. Resuscitative measures include PGE2 infusion (0.05–0.1 mcg/kg/min) to reopen the ductus arteriosus. End-organ damage distal to the coarctation is not uncommon, and inotropic support is frequently needed. Once stabilized, the infant should undergo corrective repair. In patients with poor LV function, balloon angioplasty of the coarctation is sometimes performed as a palliative measure. Recent data suggest that balloon angioplasty of the aorta can be the definitive procedure in many patients with good LV function. Surgery also has a high success rate. The main complication of both surgery and balloon angioplasty is recurrent coarctation. Fortunately, this complication is treatable in the catheterization laboratory. In older patients, particularly those of adult size, transcatheter stent placement is effective for recurrent coarctation.
Course & Prognosis
Children who survive the neonatal period without developing HF do well through childhood and adolescence. Fatal complications (eg, hypertensive encephalopathy or intracranial bleeding) are uncommon in childhood. Infective endarteritis is rare before adolescence, but can occur in both repaired and unrepaired coarctation. Children with coarctation corrected after age 5 years are at increased risk for systemic hypertension and myocardial dysfunction even with successful surgery. Exercise testing is mandatory for these children prior to their participation in athletic activities.
Golden AB, Hellenbrand WE: Coarctation of the aorta: stenting in children and adults. Catheter Cardiovasc Interv 2007;69:289–299 [PMID: 17191237].
Rodes-Cabau J et al: Comparison of surgical and transcatheter treatment for native coarctation of the aorta in patients > or = 1 year old. The Quebec Native Coarctation of the Aorta study. Am Heart J 2007;154:186–192 [PMID: 17584575].
2. Aortic Stenosis
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Harsh systolic ejection murmur at the upper right sternal border with radiation to the neck.
Thrill in the carotid arteries.
Systolic click at the apex.
Dilation of the ascending aorta on chest radiograph.
Aortic stenosis is defined as obstruction to outflow from the LV at or near the aortic valve producing a systolic pressure gradient of more than 10 mm Hg between the LV and the aorta. Aortic stenosis accounts for approximately 7% of congenital heart disease. There are three anatomic types of congenital aortic stenosis.
A. Valvular Aortic Stenosis (75%)
In critical aortic stenosis presenting in infancy, the aortic valve is usually a unicuspid diaphragm-like structure without well-defined commissures. A bicuspid aortic valve or a trileaflet valve with partially fused leaflets is another anatomic possibility that can be associated with aortic stenosis. Aortic stenosis is more common in males than in females.
B. Subvalvular Aortic Stenosis (23%)
In this type, a membranous or fibrous ring occurs just below the aortic valve that causes obstruction to LV outflow. The aortic valve itself and the anterior leaflet of the mitral valve are often malformed.
C. Supravalvular Aortic Stenosis (2%)
In this type, constriction of the ascending aorta occurs just above the coronary arteries. The condition is often familial, and two different genetic patterns are found, one with abnormal facies and mental retardation (William syndrome) and one with normal facies and no developmental delay.
A. Symptoms and Signs
Although isolated valvular aortic stenosis seldom causes symptoms in infancy, severe HF occasionally occurs when critical obstruction is present at birth. Response to medical therapy is poor; therefore, an aggressive approach using interventional catheterization or surgery is required. The physical findings vary depending on the anatomic type of lesion:
1. Valvular aortic stenosis—If the stenosis is severe with a gradient greater than 80 mm Hg, pulses are diminished with a slow upstroke; otherwise, pulses are usually normal. Cardiac examination reveals an LV thrust at the apex. A systolic thrill at the right base, the suprasternal notch, and over both carotid arteries may accompany moderate disease.
A prominent aortic ejection click is best heard at the apex. The click corresponds to the opening of the aortic valve. It is separated from S1 by a short but appreciable interval. It does not vary with respiration. S2 at the pulmonary area is normal. A loud, rough, medium- to high-pitched ejection-type systolic murmur is evident. It is loudest at the first and second intercostal spaces, radiating well into the suprasternal notch and along the carotids. The grade of the murmur correlates well with the severity of the stenosis.
2. Discrete membranous subvalvular aortic stenosis—The findings are the same as those of valvular aortic stenosis except for the absence of a click. The murmur and thrill are usually somewhat more intense at the left sternal border in the third and fourth intercostal spaces. In the setting of aortic insufficiency, a diastolic murmur is commonly heard.
3. Supravalvular aortic stenosis—The thrill and murmur are best heard in the suprasternal notch and along the carotids but are well transmitted over the aortic area and near the mid left sternal border. There may be a difference in pulses and blood pressure between the right and left arms if the narrowing is just distal to the takeoff of the innominate artery, with more prominent pulse and pressure in the right arm (the Coanda effect).
Of those not presenting in infancy, most patients with aortic stenosis have no cardiovascular symptoms. Except in the most severe cases, patients do well until the third to fifth decades of life. Some patients have mild exercise intolerance and fatigability. In a small percentage of patients, significant symptoms (eg, chest pain with exercise, dizziness, and syncope) manifest in the first decade. Sudden death is uncommon but may occur in all forms of aortic stenosis with the greatest risk in patients with subvalvular obstruction.
In most cases the heart is not enlarged. The LV, however, may be slightly prominent. In valvular aortic stenosis, dilation of the ascending aorta is frequently seen.
Patients with mild aortic stenosis have normal ECGs. Some patients with severe obstruction have LVH and LV strain but even in severe cases, 25% of ECGs are normal. Progressive LVH on serial ECGs indicates a significant obstruction. LV strain is one indication for surgery.
This is a reliable noninvasive technique for the evaluation of all forms of aortic stenosis. Doppler accurately estimates the transvalvular gradient, and the level of obstruction can be confirmed by both two-dimensional echocardiographic images and by the level of flow disturbance revealed by color Doppler.
E. Cardiac Catheterization and Angiocardiography
Left heart catheterization demonstrates the pressure differential between the LV and the aorta and the anatomic level at which the gradient exists. Catheterization is reserved for patients whose resting gradient has reached 60–80 mm Hg and in whom intervention is planned. For those with valvular aortic stenosis, balloon valvuloplasty is usually the first option. In subvalvular or supravalvular aortic stenosis, interventional catheterization is not effective and surgery is required.
Percutaneous balloon valvuloplasty is now standard initial treatment for patients with valvular aortic stenosis. Surgery should be considered in symptomatic patients with a high resting gradient (60–80 mm Hg) despite balloon angioplasty, or coexisting aortic insufficiency. In many cases, the gradient cannot be significantly diminished by valvuloplasty without producing aortic insufficiency. Patients who develop significant aortic insufficiency require surgical intervention to repair or replace the valve. The Ross procedure is an alternative to mechanical valve placement in infants and children. In this procedure, the patient’s own pulmonic valve is moved to the aortic position, and an RV-to-pulmonary artery conduit is used to replace the pulmonic valve. Discrete subvalvular aortic stenosis is usually surgically repaired at a lesser gradient because continued trauma to the aortic valve by the subvalvular jet may damage the valve and produce aortic insufficiency. Unfortunately, simple resection is followed by recurrence in more than 25% of patients with subvalvular aortic stenosis. Supravalvar aortic stenosis may also require surgical repair and is commonly associated with William syndrome.
Course & Prognosis
All forms of LV outflow tract obstruction tend to be progressive. Pediatric patients with LV outflow tract obstruction—with the exception of those with critical aortic stenosis of infancy—are usually asymptomatic. Symptoms accompanying severe unoperated obstruction (angina, syncope, or HF) are rare but imply serious disease. Children whose obstruction is mild to moderate have normal oxygen consumption and maximum voluntary working capacity. Children in this category with normal resting and exercising (stress) ECGs may safely participate in vigorous physical activity, including nonisometric competitive sports. Children with severe aortic stenosis are predisposed to ventricular dysrhythmias and should refrain from vigorous activity and avoid all isometric exercise.
Mavroudis C, Backer CL, Kaushal S: Aortic stenosis and aortic insufficiency in children: impact of valvuloplasty and modified Ross-Konno procedure. Semin Thorac Cardiovasc Surg Pediatr Card Surg Annu 2009;76–86 [PMID: 19349019].
McLean KM, Lorts A, Pearl JM: Current treatments for congenital aortic stenosis. Curr Opin Cardiol 2006;21:200–204 [PMID: 16601457].
3. Mitral Valve Prolapse
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Late systolic “whooping” or “honking” murmur.
Typical symptoms include chest pain, palpitations, and dizziness.
Often overdiagnosed on routine cardiac ultrasound.
In this condition as the mitral valve closes during systole, it moves posteriorly or superiorly (prolapses) into the left atrium. Mitral valve prolapse (MVP) occurs in about 2% of thin female adolescents, a minority of whom have concomitant mitral insufficiency. Although MVP is usually an isolated lesion, it can occur in association with connective tissue disorders such as Marfan, Loeys-Dietz, and Ehlers-Danlos syndromes.
A. Symptoms and Signs
Most patients with MVP are asymptomatic. Chest pain, palpitations, and dizziness may be reported, but it is unclear whether these symptoms are more common in affected patients than in the normal population. Chest pain on exertion is rare and should be assessed with cardiopulmonary stress testing. Significant dysrhythmias have been reported, including increased ventricular ectopy and nonsustained ventricular tachycardia. If significant mitral regurgitation is present, atrial arrhythmias may also occur. Standard auscultation technique must be modified to diagnose MVP. A midsystolic click (with or without a systolic murmur) is elicited best in the standing position and is the hallmark of this entity. Conversely, maneuvers that increase LV volume, such as squatting or handgrip exercise, will cause delay or obliteration of the click-murmur complex. The systolic click usually is heard at the apex but may be audible at the left sternal border. A late, short systolic murmur after the click implies mitral insufficiency and is much less common than isolated prolapse. The murmur is not holosystolic, in contrast to rheumatic mitral insufficiency.
Most chest radiographs are normal and are not usually indicated in this condition. In the rare case of significant mitral valve insufficiency, the left atrium may be enlarged.
The ECG is usually normal. Diffuse flattening or inversion of T waves may occur in the precordial leads. U waves are sometimes prominent.
Significant posterior systolic movement of the mitral valve leaflets to the atrial side of the mitral annulus is diagnostic. Echocardiography assesses the degree of myxomatous change of the mitral valve and the degree of mitral insufficiency.
E. Other Testing
Invasive procedures are rarely indicated. Holter monitoring or event recorders may be useful in establishing the presence of ventricular dysrhythmias in patients with palpitations.
Treatment & Prognosis
Propranolol may be effective in treatment of coexisting arrhythmias. Prophylaxis for infectious endocarditis is no longer indicated, based on 2007 AHA guidelines. The natural course of this condition is not well defined. Twenty years of observation indicate that isolated MVP in childhood is usually a benign entity. Surgery for mitral insufficiency is rarely needed.
Knackstedt C et al: Ventricular fibrillation due to severe mitral valve prolapse. Int J Cardiol 2007;116:e101–e102 [PMID: 17137658].
Mechleb BK et al: Mitral valve prolapse: relationship of echocardiography characteristics to natural history. Echocardiography 2006;23:434–437 [PMID: 16686634].
4. Other Congenital Left Heart Valvular Lesions
A. Congenital Mitral Stenosis
Congenital mitral stenosis is a rare disorder in which the valve leaflets are thickened and/or fused, producing a diaphragm- or funnel-like structure with a central opening. In many cases, the subvalve apparatus (papillary muscles and chordae) is also abnormal. When mitral stenosis occurs with other left-sided obstructive lesions, such as subaortic stenosis and coarctation of the aorta, the complex is called Shone syndrome. Most patients develop symptoms early in life with tachypnea, dyspnea, and failure to thrive. Physical examination reveals an accentuated S1 and a loud pulmonary closure sound. No opening snap is heard. In most cases, a presystolic crescendo murmur is heard at the apex. Occasionally, only a mid-diastolic murmur can be heard. ECG shows right axis deviation, biatrial enlargement, and RVH. Chest radiograph reveals left atrial enlargement and frequent pulmonary venous congestion. Echocardiography shows abnormal mitral valve structures with reduced leaflet excursion and left atrial enlargement. Cardiac catheterization reveals an elevated pulmonary capillary wedge pressure and pulmonary hypertension, owing to the elevated left atrial pressure.
Mitral valve repair or mitral valve replacement with a prosthetic mitral valve may be performed, even in young infants, but it is a technically difficult procedure. Mitral valve repair is the preferred surgical option, as valve replacement can have a poor outcome in infants.
B. Cor Triatriatum
Cor triatriatum is a rare abnormality in which the pulmonary veins join in a confluence that is not completely incorporated into the left atrium. The pulmonary vein confluence communicates with the left atrium through an opening of variable size, and may be obstructed. Patients may present in a similar way as those with mitral stenosis. Clinical findings depend on the degree of obstruction of pulmonary venous flow into the left atrium. If the communication between the confluence and the left atrium is small and restrictive to flow, symptoms develop early in life. Echocardiography reveals a linear density in the left atrium with a pressure gradient present between the pulmonary venous chamber and the true left atrium. Cardiac catheterization may be needed if the diagnosis is in doubt. High pulmonary wedge pressure and low left atrial pressure (with the catheter passed through the foramen ovale into the true left atrium) support the diagnosis. Angiocardiography identifies the pulmonary vein confluence and the anatomic left atria. Surgical repair is always required in the presence of an obstructive membrane, and long-term results are good. Coexisting mitral valve abnormalities may be noted, including a supravalvular mitral ring or a dysplastic mitral valve.
C. Congenital Mitral Regurgitation
Congenital mitral regurgitation is a rare abnormality usually associated with other congenital heart lesions, such as congenitally corrected transposition of the great arteries (ccTGA), AV septal defect, and coronary artery anomalies (anomalous left coronary artery from the pulmonary artery). Isolated congenital mitral regurgitation is very rare. It is sometimes present in patients with connective tissue disorders (Marfan or Loeys-Dietz syndrome), usually related to a myxomatous prolapsing mitral valve.
D. Congenital Aortic Regurgitation
Congenital aortic regurgitation is rare. The most common associations are bicuspid aortic valve, with or without coarctation of the aorta; VSD with aortic cusp prolapse; and fenestration of the aortic valve cusp (one or more holes in the cusp).
Beierlein W et al: Long-term follow-up after mitral valve replacement in childhood: poor event-free survival in the young child. Eur J Cardiothorac Surg 2007;31:860–865 [PMID: 17383889].
DISEASES OF THE AORTA
Patients at risk for progressive aortic dilation and dissection include those with isolated bicuspid aortic valve, Marfan syndrome, Loeys-Dietz syndrome, Turner syndrome, and type IV Ehlers-Danlos syndrome.
1. Bicuspid Aortic Valve
Patients with bicuspid aortic valves have an increased incidence of aortic dilation and dissection, regardless of the presence of aortic stenosis. Histologic examination demonstrates cystic medial degeneration of the aortic wall, similar to that seen in patients with Marfan syndrome. Patients with an isolated bicuspid aortic valve require regular follow-up even in the absence of aortic insufficiency or aortic stenosis. Significant aortic root dilation requiring surgical intervention typically does not occur until adulthood.
2. Marfan and Loeys-Dietz Syndromes
Marfan syndrome is an autosomal dominant disorder of connective tissue caused by a mutation in the fibrillin-1 gene. Spontaneous mutations account for 25%–30% of cases, and thus family history is not always helpful. Patients are diagnosed by the Ghent criteria and must have at a minimum, major involvement of two body systems plus involvement of a third body system or a positive family history. Body systems involved include cardiovascular, ocular, musculoskeletal, pulmonary, and integumentary. Cardiac manifestations include aortic root dilation and MVP, which may be present at birth. Patients are at risk for aortic dilation and dissection and are restricted from competitive athletics, contact sports, and isometric activities. β-Blockers or ACE inhibitors are used to lower blood pressure and slow the rate of aortic dilation. More recently, studies are ongoing to evaluate the effectiveness of angiotensin receptor blockers (losartan). Elective surgical intervention is performed in patients of adult size when the aortic root dimension reaches 50 mm or if there is an increase of greater than 1 cm in root dimension in 1 year. The ratio of actual to expected aortic root dimension is used to determine the need for surgery in the young child. Surgical options include replacement of the dilated aortic root with a composite valve graft (Bentall technique) or a David procedure in which the patient’s own aortic valve is spared and a Dacron tube graft is used to replace the dilated ascending aorta. Young age at diagnosis was previously thought to confer a poor prognosis; however, early diagnosis with close follow-up and early medical therapy has more recently been associated with more favorable outcome. Ventricular dysrhythmias may contribute to the mortality in Marfan syndrome.
Loeys-Dietz syndrome is a connective tissue disorder first described in 2005. Many patients with Loeys-Dietz were thought to have Marfan syndrome in the past. Loeys-Dietz is a result of a mutation in the transforming growth factor β (TGF β) receptor and is associated with musculoskeletal, skin, and cardiovascular abnormalities. Cardiovascular involvement includes mitral and tricuspid valve prolapse, aneurysms of the PDA, and aortic and pulmonary artery dilation. Dissection and aneurysm formation of arteries throughout the body can occur including in the head and neck vessels.
3. Turner Syndrome
Cardiovascular abnormalities are common in Turner syndrome. Patients are at risk for aortic dissection, typically during adulthood. Risk factors include hypertension regardless of cause, aortic dilation, bicuspid aortic valve, and coarctation of the aorta. There are rare reports of aortic dissection in adult Turner syndrome patients in the absence of any risk factors suggesting that there is a vasculopathic component to this syndrome. Patients with Turner syndrome require routine follow-up from adolescence onward to monitor for this potentially lethal complication.
Beroukhim RS, Roosevelt G, Yetman AT: Comparison of the pattern of aortic dilation in children with the Marfan’s syndrome versus children with a bicuspid aortic valve. Am J Cardiol 2006;98:1094–1095 [PMID: 17027578].
Brooke BS et al: Angiotensin II blockade and aortic-root dilation in Marfan’s syndrome. N Engl J Med 2008 Jun 26;358(26):2787–2795 [PMID: 18579813].
Dulac Y et al: Cardiovascular abnormalities in Turner’s syndrome: What prevention? Arch Cardiovasc Dis 2008;101:485–490 [PMID: 18848691].
Everitt MD et al: Cardiovascular surgery in children with Marfan syndrome or Loeys-Dietz syndrome. J Thorac Cardiovasc Surg 2009;137:1327–1332; discussion 1332–1333 [PMID: 19464442].
