Chapter 18. Transesophageal Echocardiography for Congenital Heart Disease

The incidence of congenital heart disease (CHD) is 0.5% to 1%, and common malformations are less frequent (0.15%).1 An increasing percentage of these infants survive to adulthood largely due to advances in cardiology, cardiac surgery, and perioperative anesthetic and critical care management.2 At present, adults with congenital heart disease constitute a significant and growing cardiac population of 5%.

In patients with CHD, transesophageal echocardiography (TEE) allows for the real-time acquisition of both anatomic and hemodynamic information, thereby helping in clinical decision making. During interventional cardiac catheterization procedures, TEE is instrumental in the monitoring and guidance of valvuloplasties, angioplasties, closure of intracardiac shunts, trans-septal atrial puncture, and electrophysiological ablation. During palliative and corrective surgical procedures, TEE is fundamental in confirming diagnosis; detection of unanticipated findings; modification of surgical procedures; assessment of the adequacy of the procedure; guidance of revision; monitoring of intracardiac air, ventricular volume, and myocardial performance; and formulation of anesthetic and postoperative management. The primary objectives of TEE in patients with CHD are to define important anatomic and hemodynamic information when data provided by other modalities are inadequate, establish a complete evaluation of complex congenital heart disease, and confirm or exclude a diagnosis of clinical relevance.

Congenital heart disease has been classified based on the level of complexity, presence or absence of cyanosis, and primary physiologic alterations. TEE image interpretation is therefore best performed using a segmental approach,3 where the heart is considered in terms of three segments (atria, ventricles, and arterial trunks), and these are connected via two junctions (atrioventricular and ventriculoarterial).4 The use of a segmental approach provides a systematic guide for verification that all significant chambers and valves and their relationships have been recorded. Important determinants in this segmental analysis include:

• Visceral situs
• Venoatrial connections (systemic and pulmonary veins)
• Atrial situs (normal, inversus, right isomerism, or left isomerism)
• Ventricular morphology (right versus left)
• Atrioventricular septae
• Atrioventricular valves
• Semilunar valves
• Ventricular outflows
• Great arteries
• Atrioventricular connections (concordant, discordant, double inlet, straddling, absent)
• Ventriculoarterial connections (concordant, discordant, double outlet, single outlet)

The usual orientation of the organs with the liver on the right and the spleen on the left is referred to as situs solitus. Situs inversus refers to a situation where given organs, or even all bodily organs, are reversed (eg, liver on the left and spleen on the right). Asplenia is associated with bilateral right-sidedness (right isomerism—liver on both sides), while polysplenia is associated with bilateral left-sidedness (left isomerism—spleen on both sides).

Persistent Left Superior Vena Cava

A persistent left superior vena cava (PLSVC) is the most common thoracic venous anomaly and occurs in 0.4% of the general population and in 4% to 11% of patients with congenital heart disease.5 The etiology of this defect is thought to be the failure of regression of left anterior and common cardinal veins and left sinus horn. In 90% of cases, the PLSVC connects to the right atrium through the coronary sinus (Figure 18–1). In the remainder, the PLSVC connects to the left atrium. A PLSVC is associated with atrioventricular canal defects, tetralogy of Fallot, and anomalies of the inferior vena cava. The clinical presentation and physiologic consequence of a PSLVC depend on its association with other anomalies. If the PSLVC is isolated, patients may remain asymptomatic.

The diagnosis of this defect in patients undergoing cardiac surgery raises several issues. First, the passage of a pulmonary artery catheter into the right ventricle via puncture of the left internal jugular vein may be difficult because the catheter may traverse the coronary sinus. Similarly, a PSLVC can complicate placement of permanent pacemakers and automatic implantable cardioverter defibrillators. Second, placement of a separate cannula in the coronary sinus may be necessary for complete venous drainage into the cardiopulmonary bypass machine. Third, retrograde cardioplegia in these patients will be ineffectively delivered to the myocardium. Finally, if patients with PLSVC undergo a heart transplant, the coronary sinus would have to be carefully dissected so that the PLSVC can be re-anastomosed to the right atrium

Echocardiographic assessment

The bicaval view, midesophageal (ME) four-chamber view, and ME two-chamber view are the most useful in assessing this lesion. On two-dimensional examination, an enlarged coronary sinus (normal coronary sinus size is 1 cm) is most often the first clue to the presence of a PLSVC (Figure 18–2). The diagnosis can be confirmed by injecting agitated saline solution into a vein in the left arm. In patients with a PLSVC, the “contrast” will be seen first in the coronary sinus before arriving into the right atrium (see Figure 18–2C).

