Heart Murmurs and Mitral Valve Prolapse
Amy D. DiVasta
Mark E. Alexander
Cardiac murmurs occur in at least 50% of all normal children and often persist into adolescence. Murmurs are the most frequent reason for referral to a cardiology specialist (Geggel, 2004). The vast majority of these murmurs occur in the absence of an anatomical or physiological abnormality of the heart, and are considered to be “innocent,” “normal,” or “physiological” in origin. It is the task of the primary care physician to differentiate normal murmurs from those that are pathological. In most patients with a cardiac murmur, a careful history and physical examination serve to establish a diagnosis and/or to guide further referral and evaluation. When a pathological murmur is suspected, pediatric cardiology referral is generally a more effective approach than first obtaining an echocardiogram, particularly if working with adult-focused echocardiogram resources.
Diagnosis begins with a thorough history and physical examination. If a diagnosis of congenital heart disease is already known, the specific diagnoses will drive further cardiology evaluation. Murmurs first heard in childhood or adolescence are more likely to be innocent murmurs than murmurs caused by organic heart disease. Complaints of fatigue, decreased exercise tolerance, exertional chest pain, or palpitations are suggestive of pathological heart disease. Any patient with syncope or near-syncope during exercise merits cardiac evaluation. A thorough family history should also be obtained, including a history of sudden death.
- Growth and maturation should be carefully assessed.
- Presence of dysmorphic features is frequently associated with congenital heart disease, as in Trisomy 21, Turner, Noonan, or Marfan syndromes.
- Cyanosis and clubbing are strongly suggestive strongly suggestive of uncorrected cyanotic congenital heart disease.
- Pectus excavatum deformity (narrow anteroposterior diameter of the chest) is often associated with a normal murmur, but is also associated with systemic connective tissue abnormalities such as Marfan syndrome.
- Pulses in upper and lower extremities
- Observe for any discrepancies in intensity or timing.
- Delayed or absent pulses in the lower extremities may indicate coarctation of the aorta.
- Bounding pulses due to a wide pulse pressure may indicate structural disease related to “run-off” from a region of higher pressure to one of relatively lower pressure, for example, aortic regurgitation or patent ductus arteriosus.
- Blood pressures in arm and leg
- Sizing of the blood pressure cuff is essentia A good general rule is to size the length of the bladder (the inflatable portion) of the cuff so that it completely encircles the upper arm of the patient. Using a cuff size that is too small leads to falsely high readings. When in doubt, err on the side of a cuff that is slightlytoo large. While a manual blood pressure may be the most accurate office method, automated oscillometric methods have the significant advantages of lacking observer bias, and the ability to delegate the procedure to ancillary office staff.
- The leg systolic pressure is normally slightly higher (10 mm Hg) than that of the arm. A lower leg pressure can often indicate coarctation of the aorta.
- Presence of thrill, heave, or lift over the precordium or suprasternal notch is usually an indication of pathology.
- The point of maximal impulse (PMI) should be dimesized, limited to one intercostal space, and located in the midclavicular line. Increased intensity and lateral displacement of the PMI suggests left ventricular (LV) enlargement.
All components of the cardiac cycle should be assessed systematically at the base, at the apex, and along both sides of the sternal border, using both the bell and diaphragm. A dynamic cardiac examination is completed by moving the patient through some combination of positions and maneuvers: supine, sitting, standing, squatting, or isometric hand contraction which allows different cardiac loading conditions to amplify murmurs.
- First heart sound (S1): S1is produced by closure of the mitral and then the tricuspid valve. It is best heard at the cardiac ape Splitting of S1 can be a normal finding. However, auscultation of another sound close to S1 is usually either a presystolic fourth heart sound (S4) or an ejection click (see following text).
- Second heart sound (S2): The quality of S2is of great diagnostic importance. The first component (aortic valve closure, A2) and the second component (pulmonary valve closure, P2)ofS2 should be of equal intensity. An accentuated P2 suggests pulmonary hypertension. Normally, there is respiratory variation or physiological splitting of the S2, with widening of the separation with inspiration and narrowing or disappearance of the split with exhalation. This is easiest to hear at the upper left sternal border (LSB). Wide, fixed splitting suggests an abnormality of right ventricular (RV) volume overload such as an atrial septal defect. A single S2 is also abnormal, and may indicate severe stenosis of one of the semilunar valves.
- Third heart sound (S3): S3corresponds to ventricular filling during early diastole, and is normally heard as a soft sound following S2 at the cardiac apex. S3 may be a normal finding in adolescents, and is more prominent in hyperdynamic states.