CORONARY ARTERY ABNORMALITIES
Several anomalies involve the origin, course, and distribution of the coronary arteries. Abnormal origin or course of the coronary arteries are often asymptomatic and can go undetected. However, in some instances these children are at risk for sudden death. The most common congenital coronary artery abnormality in infants is anomalous origin of the left coronary artery from the pulmonary artery (ALCAPA) and is discussed in more detail here.
Anomalous Origin of the Left Coronary Artery from the Pulmonary Artery
In this condition, the left coronary artery arises from the pulmonary artery rather than the aorta. In neonates, whose pulmonary artery pressure is high, perfusion of the left coronary artery may be adequate and the infant may be asymptomatic. By age 2 months the pulmonary arterial pressure falls, causing a progressive decrease in myocardial perfusion provided by the anomalous left coronary artery. Ischemia and infarction of the LV is the result. Immediate surgery is indicated to reimplant the left coronary artery and restore myocardial perfusion.
A. Symptoms and Signs
Neonates appear healthy and growth and development are relatively normal until pulmonary artery pressure decreases. Detailed questioning may disclose a history of intermittent abdominal pain (fussiness or irritability), pallor, wheezing, and sweating, especially during or after feeding. Presentation may be subtle, with nonspecific complaints of “fussiness” or intermittent “colic.” The colic and fussiness are probably attacks of true angina. Presentation may be fulminant at age 2–4 months with sudden, severe HF due to LV dysfunction and mitral insufficiency. On physical examination, the infants are usually well developed and well nourished. The pulses are typically weak but equal. A prominent left precordial bulge is present. A gallop and/or holosystolic murmur of mitral regurgitation is sometimes present, though frequently auscultation alone reveals no obvious abnormalities.
Chest radiographs show cardiac enlargement, left atrial enlargement, and may show pulmonary venous congestion if left ventricular function has been compromised.
On the ECG, there is T-wave inversion in leads I and aVL. The precordial leads also show T-wave inversion from V4–V7. Deep and wide Q waves are present in leads I, aVL, and sometimes in V4–V6. These findings of myocardial infarction are similar to those in adults.
The diagnosis can be made with two-dimensional echo techniques by visualizing a single large right coronary artery arising from the aorta and visualization of the anomalous left coronary artery arising from the main pulmonary artery. Flow reversal in the left coronary (heading toward the pulmonary artery, rather than away from the aorta) confirms the diagnosis. LV dysfunction, echo-bright (ischemic) papillary muscles, and mitral regurgitation are commonly seen.
E. Cardiac Catheterization and Angiocardiography
Angiogram of the aorta fails to show the origin of the left coronary artery. A large right coronary artery fills directly from the aorta, and contrast flows from the right coronary system via collaterals into the left coronary artery and finally into the pulmonary artery. Angiogram of the RV or main pulmonary artery may show the origin of the anomalous vessel. Rarely, a left-to-right shunt may be detected as oxygenated blood passes through the collateral system without delivering oxygen to the myocardium, and passes into the pulmonary artery.
Treatment & Prognosis
The prognosis of ALCAPA depends in part on the clinical appearance of the patient at presentation. Medical management with diuretics and afterload reduction can help stabilize a critically ill patient, but surgical intervention should not be delayed. Surgery involves reimplantation of the anomalous coronary button onto the aorta. The mitral valve may have to be replaced, depending on the degree of injury to the papillary muscles and associated mitral insufficiency. Although a life-threatening problem, cardiac function nearly always recovers if the infant survives the surgery and postoperative period.
Imamura M et al: Reoperation and mechanical circulatory support after repair of anomalous origin of the left coronary artery from the pulmonary artery: a twenty-year experience. Ann Thorac Surg 2011;92(1):167–172; discussion 172–173 [PMID: 21592461].
Lange R et al: Long-term results of repair of anomalous origin of the left coronary artery from the pulmonary artery. Ann Thorac Surg 2007;83:1463–1471 [PMID: 17383358].
CYANOTIC CONGENITAL HEART DISEASE
TETRALOGY OF FALLOT
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Hypoxemic spells during infancy.
Right-sided aortic arch in 25% of patients.
Systolic ejection murmur at the upper left sternal border.
In tetralogy of Fallot (ToF), anterior deviation of the infundibular (pulmonary outflow) septum causes narrowing of the right ventricular outflow tract. This deviation also results in a VSD and the aorta then overrides the crest of the ventricular septum. The RV hypertrophies, not because of pulmonary stenosis, but because it is pumping against systemic resistance across a (usually) large VSD. ToF is the most common cyanotic cardiac lesion and accounts for 10% of all congenital heart disease. A right-sided aortic arch is present in 25% of cases, and ASD occurs in 15%.
Obstruction to RV outflow with a large VSD causes a right-to-left shunt at the ventricular level with arterial desaturation. The greater the obstruction and the lower the systemic vascular resistance, the greater is the right-to-left shunt. ToF is associated with deletions in the long arm of chromosome 22 (22q11, DiGeorge syndrome) in as many as 15% of affected children. This is especially common in those with an associated right aortic arch.
A. Symptoms and Signs
Clinical findings vary with the degree of RV outflow obstruction. Patients with mild obstruction are minimally cyanotic or acyanotic. Those with severe obstruction are deeply cyanotic from birth. Few children are asymptomatic. In those with significant RV outflow obstruction, many have cyanosis at birth, and nearly all have cyanosis by age 4 months. The cyanosis usually is progressive, as subvalvular obstruction increases. Growth and development are not typically delayed, but easy fatigability and dyspnea on exertion are common. The fingers and toes show variable clubbing depending on age and severity of cyanosis. Historically, older children with ToF would frequently squat to increase systemic vascular resistance. This decreased the amount of right-to-left shunt, forcing blood through the pulmonary circuit, and would help ward off cyanotic spells. Squatting is rarely seen as the diagnosis is now made in infancy.
Hypoxemic spells, also called cyanotic or “Tet spells,” are one of the hallmarks of severe ToF. These spells can occur spontaneously and at any time, but in infants occur most commonly with crying or feeding, while in older children they can occur with exercise. They are characterized by (1) sudden onset of cyanosis or deepening of cyanosis; (2) dyspnea; (3) alterations in consciousness, from irritability to syncope; and (4) decrease or disappearance of the systolic murmur (as RV the outflow tract becomes completely obstructed). These episodes most commonly start at age 4–6 months. Cyanotic spells are treated acutely by administration of oxygen and placing the patient in the knee-chest position (to increase systemic vascular resistance). Intravenous morphine should be administered cautiously, but is helpful for its sedative effect. Propranolol produces β-blockade and may reduce the obstruction across the RV outflow tract through its negative inotropic action. Acidosis, if present, should be corrected with intravenous sodium bicarbonate. Chronic oral prophylaxis of cyanotic spells with propranolol may be useful to delay surgery, but the onset of Tet spells usually prompts surgical intervention. In fact, in the current era, elective surgical repair generally occurs around the age of 3 months so as to avoid the development of Tet spells.
On examination, an RV lift is palpable. S2 is predominantly aortic and single. A grade II–IV/VI, rough, systolic ejection murmur is present at the left sternal border in the third intercostal space and radiates well to the back.
B. Laboratory Findings
Hemoglobin, hematocrit, and red blood cell count are usually elevated in older infants or children secondary to chronic arterial desaturation.
Chest radiographs show a normal-size heart. The RV is hypertrophied, often shown by an upturning of the apex (boot-shaped heart). The main pulmonary artery segment is usually concave and, if there is a right aortic arch, the aortic knob is to the right of the trachea. The pulmonary vascular markings are usually decreased.
The QRS axis is rightward, ranging from +90 to+180 degrees. The P waves are usually normal. RVH is always present, but RV strain patterns are rare.
Two-dimensional imaging is diagnostic, revealing thickening of the RV wall, overriding of the aorta, and a large subaortic VSD. Obstruction at the level of the infundibulum and pulmonary valve can be identified, and the size of the proximal pulmonary arteries measured. The anatomy of the coronary arteries should be visualized, as abnormal branches crossing the RV outflow tract are at risk for transection during surgical enlargement of the area.
F. Cardiac Catheterization and Angiocardiography
Cardiac catheterization is generally done mainly in those patients with hypoplastic pulmonary arteries. If a catheterization is done, it reveals a right-to-left shunt at the ventricular level in most cases. Arterial desaturation of varying degrees is present. The RV pressure is at systemic levels and the pressure tracing in the RV is identical to that in the LV if the VSD is large. The pulmonary artery pressure is invariably low. Pressure gradients may be noted at the pulmonary valvular level, the infundibular level, or both. RV angiography reveals RV outflow obstruction and a right-to-left shunt at the ventricular level. The major indications for cardiac catheterization are to establish coronary artery and distal pulmonary artery anatomy if not able to be clearly defined by echocardiography.
A. Palliative Treatment
Most centers currently advocate complete repair of ToF during the neonatal or infant period regardless of patient size. However, some centers prefer palliative treatment for small neonates in whom complete correction is deemed risky. Surgical palliation consists of the insertion of a GoreTex shunt from the subclavian artery to the ipsilateral pulmonary artery [modified Blalock-Taussig (BT) shunt] to replace the ductus arteriosus (which is ligated and divided) or stenting of the ductus. This secures a source of pulmonary blood flow regardless of the level of infundibular or valvular obstruction, and some believe, allows for growth of the patient’s pulmonary arteries (which are usually small) prior to complete surgical correction.
B. Total Correction
Open-heart surgery for repair of ToF is performed at ages ranging from birth to 2 years, depending on the patient’s anatomy and the experience of the surgical center. The current surgical trend is toward earlier repair for symptomatic infants. The major limiting anatomic feature of total correction is the size of the pulmonary arteries. During surgery, the VSD is closed and the obstruction to RV outflow removed. Although a valve sparing procedure is preferred, in many cases a transannular patch is placed across the RV outflow tract as the pulmonary valve is contributing to the obstruction. When a transannular patch repair is done, the patient has pulmonary insufficiency that is usually well tolerated for years. However, pulmonary valve replacement is eventually necessary once symptoms (usually exercise intolerance) and right ventricular dilation occur. Surgical mortality is low.
Course & Prognosis
Infants with severe ToF are usually deeply cyanotic at birth. These children require early surgery. Complete repair before age 2 years usually produces a good result, and patients are currently living well into adulthood. Depending on the extent of the repair required, patients frequently require additional surgery 10–15 years after their initial repair for replacement of the pulmonary valve. Transcatheter pulmonary valves are now performed in some adolescents and young adults with a history of ToF, avoiding the need for open heart surgery. Patients with ToF are at risk for sudden death due to ventricular dysrhythmias. A competent pulmonary valve without a dilated RV appears to diminish arrhythmias and enhance exercise performance.
Batra AS et al: Cardiopulmonary exercise function among patients undergoing transcatheter pulmonary valve implantation in the US Melody valve investigational trial. Am Heart J 2012;163(2):280–287 [PMID: 22305848].
Harrild DM et al: Pulmonary valve replacement in tetralogy of Fallot: impact on survival and ventricular tachycardia. Circulation 2009;119:445–451 [PMID: 19139389].
PULMONARY ATRESIA WITH VENTRICULAR SEPTAL DEFECT
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Symptoms depend on degree of pulmonary blood flow.
Pulmonary blood flow via PDA and/or aortopulmonary collaterals.
Complete atresia of the pulmonary valve in association with a VSD is essentially an extreme form of ToF. Because there is no antegrade flow from the RV to the pulmonary artery, pulmonary blood flow must be derived from a PDA or from multiple aortopulmonary collateral arteries (MAPCAs). Symptoms depend on the amount of pulmonary blood flow. If flow is adequate, patients may be stable. If pulmonary flow is inadequate, severe hypoxemia occurs and immediate palliation is required. Newborns are stabilized with intravenous prostaglandin E1 (PGE1) to maintain the PDA while being prepared for surgery. Rarely, if the ductus does not contribute significantly to pulmonary blood flow (eg, the MAPCAs alone are sufficient), PGE1 may be discontinued. Once stabilized, a BT shunt, stenting of the ductus or complete repair is undertaken. The decision to perform palliation or complete repair in a newborn is dependent on surgical expertise and preference in combination with pulmonary artery anatomy. In many centers, a palliative shunt is performed in newborns with severely hypoplastic pulmonary arteries or in those with only MAPCAs as a source of pulmonary blood flow. The goal of the shunt is to augment pulmonary blood flow and encourage vascular growth, and open-heart surgical correction is planned several months later. In children with MAPCAs, relocation of the MAPCAs is performed so that they are connected to the pulmonary artery (unifocalization) to complete the repair.
Echocardiography is usually diagnostic. Cardiac catheterization and angiocardiography or cardiac MRI can confirm the source(s) of pulmonary blood flow and document size of the distal pulmonary arteries.
Pulmonary vascular disease is common in pulmonary atresia with VSD, due both to intrinsic abnormalities of the pulmonary vasculature and to abnormal amounts of pulmonary blood flow. Even patients who have undergone surgical correction as infants are at risk. Pulmonary vascular disease is a common cause of death as early as the third decade of life.
Mainwaring RD: Hemodynamic assessment after complete repair of pulmonary atresia with major aortopulmonary collaterals. Ann Thorac Surg 2013 Apr;95(4):1397-1402 [PMID: 23453744].
Ten Cate FA: Stenting the arterial duct in neonates and infants with congenital heart disease and duct-dependent pulmonary blood flow: a multicenter experience of an evolving therapy over 18 years. Catheter Cardiovasc Interv 2013 Sep 1;82(3):E233-43 [PMID: 23420699].
PULMONARY ATRESIA WITH INTACT VENTRICULAR SEPTUM
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Completely different lesion from pulmonary atresia with VSD.
Cyanosis at birth.
Pulmonary blood flow is always ductal dependent with rare aortopulmonary collateral arteries being present.
RV-dependent coronary arteries sometimes are present.
Although pulmonary atresia with intact ventricular septum (PA/IVS) sounds as if it might be related to pulmonary atresia with VSD, it is a distinct cardiac condition. As the name suggests, the pulmonary valve is atretic. The pulmonic annulus usually has a small diaphragm consisting of the fused valve cusps. The ventricular septum is intact. The main pulmonary artery segment is usually present and closely approximated to the atretic valve, but is somewhat hypoplastic. Although the RV is always reduced in size, the degree of reduction is variable. The size of the RV is critical to the success of surgical repair. In some children with PA/IVS, the RV is adequate for an ultimate two-ventricular repair. A normal RV has three component parts (inlet, trabecular or body, and outlet). The absence of any one of the components makes adequate RV function unlikely and a single ventricle palliative approach is necessary. Even with all three components, some RVs are inadequate.
After birth, the pulmonary flow is provided by the ductus arteriosus. MAPCAs are usually not present in this disease, in contrast to pulmonary atresia with VSD. A continuous infusion of PGE1 must be started as soon as possible after birth to maintain ductal patency.
A. Symptoms and Signs
Neonates are usually cyanotic and become more so as the ductus arteriosus closes. A blowing systolic murmur resulting from the associated PDA may be heard at the pulmonary area. A holosystolic murmur is often heard at the lower left sternal border, as many children develop tricuspid insufficiency if the RV is of good size and egress from that ventricle is only through the tricuspid valve. A PFO or ASD is essential for decompression of the right side of the heart.
The heart size varies depending on the degree of tricuspid insufficiency. With severe tricuspid insufficiency, right atrial enlargement may be massive and the cardiac silhouette may fill the chest on radiograph. In patients with an associated hypoplastic tricuspid valve and or RV, most of the systemic venous return travels right-to-left across the ASD and so the heart size can be normal.
ECG reveals a left axis for age (45–90 degrees) in the frontal plane. Left ventricular forces dominate the ECG, and there is a paucity of RV forces, particularly with a hypoplastic RV. Findings of right atrial enlargement are usually striking.
Echocardiography shows atresia of the pulmonary valve with varying degrees of RV cavity and tricuspid annulus hypoplasia. Patency of an intra-atrial communication and ductus are verified by echocardiography.
E. Cardiac Catheterization and Angiocardiography
RV pressure is often suprasystemic. Angiogram of the RV reveals no filling of the pulmonary artery. Unrestricted flow through the ASD is a necessity, since egress of blood from the right heart can only occur across the atrial defect and into the left atrium. A Rashkind balloon atrial septostomy may be required to open any inadequate existing communication across the atrial septum. Some children with pulmonary atresia and an intact ventricular septum have sinusoids between the RV and the coronary arteries. In some patients, the coronary circulation may depend on high right ventricular pressure. Any attempt to decompress the RV in patients with RV-dependent coronary circulation causes myocardial infarction and death because of the precipitous decrease in coronary perfusion, so precise coronary angiography is required to evaluate the anatomy. If the RV is tripartite, coronary circulation is not RV-dependent and an eventual two-chamber repair is planned. The pulmonary valve plate may be perforated and dilated during cardiac catheterization in the newborn to allow antegrade flow from the RV to the pulmonary artery and thus encourage RV cavity growth.
Treatment & Prognosis
As in all ductal-dependent lesions, PGE1 is used to stabilize the patient and maintain patency of the ductus until surgery can be performed. Surgery is usually undertaken in the first week of life. If the RV is hypoplastic, significant sinusoids are present, there is RV-dependent coronary circulation (lack of antegrade filling of the coronaries from the aorta), or the pulmonic valve cannot be opened successfully during cardiac catheterization, a BT shunt or ductal stenting is performed to establish pulmonary blood flow. Later in infancy, a communication between the RV and pulmonary artery can be created to stimulate RV cavity growth. If either RV dimension or function is inadequate for two-ventricular repair, an approach similar to that taken for a single ventricle pathway best serves these children (see section on Hypoplastic Left Heart Syndrome). Children with significant sinusoids or coronary artery abnormalities are considered for cardiac transplantation because they are at risk for coronary insufficiency and sudden death.
The prognosis in this condition is guarded.
Alwi M: Management algorithm in pulmonary atresia with intact ventricular septum. Catheter Cardiovasc Interv 2006 May;67(5):679–686 [Review] [PMID: 16572430].
Tuo G et al: Impact of prenatal diagnosis on outcome of pulmonary atresia and intact ventricular septum. J Matern Fetal Neonatal Med 2012 Jun;25(6):669–674 [PMID: 21699439].
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Marked cyanosis present from birth.
ECG with left axis deviation, right atrial enlargement, and LVH.
In tricuspid atresia, there is complete atresia of the tricuspid valve with no direct communication between the right atrium and the RV. There are two types of tricuspid atresia based on the relationship of the great arteries (normally related or transposed great arteries). The entire systemic venous return must flow through the atrial septum (either ASD or PFO) to reach the left atrium. The left atrium thus receives both the systemic venous return and the pulmonary venous return. Complete mixing occurs in the left atrium, resulting in variable degrees of arterial desaturation.
