Lange Review Ultrasonography Examination, 4th Edition

Chapter 3. Pediatric Echocardiography

David A. Parra*

Study Guide

INTRODUCTION

Effective echocardiographic evaluation of congenital heart disease requires an appreciation of malformation severity and cardiovascular hemodynamics. In the current clinical practice, two-dimensional (2-D) echocardiography is the primary tool for imaging and involves the use of every modality available. Anatomy should be carefully delineated because malformations frequently occur in combination rather than as isolated lesions. Doppler techniques provide information about shunt patterns, flow volumes, gradients through obstructions, and severity of regurgitation. Color-flow Doppler facilitates rapid detection of flow abnormalities and qualitative assessment of such flow characteristics as direction, timing, and degree of turbulence. Pulsed-wave (PW) Doppler provides range (spatial) resolution of flow patterns. Quantification of high-velocity flows requires the use of continuous-wave (CW) Doppler. M-mode is used primarily to evaluate subtle movements and to measure chamber, vessel, and wall size. Contrast echocardiography is useful in the demonstration of intracardiac and extracardiac shunts, particularly in cases in which 2-D and color-flow imaging are suboptimal.

The study outline is intended as a guide for the entry-level pediatric echocardiographer and, as such, includes malformations that occur with relative frequency as well as those that occur rarely but are relatively straightforward. The outline includes a definition of the anatomic malformation, a list of variants, the hemodynamic effect of the lesion, characteristic clinical findings, key echocardiographic concepts, the natural history of the disease, commonly associated cardiac malformations, interventional catheterization techniques, and palliative as well as corrective surgical procedures. Complex malformations such as single ventricle, double-inlet ventricle, and double-outlet ventricle are beyond the scope of this chapter. For information regarding these malformations, the reader is referred to more extensive texts.

Sample examination questions are provided following the text to give the reader an appreciation of the scope of knowledge required to perform routine diagnostic pediatric echocardiograms. The questions are not intended to be a comprehensive review but to assist the reader in determining what needs to be studied in greater detail.

For discussions of normal anatomy, general scanning technique, echocardiographic physics and instrumentation, and acquired heart disease that are not specific to the pediatric population, the reader is referred to other chapters within this book. Acquired pathologies that occur in the pediatric as well as adult population include mitral valve prolapse, rheumatic heart disease, cardiac masses, cardiomyopathies, pericardial effusions, and bacterial endocarditis. Evaluation of ventricular function in the pediatric population is identical to that of the adult population and, therefore, will not be repeated within this chapter.

SEGMENTAL ANATOMY

When evaluating congenital heart disease, the echocardiographer begins by determining whether the heart within the thorax is located mostly in the left chest (levocardia), right chest (dextrocardia), or directly posterior to the sternum (mesocardia). The direction in which the apex is pointing is also noted. The echocardiographer should demonstrate segmental anatomy by delineating situs, ventricular looping, and great vessel relationship. This will allow an accurate description of cardiac anomalies and can be used to compare with other imaging modalities.

This may be done by documenting anatomic landmarks for each chamber and vessel, as follows:

1. Atrial situs12

A. Determined by

(1) Positions of the atria as proven by anatomic landmarks

a. Right atrium

• Presence of Eustachian valve

• Right atrial appendage (broad connection to atrium)—parasternal or subcostal sagittal views

• Entrance of superior vena cava and inferior vena cava (the superior vena cava is not a reliable marker of the right atrium, as it may drain into the left atrium; inferior vena cava may also be interrupted), and coronary sinus

b. Left atrium

• Left atrial appendage (tubular, with narrow connection)—parasternal long- or short-axis, subcostal, apical four-chamber views

• Entrance of pulmonary veins—posterior subcostal coronal plane (pulmonary veins are not reliable marker of the left atrium due to potential anomalous drainage)

B. Types

(1) Solitus—normal

• Right atrium is right sided; receives the inferior vena cava, superior vena cava, and coronary sinus

• Left atrium is left sided and receives the pulmonary veins

• Descending aorta to the left; inferior vena cava to the right

(2) Inversus—mirror image visceral placement

• Very rare

(3) Left atrial isomerism—double left-sidedness

• Both atria have left atrial morphology

• Seventy percent have interrupted inferior vena cava with dilated azygos vein located posterior to the aorta on the same side of the spine or direct hepatic vein drainage into atria bilaterally (2-D transverse subcostal views; confirm venous versus arterial structures by Doppler from sagittal views)

• Usually have polysplenia

• Frequently have complex cardiac anomalies

(4) Right atrial isomerism—double right-sidedness

• Inferior vena cava located anterior to the aorta on the same side of the spine

• Usually have asplenia

• Frequently have other cardiac lesions

2. Ventricular connection (looping)3-5

A. Determined by positions of the ventricles as proven by anatomic landmarks

(1) Right ventricle

• Trabeculated endocardial surface

• Tricuspid valve (three leaflets)

— annulus inserts more apically than the mitral valve

— chordal insertion into ventricular septum or free wall

• Moderator band

(2) Left ventricle

• Smooth endocardial surface

• Mitral valve (two leaflets)

• Two prominent papillary muscles

B. Types

(1) Dextro—right ventricle to the right

(2) Levo—right ventricle to the left

3. Great vessel relationship1

A. Types

(1) Dextro—aortic valve to the right and posterior of the pulmonic valve

(2) Levo—aortic valve to the left of the pulmonic valve

B. Determined by positions of the great arteries as proven by anatomical landmarks

(1) Pulmonary artery

• Bifurcates soon after exiting the heart

• Posterior course from base of the heart

(2) Aorta

• Superior course from base of the heart, to form aortic arch

• Coronary arteries

NORMAL HEMODYNAMICS6

Image

IMPORTANT DOPPLER CALCULATIONS

1. Conversion of frequency shift into velocity by use of the Doppler equation7

2. Estimation of pressure gradient by application of the modified Bernoulli equation7

3. Determination of flow volume8

4. Determination of pulmonary to systemic flow ratio, referred to as Qp; Qs9-11

5. Estimation of valve area by use of the continuity equation12

ESTIMATION OF PULMONARY ARTERY PRESSURE

The development and progression of elevated pulmonary artery pressure is of concern in any patient with congenital heart disease. Pulmonary artery pressures rise in response to increased flow volume or pressure as pulmonary vascular resistance becomes elevated. Increased flow volume or high pressure causes the intimal and medial layers of the pulmonary arterioles to hypertrophy, thereby increasing pulmonary vascular resistance. With prolonged exposure to high-flow volume or pressure, the patient develops pulmonary hypertension and eventually pulmonary vascular obstructive disease, which is irreversible. When pulmonary artery pressures exceed systemic pressures, blood flow through intracardiac and extracardiac shunts reverses, so that they become pulmonary-to-systemic or right-to-left shunts. Mixing of deoxygenated blood with oxygenated blood leads to cyanosis. The right ventricle eventually fails because of the increased resistance against which it must work to eject blood. Pulmonary vascular disease that results from prolonged increased volume and pressure to the pulmonary vascular bed from a systemic to pulmonary (left to right) shunt is referred to as Eisenmenger’s syndrome.13

Echocardiographic Signs of Elevated Pulmonary Artery Pressure (Pulmonary Hypertension)

• Dilated right atrium14 and ventricle with thickened right ventricular free wall

• Disappearance of the “a” wave on the pulmonic valve M-mode1516

• Midsystolic closure of the pulmonic valve on M-mode, also known as the “flying W”17

• Tricuspid and/or pulmonic regurgitation in the absence of structural abnormalities of the valves18

Estimation of Systolic Pulmonary Artery Pressure

• Peak tricuspid regurgitation gradient plus 7 mm Hg (assumed central venous pressure)1819

• Enhancement of tricuspid regurgitation Doppler tracing by use of echocardiographic contrast20

Estimation of Diastolic Pulmonary Artery Pressure

• End-diastolic pulmonary regurgitation gradient plus 7 mm Hg (assumed central venous pressure)21

• Pulmonary artery diastolic pressure = 0.49 × PA systolic pressure (from peak TR gradient)22

Estimation of Mean Pulmonary Artery Pressure

• Acceleration time (AcT) divided by ejection time (ET) flow through the right ventricular outflow tract as recorded by PW Doppler23

SIMPLE SHUNT LESIONS

Persistent Patent Ductus Arteriosus

Anatomy. The ductus arteriosus is a vessel connecting the left pulmonary artery to the descending aorta (immediately distal to the level of the left subclavian artery) that allows blood to bypass the pulmonary circulation during fetal life. Shortly after birth, this vessel should close so blood can enter the pulmonary circulation to be oxygenated. When the vessel remains patent, it is referred to as a persistent patent ductus arteriosus.