- Fourth heart sound (S4): S4is due to atrial contraction. It is heard late in diastole, particularly at the apex, and is almost always pathological in adolescents, although may be normal in older adults.
- Clicks: A click is a sharp, high-frequency sound that provides an important clue to the diagnosis of organic disease.
- Early systolic ejection clicks are of either pulmonary or aortic origin, and occur shortly after S1.
- A pulmonary ejection click is best heard at the upper LSB and is associated with valvular pulmonary stenosis. The intensity of the pulmonary valve ejection click varies with respiration (louder with expiration) and the severity of pulmonary stenosis.
- An aortic ejection click is best heard at the apex and does not vary with respiration. It is associated with a bicuspid aortic valve, which in turn may include aortic stenosis, or coarctation.
- Nonejection clicks are usually midsystolic and are present at the apex. These clicks move within systole as ventricular loading conditions change (with squatting or isometric hand contraction). They are associated with mitral valve prolapse (MVP).
- Murmurs: The presence of a systolic or diastolic murmur requires careful analysis of its characteristics, including timing, loudness, length, tonal quality, and location. For practical purposes, all diastolic murmurs, except venous hums, should be considered pathological.
Diagnostic Clues for Innocent Murmurs
- History: Asymptomatic, no family history of cardiac disease
- Physical examination: Normal, other than the presence of the murmur
- Timing of murmur: Early systolic; almost never diastolic
- Duration: Not holosystolic
- Intensity: Usually grade 1–3/6
- Radiation: Not extensive
- Quality: Vibratory; no clicks
- Location: May vary, but frequently at lower or upper LSB
- Change with position: Increase in supine position, decrease with sitting or standing
- S2: Physiological splitting
- Laboratory findings: Generally, no laboratory studies are indicated. In the primary care setting, electrocardiograms (ECGs) are obtained only selectively. When obtained, they should be normal.
Diagnostic Clues for Pathological Murmurs
- Significant history: Growth failure, decreased exercise tolerance, exertional syncope or near-syncope, exertional chest pain.
- Physical examination: Clubbing, cyanosis, decreased or delayed femoral pulses, apical heave, palpable thrill, tachypnea, inappropriate tachycardia.
- Murmur: Diastolic, holosystolic, loud or harsh, extensive radiation, increases with standing, associated with a thrill, abnormal S2. See Table 14.1.
A number of normal murmurs have been described. They have identifiable characteristics that allow them to be recognized by physical examination alone. Characterizing a murmur as “normal” is not a diagnosis of exclusion; each has definite criteria that should be fulfilled.
- Cause: Turbulence of flow from blood ejected through the LV outflow tract or the presence of ventricular false tendons.
- Low- to medium-pitched murmur with vibratory or musical quality.
- Grade 1-3/6 early to midsystolic murmur; never holosystolic; S1can be clearly distinguished from the murmur.
- Location: Maximal at lower LSB, extending to the apex.
- Maneuvers: Murmur decreased on sitting or standing, loudest in supine position.
- Differential diagnosis: Differentiated from valvular aortic stenosis by the absence of a click or radiation to the upper right sternal border (RSB). Differentiated from hypertrophic cardiomyopathy (HCM) because the murmur decreases with standing. Less harsh than a murmur associated with a ventricular septal defect (VSD).
Pulmonary Flow Murmur
- Cause: Turbulence of flow in the RV outflow tract across a normal pulmonary valve (the right-sided equivalent
of Still's murmur). Often heard with tachycardia due to fever, anxiety, or exertion. Associated with pectus excavatum or kyphoscoliosis.
- Quality: Short crescendo–decrescendo midsystolic murmur. Grade 1-3/6. No ejection click. Normal splitting of S2.
- Location: Upper LSB, second to third left intercostal space.
- Maneuvers: Murmur decreased by inspiration and sitting, increased in supine position.
- Differential diagnosis: Differentiated from valvular pulmonary stenosis by absence of a click; differentiated from an atrial septal defect because S2splits normally.
Cervical Venous Hum
- Cause: Turbulence of venous flow at the sharp angle made between the internal jugular and subclavian veins and the superior vena cava.
- Quality: Medium-pitched, soft, blowing continuous murmur with diastolic accentuation.
- Location: Heard best above the sternal end of clavicle, at the base of the neck. May be bilateral or unilateral (right side usually louder; most people have only a right-sided superior vena cava).
- Murmur is increased by rotating the head away from the side of the murmur.