Because there is no flow to the RV, development of the RV depends on the presence of a ventricular left-to-right shunt. Severe hypoplasia of the RV occurs when there is no VSD or when the VSD is small.
A. Symptoms and Signs
Symptoms usually develop in early infancy with cyanosis present at birth in most infants. Growth and development are poor, and the infant usually exhibits exhaustion during feedings, tachypnea, and dyspnea. Patients with increased pulmonary blood flow may develop HF with less prominent cyanosis. The degree of pulmonary blood flow is most dependent on pulmonary vascular resistance. Those patients with low pulmonary vascular resistance will have increased pulmonary blood flow. A murmur from the VSD is usually present and heard best at the lower left sternal border. Digital clubbing is present in older children with long-standing cyanosis.
The heart is slightly to markedly enlarged. The main pulmonary artery segment is usually small or absent. The size of the right atrium is moderately to massively enlarged, depending on the size of the communication at the atrial level. The pulmonary vascular markings are usually decreased. Pulmonary vascular markings may be increased if pulmonary blood flow is not restricted by the VSD or pulmonary stenosis.
The ECG shows marked left axis deviation. The P waves are tall and peaked, indicative of right atrial hypertrophy. LVH or LV dominance is found in almost all cases. RV forces on the ECG are usually low or absent.
Two-dimensional methods are diagnostic and show absence of the tricuspid valve, the relationship between the great arteries, the anatomy of the VSD, presence of an ASD or PFO, and the size of the pulmonary arteries. Color-flow Doppler imaging can help identify atrial level shunting and levels of restriction of pulmonary blood flow, either at the VSD or in the RV outflow tract.
E. Cardiac Catheterization and Angiocardiography
Catheterization reveals a right-to-left shunt at the atrial level. Because of mixing in the left atrium, oxygen saturations in the LV, RV, pulmonary artery, and aorta are identical to those in the left atrium. Right atrial pressure is increased if the ASD is restrictive. LV and systemic pressures are normal. The catheter cannot be passed through the tricuspid valve from the right atrium to the RV. A balloon atrial septostomy is performed if a restrictive PFO or ASD is present.
Treatment & Prognosis
In infants with unrestricted pulmonary blood flow, conventional anticongestive therapy with diuretics and afterload reduction should be given until the infant begins to outgrow the VSD. Sometimes, a pulmonary artery band is needed to protect the pulmonary bed from excessive flow and development of pulmonary vascular disease.
Staged palliation of tricuspid atresia is the usual surgical approach. In infants with diminished pulmonary blood flow, PGE1 is given until an aortopulmonary shunt (BT shunt or ductal stent) can be performed. A Glenn procedure (superior vena cava to pulmonary artery anastomosis) is done with takedown of the aortopulmonary/BT shunt at 4–6 months when saturations begin to fall, and completion of the Fontan procedure (redirection of inferior vena cava and superior vena cava to pulmonary artery) is performed when the child reaches around 15 kg.
The long-term prognosis for children treated by the Fontan procedure is unknown, although patients now are living into their late 20s and early 30s. In the short term, the best results for the Fontan procedure occur in children with low pulmonary artery pressures prior to open-heart surgery.
Wald RM et al: Outcome after prenatal diagnosis of tricuspid atresia: a multicenter experience. Am Heart J 2007;153:772–778 [PMID: 17452152].
HYPOPLASTIC LEFT HEART SYNDROME
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Mild cyanosis at birth.
Minimal auscultatory findings.
Rapid onset of shock with ductal closure.
Hypoplastic left heart syndrome (HLHS) includes several conditions in which obstructive lesions of the left heart are associated with hypoplasia of the LV. The syndrome occurs in 1.4%–3.8% of infants with congenital heart disease.
Stenosis or atresia of the mitral and aortic valves is the rule. In the neonate, survival depends on a PDA because ante-grade flow into the systemic circulation is inadequate or nonexistent. The PDA provides the only flow to the aorta and coronary arteries. Children with HLHS are usually stable at birth, but they deteriorate rapidly as the ductus closes in the first week of life. Untreated, the average age at death is the first week of life. Rarely, the ductus remains patent and infants may survive for weeks to months without PGE1 therapy.
The diagnosis is often made prepartum by fetal echocardiography. Prepartum diagnosis aids in counseling for the expectant parents and planning for the delivery of the infant at or near a center with experience in treating HLHS.
A. Symptoms and Signs
Neonates with HLHS appear stable at birth because the ductus is patent. They deteriorate rapidly as the ductus closes, with shock and acidosis secondary to inadequate systemic perfusion. Oxygen saturation may actually increase for a period of time as the ductus closes due to increased blood flowing to the lungs.
Chest radiograph in the first day of life may be relatively unremarkable, with the exception of a small cardiac silhouette. Later, chest radiographs demonstrate cardiac enlargement with severe pulmonary venous congestion if the PDA has begun closing or if the baby has been placed on supplemental oxygen increasing pulmonary blood flow.
The ECG shows right axis deviation, right atrial enlargement, and RVH with a relative paucity of LV forces. The small Q wave in lead V6 may be absent, and a qR pattern is often seen in lead V1.
Echocardiography is diagnostic. A hypoplastic aorta and LV with atretic or severely stenotic mitral and aortic valves are diagnostic. The systemic circulation is dependent on the PDA. Color-flow Doppler imaging shows retrograde flow in the ascending aorta, as the coronary arteries are supplied by the ductus via the small native aorta.
Treatment & Prognosis
Initiation of PGE1 is essential and lifesaving, as systemic circulation depends on a patent ductus arteriosus. Later management depends on balancing pulmonary and systemic blood flow both of which depend on the RV. At a few days of age the pulmonary resistance falls, favoring pulmonary over-circulation and systemic underperfusion. Therapy is then directed at encouraging systemic blood flow. Despite hypoxia and cyanosis, supplemental oxygen is avoided as this will decrease pulmonary resistance and lead to further increases in pulmonary blood flow. In some centers, nitrogen is used to decrease inspired oxygen to as low as 17%. This therapy must be carefully monitored, but results in increased pulmonary arterial resistance, which encourages systemic blood flow and improves systemic perfusion. Systemic afterload reduction will also increase systemic perfusion. Adequate perfusion can usually be obtained by keeping systemic O2 saturation between 65% and 80%, or more accurately a Po2 of 40 mm Hg.
Staged surgical palliation is the most common management approach. In the Norwood procedure, the relatively normal main pulmonary artery is transected and connected to the small ascending aorta. The entire aortic arch must be reconstructed due to its small size. Then, either a BT shunt (from the subclavian artery to the pulmonary artery) or a Sano shunt (from the RV to the pulmonary artery) must be created to restore pulmonary blood flow. Children who have a Norwood procedure will later require a Glenn anastomosis (superior vena cava to pulmonary artery with takedown of the systemic-pulmonary shunt) and then a Fontan (inferior vena cava to pulmonary artery, completing the systemic venous bypass of the heart) at ages 6 months and 2–3 years, respectively. Despite advances in surgical technique and postoperative care, HLHS remains one of the most challenging lesions in pediatric cardiology, with one-year survival as low as 70%.
Orthotopic heart transplantation is also a treatment option for newborns with HLHS, but in the current era is typically only performed in infants who are considered poor Norwood candidates. Heart transplantation is more commonly utilized in the event of a failed surgical palliation or if the systemic RV fails (often in adolescence or young adulthood).
Recently, some centers offer a “hybrid” approach to HLHS as a result of collaboration between surgeons and interventional cardiologists. In the hybrid procedure, the chest is opened surgically and the branch pulmonary arteries are banded, to limit pulmonary blood flow. Then, also through the open chest, a PDA stent is placed by the interventionalist to maintain systemic output. The second stage is considered a “comprehensive Glenn,” in which the pulmonary artery bands and ductal stent are taken down, the aortic arch is reconstructed and the superior vena cava is surgically connected to the pulmonary arteries. Short term (30 day) survival after the first-stage “hybrid” is greater than 90% at the most experienced centers, but second stage risks and complications mitigate some of that initial survival advantage. Long-term follow-up data are not yet available.
Ohye RG et al: Comparison of shunt types in the Norwood procedure for single-ventricle lesions. N Engl J Med 2010;362(21):1980–1992 [PMID: 20505177].
TRANSPOSITION OF THE GREAT ARTERIES
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Cyanotic newborn without respiratory distress.
More common in males.
Transposition of the great arteries (TGA) is the second most common cyanotic congenital heart disease, accounting for 5% of all cases of congenital heart disease. The male-to-female ratio is 3:1. It is caused by an embryologic abnormality in the spiral division of the truncus arteriosus in which the aorta arises from the RV and the pulmonary artery from the LV. This is referred to as “ventriculoarterial discordance.” Patients may have a VSD, or the ventricular septum may be intact. Left unrepaired, transposition is associated with a high incidence of early pulmonary vascular obstructive disease. Because pulmonary and systemic circulations are in parallel, survival is impossible without mixing between the two circuits. Specifically an interatrial communication (PFO or ASD) is critically important. The majority of mixing occurs at the atrial level (some mixing can occur at the level of the ductus as well), so even in the presence of a VSD an adequate interatrial communication is needed. If the atrial communication is inadequate at birth, the patient is severely cyanotic.
A. Symptoms and Signs
Many neonates are large (up to 4 kg) and profoundly cyanotic without respiratory distress or a significant murmur. Infants with a large VSD may be less cyanotic and they usually have a prominent murmur. The findings on cardiovascular examination depend on the intracardiac defects. Obstruction to outflow from either ventricle is possible, and coarctation must be ruled out.
The chest radiograph in transposition is usually nondiagnostic. Sometimes there is an “egg on a string” appearance because the aorta is directly anterior to the main pulmonary artery, giving the image of a narrow mediastinum.
Because the newborn ECG normally has RV predominance, the ECG in transposition is of little help, as it will frequently look normal.
Two-dimensional imaging and Doppler evaluation demonstrate the anatomy and physiology well. The aorta arises from the RV and the pulmonary artery arises from the LV. Associated defects, such as a VSD, RV, or LV outflow tract obstruction, or coarctation, must be evaluated. The atrial septum should be closely examined, as any restriction could prove detrimental as the child awaits repair. The coronary anatomy is variable and must be defined prior to surgery.
E. Cardiac Catheterization and Angiocardiography
A Rashkind balloon atrial septostomy is frequently performed in complete transposition if the interatrial communication is restrictive. This procedure can be done at the bedside with echocardiographic guidance in most cases. The coronary anatomy can be delineated by ascending aortography if not well seen by echocardiography.
Early corrective surgery is recommended. The arterial switch operation (ASO) has replaced the previously performed atrial switch procedures (Mustard and Senning operations). The ASO is performed at age 4–7 days. The arteries are transected above the level of the valves and switched, while the coronaries are separately reimplanted. Small associated VSDs may be left to close on their own, but large VSDs are repaired. The ASD is also closed. Early surgical repair (< 14 days of age) is vital for patients with TGA and an intact ventricular septum to avoid potential deconditioning of the LV as it pumps to the low-resistance pulmonary circulation. If a large, unrestrictive VSD is present, LV pressure is maintained at systemic levels, the LV does not become deconditioned, and corrective surgery can be delayed for a few months. Surgery should be performed by age 3–4 months in those with TGA and a VSD because of the high risk of early pulmonary vascular disease associated with this defect.
Operative survival after the ASO is greater than 95% in major centers. The main advantage of the arterial switch procedure in comparison to the atrial switch procedures (Mustard and Senning operations) is that the systemic ventricle is the LV. Patients who have undergone an atrial switch undergo surgical patch placement to baffle the venous return through the atria to the opposite ventricle. They then have an RV as their systemic ventricle, leaving them with significant late risk of RV failure and need for heart transplantation and are at risk for atrial baffle obstruction.
Lalezari S, Bruggemans EF, Blom NA, Hazekamp MG: Thirty-year experience with the arterial switch operation. Ann Thorac Surg 2011 Sep;92(3):973–979 [PMID: 21871285].
Warnes CA: Transposition of the great arteries. Circulation 2006;114:2699–2709 [PMID: 17159076].
1. Congenitally Corrected Transposition of the Great Arteries
Congenitally corrected transposition of the great arteries (ccTGA) is a relatively uncommon congenital heart disease. Patients may present with cyanosis, heart failure, or be asymptomatic, depending on the associated lesions. In ccTGA, both atrioventricular and ventriculoarterial discordance occurs so that the right atrium connects to a morphologic LV, which supports the pulmonary artery. Conversely, the left atrium empties via a tricuspid valve into a morphologic RV, which supports the aorta. Common associated lesions are VSD and pulmonary stenosis. A dysplastic left-sided tricuspid valve is almost always present. In the absence of associated lesions, patients with ccTGA are often undiagnosed until adulthood when they present with left-sided AV valve insufficiency or arrhythmias.
Previously, surgical repair was directed at VSD closure and relief of pulmonary outflow tract obstruction—a technique that maintained the RV as the systemic ventricle with outflow to the aorta. It is now recognized that these patients have a reduced life span due to systemic RV failure; thus other surgical techniques have been advocated. The double-switch procedure is one such technique. An atrial level switch (Mustard or Senning technique) is performed, in which pulmonary and systemic venous blood are baffled such that they drain into the contralateral ventricle (systemic venous return drains into the RV and pulmonary venous return drains into the LV). An ASO then restores the morphologic LV to its position as systemic ventricle.
Patients with ccTGA have an increased incidence of complete heart block with an estimated risk of 1% per year and an overall frequency of 50%.
Malhotra SP et al: The hemi-Mustard/bidirectional Glenn atrial switch procedure in the double-switch operation for congenitally corrected transposition of the great arteries: rationale and midterm results. J Thorac Cardiovasc Surg 2011;141(1):162–170 [PMID: 21055773].
2. Double-Outlet Right Ventricle
In this uncommon malformation, both great arteries arise from the RV. There is always a VSD that allows blood to exit the LV. Presenting symptoms depend on the relationship of the VSD to the semilunar valves. The VSD can be in variable positions, and the great arteries could be normally related or malposed. In the absence of outflow obstruction, a large left-to-right shunt exists and the clinical picture resembles that of a large VSD. Pulmonary stenosis may be present, particularly if the VSD is remote from the pulmonary artery. This physiology is similar to ToF. Alternatively, if the VSD is nearer the pulmonary artery, aortic outflow may be obstructed (called the Taussig-Bing malformation). Early primary correction is the goal. LV flow is directed to the aorta across the VSD (closing the VSD), and an RV to pulmonary artery conduit is placed to maintain unobstructed flow through the pulmonary circulation. If the aorta is far from the VSD, an arterial switch may be necessary. Echocardiography is usually sufficient to make the diagnosis and determine the orientation of the great vessels and their relationship to the VSD.
Mahle WT et al: Anatomy, echocardiography, and surgical approach to double outlet right ventricle. Cardiol Young 2008;18(Suppl 3):39–51 [PMID: 19094378].
TOTAL ANOMALOUS PULMONARY VENOUS RETURN
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Abnormal pulmonary venous connection leading to cyanosis.
Occurs with or without a murmur and may have accentuated P2.
Right atrial enlargement and RVH.
This malformation accounts for 2% of all congenital heart lesions. Instead of the pulmonary veins draining into the left atrium, the veins empty into a confluence that usually is located behind the left atrium. However, the confluence is not connected to the left atrium and instead the pulmonary venous blood drains into the systemic venous system. Therefore, there is complete mixing of the systemic and pulmonary venous blood at the level of the right atrium. The presentation of a patient with total anomalous pulmonary venous return (TAPVR) depends on the route of drainage into the systemic circulation and whether or not this drainage route is obstructed.
The malformation is classified as either intra-, supra-, or infracardiac. Intracardiac TAPVR occurs when the pulmonary venous confluence drains directly into the heart, usually via the coronary sinus into the right atrium (rarely direct drainage into the right atrium). Supracardiac (or supradiaphragmatic) return is defined as a confluence that drains into the right superior vena cava, innominate vein, or persistent left superior vena cava. In infracardiac (or infradiaphragmatic) return, the confluence drains below the diaphragm usually into the portal venous system which empties into the inferior vena cava. Infracardiac pulmonary venous return is very frequently obstructed. This obstruction to pulmonary venous drainage makes this lesion a potential surgical emergency. Supracardiac veins may also be obstructed, though less commonly. Rarely, the pulmonary venous confluence drains to more than one location, called mixed TAPVR.
Because the entire venous drainage from the body returns to the right atrium, a right-to-left shunt must be present at the atrial level, either as an ASD or a PFO. Occasionally, the atrial septum is restrictive and balloon septostomy is needed at birth to allow filling of the left heart.
A. Unobstructed Pulmonary Venous Return
Patients with unobstructed TAPVR and a large atrial communication tend to have high pulmonary blood flow and typically present with cardiomegaly and HF rather than cyanosis. Oxygen saturations in the high 80s or low 90s are common. Most patients in this group have mild to moderate elevation of pulmonary artery pressure owing to elevated pulmonary blood flow. In most instances, pulmonary artery pressure does not reach systemic levels.
1. Symptoms and signs—Patients may have mild cyanosis and tachypnea in the neonatal period and early infancy. Examination discloses dusky nail beds and mucous membranes, but overt cyanosis and digital clubbing are usually absent. An RV heave is palpable, and P2 is increased. A systolic and diastolic murmur may be heard as a result of increased flow across the pulmonary and tricuspid valves, respectively.
2. Imaging—Chest radiography reveals cardiomegaly involving the right heart and pulmonary artery. Pulmonary vascular markings are increased.
3. Electrocardiography—ECG shows right axis deviation and varying degrees of right atrial enlargement and right ventricular hypertrophy. A qR pattern is often seen over the right precordial leads.
4. Echocardiography—Demonstration by echocardiography of a discrete chamber posterior to the left atrium and a right-to-left atrial level shunt is strongly suggestive of the diagnosis. The availability of two-dimensional echocardiography plus color-flow Doppler has increased diagnostic accuracy such that diagnostic cardiac catheterization is rarely required.
B. With Obstructed Pulmonary Venous Return
This group includes many patients with infracardiac TAPVR and a few of the patients in whom venous drainage is into a systemic vein above the diaphragm. The pulmonary venous return is usually obstructed at the level of the ascending or descending vein that connects the confluence to the systemic veins to which it is draining. Obstruction can be caused from extravascular structures (such as the diaphragm), or by inherent stenosis within the ascending or descending vein.