Hemodynamics. During fetal life, pulmonary vascular resistance is higher than systemic vascular resistance; therefore, pulmonary pressure is higher than systemic pressure, so blood flows from the pulmonary artery to the descending aorta. After birth, pulmonary vascular resistance decreases and becomes much lower than systemic vascular resistance. The reversal in pressure differences between the pulmonary and systemic circulations causes a reversal of flow through a persistently patent ductus arteriosus, so that the blood from the descending aorta enters the pulmonary circulation. The resulting increase in pulmonary flow continues into the left atrium as a volume overload, causing the left atrium and ventricle to dilate. The magnitude of the systemic to pulmonary shunt is determined by the difference between the pulmonary and systemic vascular resistances, the difference in pulmonary artery and descending aortic pressures, and by the luminal diameter and length of the ductus arteriosus.6

Clinical Presentation.624 Patients are usually asymptomatic if ductus is small; in cardiac failure if the shunt is large.

• Physical exam: bounding pulses (moderate to large patent ductus arteriosus)

• Auscultation: systolic murmur in infants, continuous murmur at older age

• ECG (electrocardiogram): variable

• Chest x-ray: enlarged pulmonary artery and aorta, increased vascular markings, ductus “bump” off the descending aorta (large ductus)

Key Echocardiographic Concepts

• Demonstrate position, size, and course of patent ductus arteriosus in 2-D and color

• 2-D visualization of the ductus entering the pulmonary artery (parasternal short-axis or high parasternal view)2526

• 2-D visualization of the ductus entering the descending aorta (suprasternal notch or high parasternal view)27, 28

• Continuous flow in the pulmonary artery by PW or color-flow Doppler2930

• Diastolic flow reversal in the descending aorta distal to the left subclavian artery by PW or color-flow Doppler1231

• Demonstration of shunt by contrast echocardiography2532

• Left atrial to aortic root ratio (LA/Ao ratio) greater than 1.2 in the absence of left ventricular failure32

• Estimation of pulmonary artery pressure by determining the pressure gradient through the duct by CW Doppler and subtracting this value from the systolic blood pressure12

• Demonstrate arch sidedness, assess for possible coarctation or LPA stenosis

Populations at Increased Risk6

• Preterm infant

• Infant born at altitudes >4,500 m above sea level

• Rubella syndrome

• Family history

• Complex congenital heart disease13

Natural History.6 A large shunt may cause congestive heart failure, failure to thrive, and recurrent respiratory infections. Pulmonary vascular obstructive disease will develop if left untreated.

Treatment6

• Indomethacin: to close ductus medically

• Device (Amplatzer, Helix) closure by interventional catheterization33

• Surgical ligation

• Prostaglandin E1: to keep ductus patent in the presence of a “duct-dependent” lesion, in which the ductus is necessary to provide pulmonary or systemic circulation

Postoperative Echocardiographic Evaluation. Left atrial and ventricular size should regress to normal. Color-flow or PW Doppler should be used to check for residual shunting.

Assessment of the aortic arch and branch pulmonary arteries is essential to determine residual obstruction or inadvertent impingement of the LPA or descending aorta

Other Systemic to Pulmonary Shunts

Echocardiographic Concepts

• PW Doppler documentation of diastolic descending aortic flow reversal to evaluate patency of the shunt

• Localization of shunt by PW Doppler (determines the level at which the diastolic reversal begins)

• Visualization of shunt on 2-D and color-flow Doppler

Types

A. Aortopulmonary window: a defect in the walls of the ascending aorta and main pulmonary artery resulting in blood shunting between these structures; Doppler findings are similar to those of persistent patent ductus arteriosus, except reversal of flow may be detected in the ascending as well as descending aorta.12

B. Surgically Created Systemic to Pulmonary Shunts634

1. Blalock-Taussig: subclavian artery to pulmonary artery (classic BT shunt), currently the shunt of choice is the modified BT shunt (Gore-Tex tube from the innominate artery to pulmonary artery) on side opposite the aortic arch; modified versions may be placed on either side.

2. Central: anastomosis or conduit between the pulmonary artery and aorta

3. Potts: descending aorta to pulmonary artery; difficult to control size; older technique

4. Waterston: ascending aorta to right pulmonary artery; difficult to control size; older technique

5. Glenn (cavopulmonary shunt): superior vena cava to right main pulmonary artery; occlusion may lead to various complications; including superior vena cava syndrome

Atrial Septal Defects

Anatomy. Atrial septal defect is incomplete septation of the atrial septum that results in a “hole” or communication through which blood can flow directly from one atrium to the other. Types of atrial septal defects, as determined by physical location, are listed below.2635

• Secundum: area of the foramen ovale; most common

• Primum: posterior, near the atrioventricular valves; associated with cleft mitral valve and mitral regurgitation

• Sinus venosus: posterior and superior, near the entrance of the superior vena cava; associated with anomalous right pulmonary venous return into the right atrium

• Coronary sinus: area of the entrance of the coronary sinus; rare; associated with persistent left superior vena cava, absent coronary sinus, and complex congenital heart disease.36

Hemodynamics. Blood is “shunted” from the higher pressure left atrium to the lower pressure right atrium causing a volume overload and, therefore, dilation of the right atrium, right ventricle, and pulmonary arteries. Doppler interrogation reveals blood flow through the interatrial septum and increased flow velocities through the tricuspid and pulmonic valves.

Clinical Presentation.624 Patients are usually asymptomatic.

• Physical exam: systolic impulse may be felt at the lower left sternal border

• Auscultation: fixed splitting of the second heart sound, systolic crescendo-decrescendo (ejection) murmur that is heard best at upper left sternal border (relative pulmonary stenosis)

• ECG: right ventricular hypertrophy

• Chest x-ray: enlarged heart and increased pulmonary vascular markings

Key Echocardiographic Concepts

• Visualization of defect on 2-D and with color-flow Doppler (subcostal long and short, parasternal short axis, and apical four-chamber views)2630

• Determine defect location and size and relationship with surrounding structures (atrioventricular valves, pulmonary and systemic veins) for possible device closure

• PW Doppler tracing characteristic of left to right shunt through an atrial septal defect37

• Degree of right atrial and ventricular dilatation to estimate severity of shunt

• PW Doppler technique to calculate Qp:Qs (i.e., magnitude of the shunt)

• Use of echocardiographic contrast to confirm the presence of a shunt3839

Associated Disease2432

• Mitral valve prolapse

• Left ventricular inflow obstruction (Lutembacher’s syndrome—rare and associated with rheumatic heart disease)

• Subaortic stenosis

• Atrial septal aneurysm

• Partial anomalous pulmonary venous return

Natural History624

• May close spontaneously

• Symptoms occur in the second decade of life

• Pulmonary vascular obstructive disease may develop, usually in adulthood

Treatment

• Device closure by interventional catheterization (in secundum defects with adequate rims)

• Elective surgical patch closure with pericardial or Teflon patch

• Elective surgical suture closure

Postoperative/Device Closure Echocardiographic Evaluation

• Right atrial and ventricular size should regress to normal.

• Color flow, PW Doppler, or contrast echo40 should be used to check for residual shunting around the patch

• Visualization of device and possible migration, obstruction of neighboring structures, perforation or rupture of cardiac structures4143

Ventricular Septal Defects

Anatomy. A communication exists between the ventricles as a result of incomplete septation. Type is determined by location, as listed below.2644

• Perimembranous: including the membranous septum and frequently portions of the muscular septum directly under the aortic valve

• Malalignment: the aorta or pulmonary artery overrides the interventricular septum

• Inflow (atrioventricular canal, endocardial cushion): posterior, at the level of the atrioventricular valves

• Doubly committed subarterial (subpulmonic, supracristal): immediately proximal to the pulmonic valve, in the right ventricular outflow tract

• Muscular: in the body of the ventricular septum; may be localized at the apex or in the anterior, mid, or posterior portion of the muscular septum

• Left ventricular to right atrial shunt: rare; mimics tricuspid regurgitation45

Hemodynamics. Blood from the higher-pressure left ventricle courses through the communication into the lower-pressure right ventricle. The greatest volume of blood is shunted during systole, when the pressure difference between the ventricles is most pronounced. Because the pulmonic valve is open during systole, the high-velocity jet from the left ventricle proceeds through the right ventricle directly into the pulmonary artery. The pulmonary vasculature, therefore, is affected more by the increased volume and pressure than the right ventricle. The increased blood volume proceeds into the left atrium and ventricle causing dilatation of these chambers.

The degree of shunting depends on the pulmonary vascular resistance.