- Murmur is decreased or obliterated by jugular venous compression.
- Murmur decreasedwith supine position—unique for a normal murmur.
- Differential diagnosis: If murmur is louder over the chest than over the supraclavicular area, and does not change with the maneuvers described, patent ductus arteriosus or coronary artery fistula must be excluded.
Supraclavicular (Carotid) Bruit
- Cause: Turbulence at the site of branching of the brachiocephalic arteries from the aortic arch.
- Quality: Short, high-pitched early systolic murmur, usually grade 2/6.
- Location: Maximal above the clavicles and lower portion of the sternocleidomastoid muscle, with radiation to the neck.
- Murmur is eliminated by compression of the subclavian artery against the first rib.
- Murmur is decreased by hyperextending the shoulders (bringing the elbows behind the back).
- Murmur is heard best in the sitting position with the bell of the stethoscope.
- Differential diagnosis: Differentiated from aortic or pulmonary stenosis because murmur is louder over the neck than the chest, there is no click, and it changes with the above maneuvers.
Murmurs Associated with Structural Heart Disease
Although less common, mildly symptomatic congenital heart disease may not be recognized until adolescence, particularly in underserved populations. Therefore, a careful differential diagnosis must be considered when the examiner first notes a cardiac murmur. A review of these lesions is presented in Table 14.2.
Atrial Septal Defect
Other than MVP and bicuspid aortic valve, atrial septal defect is the most common congenital cardiac lesion diagnosed de novo in adolescence or adulthood.
- Physical examination: Signs and symptoms depend on shunt size.
- Hyperdynamic precordium with RV lift with sizable shunt; no thrill.
- Widely split and fixed S2.
- Pulmonary flow murmur: Grade 2-3/6 systolic ejection murmur at upper LSB.
- Middiastolic rumble at lower LSB (increased flow across tricuspid valve).
- Further evaluation
- ECG: Right axis deviation, RV conduction delay (rSR' pattern), right atrial enlargement, or RV hypertrophy.
- Chest radiograph: Mild to moderate cardiomegaly with increased pulmonary vascularity.
- Echocardiogram: Diagnostic with visualization of location and size of defect.
- Other imaging studies: Both nuclear flow scans and cardiac magnetic resonance imaging (MRI) offer
noninvasive tools that permit quantification of the right to left shunt. Cardiac MRI allows excellent imaging of the atrial septum and RV volume. This information can help in deciding whether defects are good candidates for device closure, or have sufficient right to left shunt to deserve therapy.
- Management: Both surgical closure and transcatheter device closure are safe, effective, and popular management choices. Transcatheter device closure has the advantages of avoiding cardiopulmonary bypass and preventing a thoracic scar; however, a permanent foreign body is left in place. Conversely, surgical management has now evolved, leading to low postoperative morbidity and rapid recovery. Surgical repair carries with it the inherent risk of bypass, and the postoperative potential for postpericardiotomy syndrome or atrial arrhythmia. Decisions continue to be made on a case-by-case basis.
Ventricular Septal Defect
- Physical examination: Shunt volume determines findings.
- With increasing shunt size, the precordium becomes increasingly hyperdynamic. A thrill may be present with either a large or small shunt.
- S2is normal with small shunts, accentuated with larger shunts. An S3 may be present. A loud P2 (suggesting pulmonary hypertension), particularly with a soft or absent murmur, is a worrisome finding.
- Grade 2–3/6 holosystolic murmur at lower LSB (very small defects may be quite localized with a high-frequency, blowing quality).
- Middiastolic rumble at the apex with large shunts (increased flow across the mitral valve).
- Further evaluation
- ECG: Normal in small defects; LV hypertrophy with large defects.
- Chest radiograph: Normal in small defects; cardiomegaly with increased pulmonary vascularity in large defects.
- Echocardiogram: Provides anatomical detail of location and size of defect; color Doppler permits visualization of very small defects.
- Management: Some patients with small lesions will be lost to follow-up, and have no recollection of this previous diagnosis when being evaluated as a teen. Even large VSDs may not be identified until adolescence. If the echocardiogram confirms low RV pressure, little additional data is required to make appropriate decisions regarding expectant or surgical management. However, when large VSDs are identified in adolescence, pulmonary artery and RV pressures are typically elevated. For these patients, catheterization is critical in assessing pulmonary vascular resistance and reactivity. Some adolescents with late presentation of VSD will need palliative care focused on their pulmonary vascular disease. It is important to note that infectious endocarditis prophylaxis is no longer recommended for VSD.