1. Symptoms and signs—Infants usually present shortly after birth with severe cyanosis and respiratory distress and require early corrective surgery. Cardiac examination discloses a striking RV impulse. S2 is markedly accentuated and single. Although there is often no murmur, sometimes, a systolic murmur is heard over the pulmonary area with radiation over the lung fields. Diastolic murmurs are uncommon.
2. Imaging—The heart is usually small and pulmonary venous congestion severe with associated air bronchograms. The chest radiographic appearance may lead to an erroneous diagnosis of severe lung disease. In less severe cases, the heart size may be normal or slightly enlarged with mild pulmonary venous congestion.
3. Electrocardiography—The ECG shows right axis deviation, right atrial enlargement, and RVH.
4. Echocardiography—Echocardiography shows a small left atrium and LV, a dilated right heart with high RV pressure. For infracardiac TAPVR, appearance of a vessel lying parallel and anterior to the descending aorta and to the left of the inferior vena cava may represent the vein draining the confluence caudally toward the diaphragm. Color-flow Doppler echocardiography will demonstrate a right-to-left atrial level shunt and may reveal flow disturbance, commonly near the confluence or in the liver, where flow is obstructed.
5. Cardiac catheterization and angiocardiography—If echocardiography does not confirm the anatomy, cardiac catheterization and angiography demonstrate the site of entry of the anomalous veins, determine the degree of pulmonary hypertension, and calculate pulmonary vascular resistance.
Surgery is always required for TAPVR. If pulmonary venous return is obstructed, surgery must be performed immediately (obstructed TAPVR represents one of the few surgical emergencies in congenital heart disease). If early surgery is not required and the atrial septum is restrictive, a balloon atrial septostomy can be performed in newborns, to be followed shortly by less emergent surgical repair.
Course & Prognosis
Most children with TAPVR do well after surgery. However, some surgical survivors develop late stenosis of the pulmonary veins. Pulmonary vein stenosis is an intractable condition that is difficult to treat either with interventional catheterization or surgery and has a poor prognosis. A heart-lung transplant may be the only remaining option available to those with severe pulmonary vein stenosis. By avoiding direct suturing at the pulmonary venous ostia, the chance of recurrent stenosis at the anastomotic site is lessened. Unfortunately, any manipulation of the pulmonary veins increases the risk of stenosis.
Seale AN et al: Total anomalous pulmonary venous connection: morphology and outcome from an international population-based study. Circulation 2010 Dec 21;122(25):2718–2726 [Epub 2010 Dec 6] [PMID: 21135364].
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Early HF with or without cyanosis.
Systolic ejection click.
Truncus arteriosus accounts for less than 1% of congenital heart malformations. A single great artery arises from the heart, giving rise to the systemic, pulmonary, and coronary circulations. Truncus develops embryologically as a result of failure of the division of the common truncus arteriosus into the aorta and the pulmonary artery. A VSD is always present. The number of truncal valve leaflets varies from two to six, and the valve may be insufficient or stenotic.
Truncus arteriosus is divided into subtypes by the anatomy of the pulmonary circulation. A single main pulmonary artery may arise from the base of the trunk and gives rise to branch pulmonary arteries (type 1). Alternatively, the pulmonary arteries may arise separately from the common trunk, either in close association with one another (type 2) or widely separated (type 3). This lesion can occur in association with an interrupted aortic arch.
In patients with truncus, blood from both ventricles leaves the heart through a single exit. Thus, oxygen saturation in the pulmonary artery is equal to that in the systemic arteries. The degree of systemic arterial oxygen saturation depends on the ratio of pulmonary to systemic blood flow. If pulmonary vascular resistance is normal, the pulmonary blood flow is greater than the systemic blood flow and the saturation is relatively high. If pulmonary vascular resistance is elevated because of pulmonary vascular obstructive disease or small pulmonary arteries, pulmonary blood flow is reduced and oxygen saturation is low. The systolic pressures are systemic in both ventricles.
A. Symptoms and Signs
High pulmonary blood flow characterizes most patients with truncus arteriosus. These patients are usually minimally cyanotic and present in HF. Examination of the heart reveals a hyperactive precordium. A systolic thrill is common at the lower left sternal border. A loud early systolic ejection click is commonly heard. S2 is single and accentuated. A loud holosystolic murmur is audible at the left lower sternal border. A diastolic flow murmur can often be heard at the apex due to increased pulmonary venous return crossing the mitral valve. An additional diastolic murmur of truncal insufficiency may be present.
Patients with decreased pulmonary blood flow are more profoundly cyanotic early. The most common manifestations are growth retardation, easy fatigability, and HF. The heart is not hyperactive. S1 and S2 are single and loud. A systolic murmur is heard at the lower left sternal border. No mitral flow murmur is heard, as pulmonary venous return is decreased. A loud systolic ejection click is commonly heard. In the current era, this lesion is often diagnosed by prenatal screening echocardiography.
The common radiographic findings are a boot-shaped heart, absence of the main pulmonary artery segment, and a large aorta that has a right arch 30% of the time. The pulmonary vascular markings vary with the degree of pulmonary blood flow.
The axis is usually normal. RVH or combined ventricular hypertrophy is commonly present.
Images generally show override of a single great artery (similar to ToF, but no second great artery arises directly from the heart). The origin of the pulmonary arteries and the degree of truncal valve abnormality can be defined. Color-flow Doppler can aid in the description of pulmonary flow and the function of the truncal valve, both of which are critical to management. Echocardiography is critical in identifying associated lesions which will impact surgical planning, such as the presence of an interrupted aortic arch.
Cardiac catheterization is not routinely performed but may be of value in older infants in whom pulmonary vascular disease must be ruled out. The single most important angiogram would be from the truncal root, as both the origin of the pulmonary arteries and the amount of truncal insufficiency would be seen from one injection.
Anticongestive measures are needed for patients with high pulmonary blood flow and congestive failure. Surgery is always required in this condition. Because of HF and the risk of development of pulmonary vascular disease, surgery is usually performed in the neonatal period or early infancy. The VSD is closed to allow LV egress to the truncal valve. The pulmonary artery (type 1) or arteries (types 2–3) are separated from the truncus as a block, and a valved conduit is fashioned from the RV to the pulmonary circulation.
Course & Prognosis
Children with a good surgical result generally do well. Outcome is also dependent to some degree on anatomy and integrity of the truncal valve, which becomes the “neoaortic” valve. Patients with a dysplastic valve may eventually require surgical repair or replacement of this valve. In addition, similar to patients with ToF, they eventually outgrow the RV-to-pulmonary artery conduit placed in infancy and require revision of the conduit in later childhood. The risk of early pulmonary vascular obstructive disease is high in the unrepaired patient and a decision to delay open-heart surgery beyond age 4–6 months is not wise even in stable patients.
Henaine R et al: Fate of the truncal valve in truncus arteriosus. Ann Thorac Surg 2008 Jan;85(1):172–178 [PMID: 18154803].
Konstantinov IE et al: Truncus arteriosus associated with interrupted aortic arch in 50 neonates: a Congenital Heart Surgeons Society study. Ann Thorac Surg 2006 Jan;81(1):214–222 [PMID: 16368368].
QUALITY IMPROVEMENT IN CONGENITAL HEART DISEASE
The National Pediatric Cardiology Quality Improvement Collaborative (NPC-QIC) was formed in response to the Joint Council on Congenital Heart Disease (JCCHD) initiative to improve outcomes of children with heart disease. The mission of the NPC-QIC is to build a collaborative network of pediatric cardiologists and an associated database to serve as the foundation for improvement projects. The inaugural project of the NPC-QIC was an improvement project aimed at improving survival and quality of life of infants with HLHS between stages 1 (Norwood) and 2 (bidirectional Glenn) of their palliative surgery.
As outcomes improve and even those with complex congenital heart disease are surviving into adulthood, the care of adults with congenital heart disease is an expanding area of need within pediatric cardiology. Subspecialty clinics addressing the needs of adults with repaired or palliated congenital heart disease are needed to assess and advise patients regarding such adult issues as the impact of pregnancy, the risks of anticoagulation during pregnancy, and appropriate adult career choices.
Baker-Smith CM et al: Variation in postoperative care following stage I palliation for single-ventricle patients: a report from the Joint Council on Congenital Heart Disease National Quality Improvement Collaborative. Congenit Heart Dis 2011 Mar–Apr;6(2):116–127 [PMID: 21426525].
NPC-QIC website: http://jcchdqi.org/
ACQUIRED HEART DISEASE
Rheumatic fever remains a major cause of morbidity and mortality in developing countries that suffer from poverty, overcrowding, and poor access to health care. Even in developed countries, rheumatic fever has not been entirely eradicated. The overall incidence in the United States is less than 1 per 100,000. Group A β-hemolytic streptococcal infection of the upper respiratory tract is the essential trigger in predisposed individuals. Only certain serotypes of group A Streptococcus cause rheumatic fever. The latest attempts to define host susceptibility implicate immune response genes that are present in approximately 15% of the population. The immune response triggered by infection of the pharynx with group A streptococci consists of (1) sensitization of B lymphocytes by streptococcal antigens, (2) formation of anti-streptococcal antibody, (3) formation of immune complexes that cross-react with cardiac sarcolemma antigens, and (4) myocardial and valvular inflammatory response.
The peak age of risk in the United States is 5–15 years. The disease is slightly more common in girls and in African Americans. The annual death rate from rheumatic heart disease in school-aged children (whites and non-whites) recorded in the 1980s was less than 1 per 100,000.
Two major or one major and two minor manifestations (plus supporting evidence of streptococcal infection) based on the modified Jones criteria are needed for the diagnosis of acute rheumatic fever (Table 20–13). Except in cases of rheumatic fever manifesting solely as Sydenham chorea or long-standing carditis, there should be clear evidence of a streptococcal infection such as scarlet fever, a positive throat culture for group A β-hemolytic Streptococcus, and increased antistreptolysin O or other streptococcal antibody titers. The antistreptolysin O titer is significantly higher in rheumatic fever than in uncomplicated streptococcal infections.
Table 20–13. Jones criteria (modified) for diagnosis of rheumatic fever.
Carditis is the most serious consequence of rheumatic fever and varies from minimal to life-threatening HF. The term carditis implies pancardiac inflammation, but it may be limited to valves, myocardium, or pericardium. Valvulitis is frequently seen, with the mitral valve most commonly affected. Mitral insufficiency is the most common valvular residua of acute rheumatic carditis. Mitral stenosis after acute rheumatic fever is rarely encountered until 5–10 years after the first episode. Thus, mitral stenosis is much more commonly seen in adults than in children.
An early decrescendo diastolic murmur consistent with aortic insufficiency is occasionally encountered as the sole valvular manifestation of rheumatic carditis. The aortic valve is the second most common valve affected in polyvalvular as well as in single-valve disease. The aortic valve is involved more often in males and in African Americans. Dominant aortic stenosis of rheumatic origin does not occur in pediatric patients. In one large study, the shortest length of time observed for a patient to develop dominant aortic stenosis secondary to rheumatic heart disease was 20 years.
The large joints (knees, hips, wrists, elbows, and shoulders) are most commonly involved and the arthritis is typically migratory. Joint swelling and associated limitation of movement should be present. This is one of the more common major criteria, occurring in 80% of patients. Arthralgia alone is not a major criterion.
C. Sydenham Chorea
Sydenham chorea is characterized by involuntary and purposeless movements and is often associated with emotional lability. These symptoms become progressively worse and may be accompanied by ataxia and slurring of speech. Muscular weakness becomes apparent following the onset of the involuntary movements. Chorea is self-limiting, although it may last up to 3 months. Chorea may not be apparent for months to years after the acute episode of rheumatic fever.
D. Erythema Marginatum
A macular, serpiginous, erythematous rash with a sharply demarcated border appears primarily on the trunk and the extremities. The face is usually spared.
E. Subcutaneous Nodules
These usually occur only in severe cases, and then most commonly over the joints, scalp, and spinal column. The nodules vary from a few millimeters to 2 cm in diameter and are non-tender and freely movable under the skin.
Treatment & Prophylaxis
A. Treatment of the Acute Episode
1. Anti-infective therapy—Eradication of the streptococcal infection is essential. Long-acting benzathine penicillin is the drug of choice. Depending on the age and weight of the patient, a single intramuscular injection of 0.6–1.2 million units is effective; alternatively, give penicillin V, 250–500 mg orally 2–3 times a day for 10 days, or amoxicillin, 50 mg/kg (maximum 1 g) once daily for 10 days. Narrow-spectrum cephalosporins, clindamycin, azithromycin, or clarithromycin are used in those allergic to penicillin.
2. Anti-inflammatory agents
A. ASPIRIN—Aspirin, 30–60 mg/kg/d, is given in four divided doses. This dose is usually sufficient to effect dramatic relief of arthritis and fever. Higher dosages carry a greater risk of side effects and there are no proven short- or long-term benefits of high doses that produce salicylate blood levels of 20–30 mg/dL. The duration of therapy is tailored to meet the needs of the patient, but 2–6 weeks of therapy with reduction in dose toward the end of the course is usually sufficient. Other nonsteroidal anti-inflammatory agents used because of concerns about Reye syndrome are less effective than aspirin.
B. CORTICOSTEROIDS—There is no clear evidence to support the use of corticosteroids, but they are occasionally used for those with severe carditis.
3. Therapy in heart failure—Treatment for HF is based on symptoms and severity of valve involvement and cardiac dysfunction (see section on Heart Failure, earlier).
4. Bed rest and ambulation—Bed rest is not required in most cases. Activity level should be commensurate with symptoms and children should be allowed to self-limit their activity level while affected. Most acute episodes of rheumatic fever are managed on an outpatient basis.
B. Treatment After the Acute Episode
1. Prevention—Prevention is critical, as patients who have had rheumatic fever are at greater risk of recurrence if future group A β-hemolytic streptococcal infections are inadequately treated. Follow-up visits are essential to reinforce the necessity for prophylaxis, with regular intramuscular long-acting benzathine penicillin injections preferred to oral medication due to better adherence. Long-term (possibly lifelong) prophylaxis is recommended for patients with residual rheumatic heart disease. More commonly, with no or transient cardiac involvement, 5–10 years of therapy or discontinuance in early adulthood (age 21) (whichever is longer) is an effective approach.
The following preventive regimens are in current use:
A. PENICILLIN G BENZATHINE—600,000 units for less than 27 kg, 1.2 million units for more than 27 kg intramuscularly every 4 weeks is the drug of choice.
B. PENICILLIN V—250 mg orally twice daily is much less effective than intramuscular penicillin benzathine G (5.5 vs 0.4 streptococcal infections per 100 patient-years).
C. SULFADIAZINE—500 mg for less than 27 kg and 1 g for more than 27 kg, once daily. Blood dyscrasias and lesser effectiveness in reducing streptococcal infections make this drug less satisfactory than penicillin benzathine G. This is the recommended regimen for penicillin-allergic patients.
D. ERYTHROMYCIN—250 mg orally twice a day may be given to patients who are allergic to both penicillin and sulfonamides. Azithromycin or clarithromycin may also be used.
2. Residual valvular damage—As described above, the mitral and aortic valves are most commonly affected by rheumatic fever and the severity of carditis is quite variable. In the most severe cases, cardiac failure or the need for a valve replacement can occur in the acute setting. In less severe cases, valve abnormalities can persist, requiring lifelong medical management and eventual valve replacement. Other patients fully recover without residual cardiac sequelae.
Although antibiotic prophylaxis to protect against endocarditis used to be recommended for those with residual valvular abnormalities, the criteria for prevention of IE were revised in 2007 and routine prophylaxis is recommended only if a prosthetic valve is in place.
Cilliers A et al: Anti-inflammatory treatment for carditis in acute rheumatic fever. Cochrane Database Syst Rev 2012 Jun 13; 6:CD003176 [PMID: 22696333].
Gerber MA et al: Prevention of rheumatic fever and diagnosis and treatment of acute Streptococcal pharyngitis: a scientific statement from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee of the Council on Cardiovascular Disease in the Young, the Interdisciplinary Council on Functional Genomics and Translational Biology, and the Interdisciplinary Council on Quality of Care and Outcomes Research: endorsed by the American Academy of Pediatrics. Circulation 2009;119:1541–1551 [PMID: 19246689].
Kawasaki disease was first described in Japan in 1967 and was initially called mucocutaneous lymph node syndrome. The cause is unclear and there is no specific diagnostic test. Kawasaki disease is the leading cause of acquired heart disease in children in the United States. Eighty percent of patients are younger than 5 years old (median age at diagnosis is 2 years), and the male-to-female ratio is 1.5:1. Diagnostic criteria are fever for more than 5 days and at least four of the following features: (1) bilateral, painless, nonexudative conjunctivitis; (2) lip or oral cavity changes (eg, lip cracking and fissuring, strawberry tongue, and inflammation of the oral mucosa); (3) cervical lymphadenopathy greater than or equal to 1.5 cm in diameter and usually unilateral; (4) polymorphous exanthema; and (5) extremity changes (redness and swelling of the hands and feet with subsequent desquamation). Clinical features not part of the diagnostic criteria, but frequently associated with Kawasaki disease, are shown in Table 20–14.
Table 20–14. Noncardiac manifestations of Kawasaki disease.
The potential for cardiovascular complications is the most serious aspect of Kawasaki disease. Complications during the acute illness include myocarditis, pericarditis, valvular heart disease (usually mitral or aortic regurgitation), and coronary arteritis. Patients with fever for at least 5 days but fewer than four of the diagnostic features can be diagnosed with incomplete Kawasaki disease, especially if they have coronary artery abnormalities detected by echocardiography. Comprehensive recommendations regarding the evaluation for children with suspected incomplete Kawasaki disease were outlined in a 2004 Statement by the American Heart Association (see references at the end of this section).
Coronary artery lesions range from mild transient dilation of a coronary artery to large aneurysms. Aneurysms rarely form before day 10 of illness. Untreated patients have a 15%–25% risk of developing coronary aneurysms. Those at greatest risk for aneurysm formation are males, young infants (< 6 months), and those not treated with intravenous immunoglobulin (IVIG). Most coronary artery aneurysms resolve within 5 years of diagnosis; however, as aneurysms resolve, associated obstruction or stenosis (19% of all aneurysms) may develop, which may result in coronary ischemia. Giant aneurysms (> 8 mm) are less likely to resolve, and nearly 50% eventually become stenotic. Of additional concern, acute thrombosis of an aneurysm can occur, resulting in myocardial infarction that is fatal in approximately 20% of cases.