Clinical Presentation.24 Patients usually are asymptomatic if the defect is small, but may present in cardiac failure if the shunt is moderate to large.

Small ventricular septal defect

• Physical exam: palpable thrill over the chest

• Auscultation: harsh holosystolic murmur; variably split second heart sound

Moderate to large ventricular septal defect

• Physical exam: failure to thrive, prominent precordium; left ventricular heave; tachypnea, tachycardia, hepatomegaly

• Auscultation: low-pitched holosystolic murmur; gallop

• ECG: left ventricular hypertrophy with or without right ventricular hypertrophy

• Chest x-ray: dilated pulmonary artery, pulmonary vessels, left atrium, left ventricle

Key Echocardiographic Concepts

• Visualization of defect on 2-D (size and location) and of the shunt (jet) by color-flow Doppler263046

• Relationship of ventricular septal defect with neighboring structures (tricuspid, aortic, and pulmonary valves)

• Systolic flow into the right ventricle through the interventricular septum by PW or CW Doppler10,47

• Evidence of shunt by contrast echocardiography44

• Estimation of right ventricular pressure by determining the pressure gradient through the ventricular septal defect by CW Doppler and subtracting this value from the systolic blood pressure48

• Restrictive versus nonrestrictive ventricular septal defect13

• Estimation of the magnitude of the shunt by calculation of the Qp:Qs by Doppler technique, and mostly by determination of size of left cardiac chambers

Associated Disease

• Multiple ventricular septal defects may occur

• Aortic insufficiency (particularly with doubly committed subarterial and perimembranous types)2649

• Membranous subaortic stenosis45

Natural History613

• Small defects may close spontaneously

• Risk of developing endocarditis

• Aneurysms of tricuspid valve tissue may partially or completely occlude perimembranous ventricular septal defects44

• Doubly committed subarterial ventricular septal defects may develop coronary cusp herniation (prolapse) and subsequent aortic insufficiency of increasing severity49

• Development of pulmonary vascular obstructive disease if a significant defect remains open

• Increased risk of progression of pulmonary vascular obstructive disease if closure is delayed beyond 2 years of life.

Treatment

• Elective surgical stitch or patch closure

• Repair of aortic valve herniation

Postoperative Echocardiographic Evaluation

• Left atrial and ventricular size should regress to normal32

• Assess for peripatch residual shunts by PW Doppler, color flow, or contrast echo401329

• Assess for patch dehiscence32

Atrioventricular Septal Defects

Anatomy. A spectrum of malformations that occur at the crux of the heart where the atrioventricular valves, interatrial septum, and interventricular septum intersect. These malformations may also be referred to as endocardial cushion defects or atrioventricular canals. Any combination of the following malformations may exist. When there is atrial, ventricular, and atrioventricular valve involvement, the patient is said to have a complete atrioventricular septal defect50:

• Primum atrial septal defect

• Inlet ventricular septal defect

• Atrioventricular valve malformation: including cleft mitral valve, single atrioventricular valve, overriding atrioventricular valve, straddling atrioventricular valve

• Common atrium: interatrial septum is completely absent (associated with atrial isomerism)

Hemodynamics. The defects are generally large; therefore, equalization of pressures may occur between chambers, resulting in bidirectional shunting through septal defects. The right heart is dilated because of increased volume or pressure. Atrioventricular valve regurgitation may cause atrial dilatation.

Clinical Presentation.624 Patients are usually symptomatic during infancy.

• Physical exam: failure to thrive, fatigue, dyspnea, heart failure, recurrent respiratory infections

• Auscultation: variety of murmurs

• ECG: left-axis deviation, biventricular hypertrophy

• Chest x-ray: gross cardiomegaly with increased vascular markings

Key Echocardiographic Concepts

• 2-D evaluation of size, location, and additional ventricular and atrial septal defects

• Relative right ventricular and left ventricular size by 2-D50

• Atrioventricular valve competency by PW or color-flow Doppler10

• Structure of the atrioventricular valves, particularly chordal attachments44

• Assessment of spacing of the left ventricle papillary muscles

• Assessment of atrial and/or ventricular unbalance

• Visualize atrioventricular valve annulus and inflow into the ventricle by color (four-chamber view) and

• Distribution of atrioventricular valve over the ventricles (subcostal view)51

• Assessment of pulmonary artery pressure by Doppler methods

Associated Disease63250

• Left heart and aortic obstructive lesions

• Secundum atrial septum defects

• Muscular ventricular septal defects

• Atrial isomerisms

Natural History

• Pulmonary vascular obstructive disease develops at an early age24

Treatment.6 Surgery is usually done during the first year of life

• Elective surgical repair of atrioventricular valves and patch closure of septal defects

• Pulmonary artery band: surgical palliation in which supravalvular pulmonary stenosis is created to limit blood flow to the pulmonary vascular bed to retard progression of pulmonary vascular disease

Postoperative Echocardiographic Evaluation

• After definitive repair, evaluate ventricular function, check for residual shunts and assess competency of atrioventricular valves.

• After pulmonary artery banding, determine the anatomic position of the band and the pressure gradient across it by CW Doppler.

OBSTRUCTIVE LESIONS

Left Ventricular Outflow Obstructions

Anatomy. Various types of obstruction are listed below.6132632

• Bicuspid aortic valve: one of the commissures remains fused; the most common type of congenital heart disease; frequently hemodynamically insignificant until adulthood

• Unicuspid aortic valve: in place of a valve, there is a membrane with an orifice

• Discrete subaortic stenosis: membrane or ridge in the left ventricular outflow tract; may also affect the anterior leaflet of the mitral valve

• Dynamic subaortic stenosis (idiopathic hypertrophic subaortic stenosis, hypertrophic obstructive cardiomyopathy): thickened interventricular septum; genetically transmitted

• Tunnel aortic stenosis: diffuse narrowing of the left ventricular outflow tract; rare

• Supravalvular aortic stenosis: localized or diffuse narrowing of the ascending aorta, generally just distal to the sinuses of Valsalva; usually associated with Williams syndrome

Hemodynamics. Obstruction increases resistance to flow out of the left ventricle. The left ventricle must, therefore, generate higher systolic pressures to force the blood past the obstruction. This pressure overload results in thickening of the left ventricular walls.

Clinical Presentation.624 Patients are usually asymptomatic unless obstruction is severe.

• Physical exam: anacrotic notch and prolonged upstroke in peripheral arterial pulse; left ventricular lift and precordial systolic thrill may be palpable

• Auscultation: ejection click and systolic ejection murmur, narrowed splitting of the second heart sound; reversed splitting of the second heart sound if obstruction is severe

• ECG: left ventricular hypertrophy

• Chest x-ray: dilated ascending aorta

Key Echocardiographic Concepts

General Concepts

• High-velocity turbulent jet distal to obstruction by PW or color-flow Doppler8729

• Increased thickness of left ventricular walls32

• Prolonged time to peak velocity (acceleration time to left ventricular ejection time ratio >0.30 suggests pressure >50 mm Hg, >0.55 requires surgery)7

• Estimation of pressure gradient through the obstruction by CW Doppler-peak systolic pressure gradient >75 mm Hg and a mean gradient >50 mm Hg with a normal cardiac output is critical aortic stenosis and a surgical emergency267

• Estimation of valve area by continuity equation—area less than 0.5 cm2 is critical aortic stenosis and a surgical emergency6

Valve area:

• Mild stenosis: effective orifice area >1.4 cm2

• Moderate stenosis: effective orifice area 1.0–1.4 cm2

• Severe stenosis: effective orifice <1.0 square cm52

• Calculation of left ventricular wall stress32

• Estimation of left ventricular pressure as posterior left ventricular wall thickness at end systole divided by end-systolic diameter multiplied by 22553

Bicuspid Aortic Valve

• Delineation of configuration of cusps and commissural fusion by 2-D

• Doming of cusps on 2-D

• Aortic eccentricity index greater than 1.5 determined by M-mode32

Discrete Subaortic Stenosis2632

• 2-D visualization of the membrane from the parasternal long-axis or apical five-chamber and subcostal coronal view

• Premature closure or midsystolic notch on the aortic valve M-mode or PW Doppler tracing

• Coarse systolic fluttering of the aortic cusps on M-mode

• Increased velocity of flow proximal to the aortic valve by PW and color-flow Doppler and development of aortic insufficiency

Dynamic Subaortic Stenosis54

• 2-D demonstration of distribution of myocardial thickening

• Late systolic peak on CW Doppler tracing

Tunnel Aortic Stenosis

• 2-D visualization of diffusely narrow left ventricular outflow tract, hypoplastic aortic valve with thick cusps, and hypoplastic ascending aorta26

Associated Disease6

• Bicuspid aortic valve: aortic insufficiency, Coarctation of the Aorta and ventricular septal defect

• Unicuspid aortic valve: aortic insufficiency

• Discrete subaortic stenosis: aortic insufficiency

Natural History6

• Obstruction usually progresses

• Development of aortic regurgitation

Treatment.613 Patients are generally prophylaxed and may be restricted from participating in competitive sports depending on the degree of stenosis.