Patent Ductus Arteriosus
- Physical examination: Shunt volume determines findings.
- Normal precordium with small shunt; hyperdynamic with a thrill with large shunt.
- Grade 2–4/6 continuous murmur at upper LSB.
- Wide pulse pressure and bounding pulses with large shunt.
- Further evaluation
- ECG: Often normal. LV hypertrophy seen if left to right shunting is significant.
- Chest radiograph: Cardiomegaly with increased pulmonary vascularity with large shunt.
- Echocardiogram: Visualization with two-dimensional and color Doppler imaging.
- Management: Cardiac catheterization is rarely required for diagnosis but is commonly done for coil or device occlusion. In the adolescent with a large patent ductus, catheterization is critical in evaluating the level of pulmonary vascular obstructive disease.
Valvular Pulmonary Stenosis
- Physical examination: Severity of obstruction determines findings.
- RV lift with systolic thrill at upper LSB in more severe forms.
- Systolic ejection click at upper LSB, which is louder with expiration. In severe pulmonary stenosis, the click becomes more difficult to hear as it moves closer to the S1.
- Normal to soft S2or widely split S2, depending on severity of stenosis.
- Grade 2–4/6 harsh systolic ejection murmur at upper LSB; may radiate to the lung fields and back. Intensity and duration of the murmur increase as stenosis severity increases.
- Further evaluation
- ECG: Normal, with progression to RV hypertrophy (upright T wave in lead V1) as stenosis increases
- Chest radiogram: Prominent pulmonary artery segment with normal vascularity.
- Echocardiogram: Permits evaluation of valve morphology. Doppler evaluation of maximum gradient across the valve has proved to have excellent correlation with cardiac catheterization measurement of gradient.
- Management: Cardiac catheterization is rarely required for diagnosis. Treatment of choice is balloon pulmonary valvuloplasty.
Valvular Aortic Stenosis
- Physical examination: Severity of obstruction determines findings.
- Prominent apical impulse and systolic thrill (at upper RSB or suprasternal notch) in more severe forms.
- Intensity of S1may be diminished due to poor ventricular compliance.
- Systolic ejection click at lower LSB/apex; does not vary with respiration. Radiates to aortic area at upper RSB. Click is not present in supravalvular or subvalvular types.
- Grade 2–4/6 long, harsh systolic crescendo–decrescendo ejection murmur at upper RSB; subvalvular murmur may be heard best at mid-LSB.
- High-frequency early diastolic decrescendo murmur of aortic regurgitation.
- Careful general physical examination looking for features of associated Turner or Williams syndrome.
- Further evaluation
- ECG: Normal to LV hypertrophy, depending on severity of stenosis. Strain pattern (ST segment depression and T wave inversion in left precordium) indicates severe stenosis.
- Chest radiograph: Normal heart size with prominent ascending aorta.
- Echocardiogram: Permits evaluation of valve morphology and determination of level of stenosis.
- Seventy percent to 85% of stenotic valves are bicuspid. Mean pressure gradient obtained by Doppler evaluation has good correlation with valve gradient measured by cardiac catheterization.
- Management: Cardiac catheterization is rarely required for diagnosis. In selective cases, aortic balloon valvuloplasty may be an initial palliative procedure.
HCM is the most common unrecognized cause of sudden cardiac death in young people. Although patients with HCM can present with cardiac symptoms (chest pain, dyspnea, palpitations, or syncope), they are frequently asymptomatic. The physical examination is quite dynamic and may either be normal or only transiently abnormal.
- Physical examination
- Careful general physical examination to assess for features of skeletal myopathy.
- Normal to hyperdynamic precordium with increased LV impulse, dynamic thrill.
- Auscultation may be normal. Adequate examination includes supine, standing, squatting, and repeat examination upon resumption of standing position.
- Dynamic aortic stenosis murmur: Systolic ejection murmur at the lower LSB with increasingintensity in standing position and with decreasing intensity in squatting or Valsalva maneuver.
- Dynamic murmur of mitral insufficiency.
- Further evaluation
- ECG: Normal in some cases. LV and/or septal hypertrophy, T wave discordance, atrial enlargement may be seen.
- Chest radiograph: Usually normal. Cardiomegaly may be seen.