Immediate management of Kawasaki disease includes IVIG and high-dose aspirin. This therapy is effective in decreasing the incidence of coronary artery dilation and aneurysm formation. The currently recommended regimen is 2 g/kg of IVIG administered over 10–12 hours and 80–100 mg/kg/d of aspirin in four divided doses. The duration of high-dose aspirin is institution-dependent: many centers reduce the dose once the patient is afebrile for 48–72 hours; others continue through 5 afebrile days or day 14 of the illness. Once high-dose aspirin is discontinued, low-dose aspirin (3–5 mg/kg/d) is given through the subacute phase of the illness (6–8 weeks) or until coronary artery abnormalities resolve. If fever recurs within 48–72 hours of the initial treatment course and no other source of the fever is detected, a second dose of IVIG is often recommended; however, the effectiveness of this approach has not been clearly demonstrated. A multicenter, randomized, double-blind, placebo-controlled study demonstrated no beneficial effect of pulsed corticosteroids on the development of coronary abnormalities in patients responsive to IVIG. However, corticosteroids or other anti-inflammatory therapy (eg, infliximab) should be considered for patients with persistent fever despite one or two infusions of IVIG.
Follow-up of patients with treated Kawasaki disease depends on the degree of coronary involvement. In those with no or minimal coronary disease at the time of diagnosis, an echocardiogram 2 weeks and again 6–8 weeks after diagnosis is sufficient. Repeat echocardiography more than 8 weeks after diagnosis in those with no coronary abnormalities is optional. The risk stratification and recommended follow-up is reviewed in Table 20–15.
Table 20–15. Long-term management in Kawasaki disease.
McCrindle BW et al: Coronary artery involvement in children with Kawasaki disease: risk factors from analysis of serial normalized measurements. Circulation 2007 Jul 10;116(2): 174–179 [PMID: 17576863].
Newburger JW et al: Diagnosis, treatment, and long-term management of Kawasaki disease: a statement for health professionals from the Committee on Rheumatic Fever, Endocarditis and Kawasaki Disease, Council on Cardiovascular Disease in the Young, American Heart Association. Circulation 2004 Oct 26;110(17):2747–2771 [PMID: 15505111].
Newburger JW et al: Randomized trial of pulsed corticosteroid therapy for primary treatment of Kawasaki disease. N Engl J Med 2007 Feb 15;356(7):663–675 [PMID: 17301297].
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Positive blood culture.
Intracardiac oscillating mass, abscess, or new valve regurgitation on echocardiogram.
Elevated erythrocyte sedimentation rate or C-reactive protein.
Bacterial or fungal infection of the endocardium of the heart is rare and usually occurs in the setting of a preexisting abnormality of the heart or great arteries. It may occur in a normal heart during septicemia or as a consequence of infected indwelling central catheters.
The frequency of infective endocarditis (IE) appears to be increasing for several reasons: (1) increased survival in children with congenital heart disease, (2) greater use of central venous catheters, and (3) increased use of prosthetic material and valves. Pediatric patients without preexisting heart disease are also at increased risk for IE because of (1) increased survival rates for children with immune deficiencies, (2) long-term use of indwelling lines in ill newborns and patients with chronic diseases, and (3) increased intravenous drug abuse.
Patients at greatest risk are children with unrepaired or palliated cyanotic heart disease (especially in the presence of an aorta to pulmonary shunt), those with implanted prosthetic material, and patients who have had a prior episode of IE. Common organisms causing IE are viridans streptococci (30%–40% of cases), Staphylococcus aureus (25%–30%), and fungal agents (about 5%).
The majority of patients with IE have a history of heart disease. There may or may not be an antecedent infection or surgical procedure (cardiac surgery, tooth extraction, tonsillectomy). Transient bacteremia occurs frequently during normal daily activities such as flossing or brushing teeth, using a toothpick and even when chewing food. Although dental and nonsterile surgical procedures also can result in transient bacteremias, these episodes are much less frequent for a given individual. This may be why a clear inciting event is often not identified in association with IE and also underlies the recent changes in guidelines for antibiotic prophylaxis to prevent IE (for details, see Wilson et al reference).
B. Symptoms, Signs, and Laboratory Findings
Although IE can present in a fulminant fashion with cardiovascular collapse, often it presents in an indolent manner with fever, malaise, and weight loss. Joint pain and vomiting are less common. On physical examination, there may be a new or changing murmur, splenomegaly, and hepatomegaly. Classic findings of Osler nodes (tender nodules, usually on the pulp of the fingers), Janeway lesions (nontender hemorrhagic macules on palms and soles), splinter hemorrhages, and Roth spots (retinal hemorrhage) are uncommonly noted in children. Laboratory findings include multiple positive blood cultures, elevated erythrocyte sedimentation rate or C-reactive protein, and hematuria. Transthoracic echocardiography can identify large vegetations in some patients, but transesophageal imaging has better sensitivity and may be necessary if the diagnosis remains in question.
In 2007, the AHA revised criteria for patients requiring prophylaxis for IE (Table 20–16). Only the high-risk patients listed require antibiotics before dental work (tooth extraction or cleaning) and procedures involving the respiratory tract or infected skin or musculoskeletal structures. IE prophylaxis is not recommended for gastrointestinal or genitourinary procedures, body piercing, or tattooing.
Table 20–16. Conditions requiring antibiotic prophylaxis for the prevention of infective endocarditis (IE).
Recommended propylaxis is under 40 kg, 50 mg/kg of oral amoxicillin for patients < 40 kg and 2000 mg for those > 40 kg. This dose is to be given 1 hour prior to procedure. If the patient is allergic to amoxicillin, alternative prophylactic antibiotics are recommended in the AHA guidelines.
In general, appropriate antibiotic therapy should be initiated as soon as IE is suspected and several large volume blood cultures have been obtained via separate venipunctures. Therapy can be tailored once the pathogen and sensitivities are defined. Vancomycin or a β-lactam antibiotic, with or without gentamicin, for a 6-week course is the most common regimen. If HF occurs and progresses in the face of adequate antibiotic therapy, surgical excision of the infected area and prosthetic valve replacement must be considered.
Course & Prognosis
Factors associated with a poor outcome are delayed diagnosis, presence of prosthetic material, perioperative associated IE, and S aureus infection. Mortality for bacterial endocarditis in children ranges from 10% to 25%, with fungal infections having a much greater mortality (50% or more).
Wilson W et al: Prevention of infective endocarditis: guidelines from the American Heart Association: a guideline from the American Heart Association Rheumatic Fever, Endocarditis, and Kawasaki Disease Committee, Council on Cardiovascular Disease in the Young, and the Council on Clinical Cardiology, Council on Cardiovascular Surgery and Anesthesia, and the Quality of Care and Outcomes Research Interdisciplinary Working Group. Circulation 2007;116:1736–1754 [PMID: 17446442].
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Chest pain made worse by deep inspiration and decreased by leaning forward.
Fever and tachycardia.
Shortness of breath.
Pericardial friction rub.
ECG with elevated ST segments.
Pericarditis is an inflammation of the pericardium and is commonly related to an infectious process. The most common cause of pericarditis in children is viral infection (eg, coxsackievirus, mumps, Epstein-Barr, adenovirus, influenza, and human immunodeficiency virus [HIV]). Purulent pericarditis results from bacterial infection (eg, pneumococci, streptococci, staphylococci, and Haemophilus influenzae) and is less common but potentially life-threatening.
In some cases, pericardial disease occurs in association with a generalized process. Associations include rheumatic fever, rheumatoid arthritis, uremia, systemic lupus erythematosus, malignancy, and tuberculosis. Pericarditis after cardiac surgery (postpericardiotomy syndrome) is most commonly seen after surgical closure of an ASD. Postpericardiotomy syndrome appears to be autoimmune in nature with high titers of antiheart antibody and evidence of acute or reactivated viral illness. The syndrome is often self-limited and responds well to short courses of aspirin or corticosteroids.
A. Symptoms and Signs
Childhood pericarditis usually presents with sharp stabbing mid chest, shoulder, and neck pain made worse by deep inspiration or coughing, and decreased by sitting up and leaning forward. Shortness of breath and grunting respirations are common. Physical findings depend on the presence of fluid accumulation in the pericardial space (effusion). In the absence of significant accumulation, a characteristic scratchy, high-pitched friction rub may be heard. If the effusion is large, heart sounds are distant and muffled and a friction rub may not be present. In the absence of cardiac tamponade, the peripheral, venous, and arterial pulses are normal.
Cardiac tamponade occurs in association with a large effusion, or one that has rapidly accumulated. Tamponade is characterized by jugular venous distention, tachycardia, hepatomegaly, peripheral edema, and pulsus paradoxus, in which systolic blood pressure drops more than 10 mm Hg during inspiration. Decreased cardiac filling and subsequent decrease in cardiac output result in signs of right heart failure and the potential for cardiovascular collapse.
In pericarditis with a significant pericardial effusion, the cardiac silhouette is enlarged. The cardiac silhouette can appear normal if the effusion has developed over an extremely short period of time.
The ST segments are commonly elevated in acute pericarditis and PR segment depression may be present. Low voltages or electrical alternans (alteration in QRS amplitude between beats) can be seen with large pericardial effusions.
Serial echocardiography allows a direct, noninvasive estimate of the volume of pericardial fluid and its change over time. Cardiac tamponade is associated with compression of the atria or respiratory alteration of ventricular inflow demonstrated by Doppler imaging.
Treatment depends on the cause of pericarditis and the size of the associated effusion. Viral pericarditis is usually self-limited and symptoms can be improved with nonsteroidal anti-inflammatory therapy. Purulent pericarditis requires immediate evacuation of the fluid and appropriate antibiotic therapy. Cardiac tamponade from any cause must be treated by immediate removal of the fluid, usually via pericardiocentesis. Pericardiocentesis should also be considered if the underlying cause is unclear or identification of the pathogen is necessary for targeted therapy. In the setting of recurrent or persistent effusions, a surgical pericardiectomy or pericardial window may be necessary. Diuretics should be avoided in the patient with cardiac tamponade because they reduce ventricular preload and can exacerbate the degree of cardiac decompensation.
Prognosis depends to a great extent on the cause of pericardial disease. Constrictive pericarditis can develop following infectious pericarditis (especially if bacterial or tuberculous) and can be a difficult problem to manage. Cardiac tamponade will result in death unless the fluid is evacuated.
Ratnapalan S, Brown K, Benson L: Children presenting with acute pericarditis to the emergency department. Pediatr Emerg Care 2011 Jul;27(7):581–585 [PMID: 21712753].
There are five classified forms of cardiomyopathy in children: (1) dilated, (2) hypertrophic, (3) restrictive, (4) arrhythmogenic right ventricular dysplasia (ARVD), and (5) left ventricular noncompaction. Discussion will be limited to the first three forms, which are the most common.
1. Dilated Cardiomyopathy
This most frequent of the childhood cardiomyopathies occurs with an annual incidence of 4–8 cases per 100,000 population in the United States and Europe. Although usually idiopathic, identifiable causes of dilated cardiomyopathy (DCM) include viral myocarditis, untreated tachyarrhythmias, left heart obstructive lesions, congenital abnormalities of the coronary arteries, medication toxicity (eg, anthracycline), and genetic (eg, dystrophin gene defects, sarcomeric mutations) and metabolic diseases (inborn errors of fatty acid oxidation and mitochondrial oxidative phosphorylation defects). Genetic causes are being discovered at an increasing rate with commercial testing now available for some of the more common genes.
A. Signs and Symptoms
As myocardial function fails and the heart dilates, cardiac output falls, and affected children develop decreased exercise tolerance, failure to thrive, diaphoresis, and tachypnea. As the heart continues to deteriorate, congestive signs such as hepatomegaly and rales develop, and a prominent gallop can be appreciated on examination. The initial diagnosis in a previously healthy child can be difficult, as presenting symptoms can resemble a viral respiratory infection, pneumonia, or asthma.
Chest radiograph shows generalized cardiomegaly with or without pulmonary venous congestion.
Sinus tachycardia with ST-T segment changes is commonly seen on ECG. The criteria for right and left ventricular hypertrophy may also be met and the QT interval may be prolonged. Evaluation for the presence of supraventricular arrhythmias on ECG is critical, as this is one of the few treatable and reversible causes of DCM in children.
The echocardiogram shows LV and left atrial enlargement with decreased LV-shortening fraction and ejection fraction. The calculated end-diastolic and end-systolic dimensions are increased and mitral insufficiency is commonly seen. A careful evaluation for evidence of structural abnormalities (especially coronary artery anomalies or left heart obstructive lesions) must be performed, especially in infant patients.
E. Other Testing
Cardiac catheterization is useful to evaluate hemodynamic status and coronary artery anatomy. Endomyocardial biopsies can aid in diagnosis. Biopsy specimens may show inflammation consistent with acute myocarditis, abnormal myocyte architecture, and myocardial fibrosis. Electron micrographs may reveal evidence of mitochondrial or other metabolic disorders. Polymerase chain reaction (PCR) testing may be performed on biopsied specimens to detect viral genome products in infectious myocarditis. Skeletal muscle biopsy may be helpful in patients with evidence of skeletal muscle involvement. Cardiopulmonary stress testing is useful for measuring response to medical therapy and as an objective assessment of the cardiac limitations on exercise. Cardiac MRI is increasingly used for the diagnosis of myocarditis and can detect the presence of fibrosis by delayed gadolinium enhancement.
Treatment & Prognosis
Outpatient management of pediatric DCM usually entails combinations of afterload-reducing agents and diuretics (see section on Heart Failure, earlier). In 2007, Shaddy et al published the results of a multicenter, placebo-controlled, doubleblind trial of carvedilol in children with HF. Children did not receive the same beneficial effects of β-blocker therapy as adults with HF, possibly due to the heterogenous nature of HF in children, but perhaps there are inherent differences in pediatric and adult HF. Aspirin or warfarin may be used to prevent thrombus formation in the dilated and poorly contractile cardiac chambers. Arrhythmias are more common in dilated hearts. Antiarrhythmic agents that do not suppress myocardial contractility, such as amiodarone, are used when necessary. Despite widespread use of internal defibrillators in the adult population, the technical difficulty of implanting internal defibrillators and the risk of adverse events (eg, high frequency of inappropriate discharge, vascular obstruction) in children limit their use.
Therapy of the underlying cause of cardiomyopathy is always indicated if possible. Unfortunately despite complete evaluation, a diagnosis is discovered in less than 30% of patients with DCM. If medical management is unsuccessful, cardiac transplantation is considered.
2. Hypertrophic Cardiomyopathy
The most common cause of hypertrophic cardiomyopathy (HCM) is familial hypertrophic cardiomyopathy, which is found in 1 in 500 individuals. HCM is the leading cause of sudden cardiac death in young persons. The most common presentation is in an older child, adolescent, or adult, although it may occur in neonates. Causes of nonfamilial HCM in neonates and young children include glycogen storage disease, Noonan syndrome (including related syndromes such as LEOPARD and Costello syndrome), Friedreich ataxia, maternal gestational diabetes, mitochondrial disorders, and other metabolic disorders.
A. Familial Hypertrophic Cardiomyopathy
In the familial form, HCM is most commonly caused by a mutation in one of the several genes that encode proteins of the cardiac sarcomere (β-myosin heavy chain, cardiac troponin T or I, α-tropomyosin, and myosin-binding protein C).
1. Clinical findings—Patients may be asymptomatic despite having significant hypertrophy, or may present with symptoms of inadequate coronary perfusion or HF such as angina, syncope, palpitations, or exercise intolerance. Patients may experience sudden cardiac death as their initial presentation, often precipitated by sporting activities. Although the cardiac examination may be normal on presentation, some patients develop a left precordial bulge with a diffuse point of maximal impulse. An LV heave or an S4 gallop may be present. If outflow tract obstruction exists, a systolic ejection murmur will be audible. A murmur may not be audible at rest but may be provoked with exercise or positional maneuvers that decrease left ventricular volume (standing), thereby increasing the outflow tract obstruction.
A. ECHOCARDIOGRAPHY—The diagnosis of HCM is usually made by echocardiography and in most familial cases demonstrates asymmetrical septal hypertrophy. Young patients with metabolic or other nonfamilial causes are more likely to have concentric hypertrophy. Systolic anterior motion of the mitral valve leaflet may occur and contribute to LV outflow tract obstruction. The mitral valve leaflet may become distorted and result in mitral insufficiency. LV outflow tract obstruction may be present at rest or provoked with either amyl nitrate or monitored exercise. Systolic function is most often hypercontractile in young children but may deteriorate over time, resulting in poor contractility and LV dilation. Diastolic function is almost always abnormal.
B. ELECTROCARDIOGRAPHY—The ECG may be normal, but more typically demonstrates deep Q waves in the inferolateral leads (II, III, aVF, V5, and V6) secondary to the increased mass of the hypertrophied septum. ST-segment abnormalities may be seen in the same leads. Age-dependent criteria for LVH are often present as are criteria for left atrial enlargement.
C. OTHER TESTING—Cardiopulmonary stress testing is valuable to evaluate for provocable LV outflow tract obstruction, ischemia, and arrhythmias, and to determine prognosis. Extreme LVH and a blunted blood pressure response to exercise have both been associated with increased mortality in children. Cardiac MRI is useful for defining areas of myocardial fibrosis or scarring. Patients are at risk for myocardial ischemia, possibly as a result of systolic compression of the intramyocardial septal perforators, myocardial bridging of epicardial coronary arteries, or an imbalance of coronary artery supply and demand due to the presence of massive myocardial hypertrophy.
D. CARDIAC CATHETERIZATION—Cardiac catheterization is performed in patients with HCM who have angina, syncope, resuscitated sudden death, or a worrisome stress test. Hemodynamic findings include elevated left atrial pressure secondary to impaired diastolic filling. If midcavitary LV outflow tract obstruction is present, an associated pressure gradient will be evident. Provocation of LV outflow tract obstruction with either rapid atrial pacing or isoproterenol may be sought, but this is not commonly done in children. Angiography demonstrates a “ballerina slipper” configuration of the LV secondary to the midcavitary LV obliteration during systole. The myocardial biopsy specimen demonstrates myofiber disarray.