• Valvular aortic stenosis: intervention when peak systolic pressure gradient exceeds 75 mm Hg or mean gradient exceeds 50 mm Hg or orifice size decreases to 1 cm2 of body surface area

• Percutaneous balloon valvuloplasty55

• Commissurotomy

• Aortic valve replacement

• Discrete subaortic stenosis: surgical resection of the membrane

• Supravalvular aortic stenosis: surgical resection of obstruction when pressure gradient exceeds 50 mm Hg

• Tunnel aortic stenosis: left ventricular to descending aorta valved conduit,56 Konno procedure (widening of aortic root and left ventricular outflow tract)

Postoperative Echocardiography Evaluation. Evaluate for residual or restenosis and aortic insufficiency.

Coarctation of the Aorta

Anatomy. There is a discrete or diffuse narrowing of the aorta, most commonly located immediately distal to the left subclavian artery in the area of the ductus arteriosus. Infrequently, the coarctation will occur proximal to the ductus arteriosus or a portion of the aortic arch may be hypoplastic. In either of these cases, patency of the ductus arteriosus may be necessary to perfuse the descending aorta and maintain life.6

Hemodynamics. Obstruction to flow at the level of the coarctation results in a build-up of pressure proximal to the obstruction and decreased flow distal to it.13 Left ventricular walls thicken in response to increased resistance. A high-velocity jet through the obstruction may weaken the aortic wall immediately distal to the obstruction causing post-stenotic dilatation.

Clinical Presentation.624 Presentation varies according to age. In the neonate, the patient may present with heart failure and shock after the ductus arteriosus has closed. Older patients are usually asymptomatic and are treated for hypertension.

• Physical exam: systemic hypertension, with systolic blood pressure much higher in the upper extremities than in the lower extremities13; weak femoral pulses; upper body may be more well developed than the lower body

• Auscultation: systolic murmur along the left sternal border transmitting to back and neck; bruits from collateral vessels in older children

• ECG: right ventricular hypertrophy in symptomatic infants; left ventricular hypertrophy in older children

• Chest x-ray: inverted “3” sign at level of coarctation; prominent descending aorta; rib notching in children older than 8 years

Key Echocardiography Concepts

• 2-D evaluation of arch anatomy, including branching and size of branches, measurement of proximal and distal arch diameters, isthmus diameter and proximal descending aortic diameter57

• Evaluation of flow in the patent ductus arteriosus

• Evaluation of left ventricular morphology (inflow and outflow) and ventricular size and function

• 2-D visualization of obstruction within the aortic lumen5859

• Determination of gradient by CW Doppler tracing through the coarctation60

• Velocity of flow proximal to the obstruction should be taken into consideration10

• Decreased pulsatility on the PW Doppler tracing of the descending aorta (blunted acceleration and slow deceleration of flow that does not return to baseline during diastole)10

Associated Disease659

• Bicuspid aortic valve (found in as many as 50% of patients with Coarctation of the Aorta)

• Additional levels of left heart obstruction

• Ventricular septal defects

• Transposition of the great arteries

• Double-outlet right ventricle

Natural History. If unrelieved, as many as 80% of patients die before reaching the age of 50 years.6

Neonatal coarctation (ductal dependent systemic blood flow lesion) will present in shock after closure of the ductus

Treatment.613 Early repair seems to decrease probability of residual systemic hypertension.

• Surgical resection of constricted area and primary anastomosis (end to end) or subclavian artery flap to widen aortic lumen. Surgery is the dominant treatment for native coarctation in the neonate.

• Balloon angioplasty and stent placement are commonly used for treatment of native coarctation in older children and adults, and to treat recurrent coarctation.6162

Postoperative Echocardiographic Evaluation

• Assessment of the lumen size and pressure gradient in the area of the re-anastomosis

• PW Doppler spectral tracing of the descending aortic flow may continue to appear somewhat blunted

Hypoplastic Left Heart Syndrome

A spectrum of left-sided hypoplasia in which the left atrium, mitral valve, left ventricle, aortic valve, and aorta may be hypoplastic, stenotic, or atretic. Frequently associated with an atrial septal defect through which pulmonary venous return flows into the right atrium and a patent ductus arteriosus, which in turn supplies the descending aorta.26

This is a ductal dependent systemic blood flow lesion.

Treatment63

• Prostaglandins started in the immediate neonatal period to ensure patency of the ductus arteriosus and maintain systemic blood flow

• Norwood procedure

• Cardiac transplantation

Pulmonary Stenosis

Anatomy. Obstruction may occur at various levels along the right ventricular outflow tract and the pulmonary arterial system. Types are listed below.624

• Valvular stenosis: fusion or dysplasia of cusps

• Infundibular stenosis: hypertrophy of muscle bands in the right ventricular outflow tract; usually associated with a ventricular septal defect or valvular pulmonary stenosis26

• Double-chamber right ventricle: hypertrophied anomalous muscle bundles in the right ventricle, effectively dividing the right ventricle into two chambers with a communication between them; associated with valvular pulmonary stenosis, perimembranous ventricular septal defects, and subaortic stenosis4464

• Peripheral pulmonary stenosis: may occur as a distinct shelf in the pulmonary artery, discrete narrowing of the pulmonary artery branches, or as diffuse tapered narrowing of the pulmonary artery branches65

Hemodynamics. Increased resistance to right ventricular outflow results in a pressure overload to this chamber. The right ventricular walls thicken. Blood flow into the pulmonary arterial system is at high velocity and turbulent. Eddy currents produced distal to the obstruction may cause poststenotic dilatation of the pulmonary artery.26

Clinical Presentation.6 Patients are usually asymptomatic.

• Auscultation: systolic ejection murmur

• ECG: right ventricular hypertrophy

• Chest x-ray: prominent pulmonary artery trunk; large right atrium

Key Echocardiographic Concepts

• 2-D visualization and measurement of pulmonary valve annulus in candidate for balloon angioplasty of valvular stenosis66

• 2-D visualization of anomalous muscle bundle and orifice from parasternal and subcostal views66

• Measure the diameter of main and branch pulmonary arteries

• Doppler estimation of pressure gradient from all available positions67

• Assess right ventricular function, free wall hypertrophy, systolic pressure (based on TR jet estimation)

• Assess tricuspid valve morphology and annulus size

• Determine the presence of a ductus arteriosus

• Accentuation of the “a wave” on M-mode6

Natural History6

• Increased risk of endocarditis

• Mild valvular and peripheral stenosis (right ventricular pressure <50 mm Hg and a pressure gradient of <40 mm Hg) is considered benign and may or may not progress.

• Severe stenosis (right ventricular pressure >100 mm Hg and a pressure gradient >60 mm Hg) requires relief.68

• Infundibular stenosis and anomalous muscle bundles tend to become progressively more obstructive.

Treatment. When the patient becomes symptomatic or pressure gradient exceeds 60 mm Hg13

• Balloon valvuloplasty: to relieve valvular and peripheral stenosis55

• Surgical valvotomy6

• Surgical resection of infundibular muscle or anomalous muscle bundles

Postoperative Echocardiographic Evaluation

• Assess patency of area of former obstruction

• Assess presence and severity of pulmonary insufficiency

Pulmonary Atresia with Intact Ventricular Septum

Anatomy. There is an imperforate membrane or thick fibrous band in place of a pulmonary valve or complete absence of the main pulmonary artery in the absence of a ventricular septal defect.6569

Hemodynamics. Life is dependent on a persistent patent ductus arteriosus. Main and branch pulmonary arteries are usually normal in size.

Clinical Presentation.6 Severe cyanosis and hypoxemia are seen in the neonate.