- Echocardiogram: Diagnostic, with excessive LV wall thickness, impaired ventricular filling, variable degrees of LV outflow tract obstruction, and variable systolic anterior motion of the mitral valve
- Management: Management of HCM remains controversial. For the symptomatic patient with aborted sudden death (and some with syncope), implantable defibrillators are the primary therapy. Those with severe and symptomatic LV outflow tract obstruction may benefit from either surgical or catheter treatment. Drug therapy is primarily reserved for relief of milder symptoms. Most patients are restricted from competitive sports. Prophylaxis for subacute bacterial endocarditis (SBE) is no longer recommended.
Mitral Valve Prolapse
MVP is a heterogeneous disorder, with a wide spectrum of pathological, clinical, and echocardiographic manifestations. Although the diagnosis of MVP is common, clinically important MVP is infrequent. The modern understanding of MVP identifies the mitral valve involvement as either part of global connective tissues abnormalities—the most common being Marfan syndrome—or as an isolated finding. Most patients with classic MVP have an excellent prognosis. Other patients, most of whom have other connective tissue disease, are at increased risk for the development of mitral regurgitation, infectious endocarditis, cerebral embolism, life-threatening arrhythmia, and sudden death. Refinement in our approach over the last two decades has led to improved differentiation between the two groups, and recognition of the associated differences in prognosis. This is an important distinction to make to avoid unnecessary anxiety, activity limitations, or antibiotic prophylaxis in otherwise healthy young people. In addition, modern understanding of the potential for over-diagnosis of MVP has led to increased skepticism of symptomatic patients with “MVP syndrome” and minimal cardiac findings.
Normal mechanical function of the mitral valve depends on the relation between the size of the mitral leaflets and the LV cavity. An excess of leaflet tissue or a disproportionately small LV cavity (which can occur with dehydration, cardiomyopathy, or anorexia nervosa) may lead to signs of MVP. MVP also has a well-established association with connective tissue disorders such as Marfan syndrome, Ehlers-Danlos syndrome (EDS), and osteogenesis imperfecta.
The reported historical prevalence of MVP has ranged from 1% to 35%, depending on the population studied and criteria utilized for diagnosis. Current diagnostic criteria have led to a prevalence estimate of 2% to 3%, with equal distribution among men and women (Freed et al., 1999). MVP may be diagnosed at any age; symptomatic patients tend to be older adolescents or young adults.
MVP can be divided into three types:
- Primary (classic) prolapse, an idiopathic but often autosomal dominant disorder (with variable penetrance) affecting the structure of the mitral valve. Valve leaflets are thickened and elongated in association with myxomatous infiltration.
- Secondary prolapse from myxomatous degeneration of mitral leaflets in individuals with connective tissue diseases such as Marfan syndrome.
- Prolapse of a normal mitral valve leaflet in individuals with papillary muscle dysfunction related to ischemia, infarction, or cardiomyopathy.
The true prevalence of the symptoms described in patients with MVP compared with the general population is unknown because prevalence rates are usually based on data from referral centers and/or hospital-based patients.
Historically, many cardiac symptoms were attributed to the presence of MVP. However, the vast majority of adolescents with complaints of chest pain, palpitations, dizziness, syncope, dyspnea on exertion, or fatigue do not have MVP. When true disease is suspected, a dynamic physical examination and two-dimensional echocardiography are the diagnostic standards for MVP. Frequently described symptoms include the following:
- Palpitations, which may be unrelated to the occurrence of arrhythmias, representing symptomatic sinus tachycardia, orthostatic intolerance and presyncope, or other “noncardiac” causes. Isolated ventricular ectopy, sometimes frequent, does seem to be more common in MVP patients as compared to controls (Kavey et al., 1984; Bobkowski et al., 2002).
- Chest pain tends to be precordial, nonexertional, and is of longer duration than anginal pain. The cause of the chest pain is unknown, and is likely unrelated to the MVP.
- Less common symptoms include exertional dyspnea, fatigue, lightheadedness, syncope (common also in adolescents without MVP), and neuropsychiatric symptoms such as anxiety. Historically, comorbidity between MVP and anxiety disorders was suggested. However, recent studies have demonstrated no association between MVP and childhood anxiety disorders (Toren et al., 1999; Arfken et al., 1990).
- Click: The mid-to-late systolic click of MVP is best heard with the diaphragm of the stethoscope. This sound is caused by the sudden ballooning of a mitral leaflet into the left atrium during systole. The click often precedes a late systolic murmur of mitral regurgitation. The interval between S1and the click varies with LV enddiastolic volume. Maneuvers on physical examination can demonstrate this dynamic variation. As end-diastolic volume increases (supine position, squatting) or as afterload increases (hand-gripping), the click moves later into systole. Conversely, with reduction of enddiastolic volume of the ventricle (standing, Valsalva), the earlier in systole the click occurs. Therefore, the intensity and position of the click may vary in the same individual depending on a variety of factors.