Anomalous Pulmonary Venous Return

Anomalous drainage of the pulmonary veins results from in utero failure of the pulmonary veins to fuse with the left atrium. Two types have been identified. In patients with total anomalous pulmonary venous drainage, all pulmonary venous return is directed into a systemic venous system, creating a large left-to-right shunt. The site of pulmonary venous drainage may be supracardiac (into the innominate vein or left- or right-sided superior vena cava), cardiac (into an enlarged coronary sinus), or infracardiac (into the portal vein, ductus venosus, hepatic vein, or inferior vena cava) (Figure 18–3). Some degree of interatrial mixing (usually atrial septal defect [ASD] or patent foramen ovale [PFO]) is mandatory and provides the only access for pulmonary venous blood to the left heart. Survival beyond infancy without surgical intervention is unlikely; hence, this entity is not encountered in the adult population.

Partial anomalous pulmonary venous drainage is characterized by failure of one or two of the pulmonary veins to connect with the left atrium. Most commonly, the right upper and/or right lower pulmonary veins drain into the superior vena cava or the junction of the right atrium and superior vena cava. A sinus venosus ASD often accompanies this lesion. In the scimitar syndrome, the right lower pulmonary vein anomalously joins the inferior vena cava.

The physiologic consequences of partial anomalous pulmonary venous drainage may be minor. If more of the pulmonary venous drainage is diverted to the right atrium, evidence of right-side volume overload will be present. Associated anomalies include sinus venosus ASD, patent ductus arteriosus, transposition of the great arteries, and pulmonic valve atresia.

Echocardiographic Assessment

A dilated coronary sinus, evidence of right ventricular (RV) and right atrial dilatation, and an ASD are sometimes the only initial abnormal echocardiographic findings and should prompt a careful search for all four pulmonary veins. The diagnosis of total anomalous pulmonary venous drainage relies on visualization of the termination of all four pulmonary veins and defining a venous confluence connecting to the right atrium, coronary sinus, or vena cava. Partial anomalous pulmonary venous drainage most often is an anomaly involving the right pulmonary vein, and the abnormal connection is usually near the right side of the atrial septum or the base of the superior vena cava and is best viewed in the bicaval view. Agitated saline injection proximal to the anomalous connection with the superior vena cava may be useful in delineating the anomalous pulmonary vein from the superior vena cava (Figure 18–4). Color Doppler aids in the detection of individual veins, the direction of flow, and the presence of turbulence. Spectral Doppler confirms or excludes pulmonary venous obstruction. Surgically corrected lesions may require reinvestigation with color and pulsed-wave Doppler to determine the patency of the venous connection. Normal pulmonary vein flow should have a biphasic systolic–diastolic pattern with a maximal velocity of less than 1 m/s. A continuous nonphasic pattern and a peak velocity of greater than 2 m/s signifies restrictive pulmonary venous flow.4

Four possible atrial arrangements can be encountered: (1) situs solitus—normal arrangement of right and left atrium; (2) situs inversus—right atrium is on the left and the left atrium is on the right; (3) right atrial isomerism—bilateral right atria; and (4) left atrial isomerism—bilateral left atria. The morphological right atrium and left atrium can be differentiated by the anatomy of the atrial appendages. The right atrial appendage is broad, whereas the left atrial appendage is narrow and pointed.

Complex CHD lesions may demonstrate one or two ventricular chambers, ventricular inversion with the RV on the left and LV on the right (atrioventricular discordance), or abnormal arterial connections to the ventricles (ventriculoarterial discordance). Hence, the ventricles need to be identified by their structure and not by their positions or connections.6 The morphologically right and left ventricles have distinctive features, which are summarized in Table 18–1. Atrioventricular valves are always associated with their respective ventricles; therefore a tricuspid valve will identify the right ventricle and a mitral valve the left ventricle.

Atrial Septal Defect (ASD)

ASD is the second most common congenital heart defect, occurring in women two to three times as often as in men. ASDs include the following types: ostium secundum (70%), ostium primum (20%), sinus venosus (10%), and coronary sinus (rare).

Although not a “true” ASD, a patent foramen ovale (PFO) persists secondary to failure of fusion of the septum primum and secundum (Figure 18–5). The prevalence of probe patent PFO is as high as 26% in autopsy series. Clinical problems attributed to PFO include paradoxical embolism leading to cerebrovascular accidents, decompression illness in divers, and migraine headaches. In a meta-analysis, the presence of a PFO alone increased the risk of recurrent cerebrovascular events fivefold, with an even higher risk in the presence of an atrial septal aneurysm.7 Other identified risk factors are the size of the PFO, the number of microbubbles in the left atrium during the first seconds after release of a Valsalva maneuver, and the presence of a eustachian valve directed toward the PFO,8 hence the rationale of PFO closure to protect against recurrent strokes. Elective surgical closure of a PFO diagnosed as an incidental finding during routine intraoperative TEE is not currently thought to be of benefit unless the patient has experienced a prior stroke of uncertain etiology or as a result of known paradoxical embolism. Some surgeons choose to repair a PFO if the atrium is to be opened as part of the scheduled surgical procedure. However, it should be noted that, even when the PFO is surgically repaired, the risk of recurrent neurologic events is not completely eliminated. Catheter-based PFO closure can be performed as an outpatient procedure, is associated with minimal risk, and has superseded surgical closure.9