• Auscultation: possibly the murmur of a persistent ductus arteriosus

• ECG: right ventricular hypertrophy; right-axis deviation

• Chest x-ray: decreased pulmonary vascular markings

Key Echocardiographic Concepts666

• 2-D delineation of anatomy

• Right ventricular outflow tract, location, and size of main pulmonary artery and branches (subcostal coronal and parasternal short axis)

• Assessment of tricuspid valve anatomy and annulus diameter (annulus predicts outcome—z score of <3 associated with lower likelihood of tolerating right ventricular decompression)7071

• Associated malformations

• Contrast echocardiography to delineate anatomy

• Doppler and color-flow delineation of flow patterns

Associated Disease66

• Persistent ductus arteriosus

• Atrial septal defect or patent foramen ovale

• Malformations of the tricuspid valve

• Coronary arterial sinusoids (interrogate myocardium by color and Doppler at low Nyquist limit)

Natural History

• Death when the persistent ductus arteriosus closes or becomes insufficient to sustain minimal blood oxygenation requirements6

Treatment613

• Prostaglandin: to keep the ductus arteriosus patent

• Palliation with a surgically created systemic to pulmonary shunt

• Surgical reconstruction and/or placement of prosthetic valve

• May need to follow single ventricle palliative route (Glenn-Fontan)

Postoperative Echocardiographic Evaluation

• Evaluate patency of systemic to pulmonary shunt

• Evaluate patency of reconstructed area

Left Ventricular Inflow Obstruction

Anatomy. Left ventricular inflow is obstructed by a membrane in the left atrium or a decrease in the mitral orifice size. Various forms exist, as listed below.2644

• Cor triatriatum: rare; left atrial membrane immediately superior to the fossa ovalis and left atrial appendage

• Supravalvular ring: more common than cor triatriatum; left atrial membrane immediately superior to the mitral valve annulus; usually associated with other mitral valve anomalies3672

• Valvular mitral stenosis: rare; dysplastic valve leaflets, chordae and papillary muscles

• Parachute mitral valve: all chordae insert onto a single papillary muscle

• Arcade mitral valve: chordae insert onto multiple papillary muscles; may be regurgitant

• Double orifice mitral valve: rare; tissue bridge divides mitral valve into two halves and chordae from each half inserting onto a particular papillary muscle; may be regurgitant; associated with atrioventricular malformation73

• Mitral valve hypoplasia: small mitral valve annulus and leaflets

• Mitral Atresia: imperforate mitral valve may be associated with a large ventricular septal defect, straddling tricuspid valve, or double-outlet right ventricle

Hemodynamics. Obstruction to left ventricular inflow results in a buildup of pressure in the left atrium causing it to dilate. Pulmonary veins become congested because they cannot empty easily into the left atrium.

Clinical Presentation6

• Physical exam: history of recurrent respiratory infections

• Auscultation: diastolic murmur heard best at the apex

• ECG: left atrial enlargement

• Chest x-ray: left atrial enlargement; increased pulmonary vascular markings; right heart enlargement

Key Echocardiographic Concepts

• Delineation of anatomy by 2-D:

Supravalvar area (cor triatriatum/supravalvar mitral ring) Annulus size

Anatomy of papillary muscles

• Doppler estimation of pressure gradient

• Estimation of orifice size by application of the continuity equation

Associated Disease6

• Other levels of left heart obstruction

• Secundum and primum atrial septal defects

• Transposition of the great arteries

• Double-outlet right ventricle

Natural History. The degree of obstruction depends on the valve area, the cardiac output, and the heart rate.74 Left ventricle inflow obstruction eventually develops into pulmonary vascular obstructive disease.7

Treatment674

• Valvular: balloon valvuloplasty (in attempt to delay surgery); commissurotomy or valve replacement

• Cor triatriatum and supramitral ring: surgical excision of membrane66

Postoperative Echocardiographic Evaluation

• Evaluate residual stenosis and regurgitation

Tricuspid Atresia

Anatomy. A dense band of tissue replaces the tricuspid valve preventing direct communication between the right atrium and ventricle. A large atrial septal defect or patent foramen ovale must coexist to provide an outlet to the right atrium (obligatory shunt).44 The right ventricle is usually small.13

Type I: Normally related great arteries; ventricular septal defect or patent ductus arteriosus is path of pulmonary blood flow.

Type II: Transposed great arteries; ventricular septal defect is the path for systemic blood; any restriction causes subaortic stenosis.75

Hemodynamics. Deoxygenated systemic venous blood returns to the right atrium and is shunted into the left atrium, where it mixes with oxygenated pulmonary venous return. This mixing of deoxygenated blood with the pulmonary venous return results in a desaturation of the oxygenated blood and, therefore, cyanosis. The right atrium and left heart are generally dilated because of increased flow volume. Because the right ventricle receives blood only indirectly through a ventricular septal defect, it is generally small.24

Clinical Presentation.624 Patients are cyanotic with a history of hypoxic spells.

• Physical exam: clubbing of the fingers; delayed growth; hyperactive cardiac impulse at the apex

• Auscultation: single first heart sound; no murmur

• ECG: left ventricular hypertrophy; left axis deviation

• Chest x-ray: decreased vascular markings

Key Echocardiographic Concepts

• 2-D visualization of dense fibrous band across tricuspid annulus and absence of tricuspid valve leaflets

• Dilated right atrium44

• Atrial septal defect (determine size and effective shunting) or single atrium

• Small right ventricle or right ventricular outflow tract

• Relationship of great arteries (normally related versus dextro-transposition of the great arteries)

Associated Disease624

• Atrial septal defect or patent foramen ovale

• Ventricular septal defect and pulmonary stenosis

• Pulmonary atresia

• Transposition of the great vessels (coarctation is common in this group—30%)75

Natural History

• Early death without intervention6

Treatment1

• Pulmonary artery band (surgical palliation to restrict flow to the pulmonary bed)

• Systemic to pulmonary shunt (surgical palliation to increase flow to the pulmonary bed)

• Balloon atrial septostomy (interventional catheterization to increase interatrial shunting)

• Park blade septostomy (interventional catheterization to increase interatrial shunting)

• Fontan procedure: definitive physiologic correction; the right atrium is connected to the pulmonary artery by placement of a patch or conduit in the hope of increasing pulmonary flow35

Postoperative Echocardiographic Evaluation

• Assess for right atrial contractility and adequacy of flow through the pulmonary artery

Tricuspid Hypoplasia/Stenosis

Anatomy. There is a small tricuspid valve annulus, usually associated with critical pulmonary stenosis, pulmonary atresia with intact interventricular septum, or Ebstein’s anomaly.44

Imperforate Tricuspid Valve

Anatomy. Membrane exists in place of a tricuspid valve, which may be surgically opened.44

MALFORMATION OF THE TRICUSPID VALVE

Ebstein’s Anomaly of the Tricuspid Valve

Anatomy. The septal leaflet is tethered to the interventricular septum and attaches at least 8 mm distal to the tricuspid valve annulus.32 Other tricuspid leaflets may also adhere to the ventricular wall and be dysplastic.76 This malformation results in a large “functional” right atrium and small “functional” right ventricle. In Ebstein’s anomaly, the tricuspid valve is “off-set” relative to the anterior leaflet of the mitral valve >0.8 mm/m2.77 The dysplastic nature of the leaflets and chordae prevents effective coaptation resulting in varying degrees of tricuspid insufficiency and stenosis.44 Contractility of the right ventricle is affected by its size.

Hemodynamics. The right atrium is dilated because of the volume overload that results from the tricuspid regurgitation. The size of the right ventricle varies with the severity of tricuspid valve leaflet displacement.

Clinical Presentation.62476 Cyanosis, dyspnea, or exertion, and profound weakness or fatigue may be present.

• Physical exam: prominent left chest

• Auscultation: systolic and diastolic murmurs; loud, widely split first heart sound—“sail sound”; triple or quadruple rhythm

• ECG: right atrial hypertrophy; right bundle branch block; Wolff-Parkinson-White syndrome; paroxysmal supraventricular tachycardia

• Chest x-ray: enlarged heart; decreased pulmonary vascular markings; right atrial enlargement

Key Echocardiographic Concepts

• 2-D delineation of the anatomy of the tricuspid valve and degree of displacement and tethering of each leaflet from parasternal short axis, apical four-chamber and subcostal long- and short-axis views78

• Determination of the size of the functional right ventricle—if less than 35% of the size of the anatomic right ventricle, prognosis is poor32

• Severity of tricuspid regurgitation

• Tricuspid valve closure delayed greater than 90 m/s after mitral valve closure on M-mode32

Associated Disease67678

• Persistent patent ductus arteriosus

• Atrial septal defect or patent foramen ovale with right to left shunting

• Mitral valve prolapse

• Pulmonary stenosis

• Pulmonary atresia with intact ventricular septum

• Congenitally corrected transposition of the great vessels

• Ventricular septal defect

Natural History67678

• Increased risk of endocarditis

• Prognosis is better with a larger functional right ventricle

• Prognosis is good if the child survives infancy but generally is poor if there are associated lesions

Treatment67678

• Annuloplasty: repair of the valve annulus to make it smaller

• Valve replacement

• Valve repair

• Plication of some of the atrialized portion of the right ventricle

Postoperative Echocardiographic Evaluation

• Assess right ventricular function and residual tricuspid insufficiency and/or stenosis

COMPLEX CONGENITAL HEART DISEASE

Tetralogy of Fallot

Anatomy. In this malformation, a large anterior malaligned ventricular septal defect is associated with malalignment of the aorta, so that the aortic root overrides the septal defect. The malalignment of the aortic root contributes to the infundibular pulmonary stenosis that occurs as part of this malformation.66

Hemodynamics. The large size of the ventricular septal defect allows equalization of left and right ventricular pressures, so that the shunting through the defect is bidirectional. The overriding aorta receives blood from both ventricles, thereby mixing deoxygenated with oxygenated blood.