- Murmur: The murmur of MVP tends to be a high-pitched, late systolic murmur, heard best at the apex of the heart. As with the click, maneuvers that decrease LV volume move the murmur closer to S1. Maneuvers that increase LV diastolic volume may diminish the murmur. Some patients have no click and only a late systolic murmur.
- Associated physical abnormalities: An association has been described between MVP and slender body habitus in both adults and children (Arfken et al., 1993). Patients should also be closely examined for stigmata of the commonly associated connective tissue disorders, and evaluated by a clinician who specializes in such disorders if the examination is worrisome. MVP with or without mitral regurgitation is a minor, not major, criterion for determining cardiovascular involvement for the diagnosis of Marfan syndrome (De Paepe et al., 1996). Isolated thoracic bony abnormalities such as scoliosis, pectus excavatum, and decreased anteroposterior diameter have also been associated with MVP.
- Chest x-ray: Generally normal; possible scoliosis.
- ECG: Usually normal but indicated if a patient complains of palpitations.
- Holter or event monitoring: Indicated to evaluate for arrhythmia if the patient has palpitations that disrupt activities of daily living or cause serious symptoms (syncope, dizziness).
- Echocardiogram: If a systolic click or late systolic murmur is heard, an echocardiogram is essential to visualize the mitral valve and to confirm the diagnosis of MVP. The degree of prolapse, amount of mitral regurgitation, severity of the deformity, thickness of the valve leaflets, and LV function can also be evaluated. Certain echocardiographic features have been associated with a poor prognosis, including thickened and redundant mitral valve leaflets. Echocardiogram also allows measurement of the ascending aorta, aortic root diameter, and LVr dimensions for patients with significant mitral insufficiency.
Mild bowing of a mitral leaflet, a normal variant, should not be misdiagnosed as frank prolapse. It is essential that echocardiographic findings that “suggest prolapse” have firm clinical correlation before a healthy person is labeled as having MVP. Patients with less than overt prolapse on echocardiography and absence of a click, murmur, or symptoms should not be misclassified as having MVP. They do not need to follow bacterial endocarditis prophylaxis precautions.
- Reassurance: The vast majority of adolescents and young adults with MVP are asymptomatic. They should not be restricted in their activities, and serious sequelae need not be discussed. Routine follow-up echocardiography is not recommended, unless new symptoms or new physical examination findings develop.
- Health maintenance: Studies in adults have demonstrated that increased blood pressure and obesity, two potentially reversible risk factors, place patients with MVP at greater risk for severe mitral regurgitation and the need for valve surgery (Singh et al., 2000).
- Antibiotic prophylaxis: New recommendations from the American Heart Association significantly reduce the indications for antibiotic prophylaxis of infective endocarditis (Table14.3,14.4,14.5,14.6). Routine prophylaxis is no longer recommended for MVP. The complete guidelines are available at: http://www.americanheart.org/presenter.jhtml?identifier=3004539 and a wallet card is available at: http://www.americanheart.org/presenter.jhtml?identifier=11086
- β-Blocking agents may be indicated for patients with MVP who have significant symptoms from arrhythmias, to provide symptomatic relief or to target a specific arrhythmia. There is no evidence that β-blockade decreases the already low risk of sudden death (Priori et al., 2001).
- Pregnancy: Mild mitral regurgitation is generally well-tolerated during pregnancy and delivery, with no additional risk to mother or child.
- Genetic counseling: The first-degree relatives of patients with myxomatous MVP should be screened for MVP using echocardiography because of the high prevalence of the diagnosis within families.
- Exercise: Patients with mild MVP with neither significant mitral insufficiency, ventricular arrhythmias, history of cardiac syncope, nor a family history of premature sudden death need no restrictions to physical activity. Those who have more cardiac manifestations and more significant valvular disease may require some restrictions and careful consideration of athletic choices (Maron and Zipes, 2005).
Complications of MVP are rare. When complications do develop, they usually occur in patients with a mitral regurgitation murmur, thickened redundant mitral valve leaflets, or an enlarged left atrium or LV. Patients without murmur or echocardiographic evidence of more serious disease have a benign prognosis, and should be considered as a separate group. Complications that can occur include the following:
- Arrhythmias: The most frequent complication, including premature ventricular contractions, supraventricular tachyarrhythmia, ventricular tachycardia, and bradyarrhythmia.