Ostium secundum defects are located in the mid-portion of the interatrial septum in the region of the fossa ovalis and are associated with mitral valve prolapse and mitral regurgitation. Ostium primum defects are located at the inferior portion of the interatrial septum and are associated with a cleft mitral valve with variable degrees of mitral regurgitation. Sinus venosus defects may be of the superior or inferior vena caval type. Most defects in this category are located near the entrance of the superior vena cava and right pulmonary veins high in the atrial septum (superior vena caval type) and are associated with anomalous return of the right upper and lower pulmonary veins (Figure 18–6). The relatively uncommon defects in the inferior vena caval–atrial junction are characterized by a deficiency of the inferior limbic septum. Coronary sinus defects occur from a partial or complete absence of the roof of the coronary sinus, creating a left-to-right shunt from the left atrium to the coronary sinus and then into the right atrium. These lesions are associated with a persistent left superior vena cava. The fundamental physiology of all these lesions is a transatrial shunt, and the direction and magnitude of shunting is determined by the size of the defect and the relative compliance of the ventricles.

Echocardiographic Assessment

TEE provides excellent interrogation of the interatrial septum, with a sensitivity exceeding that of transthoracic echocardiography for the detection of ASDs. Two-dimensional interrogation of the entire atrial septum should be performed in transverse and longitudinal planes to ensure that small defects at the margins of the septum are not missed. The dimension of and the relative size of the defect to the entire interatrial septum should be determined. The best views are midesophageal four chamber, two chamber, and bicaval.

Secundum defects are located in the midportion of the interatrial septum in the region of the fossa ovalis (Figure 18–7), and ostium primum defects are located at the inferior portion of the interatrial septum (Figure 18–8). The bicaval view is particularly useful in detecting inferior and superior sinus venosus ASDs (Figure 18–9). The least common type of atrial septal defect, the coronary sinus communication, is defined by an enlarged coronary sinus with a deficient roof (unroofed coronary sinus), and is found in association with a persistent left superior vena cava. In the transverse axis, this is seen as an echo-free space wedge between the left upper pulmonary vein and left atrial appendage, and in the longitudinal plane, it can be identified as it enters the coronary sinus.

Color-flow Doppler allows for evaluation of flow across the defect and the detection of mitral or tricuspid regurgitation. Saline contrast injection may be useful in confirming right-to-left shunting and aid in detection of small lesions, but it must be used cautiously in light of the potential for cerebral embolism. Spectral Doppler is used to assess the hemodynamic consequences of the lesion. Measurement of the tricuspid regurgitant jet velocity can estimate systolic pulmonary artery pressures and diagnose pulmonary hypertension. In the absence of significant valvular disease, the shunt magnitude can be determined by measuring the velocity-time integrals (VTIs) across the RV and LV outflow tracts. A ratio of pulmonary to systemic flow (Qp/Qs) of greater than 1.5 is considered significant. Further intraoperative evaluation includes detection of associated lesions, assessment of adequacy of surgical repair and postoperative atrioventricular valve competency, and evaluation of ventricular function.

Ventricular Septal Defect (VSD)

Even though VSDs are the most common congenital anomaly recognized at birth, they account for only 10% to 15% of defects observed in adults with CHD.10 VSDs can occur in isolation or as part of complex lesions, and are classified by location into four major groups: (1) supracristal (also known as subarterial, outlet, subpulmonic, doubly committed, and infundibular); (2) infracristal (perimembranous); (3) muscular; and (4) atrioventricular canal (inlet) types (Figure 18–10).

The perimembranous type (Figure 18–11) accounts for 70% of all VSDs and involves the membranous septum. The defect is adjacent to the aortic valve and the annulus of the tricuspid valve contributes to the rim of the defect. When the VSD is primarily adjacent to the tricuspid valve, it is called a perimembranous inlet defect but when the defect extends primarily toward the aortic valve, it is referred to as a perimembranous outlet defect. In an inlet defect, shunting of blood occurs from the LV outflow tract to the right ventricle just beneath the septal leaflet of the tricuspid valve. There may be an associated tricuspid valve aneurysm or redundant tricuspid septal leaflet tissue that may plug the defect. In 10% of cases, a perimembranous defect can undermine the right aortic cusp, causing herniation of the cusp and aortic insufficiency. Rarely, a perimembranous VSD may lead to the formation of a communication between the LV outflow tract and the right atrium known as Gerbode defect. Small membranous VSDs may close spontaneously during childhood by approximation of the tricuspid valve septal leaflet across the defect. This defect closure may be undetectable in adulthood, or a residual anatomic abnormality, a “ventricular septal aneurysm,” may be visualized at the closure site.