Clinical Presentation.624 Cyanosis and a history of “tet spells” (transient cerebral ischemia resulting in limpness, paleness, and unconsciousness); history of squatting may present.

• Physical exam: prominent left chest, “clubbing” of fingers in older patients, right ventricular heave

• Auscultation: single second heart sound; systolic ejection murmur

• ECG: right ventricular hypertrophy; right axis deviation

• Chest x-ray: boot-shaped heart with decreased vascular markings

Key Echocardiographic Concepts66

• Assessment of cardiac position

• Assessment of atrial level communication and pulmonary venous return

• 2-D visualization of large perimembranous ventricular septal defect and assessment of degree of aortic override

• 2-D assessment of degree and levels of right ventricular outflow obstruction

• Size of pulmonary valve annulus and morphology

• Size of pulmonary artery and branches from high parasternal short axis and suprasternal notch views (aneurysmally dilated in cases of absent pulmonic valve)79

• Thickened RV free wall

• 2-D delineation of coronary artery (rule out anomalous origin of LAD from the right coronary artery or other prominent branches crossing the right ventricular outflow tract) and aortic arch anatomy to determine surgical approach80

Associated Disease6326679

• Valvular pulmonary stenosis or pulmonary atresia

• Congenitally absent pulmonic valve

• Right-sided aortic arch

• Atrioventricular malformation (Ebstein’s malformation, mitral stenosis, common atrioventricular valve)

• Coronary artery anomalies

• Persistent left superior vena cava

Natural History.6 Severe infundibular stenosis may result in a fatal “tet spell,” in which the infundibulum becomes totally occluded. Recognition and surgical treatment have had a tremendous impact on the natural history of this disease, leaving now a population of adults with repaired tetralogy of Fallot that needs adequate imaging for follow-up.

Treatment6

• Palliation by surgical creation of a systemic to pulmonary shunt

• Patch closure of ventricular septal defect and possible myomectomy of the right ventricular outflow tract, pulmonary valvotomy (valve sparing technique) or transannular patch repair

Postoperative Echocardiographic Evaluation

• Evaluation of patency of surgically created systemic to pulmonary shunt

• Evaluation of residual right ventricular outflow obstruction and residual shunting around ventricular septal defect patch

• Evaluation of ventricular function

• Evaluation of degree of pulmonary regurgitation

Transposition of the Great Arteries

Anatomy. The aorta arises from the embryologic right ventricle, and the pulmonary artery arises from the embryologic left ventricle. Terminology is listed below.

• D-transposition of the great arteries (D-TGA, frequently referred to simply as transposition of the great arteries or complete transposition): the ventricles are concordant with the atria; however, the aorta originates from the right ventricle and the pulmonary artery originates from the embryologic left ventricle.

• Congenitally corrected transposition of the great arteries (L-transposition): ventricular inversion with the great vessels originating from the incorrect ventricle; blood flow sequence is normal; however, there is a high incidence of associated congenital heart disease.

Hemodynamics

• D-TGA: Blood flows in two parallel circuits. It flows from the systemic veins into the right atrium, through the tricuspid valve, into the right ventricle and out the aorta, to return again through the systemic veins. Pulmonary venous return flows into the left atrium, through the mitral valve into the left ventricle, and out the pulmonary artery, to return again through the pulmonary veins. In short, deoxygenated blood flows in a continuous loop, and oxygenated blood flows in a separate continuous loop. Unless a communication exists between the systemic and pulmonary circulations (i.e., an obligatory shunt), this situation is incompatible with life. In the newborn period, a left-to-right shunt occurs at the level of the foramen ovale and through a persistent ductus arteriosus, allowing mixing of oxygenated with deoxygenated blood.

• Congenitally corrected TGA: Blood flows in the normal sequence—from the systemic veins into the right atrium, through the mitral valve into the left ventricle, and out the pulmonary artery, returns to the left atrium via the pulmonary veins, courses through the tricuspid valve, into the right ventricle and out the aorta.

Clinical Presentation for D-TGA.624 Newborns become cyanotic, as the ductus arteriosus closes.

• Physical exam: normal weight, healthy-looking infant

• Auscultation: no murmurs; single second heart sound

• ECG: right ventricular hypertrophy

• Chest x-ray: cardiomegaly; narrow mediastinum (egg on a string); increased vascular markings

Key Echocardiographic Concepts81

• Identify situs by delineating anatomic atrial landmarks on 2-D

• Identify ventricular morphology (embryologic origins) by delineating anatomic landmarks on 2-D

• Identify great vessel morphology and relationship (will course in parallel fashion)

• Identify and evaluate magnitude of shunt through the obligatory shunt defect(s)

• Delineate coronary artery anatomy for consideration of surgical approach80

• Identify and evaluate associated congenital heart disease

Associated Disease for D-TGA3281

• Patent ductus arteriosus: obligatory shunt; most commonly associated with heart disease

• Aortic arch anomalies: coarctation, hypoplastic segment, interrupted aortic arch

• Atrial septal defect or patent foramen ovale: obligatory shunt

• Ventricular septal defect: obligatory shunt; with or without juxtaposed atrial appendages

• Outflow tract obstruction: fixed or dynamic; morphology of aortic and pulmonary valves; degree of aortic or pulmonary regurgitation

• Straddling atrioventricular valve: chordae from one atrioventricular valve attach into both ventricles

• Atrioventricular malformation: rare

• Pulmonary origin of coronary artery

Natural History. Patients with D-TGA must be palliated or repaired on an emergent basis because occlusion of the obligatory shunt would result in immediate death. The mortality rate in the absence of intervention is 95% at the end of 2 years of life.16

Patients with congenitally corrected transposition may never know they have congenital heart disease unless there is associated congenital heart disease, in which case, the natural history is determined by the associated disease.

Treatment63234

Prostaglandin E1 Treatment. Palliation; to keep ductus arteriosus patent until arterial switch can be performed.

Balloon Atrial Septostomy (Rashkind Procedure). Palliative interventional catheterization technique in which a distended balloon catheter is torn across a patent foramen ovale or small atrial septal defect creating a large atrial septal defect. Atrial level shunt is the most important site for adequate mixing.

Surgical Atrial Septectomy (Blalock-Hanlon Operation). Palliation

Arterial Switch (Jatene Procedure). Surgical procedure in which the great arteries are taken off their trunks and moved so that each is re-anastomosed to the trunk that will restore a normal blood flow sequence; coronary arteries also are removed and re-implanted into the neoaorta.

Rastelli Procedure (Intraventricular Repair and Extracardiac Conduit). Surgical procedure in which a tunnel is constructed through a large ventricular septal defect so that the left ventricular outflow is directed to the aortic valve and a valved conduit is placed between the right ventricle and pulmonary artery.

Mustard Procedure (Atrial Switch). The atrial switch (Mustard and Senning, see below) is no longer performed as a first line of choice for surgical repair; however, many adult patients with this type of repair survive. Surgical excision of the interatrial septum and placement of a baffle made of pericardium or synthetic material to redirect right atrial flow through the mitral valve into the left ventricle and allow pulmonary venous return to flow around the baffle into the tricuspid valve.

Senning Procedure (Atrial Switch). Surgical reconstruction of the atrial wall and interatrial septum to create an intra-atrial baffle redirecting venous flow through the atria.

Postoperative Echocardiographic Evaluation. Evaluation of left ventricular function.