- Infectious endocarditis: In the absence of mitral regurgitation, the incidence of infective endocarditis in patients with MVP is similar to that of the general population. However, in patients with MVP anda systolic murmur, the risk increases to approximately 0.05% per year (Steckelberg and Wilson, 1993). In the study of risk factors by Nishimura et al. (1985), all patients with endocarditis and MVP had redundant mitral valve leaflets. Although MVP is the most common cause of infective endocarditis, the absolute risk is extremely low and the morbidity is not as severe as in other conditions. Therefore, SBE prophylaxis is no longer recommended in this population (Wilson et al., 2007).
- Progressive mitral regurgitation: This complication results from either progressive myxomatous degeneration or chordal rupture, and is rare in otherwise healthy adolescents. Risk factors for regurgitation include advancing age, male gender, hypertension, overweight, thickened leaflets on echocardiogram, and increased LV dimensions (Singh et al., 2000). Patients with connective tissue disorders are at higher risk of mitral valve dysfunction. This may develop and progress without symptoms, but can lead to significant morbidity and mortality by the end of the second decade of life, especially in female patients (van Karnebeek et al., 2001). The severity of mitral regurgitation is an important prognostic indicator for the development of cardiac events in patients with MVP (Kim et al., 1996).
- Sudden death: Although the risk of sudden cardiac death in patients with MVP is very low (estimated yearly rate of 40 per 10,000), the incidence is still greater than that in the general population (Kligfield et al., 1987). Significant mitral regurgitation, redundant chordae, and depressed LV function increase the risk of sudden death (Kligfield et al., 1987;Nishimura et al., 1985; Grigioni et al., 1999). However, the expected survival is similar to that of the general population (Freed et al., 2002). The cases of sudden cardiac death are likely due to ventricular arrhythmia.
- Stroke: Early studies demonstrated an association between MVP and cerebrovascular accidents (CVA) in young patients. However, more recent findings have been mixed. Two investigators reported no excess risk of
CVA in young patients with MVP (Barnett et al., 1980), whereas another demonstrated a CVA event rate of 0.7% per year, twice the expected rate (Avierinos et al., 2003). These data suggest that MVP may confer a small risk of CVA, but only in older patients with advanced mitral regurgitation. Currently, the American College of Cardiology does not recommend routine prophylactic aspirin treatment.
Mitral Valve Regurgitation
Mitral valve regurgitation is rare in adolescence unless it is associated with MVP, HCM, inflammatory heart disease (such as myocarditis or rheumatic heart disease), or congenital heart disease. A new-onset regurgitant murmur should provoke a thorough investigation.
- Physical examination: Findings depend on severity of regurgitation.
- Normal to hyperdynamic precordium.
- Grade 2–4/6 high-frequency holosystolic apical murmur; may radiate toward the base (upper LSB).
- Low-frequency apical middiastolic rumble with severe regurgitation.
- Further evaluation
- ECG: May be normal with mild regurgitation; bifid P wave of left atrial enlargement and even LV enlargement are noted if regurgitation is chronic and severe.
- Chest radiograph: Normal to cardiomegaly with large left atrium and LV.
- Echocardiogram: Evaluates cause of valve abnormality and severity of regurgitation.
- Management: The increased LV volume load induced by the regurgitation gradually increases the ventricular volumes and in turn increases the severity of the mitral regurgitation (mitral regurgitation begets mitral regurgitation). For this reason, patients are serially assessed as to their need for afterload decreasing agents (including angiotensin-converting enzyme (ACE) inhibitors) or for surgery.
Systemic Connective Tissue Disease and the Heart
Marfan syndrome is a global connective tissue disorder with specific ocular, musculoskeletal, and cardiac involvement. In approximately 75% of patients there is parental involvement, confirming the autosomal dominant inheritance. The prevalence of MVP in patients with Marfan syndrome is above 90%; it is due to both histological changes and ventricular-valvar disproportion. Patients with Marfan syndrome have mutations in the FBN1 gene, and produce abnormal fibrillin protein. Fibrillin is an extracellular matrix protein that contributes to large structures called microfibrils. The distorted microfibrils lead to the problems with elastic matrix faced by Marfan syndrome patients. The clinical diagnosis is made using a series of major and minor criteria (De Paepe et al., 1996). MVP with or without mitral insufficiency is a minor cardiac criterion. Aortic root dilation at the level of the sinuses of Valsalva and/or dissection of the ascending aorta are major cardiac criteria.