Muscular-type VSDs (20%) are located in the central (Figure 18–12) or apical trabecular portion of the septum. They are often quite large, isolated, or multiple, and can be associated with pulmonary vascular disease. In some cases, RV outflow tract hypertrophy occurs in association with the VSD and serves to limit the severity of pulmonary hypertension (known as Gasul phenomenon).

The crista supraventricularis can be considered synonymous with the infundibular septum—the muscle separating the outflow tracts of the left and the right ventricles. The supracristal defects (5%) are usually circular and are located within the infundibular portion of the right ventricular outflow tract. The superior edge of the VSD is the conjoined annulus of the aortic and pulmonary valves; both the outlet septum and septal component of subpulmonary infundibulum are absent. Thus, the superior rim may have a direct relationship with the right coronary cusp of the aortic valve such that the right aortic leaflet may prolapse into the VSD, resulting in functional restriction of the size of the VSD but worsening aortic regurgitation. Even in the presence of only mild aortic regurgitation and a small VSD, this defect should be surgically closed to prevent rapid progression of aortic valve regurgitation.11

The atrioventricular canal or inlet type defects (5%) are seen close to the atrioventricular valves in the posterior or inlet portion of the septum and usually are caused by a defect in the formation of the atrioventricular septum. As such, they can be a part of a complex defect (see below), and are associated with a cleft in the mitral or tricuspid valve, common atrioventricular valve, and fibrous aneurysms.

The physiologic consequences of these lesions are determined by the size of the defect and the relative vascular resistance in the pulmonary bed. Patients are also at a higher risk for infective endocarditis.

Echocardiographic Assessment

Two-dimensional echocardiographic assessment is focused on defining the anatomic abnormality, whereas color-flow Doppler enhances the sensitivity of detection of all forms of VSD and helps to determine the magnitude and direction of the shunt. The ventricular septum is best interrogated in the ME four-chamber view, ME long-axis (LAX) view, ME RV inflow-outflow view, and the transgastric short-axis (TG SAX) view.4 The ME RV inflow-outflow view is especially helpful in differentiating a perimembranous VSD from a supracristal VSD (Figure 18–13). Unlike the more common perimembranous type of VSD, a supracristal VSD does not lie near the tricuspid valve, and the tricuspid valve is not involved in partial closure of the defect. Color Doppler of a supracristal defect in this view shows left-to-right shunting with turbulent flow directed into the pulmonary outflow tract. It is important to remember that this defect may be missed in the ME four-chamber view. Distortion of the right aortic leaflet and aortic regurgitation may be the only clue to the presence of a significant supracristal defect.

“Ventricular septal aneurysms” are characterized on M-mode echocardiography by a pattern of multiple linear echoes moving into the right ventricle during systole. Two-dimensional imaging reveals a saccular protuberance with a rapid flicking motion extending into the right ventricle during systole and realigning with the ventricular septum during diastole.

For all types of VSDs, continuous-wave Doppler helps in measuring the peak jet velocity, and hence estimating RV systolic pressures and pulmonary artery systolic pressures. The pressure gradient between the right and left ventricle can be calculated by using the simplified Bernoulli equation as follows:

where PLV is the LV systolic pressure, which equals the aortic systolic blood pressure in the absence of LV outflow obstruction, and PRV is the RV systolic pressure, which equals the pulmonary artery systolic blood pressure in the absence of RV outflow obstruction.

The intracardiac shunt can be quantified by calculating the stroke volume across the pulmonic and aortic valves to develop the Qp/Qs ratio. The location for determining the stroke volume depends on the location of the shunt. Qp is typically measured at the level of the RV outflow tract, whereas Qs is measured at the level of the LV outflow tract. A Qp/Qs of 1.5 or greater is considered significant. The shunt volume (different from the shunt fraction) is the product of the cross-sectional area of the color-flow jet at the defect and the flow-velocity integral of the continuous-wave Doppler systolic flow signal.12

Postoperatively, residual shunting across the patch has to be excluded. A large dehiscence of the patch (>3 mm) is an indication for immediate surgical revision. The tricuspid valve also needs to be investigated carefully as surgical repair of a VSD through the right atrium may involve detachment of the septal tricuspid leaflet and reconstruction of the leaflet once the VSD is repair is completed. Also, both the right coronary cusp and the septal tricuspid leaflet can be tethered during repair of a perimembranous VSD.4

Atrioventricular Canal Defects

Also known as atrioventricular septal defects (AVSDs) or endocardial cushion defects, these lesions are produced by anomalies of the atrial and ventricular septa and the adjacent parts of the atrioventricular (AV) valve. Three types are described: (1) partial AVSDs, consisting of two separate atrioventricular valves, an ostium primum ASD, as well as a cleft mitral valve; (2) transitional AVSDs, made up of an ostium primum ASD, a small ventricular septal defect, and two distinct atrioventricular valves; and (3) complete AVSDs, the most common defect, made up of an ostium primum ASD, inlet-type VSD, and a common atrioventricular valve that bridges both the right and the left sides of the heart, creating superior (anterior) and inferior (posterior) bridging leaflets. The Rastelli classification describes three types of complete AV canal defects based on the morphology of the anterior (superior) bridging leaflet, its degree of bridging, and its chordal attachments (Table 18–2).13 These bridging leaflets may have chordal insertions into both ventricles. In such cases it must be surgically divided into left and right portions and resuspended from a central patch to create separate atrioventricular orifices.