• Balloon atrial septostomy: 2-D visualization of definitive tear in the interatrial septum and calculation of atrial septal defect size to interatrial septal length ratio16

• Arterial switch operation: evaluate anastomotic sites of great arteries for possible constriction, assess intracardiac shunting and regional wall motion and coronary artery flow6

• Mustard and Senning procedures: rule out superior vena cava or pulmonary venous obstruction and baffle leaks6, 12 by PW Doppler, color-flow Doppler, or contrast echocardiography40

Truncus Arteriosus

Anatomy.624 A rare malformation in which a single large great artery (common trunk) arises from the heart through a single semilunar valve and receives outflow from both ventricles. In most cases, the common trunk overrides the large ventricular septal defect, which must be present. The valve of the common trunk frequently has more than three cusps. Pulmonary circulation occurs in one of the following ways:

• Type I: main pulmonary trunk arises from the common trunk (usually from the posterior aspect) and bifurcates into right and left branches

• Type II: right and left pulmonary arteries arise separately from the left posterolateral aspect of the common trunk

• Type III: right and left pulmonary arteries arise separately from lateral aspects of the common trunk

• Type IV: no pulmonary arteries exist; pulmonary circulation is through bronchiole arteries arising from the descending aorta

Hemodynamics.6 The large ventricular septal defect causes equalization of pressures between the ventricles. Flow into the pulmonary circulation is at systemic pressures because the pulmonary arteries arise from the aorta, and there is no pulmonary valve. There may be decreased flow to the pulmonary circulation if there is stenosis of the pulmonary branches or in Type IV

Clinical Presentation.624 Patients are cyanotic.

• Physical exam: early congestive heart failure or hypoxic spells

• Auscultation: single second heart sound; systolic ejection click and murmur

• ECG: biventricular hypertrophy

• Chest x-ray: cardiomegaly; biventricular enlargement; wide mediastinum

Key Echocardiographic Concepts

• 2-D delineation of anatomy:

• Presence of atrial communication

• Location and size of ventricular septal defect

• Atrioventricular valve anatomy

• Morphology of truncal valve

• Evaluation of size of pulmonary arteries

• Additional sources of pulmonary blood flow

• Aortic arch anatomy and branching

• Coronary artery anatomy (relation to pulmonary artery and truncal valve leaflets)

• Associated lesions

• Color-flow and PW Doppler:

• Truncal valve (rule out stenosis or insufficiency)

• Pulmonary arteries (suprasternal notch views may be most helpful)

• Assessment of function and size of ventricles

Associated Disease.6 Usually, truncus arteriosus is an isolated lesion.

• Right aortic arch

• Truncal valve stenosis and/or insufficiency

• Aortic arch anomalies

• Persistent patent ductus arteriosus

• Coronary ostial anomalies

• Absence of a branch pulmonary artery on the side of the arch

• Persistent LSVC

• Anomalous pulmonary venous connections

Natural History.6 If left untreated, death in infancy from heart failure or later from pulmonary vascular obstructive disease will result. Without intervention, survival beyond 1 year is unusual.

Treatment6

• Complete surgical repair involves closure of the ventricular septal defect and removal of the pulmonary arteries from the aorta and placement of a valved conduit between the right ventricle and pulmonary arteries. If coarctation or interrupted aortic arch is present, these are corrected at the same time.

Postoperative Echocardiographic Evaluation

• Evaluate truncal valve (now aortic valve) function

• Evaluate competency of the conduit valve and evaluate pulmonary artery branches for stenosis

• Look for residual lesions (ventricular septal defects)

• Ventricular size and function

• Evaluate aortic arch

ANOMALIES OF THE CORONARY ARTERIES

Kawasaki Syndrome (Mucocutaneous Lymph Node Syndrome)

Definition. Kawasaki disease is an acute systemic vasculitis of unknown cause. It is a common form of acquired heart disease in the pediatric population. The acute phase of the illness features microvascular angiitis, endarteritis, and perivascular inflammation of coronary arteries. The subacute phase may have persistent panvasculitis of the coronary arteries. The convalescent phase shows resolution of the microvascular angiitis replaced by intimal thickening of the coronary arteries. In addition, the inflammatory process may involve pericarditis, myocarditis, and endocarditis.82

The proximal branches seem to be most frequently involved. Distal aneurysms may occur in addition, although rarely without proximal involvement.83

Clinical Presentation.84 There is no diagnostic test for Kawasaki disease, so the diagnosis is made clinically. It begins as a febrile illness of more than 5 days in children between 1 and 5 years. In addition to the fever, at least four of the following five findings are noted:

• Physical exam: (1) nonexudative bilateral conjunctivitis; (2) dry, fissured lips, strawberry tongue; (3) polymorphous truncal rash; erythema of palms and soles; (4) desquamation of fingertips and toes; (5) anterior cervical lymphadenopathy of 1.5 cm or greater.

Diagnosis can be made with fewer than four of five criteria in the presence of echocardiographic evidence of coronary involvement.

• Lab tests: elevated white count, platelet count, erythrocyte sedimentation rate, α2-globulin, immunoglobulin E, transaminase, and lactic acid dehydrogenase

• ECG: infrequent, minimal changes

Key Echocardiographic Concepts

Acute Phase8085

• Left ventricular dysfunction

• Valvular regurgitation

• Pericardial effusion

Convalescent Phase

• 2-D demonstration of saccular or fusiform coronary aneurysms (Table 3–1)

• Segmental wall motion abnormalities

TABLE 3–1 • Echocardiographic Views Used Evaluate Coronary Artery Anatomy

Image

Natural History. The majority of aneurysms resolve; however, those with diameters larger than 8 mm are at increased risk for thrombosis, which may result in myocardial infarction.85 Other factors related to aneurysm regression are age younger than 1 year at diagnosis, saccular aneurysm, and distal aneurysm location. Giant aneurysms are more frequently associated with late sudden death from infarction.

Follow Up. Serial echocardiographic exams are performed at 2 weeks and again at 6-8 weeks after diagnosis. This is the time at which transient changes in coronary ectasia or dilatation will resolve or that aneurysms obtain their maximal size.

Imaging of coronary arteries should be performed with the highest transducer frequency possible.

Treatment. Patients are treated with intravenous immunoglobulin and high-dose aspirin per day until defervescence, and then the aspirin is changed to a low dose for 6-8 weeks to decrease risk of thrombosis.

With persistent aneurysms, coronary angiography is indicated at intervals to determine whether coronary artery bypass surgery is indicated.6

Anomalous Origin of the Left Coronary Artery

Anatomy. A rare malformation in which the left coronary artery originates from the main pulmonary artery rather than from the aortic root.80

Hemodynamics. In the newborn period, the myocardium of the left ventricle is inadequately perfused with oxygen because the blood flowing into the left coronary artery is deoxygenated blood from the pulmonary artery when pulmonary vascular resistance is high; however, this does not cause ischemia. During the transitional period, when pulmonary vascular resistance and pressure decrease, flow in the left coronary becomes retrograde (from right coronary to left coronary via collaterals) and left coronary artery perfusion pressure decreases. This is the usual stage at presentation. Some may pass this stage and present as adults once myocardial ischemia is produced from “steal” phenomenon (left coronary artery drains right coronary blood into the pulmonary artery).

Clinical Presentation.80 It is symptomatic in infancy

• Physical exam: irritable, dyspneic, tachypneic

• Auscultation: mitral insufficiency murmur

• ECG: left ventricular hypertrophy with anterolateral myocardial infarction and deep Q wave in lead I and aVL

• Chest x-ray: enlarged heart

Key Echocardiographic Concepts80

• 2-D visualization of left coronary artery originating from the pulmonary artery

• 2-D visualization of a dilated right coronary artery originating from the right sinus of Valsalva

• PW Doppler or color-flow demonstration of diastolic flow entering the main pulmonary artery just distal to the pulmonary valve

• Decreased left ventricular contractility

• Mitral insufficiency

Natural History. In the absence of intervention, permanent myocardial damage occurs.

Treatment. Surgery to reimplant the left coronary artery into the aortic root is recommended.80

Coronary Arteriovenous Fistula

Anatomy. A variably tortuous coronary artery courses along the surface of the heart or within the myocardium to empty into a cardiac chamber or great vessel. Generally, it is the right coronary artery (60%) that is involved, and the site of drainage is usually a right heart structure.80

Hemodynamics. Rather than perfusing the myocardium, blood from the coronary artery flows into the cardiac chamber or vessel into which it empties. The amount of blood that is “stolen” from the myocardium is small, evidenced by the rare presentation of myocardial ischemia. The physiology is more of a shunt and if fistula is large may cause symptoms of volume overload even in infancy.