The diagnosis of Marfan syndrome is based on clinical evaluation, with careful anthropometric measurements, detailed physical examination, ophthalmology examination, and echocardiogram. In the absence of family history of documented Marfan syndrome, “major” involvement in two organ systems and minor involvement in a third organ system must be met. For families with clear genetic/familial involvement, the finding of major involvement in any one organ system and at least one minor criterion in a second is sufficient. The specific management of MVP in patients with Marfan syndrome is done in context of the aortic root dilation. β-Blockers are used as prophylaxis to try slow dilation. There may be rapid progression of aortic root dilation in pregnancy. Unlike patients with isolated MVP, patients with Marfan syndrome are generally restricted from high intensity and collision sports (Maron et al., 2004). When the aortic root reaches 5.5 cm, aortic root reconstruction is generally indicated.
Other Connective Tissues Disorders that Include Mitral Valve Prolapse
EDSs are a range of connective tissue disorders dominated by their musculoskeletal involvement. Approximately 50% of patients with the classic subtype have been demonstrated to have abnormalities in type V collagen resulting from COL5A1 and COL5A2 deletions. MVP is relatively common in the classic subtype of EDS. The hypermobility subtype (EDS type III) is generally considered the least severe type, and less frequently involves MVP.
In all EDS subtypes, aortic root dilation is less severe and less frequent than in Marfan syndrome. As with Marfan syndrome, the genetic diagnosis is not required for the clinical diagnosis. Patients with EDS may demonstrate symptoms of palpitations, presyncope, and syncope associated with the autonomic dysregulation and neurally mediated hypotension of postural orthostatic tachycardia (Rowe et al., 1999). Although screening for cardiac involvement is appropriate, most patients with EDS will not have specific cardiac diagnoses, even if their orthostasis produces sufficient cardiac symptoms to require further evaluation and management.
Fragile X Syndrome
This alteration in the FMR1 gene is associated with mental retardation, joint laxity, and some incidence of aortic root dilation and MVP. The cardiac involvement may not be apparent until adolescence (Crabbe et al., 1993). Periodic cardiac screening may be warranted.
General Considerations in the Management of Heart Lesions
After obtaining a careful history and conducting a thorough physical examination, it should be possible to differentiate normal from pathological murmurs. ECGs and chest radiographs do not add to the accuracy of diagnosis of normal murmurs. The ECG and radiograph are unlikely to be grossly abnormal unless the child has a significant hemodynamic lesion; a patient with such a lesion is unlikely to be asymptomatic. In addition, because pathological disease is not always associated with abnormal test results, normal findings may lead to a false sense of security.
Although often expected to be high yield, echocardiography adds little to the diagnosis of a “normal” murmur. The cost-effective choice between referring to a pediatric cardiologist (which often includes an echocardiogram)
and directly obtaining an echocardiogram depends on the relative cost of the test, the accessibility of consultation, and the skill of the individual practitioner in identifying pathological murmurs (Danford et al., 1995). Most adult-oriented laboratories are highly skilled at evaluating LV size and function, but less experienced at diagnosing specific anatomic abnormalities or visualizing coronary artery origins. Pediatric-focused laboratories seem to do better on these imaging tasks (Stanger et al., 1999; Hurwitz et al., 1999). Each clinician will develop a practical approach which reflects his or her personal skills and the availability and cost of specialty referrals.
If diagnosed with structural heart disease, the patient and parents should be informed about the risks of bacterial endocarditis. The recommendations of the American Heart Association for prophylaxis should be provided. New recommendations have recently been published which significantly narrow the indications for antibiotic prophylaxis of IE. Changes in the new 2007 AHA recommendations are summarized in Table 14.4. Prophylactic regimens for dental procedures are outlined in Table 14.5.
Therefore, optimal management of a heart murmur requires a careful and systematic cardiovascular examination; judicious use of laboratory studies; referral, in selected cases, to a pediatric cardiologist; and, in the case of normal murmurs, confident reassurance. If the murmur is deemed innocent, the practitioner should emphasize that the heart is normal. This prohibits the labeling of healthy children with cardiac diagnoses, and prevents needless patient, parental, and provider anxiety.
For Teens and Parents
http://www.americanheart.org/presenter.jhtml?identifier=4571. American Heart Association Web site describing heart murmurs.
http://www.marfan.org. Good resource for both families and professionals on Marfan syndrome.
http://medlineplus.gov. National Library of Medicine on heart murmurs.
Especially for Parents
Sites to Hear Heart Sounds
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