2. Treatment and prognosis—Treatment varies depending on symptoms and phenotype. Affected patients are restricted from competitive athletics and isometric exercise due to associated risk of sudden cardiac death. Patients with resting or latent LV outflow tract obstruction may be treated with β-blockers, verapamil, or disopyramide with variable success in alleviating obstruction. Patients with severe symptoms despite medical therapy and an LV outflow tract gradient may require additional intervention. Surgical myectomy with resection of part of the hypertrophied septum has been used in symptomatic patients with good results. At the time of myectomy, the mitral valve may require repair or replacement in patients with a long history of systolic anterior motion of the mitral valve. Ethanol ablation is used in adults with HCM and LV outflow tract obstruction. This procedure involves selective infiltration of ethanol in a coronary septal artery branch to induce a small targeted myocardial infarction. This leads to a reduction in septal size and improvement of obstruction. The long-term effects of this procedure are unknown and it is not commonly employed in children. Although dual-chamber pacing has been used in children with good relief of obstruction, larger series demonstrate no significant improvement in obstruction. Risk stratification with respect to sudden death is important in HCM. Consideration for placement of internal defibrillators in adult patients are based on the known risk factors for sudden cardiac death: severe hypertrophy (> 3 cm septal thickness in adults), documented ventricular arrhythmias, syncope, abnormal blood pressure response to exercise, resuscitated sudden death, or a strong family history of HCM with associated sudden death. The criteria for defibrillator placement in children are not as well defined.
B. Glycogen Storage Disease of the Heart
There are at least 10 types of glycogen storage disease. The type that primarily involves the heart is Pompe disease (GSD IIa) in which acid maltase, necessary for hydrolysis of the outer branches of glycogen, is absent. There is marked deposition of glycogen within the myocardium. Affected infants are well at birth, but symptoms of growth and developmental delay, feeding problems, and cardiac failure occur by the sixth month of life. Physical examination reveals generalized muscular weakness, a large tongue, and cardiomegaly without significant heart murmurs. Chest radiographs reveal cardiomegaly with or without pulmonary venous congestion. The ECG shows a short PR interval and LVH with ST depression and T-wave inversion over the left precordial leads. Echocardiography shows severe concentric LVH. Although historically children with Pompe disease usually died before age 1 year, recent enzyme replacement clinical trials have shown some promise in reversing hypertrophy and preserving cardiac function. Death may be sudden or result from progressive HF.
3. Restrictive Cardiomyopathy
Restrictive cardiomyopathy is a rare entity in the pediatric population, accounting for less than 5% of all cases of cardiomyopathy. The cause is usually idiopathic but can be familial or secondary to an infiltrative process (eg, amyloidosis).
Patients present with signs of congestive HF as a consequence of diastolic dysfunction in the setting of preserved systolic function. The left ventricle is more severely affected than the right ventricle in restrictive cardiomyopathy, but the right ventricle is also affected in most cases resulting in signs and symptoms consistent with biventricular congestion. Patients often present with exercise intolerance, fatigue, chest pain and orthopnea. Physical examination is remarkable for a prominent S4 and jugular venous distention.
ECG demonstrates marked right and left atrial enlargement with normal ventricular voltages. ST-T–wave abnormalities including a prolonged QTc interval may be present.
The diagnosis is confirmed echocardiographically by the presence of normal-sized ventricles with normal systolic function and massively dilated atria. Cardiac MRI is useful in ruling out pericardial abnormalities (restrictive or constrictive pericarditis) and infiltrative disorders.
Treatment & Prognosis
Anticongestive therapy is used for symptomatic relief. The high risk of sudden death in restrictive cardiomyopathy and the propensity for rapid progression of irreversible pulmonary hypertension warrant close follow-up with early consideration of cardiac transplantation.
Chen LR et al: Reversal of cardiac dysfunction after enzyme replacement in patients with infantile-onset Pompe disease. J Pediatr 2009 Aug;155(2):271–275, e272 [PMID: 19486996].
Colan SD et al: Epidemiology and cause-specific outcome of hypertrophic cardiomyopathy in children: findings from the Pediatric Cardiomyopathy Registry. Circulation 2007 Feb 13; 115(6):773–781 [PMID: 17261650].
Decker JA et al: Risk factors and mode of death in isolated hypertrophic cardiomyopathy in children. J Am Coll Cardiol 2009 Jul 14;54(3):250–254 [PMID: 19589438].
Shaddy RE et al: Carvedilol for children and adolescents with heart failure: a randomized controlled trial. JAMA 2007 Sep 12;298(10):1171–1179 [PMID: 17848651].
Towbin JA et al: Incidence, causes, and outcomes of dilated cardiomyopathy in children. JAMA 2006 Oct 18;296(15):1867–1876 [PMID: 17047217].
The most common causes of viral myocarditis are adenoviruses, coxsackie A and B viruses, echoviruses, parvovirus, cytomegalovirus, and influenza A virus. HIV can also cause myocarditis. The ability to identify the pathogen has been enhanced by PCR technology, which replicates identifiable segments of the viral genome from the myocardium of affected children.
A. Symptoms and Signs
There are two major clinical patterns. In the first, sudden-onset HF occurs in an infant or child who was relatively healthy in the hours to days previously. This malignant form of the disease is usually secondary to overwhelming viremia with tissue invasion in multiple organ systems including the heart. In the second pattern, the onset of cardiac symptoms is gradual and there may be a history of upper respiratory tract infection or gastroenteritis in the previous month. This more insidious form may have a late postinfectious or autoimmune component. Acute and chronic presentations occur at any age and with all types of myocarditis.
The signs of HF are variable, but in a decompensated patient with fulminant myocarditis include pale gray skin; rapid, weak, and thready pulses; and breathlessness. In those with a more subacute presentation signs include increased work of breathing such as orthopnea, difficulty with feeding in infants, exercise intolerance and edema of the face and extremities. The patient is usually tachycardic and heart sounds may be muffled and distant; an S3 or S4gallop (or both) are common. Murmurs are usually absent, although a murmur of tricuspid or mitral insufficiency may be heard. Moist rales are usually present at both lung bases. The liver is enlarged and frequently tender.
Generalized cardiomegaly is seen on radiographs along with moderate to marked pulmonary venous congestion.
The ECG is variable. Classically, there is low-voltage QRS in all frontal and precordial leads with ST-segment depression and inversion of T waves in leads I, III, and aVF (and in the left precordial leads during the acute stage). Dysrhythmias are common, and AV and intraventricular conduction disturbances may be present.
Echocardiography demonstrates four-chamber dilation with poor ventricular function and AV valve regurgitation. A pericardial effusion may be present. Patients with a more acute presentation may have less ventricular dilation than those with a longer history of HF-related symptoms.
E. Myocardial Biopsy
An endomyocardial biopsy may be helpful in the diagnosis of viral myocarditis. An inflammatory infiltrate with myocyte damage can be seen by hematoxylin and eosin staining. Viral PCR testing of the biopsy specimen may yield a positive result in 30%–40% of patients suspected to have myocarditis. However, myocarditis is thought to be a “patchy” process, so it is possible that biopsy results are falsely negative if the area of active myocarditis was missed.
F. Cardiac MRI
Cardiac MRI is increasing in use as a potential diagnostic modality for myocarditis. Abnormalities in T2-weighted imaging (consistent with myocardial edema, inflammation) and global relative enhancement (evidence of capillary leak) are evident in patients with acute myocarditis. This imaging method requires general anesthesia in infants and young children, which is associated with significant risk in those with HF and must be a consideration when ordering this test.
The inpatient cardiac support measures outlined previously in the section on heart failure are used in the treatment of these patients. The use of digitalis in a rapidly deteriorating child with myocarditis is dangerous and should be undertaken with great caution, as it may cause ventricular dysrhythmias.
Administration of immunomodulating medications such as corticosteroids for myocarditis is controversial. If the patient’s condition deteriorates despite anticongestive measures, corticosteroids are commonly used, although conclusive data supporting their effectiveness are lacking. Subsequent to the successful use of IVIG in children with Kawasaki disease, there have been several trials of IVIG in presumed viral myocarditis. The therapeutic value of IVIG remains unconfirmed. Initiation of mechanical circulatory support in those with fulminant or severe myocarditis is another therapeutic option as a bridge to transplantation or recovery.
The prognosis of myocarditis is determined by the age at onset and the response to therapy. Children presenting with fulminant myocarditis and severe hemodynamic compromise have a 75% early mortality. Those at highest risk for a poor outcome are those presenting in the first year of life. Complete recovery is possible, although some patients recover clinically but have persistent LV dysfunction and require ongoing medical therapy for HF. It is possible that subclinical myocarditis in childhood is the pathophysiologic basis for some of the “idiopathic” DCMs later in life. Children with myocarditis whose ventricular function fails to return to normal may be candidates for cardiac transplantation if they remain symptomatic or suffer growth failure despite maximal medical management.
May LJ, Patton DJ, Fruitman DS: The evolving approach to paediatric myocarditis: A review of the current literature. Cardiol Young 2011 Jun;21(3):241–251 [Epub 2011 Jan 28] [PMID: 21272427].
Blood pressure should be determined at every pediatric visit beginning at 3 years. Because blood pressure is being more carefully monitored, systemic hypertension has become more widely recognized as a pediatric problem. Pediatric standards for blood pressure have been published. Blood pressures in children must be obtained when the child is relaxed and an appropriate-size cuff must always be used. The widest cuff that fits between the axilla and the antecubital fossa should be used (covers 60%–75% of the upper arm). Most children aged 10–11 years need a standard adult cuff (bladder width of 12 cm), and many high school students need a large adult cuff (width of 16 cm) or leg cuff (width of 18 cm). The pressure coinciding with the onset (K1) and the loss (K5) of the Korotkoff sounds determines the systolic and diastolic blood pressure, respectively. If a properly measured blood pressure exceeds the 95th percentile (Table 20-17), the measurement should be repeated several times over a 2- to 4-week interval. If it is elevated persistently, a search for the cause should be undertaken. Although most hypertension in children is essential, the incidence of treatable causes is higher in children than in adults; these include conditions such as coarctation of the aorta, renal artery stenosis, chronic renal disease, and pheochromocytoma, as well as medication side effects (eg, steroids). If no cause is identified, and hypertension is deemed essential, antihypertensive therapy should be initiated and nutritional and exercise counseling given. β-Blockers or ACE inhibitors are the usual first-line medical therapies for essential hypertension in children.
Table 20–17. The 95th percentile value for blood pressure (mm Hg) taken in the sitting position.a
Falkner B: Hypertension in children and adolescents: epidemiology and natural history. Pediatr Nephrol 2010 Jul;25(7):1219-1224 [PMID: 19421783].
ATHEROSCLEROSIS & DYSLIPIDEMIAS
Awareness of coronary artery risk factors in general, and atherosclerosis in particular, has risen dramatically in the general population since the mid-1970s. Although coronary artery disease is still the leading cause of death in the United States, the age-adjusted incidence of death from ischemic heart disease has been decreasing as a result of improved diet, decreased smoking, awareness and treatment of hypertension, and an increase in physical activity. The level of serum lipids in childhood usually remains constant through adolescence. Biochemical abnormalities in the lipid profile appearing early in childhood correlate with higher risk for coronary artery disease in adulthood. Low-density lipoprotein (LDL) is atherogenic, while its counterpart, high-density lipoprotein (HDL) has been identified as an anti-atherogenic factor.
Routine lipid screening of children at age 3 years remains controversial. The National Cholesterol Education Program recommends selective screening in children with high-risk family members, defined as a parent with total cholesterol greater than 240 mg/dL or a parent or grandparent with early-onset cardiovascular disease. When children have LDL levels greater than 130 mg/dL on two successive tests, dietary lifestyle counseling is appropriate. Dietary modification may decrease cholesterol levels by 5%–20%. If the patient is unresponsive to diet change and at extreme risk (eg, LDL > 160 mg/dL, HDL < 35 mg/dL, and a history of cardiovascular disease in a first-degree relative at an age < 40 years), drug therapy may be indicated. Cholestyramine, a bile acid–binding resin, is rarely used today due to poor adherence. The 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) are more commonly used in the pediatric population. Niacin is useful for treatment of hypertriglyceridemia.
Gidding SS et al: Dietary recommendations for children and adolescents: a guide for practitioners: consensus statement from the American Heart Association. Circulation 2005 Sep 27;112(13):2061–2075 [PMID: 16186441].
McCrindle BW et al: Drug therapy of high-risk lipid abnormalities in children and adolescents: a scientific statement from the American Heart Association Atherosclerosis, Hypertension, and Obesity in Youth Committee, Council of Cardiovascular Disease in the Young, with the Council on Cardiovascular Nursing. Circulation 2007 Apr 10;115(14):1948–1967 [PMID: 17377073].
Chest pain is a common pediatric complaint, accounting for 6 in 1000 visits to urban emergency departments and urgent care clinics. Although children with chest pain are commonly referred for cardiac evaluation, chest pain in children is rarely cardiac in origin. Other more likely causes of chest pain in children include reactive airways disease, musculoskeletal pain, esophagitis, gastritis, and functional pain.
Detailed history and physical examination should guide the pediatrician to the appropriate workup of chest pain. Rarely is there a need for laboratory tests or evaluation by a specialist. The duration, location, intensity, frequency, and radiation of the pain should be documented, and possible triggering events preceding the pain should be explored. For instance, chest pain following exertion may lead to a more elaborate evaluation for a cardiac disorder. The timing of the pain in relation to meals may suggest a gastrointestinal cause. The patient should also be asked about how pain relief is achieved. A social history to reveal psychosocial stressors and cigarette smoke exposure may be revealing. On physical examination, attention must be placed on the vital signs; general appearance of the child; the chest wall musculature; cardiac, pulmonary, and abdominal examination findings; and quality of peripheral pulses. If the pain can be reproduced through direct palpation of the chest wall, it is almost always musculoskeletal in origin.
Cardiac disease is a rare cause of chest pain, but, if misdiagnosed, it may be life-threatening. Although myocardial infarction rarely occurs in healthy children, patients with diabetes mellitus, chronic anemia, abnormal coronary artery anatomy, or HCM may be at increased risk for ischemia. A history of Kawasaki disease with coronary involvement is a risk for myocardial infarction secondary to thrombosis of coronary aneurysms. More than 50% of children and adolescents who exhibit sequelae from Kawasaki disease arrive at the emergency department with chest pain.
Young children may mistake palpitations for chest pain. Supraventricular tachycardia (SVT), atrial flutter, premature ventricular contractions (PVCs), or ventricular tachycardia may be described as chest pain in children. Structural lesions that can cause chest pain include aortic stenosis, pulmonary stenosis, and mitral valve prolapse. Other cardiac lesions causing chest pain include DCM, myocarditis, pericarditis, rheumatic carditis, and aortic dissection.
Noncardiac chest pain may be due to a respiratory illness, reactive airway disease, pneumonia, pneumothorax, or pulmonary embolism. Gastrointestinal causes of chest pain include reflux, esophagitis, and foreign body ingestion. The most common cause of chest pain (30% of children) is inflammation of musculoskeletal structures of the chest wall. Costochondritis is caused by inflammation of the costochondral joints and is usually unilateral and reproducible on examination.
In most cases, sophisticated testing is not required. However, if a cardiac origin is suspected, a pediatric cardiologist should be consulted. Evaluation in these instances may include an ECG, chest radiograph, echocardiogram, Holter monitor, or serum troponin levels if there are known risk factors for ischemia.
Hanson CL, Hokanson JS: Etiology of chest pain in children and adolescents referred to cardiology clinic. WMJ 2011 Apr;110(2):58–62 [PMID: 21560558].
Cardiac transplantation is an effective therapeutic modality for infants and children with end-stage cardiac disease. Indications for transplantation include (1) progressive HF despite maximal medical therapy, (2) complex congenital heart diseases that are not amenable to surgical repair or palliation, or in instances in which the surgical palliative approach has an equal or higher risk of mortality compared with transplantation, and (3) malignant arrhythmias unresponsive to medical therapy, catheter ablation, or automatic implantable cardiodefibrillator. Approximately 300–400 pediatric cardiac transplant procedures are performed annually in the United States. Infant (< 1 year of age) transplants account for 30% of pediatric cardiac transplants. The current estimated graft half-life for children undergoing cardiac transplantation in infancy is over 19 years, while overall pediatric heart transplant graft half-life is approximately 14 years.
Careful evaluation of the recipient and the donor is performed prior to cardiac transplantation. Assessment of the recipient’s pulmonary vascular resistance is critical, as irreversible and severe pulmonary hypertension is a risk factor for post-transplant right heart failure and early death. End-organ function of the recipient may also influence post-transplant outcome and should be evaluated closely. Donor-related factors that can have an impact on outcome include cardiac function, amount of inotropic support needed, active infection (HIV and hepatitis B and C are contraindications to donation), donor size, and ischemic time to transplantation.
The ideal post-transplant immunosuppressive regimen allows the immune system to continue to recognize and respond to foreign antigens in a productive manner while avoiding graft rejection. Although there are many different regimens, calcineurin inhibitors (eg, cyclosporine and tacrolimus) remain the mainstay of maintenance immunosuppression in pediatric heart transplantation. Calcineurin inhibitors may be used in isolation in children considered to be at low risk for graft rejection. Double-drug therapy includes the addition of antimetabolite or antiproliferative medications such as azathioprine, mycophenolate mofetil, or sirolimus. Because of the significant adverse side effects of corticosteroids in children, many centers attempt to avoid chronic steroid use. Growth retardation, susceptibility to infection, impaired wound healing, hypertension, diabetes, osteoporosis, and a cushingoid appearance are some of the consequences of long-term steroid use.
Despite advances in immunosuppression, graft rejection remains the leading cause of death in the first 3 years after transplantation. The pathophysiologic mechanisms of rejection are not entirely known. T cells are required for rejection, but multiple cell lines and mechanisms are likely involved. Because graft rejection can present in the absence of clinical symptomatology, monitoring for and diagnosing rejection in a timely fashion can be difficult. Screening regimens include serial physical examinations, electrocardiography, echocardiography, and cardiac catheterization with endomyocardial biopsy.
A. Symptoms and Signs
Acute graft rejection may not cause symptoms in the early stages. With progression, patients may develop tachycardia, tachypnea, rales, a gallop rhythm, or hepatosplenomegaly. Infants and young children may present with irritability, poor feeding, vomiting, or lethargy. There is 50% mortality within 1 year for those suffering an episode of rejection associated with hemodynamic compromise, so early detection is critical.
In an actively rejecting patient, chest radiographs may show cardiomegaly, pulmonary edema, or pleural effusions.
Abnormalities in conduction can be present, although the most typical finding is reduced QRS voltages. Both atrial and ventricular arrhythmias can occur in rejection.
Echocardiography is a noninvasive rejection surveillance tool that is especially useful in infant recipients, but helpful in all ages. Changes in ventricular compliance and function may initially be subtle, but are progressive with increasing duration of the rejection episode. A new pericardial effusion or worsening valvular insufficiency may also indicate rejection.