Down syndrome occurs in 35% of patients with atrioventricular septal defect. Other associated cardiac lesions include tetralogy of Fallot, double-outlet right ventricle (DORV), total anomalous pulmonary venous connection, and pulmonary atresia. Subaortic stenosis also may occur from a discrete fibromuscular narrowing or from abnormal chordal insertions traversing the outflow tract. Subaortic obstruction can also develop postoperatively as a consequence of the reduction of LV outflow tract size after repair of the mitral valve cleft. Based on the size of the ventricular septal communication and the competence of the atrioventricular valves, patients may become symptomatic early in life or remain relatively asymptomatic until young adulthood. Surgical repair consists of patch closure of ASDs and/or VSDs and repair of the atrioventricular valves.

Echocardiographic Assessment

TEE defines the precise anatomy and allows detection of intracardiac shunts, chordal attachments, subaortic stenosis, and the presence and severity of left and right atrioventricular valve regurgitation. Shunting may occur left to right across the atria, left to right across the ventricles, or left ventricle to right atrium. Atrioventricular canal defects are readily visualized in the ME views. A four-chamber view shows that both atrioventricular valves are inserted at the same level and defines the presence and size of ASDs and VSDs (Figure 18–14). Chordal and papillary muscle arrangements of both atrioventricular valves also should be defined. The mitral valve is well visualized in a basal transgastric view at 0° and 90° and with three-dimensional imaging for number of leaflets and presence of a cleft. Color Doppler is useful to determine the presence and severity of atrioventricular valve regurgitation and to determine the location and size of shunts. Careful inspection of the right ventricle for signs of volume overload, inspection of the LV outflow tract for signs of obstruction, and exclusion of associated cardiac lesions completes the examination. Postoperative assessment includes detection of residual shunting, evaluation of atrioventricular valve regurgitation, iatrogenic atrioventricular valve stenosis, and subaortic stenosis.

Mitral Valve Anomalies

Most patients with congenital anomalies of the mitral valve present in adulthood with clinical findings of mitral insufficiency. A cleft in the anterior leaflet of the mitral valve presents by itself or as a part of a complex involving the atrioventricular septum. A double-orifice mitral valve occurs due to the abnormal fusion of the embryonic endocardial cushions and may present functionally as a stenotic or regurgitant lesion. The leaflets of a parachute mitral valve typically are attached to a single, central papillary muscle. The abnormal pattern of flow associated with these lesions predisposes these patients to infective endocarditis.

Echocardiographic Assessment

The four ME and two transgastric views define the number of leaflets, a single or double orifice, the presence of a cleft, the number and location of the papillary muscles, and chordal attachments (see Chapters 5 and 7). Color, continuous-wave, and pulsed-wave Doppler are important in assessing the functional significance of these anomalies. The possibility of endocarditis in these patients should not be overlooked. For quantification of the severity of the stenotic or regurgitant lesions, please refer to Chapter 7.

Ebstein's Anomaly of the Tricuspid Valve

Ebstein's anomaly is a rare defect, accounting for less than 1% of all congenital heart defects, but constitutes 40% of the congenital malformations of the tricuspid valve. The principal aberration occurring with Ebstein's anomaly is a malformation of the tricuspid valve. Two of the three leaflets of the valve, the septal and the posterior, are displaced downward into the right ventricle. The anterior leaflet is typically large and redundant and is often described as “sail-like.” It is abnormally attached to the RV free wall but is not displaced. The portion of the right ventricle between the atrioventricular junction and the displaced tricuspid leaflets is usually referred to as atrialized. The remaining right ventricle is hypoplastic and functionally impaired. Most commonly, the tricuspid valve is regurgitant, often with multiple eccentric jets. Eighty percent of patients with Ebstein's anomaly have an interatrial communication such as an ASD or a patent foramen ovale. With severe tricuspid regurgitation and elevated right atrial pressures, right-to-left shunting of blood may occur. The clinical presentation varies widely, depending on the degree of displacement of the tricuspid leaflets, and ranges from severe cyanosis and heart failure in the newborn to mild tricuspid insufficiency or absence of symptoms in the adult. Arrhythmias also may be the only clinical symptom occurring as a result of marked right atrial enlargement or because of Wolff-Parkinson-White syndrome, found in 10% to 15% of patients with Ebstein's anomaly.14 Arrhythmias, cyanosis, dyspnea, and exercise intolerance are the frequently seen symptoms in older patients.