Clinical Presentation. Generally, patients remain asymptomatic and are diagnosed after investigation of a murmur or incidentally during echocardiographic exam.8486

• Auscultation: atypical continuous murmur

Key Echocardiographic Concepts87

• 2-D demonstration of a dilated coronary artery

• 2-D demonstration of origin, course, and site of drainage of the fistula

• Color-flow Doppler visualization and PW Doppler confirmation of a continuous, turbulent jet entering a cardiac chamber or great vessel in a location in which shunt lesions do not enter

• PW Doppler demonstration of turbulent late systolic, early diastolic flow in a dilated coronary artery supplying the fistula

Natural History87

• Spontaneous closure may occur

• Bacterial endocarditis

• Congestive heart failure due to volume overload and myocardial ischemia

Treatment. Elective surgical ligation of the fistula.87

Postoperative Echocardiographic Evaluation. Check for residual flow through the fistula.

VENOUS MALFORMATIONS

Persistent Left Superior Vena Cava

Anatomy. In this relatively common malformation (0.5% of the general population and 3–5% of patients with congenital heart disease), a superior vena cava persists in the left chest and travels in front of the left pulmonary artery and between the left atrial appendage and left pulmonary veins. The left superior vena cava may empty into coronary sinus (62%), pulmonary venous atrium (21%), common atrium (17%), or rarely into a left-sided pulmonary vein. In most cases, there is also a right superior vena cava, and in 45-60% of cases, a communication exists between the two superior venae cavae.88

Hemodynamics. Systemic venous blood returns to the cardiac chamber to which the left superior vena cava connects. Deoxygenated blood mixes with oxygenated blood (right to left shunt) if the left superior vena cava drains into a left heart structure.

Key Echocardiographic Concepts35

• 2-D and color-flow visualization of the left superior vena cava (from a high left parasagittal view)

• Dilated coronary sinus

• Contrast echocardiography to assess for unroofed coronary sinus or drainage into the left atrium89

• Absent or small innominate vein

Associated Disease88

• Atrial septal defect

• Complex congenital heart disease

Total Anomalous Pulmonary Venous Return

Anatomy. All of the pulmonary veins drain into systemic venous channels. The types of anomalous drainage are listed below35,90

• Supracardiac: pulmonary veins drain in a confluence behind the left atrium and through a vertical vein empty into the innominate vein, superior vena cava, or occasionally the azygous vein. The vertical vein travels usually in front of the pulmonary artery.

• Cardiac: pulmonary veins drain into the right atrium or coronary sinus

• Infracardiac: pulmonary veins form a collection behind the heart and by a common vein descend below the diaphragm and empties into the portal vein, ductus venosus or hepatic vein, reentering the heart through the inferior vena cava. On echocardiogram there is the appearance of an inverted Christmas tree.

• Mixed: a combination of any of the above

Hemodynamics. There is increased flow into a systemic vein, right atrium, or coronary sinus,90 and ultimately, the right heart. There is an obligatory right-to-left shunt at the atrial level with complete mixing (all chambers will have the same saturation)2491

Clinical Presentation Without Obstruction.24 There is mild cyanosis; usually asymptomatic.

• Physical exam: poor growth; prominent left chest; right ventricular heave and hepatomegaly

• Auscultation: fixed, widely split second sound

• ECG: right ventricular hypertrophy

• Chest x-ray: enlarged right heart; increased pulmonary vascular markings; snowman- or figure 8-shaped mediastinum

Clinical Presentation in the Presence of Obstruction.24 Patients are acutely ill; there is cyanosis; symptomatic with respiratory distress during the newborn period.

• Physical exam: tachypnea; dyspnea; right ventricular failure

• Auscultation: no murmurs

• ECG: right ventricular hypertrophy

• Chest x-ray: normal size heart; increased pulmonary vascular markings

Key Echocardiographic Concepts3690

• Determine the number of pulmonary veins, their connections, and drainage by 2-D and color Doppler

• Visualization of all systemic venous return to the heart including left innominate vein, superior vena cava, inferior vena cava, and coronary sinus

• Assessment of position and patency of the atrial septum

• Color-flow Doppler interrogation of anomalous venous structures to rule out obstruction, direction of flow direction, as well as restriction of the atrial septum by colorflow and spectral Doppler

• Assessment of right ventricular dysfunction and right ventricular or pulmonary hypertension

Associated Disease

• Atrial septal defect

Natural History.24 Obstruction of the common vein or entry into a systemic venous structure will result in pulmonary edema and right heart failure, complete obstruction will cause death. Eventually, pulmonary vascular obstructive disease will develop.

Treatment. Surgical anastomosis of the common vein with the left atrium and closure of the atrial communication are the indicated treatment.

Postoperative Echocardiographic Evaluation

• Assessment of right ventricular size and function

• Evaluate area of anastomosis and individual pulmonary veins to rule out obstruction. Usually apical views are the best for assessment of the pulmonary venous confluence; individual veins are best seen in subcostal, high parasternal, and suprasternal views.

• Evaluation of right heart and pulmonary artery pressure

TRANSESOPHAGEAL ECHOCARDIOGRAPHY

Transesophageal echocardiography (TEE) is a more invasive echo technique that requires sedation of the patient. A biplane or multiplane echo probe, similar to an endoscope, allows visualization of the heart from the esophagus and stomach. Most of the ultrasound’s limiting factors are removed in this technique like lung and bone, allowing for much better imaging and resolution.

Indications: TEE is becoming a standard of care in the operating room during pediatric cardiovascular procedures. It enables the surgeon to delineate anatomy before surgery and evaluate repair effectiveness after surgery and is known to demonstrate anatomic details missed by transthoracic imaging and alter the surgical plan.92 TEE allows the probe to be left in the patient for the entire procedure with continuous monitoring, although images and hemodynamics are better assessed once reduced or the patient is off cardiopulmonary bypass. Comparison of the preoperative and postoperative left ventricular systolic function has proved helpful in perioperative medical management. Intraoperative TEE is most commonly performed by the echocardiographer or an anesthesiologist.

Routine TEE is performed in cases where acceptable images are not obtained by transthoracic echocardiography (TTE) due to poor acoustic windows (large patients, open chest after surgery, etc.). TEE is superior to TTE in most of these cases, allowing better visualization of valve apparatus, interatrial septum, and most other cardiac structures. Anterior structures such as the right ventricular outflow tract, pulmonary valve, or anterior muscular ventricular septal defects or structures close to an adjacent airway (like the left pulmonary artery and transverse aortic arch) can be difficult to visualize.

TEE is invaluable in situations where assessment of intracardiac vegetations or thrombus is required in patients with poor echocardiographic windows, as well as in the guidance of catheterization procedures such as device closure of atrial and ventricular septal defects or stenting and ballooning complex venous baffles or outflow tract obstruction.93

The review of the guidelines for TEE in children is beyond the scope of this chapter but may be accessed by the interested reader from the American Society of Echocardiography.94

HYPERTENSION

Long recognized as a contributor to heart disease in adults, hypertension is being diagnosed much more frequently in pediatric patients than in the recent past. Echocardiography is required to assess the effect on the heart.

Clinical Presentation

• Normally asymptomatic and usually noted during routine examinations

Hemodynamics

• In adults, systolic and diastolic pressures may be elevated.

Key Echocardiographic Findings

• Long-standing hypertension can result in left ventricular hypertrophy and increased left ventricular mass, resulting in impaired left ventricular filling.

• Careful evaluation of the patency of the aortic arch is required to exclude clinically unrecognized Coarctation of the Aorta

Natural History

• Untreated hypertension will result in myriad cardiac abnormalities, including left ventricular outflow obstruction, coronary artery disease, stroke, and kidney failure.

CHEST PAIN AND FATIGUE

Chest pain and fatigue are fairly common complaints among older children and adolescents. The cause is seldom cardiac and usually not serious. However, if cardiac causes are present, they are generally serious.

Causes of Cardiac Chest Pain in Children

1. Congenital coronary abnormalities (rare, associated with exercise, explained by ischemia)

a. Anomalous coronary origin (left main coronary artery from right coronary artery—left main coronary artery is compressed between great vessels)

b. Coronary fistula (rare—may cause ischemia from steal phenomenon)

2. Acquired coronary disease

a. Kawasaki’s disease (residual critical narrowing of coronary arteries)

b. Emboli

3. Aortic stenosis

4. Cardiomyopathy

a. Hypertrophic cardiomyopathy

b. Dilated cardiomyopathy

5. Pericarditis

6. Rhythm abnormalities

As previously stated, these are rare, but their seriousness requires that the echo exam for chest pain in children must be accurate and comprehensive. Particular attention should be paid to the coronary arteries.

Fatigue in children is also rarely cardiac related, but some cardiac findings may include the following:

• Dilated cardiomyopathy

• Hypertrophic cardiomyopathy

• Shunts

• Aortic stenosis

• Pulmonic stenosis

As in cases of chest pain, a complete echo exam is required to rule out any cardiac source.

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Questions

Answers and Explanations