E. Cardiac Catheterization and Endomyocardial Biopsy
Hemodynamic assessment including ventricular filling pressures, cardiac output, and oxygen consumption can be obtained via cardiac catheterization. The endomyocardial biopsy is useful in diagnosing acute graft rejection. However, because not all episodes of symptomatic rejection result in a positive biopsy result, this tool is not universally reliable. The appearance of infiltrating lymphocytes with myocellular damage on the biopsy is the hallmark of cell-mediated graft rejection and is helpful if present.
Treatment of Graft Rejection
The goal of graft rejection treatment is to reverse the immunologic inflammatory cascade. High-dose corticosteroids are the first line of treatment. Frequently additional therapy with antithymocyte biologic preparations such as antithymocyte globulin (a rabbit-based polyclonal antibody) is needed to reverse rejection. Most rejection episodes can be treated effectively if diagnosed promptly. Usually graft function returns to its baseline state, although severe rejection episodes can result in chronic graft failure, graft loss, and patient death even with optimal therapy. Antibody mediated rejection is another form of acute rejection that is treated in a similar fashion as T-cell mediated rejection, but the addition of plasmapheresis and IVIG to the treatment regimen may improve outcomes. The diagnosis of antibody mediated rejection varies across centers, but can be a combination of clinical findings consistent with rejection in the absence of evidence of cell-mediated rejection, evidence of complement deposition on endomyocardial biopsy and new or increasing antibody production (typically anti-human lymphocyte antigen [HLA] antibodies) in the circulation.
Course & Prognosis
The quality of life of pediatric heart transplant recipients is usually quite good. The risk of infection is low after the immediate post-transplant period in spite of chronic immunosuppression. Cytomegalovirus is the most common pathogen responsible for infection-related morbidity and mortality in heart transplant recipients. Most children tolerate environmental pathogens well. Nonadherence with lifetime immunosuppression is of great concern especially in adolescent patients. Several recent studies have identified nonadherence as the leading cause of late death. Post-transplant lymphoproliferative disorder, a syndrome related to Epstein-Barr virus infection, can result in a Burkitt-like lymphoma that usually responds to a reduction in immunosuppression, but occasionally must be treated with chemotherapy and can be fatal. The overwhelming majority of children are not physically limited and do not require restrictions related to the cardiovascular system.
The greatest long-term concern after heart transplantation is related to cardiac allograft vasculopathy (transplant coronary artery disease). Cardiac allograft vasculopathy results from intimal proliferation within the lumen of the coronary arteries that can ultimately result in complete luminal occlusion. These lesions are diffuse and often involve distal vessels and thus are usually not amenable to bypass grafting, angioplasty, or stent placement. The etiology of these lesions has an immune basis, but the specifics are not known making targeted therapy challenging. Overall, despite the concerns of immunosuppression, the risk of late rejection, and coronary disease, the majority of pediatric patients enjoy a good quality of life with survival rates that are improving. Currently, 10-year survival is around 60% overall for pediatric recipients. Newer, more specific, and more effective immunosuppressive agents are currently being tried in clinical studies or are being evaluated in preclinical studies, making the future promising for children after cardiac transplantation.
QUALITY IMPROVEMENT FOR PEDIATRIC HEART TRANSPLANTATION
The Pediatric Heart Transplant Study (PHTS) group is a consortium of over 40 pediatric heart transplant centers in North America and Europe that maintains an event-driven database that is used to support research aimed at improving treatment options and outcomes for children in need of a heart transplant or who have had a transplant. This group was established in 1993 and has published over 56 manuscripts in peer-reviewed journals. Each participating center receives an annual report that details center-specific outcomes compared to the collaborative group as a whole. This report is utilized for internal quality assurance purposes and as a performance benchmark.
Canter CE et al: Indications for heart transplantation in pediatric heart disease: a scientific statement from the American Heart Association Council on Cardiovascular Disease in the Young; the Councils on Clinical Cardiology, Cardiovascular Nursing, and Cardiovascular Surgery and Anesthesia; and the Quality of Care and Outcomes Research Interdisciplinary Working Group. Circulation 2007 Feb 6;115(5):658–676 [PMID: 17261651].
Kirk R et al: The Registry of the International Society for Heart and Lung Transplantation: thirteenth official pediatric heart transplantation report—2010. J Heart Lung Transplant 2010 Oct;29(10):1119–1128; no abstract available [PMID: 20870166].
International Society for Heart and Lung Transplant Registry Slides: http://www.ishlt.org/registries/slides.asp?slides=heartLungRegistryPHTS website: http://www.uab.edu/phts/
PRIMARY PULMONARY HYPERTENSION
ESSENTIALS OF DIAGNOSIS & TYPICAL FEATURES
Often subtle with symptoms of dyspnea, fatigue, chest pain, and syncope.
Loud pulmonary component of S2; ECG with RVH.
Implies exclusion of secondary causes of pulmonary hypertension.
Rare, progressive, and often fatal disease without treatment.
Unexplained or primary pulmonary hypertension (PPH) in children is a rare disease with an estimated overall incidence of 1–2 persons per million worldwide. Pulmonary hypertension is defined as a mean pulmonary pressure greater than 25 mm Hg at rest or greater than 30 mm Hg during exercise. PPH is a diagnosis made after exclusion of all other causes of pulmonary hypertension. Secondary pulmonary hypertension is most commonly associated with congenital heart disease, pulmonary parenchymal disease, causes of chronic hypoxia (upper airway obstruction), thrombosis, liver disease, hemoglobinopathies, and collagen vascular disease. PPH is difficult to diagnose in the early stages because of its subtle manifestations. Most patients with PPH are young adult women, although the gender incidence is equal in children. Although the outcome for pediatric PPH is improving due to the advent of new therapies, prognosis remains guarded with only 72% survival at 5 years. Familial PPH occurs in 6%–12% of affected individuals. When a clear familial association is known, the disease shows evidence of genetic anticipation, presenting at younger ages in subsequent generations.
A. Symptoms and Signs
The clinical picture varies with the severity of pulmonary hypertension, and usually early symptoms are subtle, delaying the diagnosis. Initial symptoms may be dyspnea, palpitations, or chest pain, often brought on by strenuous exercise or competitive sports. Syncope may be the first symptom, which usually implies severe disease. As the disease progresses, patients have signs of low cardiac output and right heart failure. Right heart failure may be manifested by hepatomegaly, peripheral edema, and an S3 gallop on examination. Murmurs of pulmonary regurgitation and tricuspid regurgitation may be present, and the pulmonary component of S2 is usually pronounced.
The chest radiograph most often reveals a prominent main pulmonary artery, and the RV may be enlarged. The peripheral pulmonary vascular markings may be normal or diminished. However, in 6% of patients with confirmed PPH, the chest radiograph is normal.
The ECG usually shows RVH with an upright T wave in V1 (when it should be negative in young children) or a qR complex in lead V1 or V3R. Also present may be evidence of right axis deviation and right atrial enlargement.
The echocardiogram is an essential tool for excluding congenital heart disease as a cause of pulmonary hypertension. It frequently shows RVH and dilation. In the absence of other structural disease, any tricuspid and PI jets can be used to estimate pulmonary artery systolic and diastolic pressures, respectively. Other echocardiographic modalities such as myocardial performance index and input vascular impedance are in the early stages of use in evaluation of pulmonary hypertension.
E. Cardiac Catheterization and Angiocardiography
Cardiac catheterization is the best method for determining the severity of disease. As an invasive test, it carries with it associated risks and should be performed with caution. The procedure is performed to rule out cardiac (eg, restrictive cardiomyopathy) or vascular (eg, pulmonary vein stenosis) causes of pulmonary hypertension, determine the severity of disease, and define treatment strategies. The reactivity of the pulmonary vascular bed to short-acting vasodilator agents (oxygen, nitric oxide, or prostacyclin) can be assessed and used to determine treatment options. Angiography may show a decrease in the number of small pulmonary arteries with tortuous vessels.
F. Other Evaluation Modalities
Cardiac MRI is used in some patients to evaluate right ventricular function, pulmonary artery anatomy, and hemodynamics, as well as thromboembolic phenomena. Cardiopulmonary exercise testing using cycle ergometry correlates with disease severity. More simply, a 6-minute walk test, in which distance walked and perceived level of exertion are measured, has a strong independent association with mortality in late disease.
The goal of therapy is to reduce pulmonary artery pressure, increase cardiac output, and improve quality of life. Cardiac catheterization data are used to determine the proper treatment. Patients responsive to pulmonary vasodilators are given calcium channel blockers such as nifedipine or diltiazem. Patients unresponsive to vasodilators initially receive one of three classes of drugs: prostanoids (such as epoprostenol), endothelin receptor antagonists (such as bosentan), or phosphodiesterase-5 inhibitors (such as tadalafil). All of these agents have distinct mechanisms of action that can reduce pulmonary vascular resistance. Warfarin is commonly used for anticoagulation to prevent thromboembolic events, usually with a goal to maintain the INR between 1.5 and 2.0.
Atrial septostomy is indicated in some patients with refractory pulmonary hypertension and symptoms. Cardiac output falls as pulmonary vascular resistance rises, so an interatrial shunt can preserve left heart output, albeit with deoxygenated blood. Lung transplantation should be considered in patients with intractable pulmonary hypertension and in those with associated anatomic lesions that contribute to high pulmonary arterial pressure, like pulmonary vein stenosis. Heart-lung transplant procedures appear to have survival benefits over isolated lung transplantation in patients with pulmonary hypertension. Recurrence of pulmonary hypertension is rare after heart-lung transplant.
Ivy D: Advances in pediatric pulmonary arterial hypertension. Curr Opin Cardiol 2012;27(2):70–81 [PMID: 22274573].
Pulmonary Hypertension Association: www.phassociation.org/
DISORDERS OF RATE & RHYTHM
Cardiac rhythm abnormalities can occur in two different patient populations: (1) healthy children with structurally normal hearts who have an intrinsic abnormality of the electrical conduction system; and (2) children with congenital heart disease who are at risk for a cardiac rhythm abnormalities based on the underlying heart defect itself. In the latter population, changes in cardiac muscle cells associated with a chronic state of altered cardiac hemodynamics and any operative procedures with surgical suture lines/scars place the patients at higher risk for certain types of arrhythmias.
The evaluation and treatment of cardiac rhythm disorders have advanced significantly over the last several decades. Arguably, the most significant advancements in the last few years have continued in the area of the genetic basis of rhythm disorders such as long QT syndrome which will be discussed at the end of the chapter. Treatment for cardiac rhythm abnormalities includes clinical monitoring with no intervention, antiarrhythmic medications, invasive electrophysiology study and ablation procedures, pacemakers, and internal cardioverter/defibrillators.
Deal BJ et al: Arrhythmic complications associated with the treatment of patients with congenital cardiac disease: consensus definitions from the Multi-Societal Database Committee for Pediatric and Congenital Heart Disease. Cardiol Young 2008 Dec;18(Suppl 2):202–205.
DISORDERS OF THE SINUS NODE
Phasic variation in the heart rate (sinus arrhythmia) is normal. Typically, the sinus rate varies with the respiratory cycle (heart rate increases with inspiration and decreases with expiration), whereas P-QRS-T intervals remain stable. Sinus arrhythmia may occur in association with respiratory distress or increased intracranial pressure, or it may be present in normal children. In isolation, it never requires treatment; however, it may be associated with sinus node dysfunction or autonomic nervous system dysfunction.
Sinus bradycardia is defined as a heart rate below the normal limit for age (neonates to 6 years, 60 beats/min; 7–11 years, 45 beats/min; > 12 years, 40 beats/min). Sinus bradycardia is often seen in athletic children. Causes of sinus bradycardia include hypoxia, central nervous system damage, eating disorders, and medication side effects. Symptomatic bradycardia (syncope, low cardiac output, or exercise intolerance) requires treatment (atropine, isoproterenol, or cardiac pacing).
The heart rate normally accelerates in response to stress such as exercise, anxiety, fever, hypovolemia, anemia, or HF. Although sinus tachycardia in the normal heart is well tolerated, symptomatic tachycardia with decreased cardiac output warrants evaluation for structural heart disease, cardiomyopathy or true tachyarrhythmias. The first evaluation should be made with a 12-lead ECG (not a one lead rhythm strip) to determine the precise mechanism of the rapid rate. Treatment may be indicated for correction of the underlying cause of sinus tachycardia (eg, transfusion for anemia or correction of hypovolemia or fever).
SINUS NODE DYSFUNCTION
Sinus node dysfunction is a clinical syndrome of inappropriate sinus nodal function and rate. The abnormality may be a true anatomic defect of the sinus node or its surrounding tissue, or it may be an abnormality of autonomic input. It is defined as one or more of the following: severe sinus bradycardia, marked sinus arrhythmia, sinus pause or arrest, chronotropic incompetence (inability of the heart rate to increase with activity or other demands), or combined bradyarrhythmias and tachyarrhythmias. It is usually associated with postoperative repair of congenital heart disease (most commonly the Mustard or Senning repair for complete TGA or the Fontan procedure), but it is also seen in normal hearts, in unoperated congenital heart disease, and in acquired heart diseases. Symptoms usually manifest between ages 2 and 17 years and consist of episodes of presyncope, syncope, palpitations, pallor, or exercise intolerance.
The evaluation of sinus node dysfunction may involve the following: baseline ECG, 24-hour ambulatory ECG monitoring, exercise stress test, and transient event monitoring. Treatment for sinus node dysfunction is indicated only in symptomatic patients. Bradyarrhythmias are treated with vagolytic (atropine) or adrenergic (aminophylline) agents or permanent cardiac pacemakers.
Atrial Premature Beats
Atrial premature beats are triggered by an ectopic focus in the atrium. They are one of the most common premature beats occurring in pediatric patients, particularly during the fetal and newborn periods. The premature beat may be conducted to the ventricle and therefore followed by a QRS complex or it may be nonconducted, as the beat has occurred so early that the AV node is still refractory (Figure 20–4). A brief pause usually occurs until the next normal sinus beat occurs. As an isolated finding, atrial premature beats are benign and require no treatment.
Figure 20–4. Lead II rhythm strip with premature atrial contractions. Beats 1, 3, 7, and 8 are conducted to the ventricles, whereas beats 2, 4, 5, and 6 are not.
Junctional Premature Beats
Junctional premature beats arise in the atrioventricular node or the bundle of His. They induce a normal QRS complex with no preceding P wave. Junctional premature beats are usually benign and require no specific therapy.
Ventricular Premature Beats
Ventricular premature beats are sometimes referred to as premature ventricular contractions (PVC) or as ventricular ectopy. They are relatively common, occurring in 1%–2% of patients with normal hearts. They are characterized by an early beat with a wide QRS complex, without a preceding P wave, and with a full compensatory pause following this early beat (Figure 20–5).
Figure 20–5. Lead V5 rhythm strip with unifocal premature ventricular contractions in a bigeminy pattern. The arrow shows a ventricular couplet.
Ventricular premature beats originating from a single ectopic focus all have the same configuration; those of multifocal origin show varying configurations. The consecutive occurrence of two ventricular premature beats is referred to as a ventricular couplet and of three or more as ventricular tachycardia. Most ventricular premature beats in otherwise normal patients are usually benign. However, patients with frequent PVCs are usually evaluated further with tests such as a 24-hour ambulatory ECG or with exercise testing to rule out concerning arrhythmias. An echocardiogram may be performed to evaluate ventricular function. The significance of ventricular premature beats can be confirmed by having the patient exercise. As the heart rate increases, benign ventricular premature beats usually disappear. If exercise results in an increase or coupling of contractions, underlying disease may be present. Multifocal ventricular premature beats are always abnormal and may be more dangerous. They may be associated with drug overdose (tricyclic antidepressants or digoxin toxicity), electrolyte imbalance, myocarditis, or hypoxia. Treatment is directed at correcting the underlying disorder.
Supraventricular tachycardia (SVT) is a term used to describe any rapid rhythm originating from the atrium, the atrioventricular node, or an accessory pathway. These tachycardias are rapid, narrow complex tachycardias. The mode of presentation depends on the heart rate, the presence of underlying cardiac structural or functional abnormalities, coexisting illness, and patient age. An otherwise healthy child with SVT may complain of intermittent periods of rapid heartbeat. An infant with SVT may have poor feeding and increased fatigue (manifesting as less awake time). Incessant tachycardia, even if fairly slow (120–150 beats/min), may cause myocardial dysfunction and HF if left untreated. In children with preexisting HF or an underlying systemic disease such as anemia or sepsis, SVT may result in decreased heart function and further signs of hemodynamic instability much more rapidly than in a healthy child.
The mechanisms of tachycardia are generally divided into reentrant and automatic mechanisms and can be described by the location of tachycardia origination (Table 20–18).
Table 20–18. Mechanism of supraventricular tachycardia.
Reentrant tachycardias represent approximately 80% of pediatric arrhythmias. Reentrant tachycardias have the following characteristics: they initiate abruptly, they have a fixed rate, they have little variation with fever or internal catecholamines, and they terminate abruptly. They can be terminated to sinus rhythm with maneuvers such as vagal maneuvers, administration of adenosine, pacing maneuvers, or DC cardioversion. (For vagal maneuvers or adenosine, the atrioventricular node must be part of the reentrant circuit.)
Reentrant tachycardia mechanisms involve two connections where electrical conduction travels down one of the pathways and then backs up the other, creating a sustained repetitive circular loop. The circuit can be confined to the atrium (atrial flutter in a normal heart or intra-atrial reentrant tachycardia in a patient with congenital heart disease) (Figure 20–6). It may be confined within the AV node (AV nodal reentrant tachycardia), or it may encompass an accessory connection between atria and ventricle (accessory pathway–mediated tachycardia). If, during tachycardia, the electrical impulse travels antegrade (from atria to ventricles) through the AV node and retrograde (from ventricle to atria) back up the accessory pathway, orthodromic reciprocating tachycardia is present. If, instead, the impulse travels antegrade through the accessory pathway and retrograde up through the AV node, antidromic reciprocating tachycardia is present. This latter tachycardia would present as a wide complex tachycardia. Wolff-Parkinson-White (WPW) syndrome is a subclass of reentrant tachycardia in which, during sinus rhythm, the impulse travels antegrade down the accessory connection, bypassing the AV node and creating ventricular preexcitation (early eccentric activation of the ventricle with a short PR interval and slurred upstroke of the QRS, a delta wave) (Figure 20–7). Most patients with WPW have otherwise structurally normal hearts. However, WPW has been noted to occur with increased frequency in association with the following congenital cardiac lesions: tricuspid atresia, Ebstein anomaly of the tricuspid valve, HCM, and ccTGA. Different than other causes of tachycardias described above where the arrhythmia is not life-threatening, there have been rare cases of sudden collapse from WPW syndrome. The mechanism of this sudden event is the development of atrial fibrillation, conducting down a rapid accessory pathway to the ventricle leading to ventricular fibrillation and sudden death. For this reason, most centers recommend that even asymptomatic patients undergo an invasive procedure to assess the conduction properties of the WPW accessory pathway (described under treatment for tachyarrhythmias).