Echocardiographic Assessment

The echocardiography views include midesophageal four-chamber, RV inflow and outflow, transgastric RV inflow, and short-axis views. The four-chamber view shows the extent of apical displacement of the tricuspid valve (Figure 18–15). Ebstein's anomaly is diagnosed when the distance from the mitral valve annulus to the displaced tricuspid septal leaflet measures more than 20 mm. In addition, the four-chamber plane is optimal for defining the degree of adherence of the anterior leaflet to the RV free wall, the size of the right atrium, and the size of the true right ventricle. Attention should be directed to the relative sizes and contractility of the atrialized and the true right ventricle. An atrialized-to-functional right ventricle ratio of greater than 0.5 indicates poor RV systolic function. The long-axis view of the RV inflow tract (RV inflow-outflow) allows evaluation of posterior leaflet displacement and demonstrates the sail-like anterior leaflet arising normally from the tricuspid annulus (see Figure 18–15B). M-mode may show increased excursion with a rounded off appearance of the anterior tricuspid valve leaflet, decreased E-F slope of the anterior leaflet, and premature opening of the pulmonic valve. Color-flow Doppler is used to determine the presence and severity of tricuspid regurgitation. Detailed Doppler and two-dimensional examination of the interatrial septum for associated defects and assessment of direction of flow across these defects should be performed.

Echocardiography is also useful in separating patients who would require valve replacement from those in whom valve repair might be successful. Information with potential implications for surgical repair includes anterior leaflet size, valve mobility and excursion, presence or absence of restriction or tethering of the anterior leaflet, size of the right ventricle, and associated defects.15 Postoperatively, TEE is used to determine the mobility and functionality of the repaired or replaced tricuspid valve.

Bicuspid Aortic Valve

The most commonly encountered congenital heart defect, bicuspid aortic valve may be present in up to 2% to 3% of the general population, with a male-to-female ratio of 4:1 or greater.10 Anatomically, the bicuspid valve is composed of two leaflets or cusps, usually of unequal size, with an eccentric commissure or “raphe,” or the cusps may be equal in size with a single central commissure. The disparity in the cusp size leads to redundancy and inappropriate valve coaptation resulting in regurgitation. Patients may be completely asymptomatic or develop aortic regurgitation at an early age secondary to redundancy or prolapse of cusp tissue. The mechanism of progressive valvular dysfunction appears to be related to abnormal hemodynamic stress leading to fibrosis and calcification of the leaflets. Symptomatic aortic stenosis usually occurs before the age of 65 years. Twenty percent of patients with bicuspid aortic valve have an associated cardiovascular abnormality,10 such as patent ductus arteriosus, or abnormalities of the aorta including aortic coarctation, dissection (due to decreased connective tissue), and poststenotic dilatation. The Shone complex, a left-side obstructive lesion, includes a biscuspid aortic valve, supravalvular mitral ring, parachute mitral valve, discrete subaortic membrane, and coarctation of aorta. Infective endocarditis is a significant problem for these patients, with a 35-times higher incidence than the general population.

Echocardiographic Assessment

TEE should be used to assess valve morphology (commissure and position of raphe), lateral mobility and separation, and annular size (see Chapter 9). Distinctive echo features include systolic doming in the long-axis view and the demonstration of a single commissural line with two functional valve cusps in the short-axis view (Figure 18–16). In patients with asymmetric leaflets and a prominent raphe, the valve may appear tricuspid in diastole; however, the elliptical “football” (sometimes referred to as “fishmouth” or “clamshell”) shape of the systolic orifice indicates that the raphe is not a functional commissure. When extensive calcification occurs, doming may no longer be noted and the morphology of the cusps in the short-axis views may be difficult to distinguish from the calcific stenosis of a tricuspid aortic valve.14

Using a transgastric approach, a quantitative evaluation of the degree of outflow obstruction can be obtained by Doppler echocardiography. Complete evaluation includes detection of left ventricular (LV) hypertrophy or dilation, identification of poststenotic aortic root dilatation and other associated cardiovascular anomalies (aortic coarctation or dissection), and an evaluation of the number of sinuses of Valsalva present (there may only be two instead of three). Planimetry of the bicuspid aortic valve, however, is unreliable as an estimation of aortic valve area. Pre- and intraoperative aortic valve annulus dimensions can be measured if a Ross procedure is planned or to guide the sizing of a mechanical valve. Severity of aortic regurgitation or stenosis and residual defects on completion of the surgical intervention are assessed as for the tricuspid aortic valve described earlier (see Chapter 9). As the Ross procedure involves reimplantation of the coronary arteries, the pre- and postoperative assessment of segmental and global left ventricular function is important.

Pulmonic Stenosis

Pulmonic stenosis constitutes 8% of all congenital heart defects. The stenosis can be valvular, subvalvular, or supravalvular. In general, pulmonic stenosis follows a benign course: with mild pulmonic stenosis (peak gradient <30 mm Hg), there is only a 5% chance of requiring valvotomy; with a moderate degree of stenosis, there is a 20% likelihood of requiring intervention.16 Pulmonic valve morphology usually involves a supple but thickened valve with commissural fusion or a bicuspid valve. Pulmonic stenosis is usually isolated but can be associated with other anomalies including congenital rubella, atrial septal defects, Noonan syndrome (small stature, shield chest, and web neck), Williams syndrome, and trisomy 13 to 15 and 18.

Echocardiographic Assessment

The best views to assess the pulmonic valve are the ME RV inflow-outflow and upper esophageal aortic arch short-axis views (see Chapter 10). Echocardiographic findings may include thickened pulmonic valve leaflets (bicuspid, tricuspid, quadricuspid, or dysplastic), systolic doming of the pulmonary leaflets, diastolic doming (pulmonary valve prolapse), and a D-shaped left ventricle in systole (if RV pressures are elevated). Measuring the pulmonic valve thickness and annulus dimensions is useful in the assessment for percutaneous balloon valvuloplasty. Variable degrees of poststenotic dilatation of the main and left pulmonary arteries may be present. Right ventricular hypertrophy develops secondary to long-standing pulmonary valve stenosis, and the hypertrophied muscle may cause significant right ventricular infundibular obstruction. Pulsed-wave Doppler sampling of the entire RV outflow is required to exclude infundibular, subinfundibular, and main or pulmonary branch stenoses. Continuous-wave Doppler is the most useful in determining the transvalvular pressure gradient and pulmonic valve area. A dagger-shaped, late-peaking systolic gradient characterizes dynamic infundibular obstruction. Color-flow Doppler aids in determining the location of the stenotic jet and quantifying the severity of pulmonary regurgitation. Pulmonary regurgitation is especially common post–pulmonary valvotomy. Detection of associated lesions such as ASD or VSD is essential.

Tetralogy of Fallot

Tetralogy of Fallot (TOF) is the most common cyanotic heart disease. It is typically characterized by four anomalies: a VSD, an overriding aorta, pulmonary valve stenosis, and RV hypertrophy. The hallmark of TOF is an anterocephalic deviation of the infundibular septum causing subpulmonary obstruction in the right ventricular outflow tract.17 The aorta is committed to both ventricles to a variable degree, but by definition is committed to the left ventricle by at least 50%. Other anomalies can be present with tetralogy of Fallot, including ASD in 10% to 15% (so-called pentalogy of Fallot), right aortic arch in 25%, anomalous origin of the left anterior descending coronary artery in 10%,18 absence of the pulmonary valve, aortopulmonary collaterals, and systemic venous anomalies (in patients with pulmonary atresia and VSD). The physiologic consequences of tetralogy of Fallot are related mainly to the RV outflow tract obstruction and the large, nonrestrictive perimembranous VSD. The severity of cyanosis depends on the degree of the ventricular right-to-left shunting and the degree of obstruction in the RV outflow tract. Clinical presentation can vary from cyanotic spells, dyspnea, and limited exercise tolerance to erythrocytosis, hyperviscosity, cerebral abscess, stroke, and endocarditis. Survival beyond childhood is unlikely in the majority of patients who have not been surgically treated. Complete correction is performed in early infancy. However, these adult patients may yet have significant problems after successful repair with the most common being residual right ventricular outflow tract obstruction and pulmonary regurgitation leading to right ventricular failure. A subset of patients may present with ongoing aortic root dilatation and aortic regurgitation.

Echocardiographic Assessment

Because it is a complex anomaly, a combination of scanning planes (ME, transgastric, and deep transgastric views) is required to define all the defects (Figure 18–17). The two-dimensional examination should identify RV hypertrophy, overriding aorta, VSDs, small pulmonic annulus, RV outflow obstruction, size of the main pulmonary artery, and ventricular dimensions and function. The perimembranous VSD is seen as a large subaortic defect on the ME aortic short- and long-axis views. An overriding aorta is best appreciated in the ME aortic valve long-axis view; evaluation of the descending thoracic aorta is helpful in detecting aortic to pulmonary artery collaterals. Color and pulsed Doppler help in assessing the direction and velocity of the ventricular shunt. Continuous-wave Doppler measures the systolic gradient across the stenotic outflow tract in the upper esophageal aortic arch short-axis view. Associated pulmonary valve anomalies such as pulmonary artery stenosis and hypoplasia are best seen as the TEE probe is withdrawn from the ME RV inflow-outflow view and by using a transgastric approach to visualize the right ventricular outflow tract (RVOT). Surgical correction involves closing the VSD and relieving the right ventricular outflow obstruction. This may be achieved with resection of infundibular muscle, an RVOT patch, a transannular patch (a patch extended across the pulmonary valve annulus), or a valved conduit placed between the RV and the pulmonary artery. After surgical intervention, TEE is helpful in evaluating residual shunt or RVOT obstruction (a peak gradient up to 20 mm Hg is considered normal; gradients above 40 mm Hg indicate significant stenosis), pulmonary valvular regurgitation after transannular repair, and ventricular function.