Figure 20–6. Leads aVF (F) and V1, showing atrial flutter with “sawtooth” atrial flutter waves.
Figure 20–7. Leads I and II with spontaneous intermittent ventricular preexcitation (Wolff-Parkinson-White syndrome).
Improved surgical survival for patients with congenital heart disease has created a new, increasingly prevalent, chronic arrhythmia which is similar to atrial flutter in a normal heart structure. These arrhythmias have been referred to by many names: intra-atrial reentrant tachycardia, incisional tachycardia, macroreentry, or postoperative atrial flutter. In this tachycardia, electrically isolated corridors of atrial myocardium (eg, the tricuspid valve–inferior vena cava isthmus, or the region between an atrial incision and the crista terminalis) act as pathways for sustained reentrant circuits of electrical activity. These tachycardias are chronic, medically refractory, and clinically incapacitating.
The automatic tachycardias represent approximately 20% of childhood arrhythmias. The characteristics of these types of arrhythmias include gradual onset, rate variability, variations in rate with fever or increasing internal catecholamines, and gradual offset. Maneuvers such as vagal maneuvers, adenosine, and attempt pacing can alter the rhythm temporarily but they do not result in termination of the rhythm to sinus rhythm as would be seen in the reentrant tachycardias. Automatic tachycardias can be episodic or incessant. They are usually under autonomic influence. When they are incessant, they are usually associated with HF and a clinical picture of DCM. Automatic tachycardias are created when a focus of cardiac tissue develops an abnormally fast spontaneous rate of depolarization. For ectopic atrial tachycardia, the ECG demonstrates a normal QRS complex preceded by an abnormal P wave (Figure 20–8). Junctional ectopic tachycardia does not have a P wave preceding the QRS waves and may be associated with AV dissociation or 1:1 retrograde conduction.
Figure 20–8. Lead II rhythm strip of ectopic atrial tachycardia. The tracing demonstrates a variable rate with a maximum of 260 beats/min, an abnormal P wave, and a gradual termination.
Cohen MI et al: PACES/HRS expert consensus statement on the management of the asymptomatic young patient with a Wolff-Parkinson-White (WPW, ventricular preexcitation) electrocardiographic pattern: developed in partnership between the Pediatric and Congenital Electrophysiology Society (PACES) and the Heart Rhythm Society (HRS). Heart Rhythm 2012;9(6):1006–1024 [PMID: 22579340].
A. Symptoms and Signs
Presentation varies with age. Infants tend to turn pale and mottled with onset of tachycardia and may become irritable. With long duration of tachycardia, symptoms of HF develop. Older children complain of dizziness, palpitations, fatigue, and chest pain. Heart rates range from 240–300 beats/min in the younger child to 150–180 beats/min in the teenager. HF is less common in children than in infants. Tachycardia may be associated with either congenital heart defects or acquired conditions such as cardiomyopathies and myocarditis.
Chest radiographs are normal during the early course of tachycardia and therefore are usually not obtained. If HF is present, the heart is enlarged and pulmonary venous congestion is evident.
ECG is the most important tool in the diagnosis of SVT and to define the precise tachycardia mechanism. Findings include a heart rate that is rapid and out of proportion to the patient’s physical status (eg, a rate of 140 beats/min with an abnormal P wave while quiet and asleep). For reentrant mechanisms, the rhythm would be extremely regular with little variability. For automatic mechanisms, the rhythm would be irregular with a gradual increasing and decreasing of the rate. The QRS complex is usually the same as during normal sinus rhythm. However, the QRS complex is occasionally widened (SVT with aberrant ventricular conduction), in which case the condition may be difficult to differentiate from ventricular tachycardia. The presence of P waves and their association with the QRS are important in determining tachycardia mechanism. With automatic tachycardias, there is often a 1:1 or 2:1 A:V relationship with P waves preceding the QRS. With reentrant tachycardias, such as accessory pathway–mediated tachycardias, a small retrograde P wave can often be seen just after the QRS. With atrioventricular nodal reentrant tachycardia, P waves cannot be identified as they are occurring at the same time as the QRS.
A. Acute Treatment
During the initial episodes of SVT, patients require close monitoring. Correction of acidosis and electrolyte abnormalities is also indicated. The following acute treatments are effective in terminating tachycardia only for patients with reentrant SVT. Acute treatment for automatic SVT is aimed at rate control, usually with a β-blocker.
1. Vagal maneuvers—The “diving reflex” produced by placing an ice bag on the nasal bridge for 20 seconds (for infants) or by immersing the face in ice water (for children or adolescents) will increase parasympathetic tone and terminate some tachycardias. The Valsalva maneuver, which can be performed by older compliant children, may also terminate reentrant tachycardias.
2. Adenosine—Adenosine transiently blocks AV conduction and terminates tachycardias that incorporate the AV node or may aid in the diagnosis of arrhythmias confined to the atrium by causing a pause in ventricular conduction, so one can identify the presence of multiple P waves. The dose is 100–250 mcg/kg by rapid intravenous bolus. It is antagonized by aminophylline and should be used with caution in patients with sinus node dysfunction or asthma.
3. Transesophageal atrial pacing—Atrial overdrive pacing and termination can be performed from a bipolar electrode-tipped catheter positioned in the esophagus adjacent to the left atrium. Overdrive pacing at rates approximately 30% faster than the tachycardia rate will interrupt a reentrant tachycardia circuit and restore sinus rhythm.
4. Direct current cardioversion—Direct current cardio-version (0.5–2 synchronized J/kg) should be used immediately when a patient presents in cardiovascular collapse. This will convert a reentrant mechanism to sinus. Automatic tachycardia will not respond to cardioversion.
B. Chronic Treatment
Once the patient has been diagnosed with SVT and the mechanism has been evaluated, then long-term treatment options can be considered. Options include monitoring clinically for tachycardia recurrences, medical management with antiarrhythmic medications, or an invasive electrophysiology study and ablation procedure. In infancy and early childhood, antiarrhythmic medications are the mainstay of therapy. Medications such as digoxin and β-blockers are the first-line therapies. Other antiarrhythmic medications (eg, verapamil, flecainide, propafenone, sotalol, and amiodarone) have increased pharmacologic actions and are extremely effective. However, these medications also have serious side effects, including induction of arrhythmias and sudden death, and should be used only under the direction of a pediatric cardiologist.
Tachycardias, both automatic and reentrant, can be more definitively addressed with an invasive electrophysiology study and ablation procedure. This is a nonsurgical transvascular catheter technique that desiccates an arrhythmia focus or accessory pathway and permanently cures an arrhythmia. The ablation catheters can utilize either a heat source (radiofrequency) or a cool source (cryoablation). The latter has been reported to be safer around the normal conduction pathway and thus decreases the risk of inadvertent atrioventricular block. The success rate from an ablation procedure in a patient with a normal heart structure is > 90%, with a recurrence risk of < 10%. The procedure can be performed in infants or adults. In children younger than age 4 years, the risks of procedural complications or failed ablation are potentially higher, and the procedure should be reserved for those whose arrhythmias are refractory to medical management. The high success rate, low complication and low recurrence rates, in addition to the elimination of the need for chronic antiarrhythmic medications have made ablation procedures the primary treatment option in most pediatric cardiovascular centers. In patients with congenital heart disease, electrophysiology study and ablation procedures are also utilized to address arrhythmia substrates. The success rate of these procedures is lower than in patients with a normal heart structure, often reported in the 75%–80% range.
SVT in infants and children generally carries an excellent prognosis. It can be treated with medical management or with the potentially curative ablation procedures. There are, however, rare cases of incessant SVT leading to HF and there is reported sudden collapse from atrial fibrillation in the presence of WPW. All patients with complaints of rapid heartbeats or other symptoms where there is a concern for tachyarrhythmia should be referred for evaluation.
Lee PC et al: The results of radiofrequency catheter ablation of supraventricular tachycardia in children. Pacing Clin Electrophysiol 2007 May;30(5):655–661 [PMID: 17461876].
Pflaumer A: Perspectives in ablation of arrhythmias in children and patients with congenital heart disease. Intern Med J 2012;42(Suppl 5):70–76 [PMID: 23035686].
Ventricular tachycardia is uncommon in childhood (Figure 20–9). It is usually associated with underlying abnormalities of the myocardium (myocarditis, cardiomyopathy, myocardial tumors, or postoperative congenital heart disease) or toxicity (hypoxia, electrolyte imbalance, or drug toxicity). On occasion, it can be secondary to a primary electrical abnormality in an otherwise normal heart. Sustained ventricular tachycardia can be an unstable situation, and, if left untreated, it could degenerate into ventricular fibrillation and sudden collapse.
Figure 20–9. Twelve-lead ECG from a child with imipramine toxicity and ventricular tachycardia.
Ventricular tachycardia must be differentiated from accelerated idioventricular rhythm. The latter is a sustained ventricular tachycardia occurring in neonates with normal hearts, with a ventricular tachycardia rate within 10% of the preceding sinus rate. This is a self-limiting arrhythmia that requires no treatment. Because of the consequences of sustained ventricular tachycardia, however, a symptomatic patient with a wide complex tachycardia should be considered to have ventricular tachycardia (not an accelerated idioventricular rhythm) until proven otherwise.
Acute termination of ventricular tachycardia involves restoration of the normal myocardium when possible (correction of electrolyte imbalance, drug toxicity, etc) and direct current cardioversion (1–4 J/kg), cardioversion with lidocaine (1 mg/kg), or with amiodarone (5 mg/kg load). Chronic suppression of ventricular arrhythmias with antiarrhythmic drugs has many side effects (including proarrhythmia and death), and it must be initiated in the hospital under the direction of a pediatric cardiologist. If the etiology of the tachycardia is a primary electrical abnormality, then catheter ablation procedures can be offered in select patients as a potentially curative treatment option. Ablation for ventricular tachycardia in the pediatric population is much less commonly performed compared to ablation for SVT.
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McCammond AN, Balaji S. Management of tachyarrhythmias in children. Curr Treat Options Cardiovasc Med 2012;14(5):490–502 [PMID: 22923097].
LONG QT SYNDROME
Long QT syndrome is a malignant disorder of cardiac conduction where cardiac repolarization is prolonged (QTc measurement on ECG) and this predisposes the patient to sudden episodes of syncope, seizures, or sudden death (5% per year if untreated). The mechanism is a pause-dependent initiation of torsades de pointes, a multifocal ventricular tachycardia. It can be congenital or acquired. Congenital long QT syndrome is inherited in an autosomal dominant (more common) or recessive pattern or it may occur spontaneously (less likely). The recessive inheritance pattern is associated with congenital deafness and the Jervell and Lange-Nielsen syndrome. Congenital long QT syndrome is caused by a defect in one of several genes that code for ion channels in cardiac myocytes. As many as 10 genes have been identified and these defects explain 75% of the patient population with symptoms and signs consistent with long QT. The diagnosis of long QT syndrome is suspected in a patient or a family with a history of sudden syncope, seizures, documented dysrrhythmia, or cardiac arrest. Evaluation includes an ECG which shows a long QTc measurement, 24-hour ambulatory ECG, and possibly an exercise test. There is a commercially available genetic test for the primary genes which cause long QT syndrome. This test is most helpful in determining who in a family has long QT syndrome. Unfortunately, this test cannot completely rule it out as there continues to be a 25% false negative rate.
The mainstay of treatment for long QT syndrome has been exercise restriction, treatment with β-blockade, and possibly the placement of an internal cardioverter/defibrillator. Within the next several years, more gene-specific therapies are anticipated to be developed.
Long QT syndrome can also be acquired, resulting from altered ventricular repolarization secondary to myocardial toxins, ischemia, or inflammation. This condition also predisposes a patient to ventricular arrhythmias. Numerous medications can also cause QT prolongation.
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Everyone in a family, school, and community are affected when an otherwise healthy child dies suddenly and unexpectedly. There are several cardiac causes of sudden death. Long QT syndrome and HCM are two of the most common cause of sudden death in young athletes. Other causes include dilated or restrictive cardiomyopathies, arrhythmogenic RV dysplasia, congenital structural anomalies of the coronary arteries, and primary arrhythmias such as catecholamine sensitive ventricular tachycardia or Brugada syndrome. Many of these causes are genetic and thus family members of the patient may also be unknowingly affected. Arrhythmias in patients with postoperative congenital heart disease are important causes of morbidity and mortality and may present as sudden death events.
Because of the genetic nature of some of the causes of sudden death, it is necessary to conduct a detailed family history looking for seizures, syncope, or early sudden death. Family members should be examined with an arrhythmia screen consisting of a physical examination, ECG, and echocardiography to detect arrhythmias or cardiomyopathies.
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DISORDERS OF ATRIOVENTRICULAR CONDUCTION
The atrioventricular node is the electrical connection between the atrium and the ventricles. Atrioventricular blocks involve a slowing or disruption of this connection and are described according to the degree of this slowing or disruption. The term “heart block” has been utilized, although “atrioventricular block” is more precise.
First-Degree Atrioventricular Block
First-degree atrioventricular block is an ECG diagnosis of prolongation of the PR interval. The block does not, in itself, cause problems. It may be associated with structural congenital heart defects, namely AV septal defects and ccTGA, and with diseases such as rheumatic carditis. The PR interval is prolonged in patients receiving digoxin therapy.
Second-Degree Atrioventricular Block
Mobitz type I (Wenckebach) atrioventricular block is recognized by progressive prolongation of the PR interval until there is no QRS following a P wave (Figure 20–10). Mobitz type I block occurs in normal hearts at rest and is usually benign. In Mobitz type II block, there is no progressive lengthening of the PR interval before the dropped beat (Figure 20–11). Mobitz type II block is frequently associated with organic heart disease, and a complete evaluation is necessary.
Figure 20–10. Lead I rhythm strip with Mobitz type I (Wenckebach) second-degree heart block. There is progressive lengthening of the PR interval prior to the nonconducted P wave (arrows).
Figure 20–11. Lead III rhythm strip with Mobitz type II second-degree heart block. There is a consistent PR interval with occasional loss of AV conduction (arrow).
Complete Atrioventricular Block
In complete atrioventricular block, the atria and ventricles beat independently. Ventricular rates can range from 40 to 80 beats/min, whereas atrial rates are faster (Figure 20–12). The most common form of complete atrioventricular block is congenital complete atrioventricular block which occurs in a fetus or infant with an otherwise normal heart. There is a very high association with maternal systemic lupus erythematosus antibodies and therefore it is recommended to screen the mother of an affected infant even if the mother has no symptoms of collagen vascular disease. Congenital complete atrioventricular block is also associated with some forms of congenital heart disease (congenitally corrected transposition of the great vessels and AV septal defect). Acquired complete atrioventricular block may be secondary to acute myocarditis, drug toxicity, electrolyte imbalance, hypoxia, and cardiac surgery.
Figure 20–12. Twelve-lead ECG and lead II rhythm strip of complete heart block. The atrial rate is 150 beats/min, and the ventricular rate is 60 beats/min.
The primary finding in infants and children with complete atrioventricular block is a significantly low heart rate for age. The diagnosis is often made prenatally when fetal bradycardia is documented. An ultrasound is then conducted as well as a fetal echocardiogram of the heart. With the fetal echocardiogram, atrial and ventricular contractions can be distinguished and the atrial rate is documented as being higher than the ventricular rate with no relationship to each other. If the heart rates are sufficiently low, then there will be low cardiac output, decreased cardiac function, and the development of hydrops fetalis. Postnatal adaptation largely depends on the heart rate; infants with heart rates less than 55 beats/min are at significantly greater risk for low cardiac output, HF, and death. Wide QRS complexes and a rapid atrial rate are also poor prognostic signs. Most patients have an innocent flow murmur from increased stroke volume. In symptomatic patients, the heart can be quite enlarged, and pulmonary edema may be present.
Complete atrioventricular block can also occur in older patients. Patients may be asymptomatic or may present with presyncope, syncope, or fatigue. Complete cardiac evaluation, including ECG, echocardiography, and Holter monitoring, is necessary to assess the patient for ventricular dysfunction and to relate any symptoms to concurrent arrhythmias.
When diagnosis of complete atrioventricular block is made in a fetus, the treatment depends on gestational age, ventricular rate, and the presence or absence of hydrops. Some centers have advocated the administration of steroids, intravenous immune globulin (IVIG), and/or β-adrenergic stimulation treatment of the mother in some instances (fetuses that have associated heart failure). Emergent delivery is sometimes warranted. Postnatal treatment for neonates or older patients who present with significant symptoms and require immediate intervention includes temporary support by the infusions of isoproterenol, temporary transvenous pacing wires, or by temporary transcutaneous pacemakers if needed. The relationship of complete congenital atrioventricular block to auto-antibody production and cardiomyopathy is the basis for the consideration of immune modulation with steroids and IVIG in neonates in addition to their mothers. Long-term treatment involves the placement of a permanent pacemaker.
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Syncope is a sudden transient loss of consciousness that resolves spontaneously. The common form of syncope (simple fainting) occurs in 15% of children and is a disorder of control of heart rate and blood pressure by the autonomic nervous system that causes hypotension or bradycardia. It is often associated with rapid rising and postural hypotension, prolonged standing, or hypovolemia. Patients exhibit vagal symptoms such as pallor, nausea, or diaphoresis. Syncope, also known as autonomic dysfunction, can be evaluated with head-up tilt table testing. The patient is placed supine on a tilt table, and then—under constant heart rate and blood pressure monitoring—is tilted to the upright position. If symptoms develop, they can be classified as vasodepressor (hypotension), cardioinhibitory (bradycardia), or mixed.
Syncope is usually self-limited (can recur over approximately 6 months to 2 years) and can be controlled with dietary salt and volume loading to prevent hypovolemia. In refractory cases, medications to manipulate the autonomic nervous system have been useful. Fludrocortisone (0.1 mg/kg/d) is a mineralocorticoid that causes renal salt resorption and thus increases intravascular volume. Although β-blockers have been used for treatment of syncope, there is a paucity of data regarding their effectiveness. Vagolytic agents (disopyramide, 2.5 mg/kg four times daily) help control hypervagotonia, and the selective serotonin reuptake inhibitors have also been effective in alleviating symptoms. Syncope that occurs during exercise or stress or is associated with a positive family history is a warning sign that a serious underlying dysrhythmia may be present, calling for further investigation.
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