Subaortic Stenosis

The most common type of congenital aortic subvalvular stenosis is an abnormal fibromuscular ridge that may encircle the LV outflow tract (LVOT; Figure 18–18). A less common type is caused by a diaphragm-like membrane adherent to the base of the aortic leaflets, the junction of muscular and membranous septum, or the anterior leaflet of the mitral valve itself. In patients with hypertrophic obstructive cardiomyopathy, obstruction of the LVOT is due to septal hypertrophy plus systolic anterior motion of the mitral valve leaflets.

Subaortic stenosis obstructs LV outflow, producing effects similar to valvular aortic stenosis: LV hypertrophy, myocardial ischemia, heart failure, and sudden death. In addition, a subaortic membrane may alter LV outflow dynamics and injure the aortic valve without any significant obstructive component. Abnormal flow patterns can produce structural damage to the aortic valve and cause aortic insufficiency. There may be other effects from a subaortic membrane, including structural injury to the mitral valve and direct damage to the aortic valve, if the membrane invades the aortic valve. Surgical repair involves excision of the membrane or ridge, septal myomectomy, and aortic valve replacement if severe aortic regurgitation is present. The abnormal flow characteristics that initiated the growth of a subaortic membrane may allow the regrowth of the membrane, even after complete resection. Associated anomalies include supramitral rings, bicuspid aortic valve and aortic coarctation, and a complex that includes a perimembranous VSD and an obstructive muscle bundle in the right ventricle. In the adult population, subaortic stenosis may occur following surgical repair of congenital heart lesions including AVSD, TOF, DORV, and transposition of the great arteries.

Echocardiographic Evaluation

The subaortic membrane is visualized most easily in the ME long-axis view, where a linear structure protrudes from the left surface of the interventricular septum and the base of the anterior mitral leaflet, causing narrowing of the LV outflow tract.

Unexplained turbulence on color-flow Doppler examination in the ME long-axis, five-chamber, and transgastric or deep transgastric long-axis views is often the first indication of the presence of an obstruction (Figure 18–19A). Measurement of increased subvalvular velocities and estimation of pressure gradients by spectral Doppler help to confirm the diagnosis (Figure 18–19B). Aortic insufficiency often is found as a result of the long-standing flow disturbance. A preoperative search for associated congenital anomalies and postoperative assessment of adequacy of resection, aortic and mitral valve injuries during the repair, and the presence of iatrogenic interventricular communications occurring as a consequence of the myomectomy concludes the TEE study.

Coronary Artery Anomalies

Coronary artery anomalies are seen in a wide range of congenital abnormalities and involve the origin, course, and structure of epicardial coronary arteries. The incidence is about 0.3% to 1.3% in the general population and in 4% to 15% of young people who experience sudden death. Presence of coronary artery anomalies may, at times, create challenges during coronary angiography, percutaneous coronary interventions, and coronary artery surgery.

Clinically they remain quiescent and do not influence the quality of life or lifespan. Certain types of coronary anomalies, such as the origin of the left main coronary artery from the pulmonary trunk, the aberrant course of the arteries between the great vessels in association with anomalous and slit-like ostium, and large coronary artery fistulas, may be associated with sudden death, myocardial ischemia, congestive heart failure, or endocarditis. Hypoplastic coronary arteries and high takeoff of coronary ostia have also been occasionally reported to have been associated with sudden death. Congenital heart diseases found to have strong association with coronary artery anomalies include truncus arteriosus, transposition of great vessels, pulmonary valve atresia, double-outlet right ventricle, bicuspid aortic valve, and tetralogy of Fallot.

In general, the coronary anomalies can be classified into normal variations, abnormal number, anomalous origin, anomalous course, anomalous termination, and abnormal coronary structure. Normal variations include (1) absence of the left main coronary artery with separate origin of the left anterior descending (LAD) and left circumflex coronary (LCX) arteries from the left coronary sinus of the aorta (described in roughly 1% of patients undergoing angiography); (2) minor variations in the position of the ostia within the coronary sinus; and (3) separate origin of conal branches. Duplication of the LAD and right coronary artery (RCA), and anomalous origin of the coronary arteries from the pulmonary artery, left/right ventricle, internal mammary, subclavian, right carotid, or higher up on the aorta (>1 cm from the sinotubular junction) have all been reported. Similarly, the left main may give rise to LAD, LCX, and RCA. An anomalous artery may course along one of four pathways: A (Anterior to the right ventricular outflow tract), B (Between the aorta and the pulmonary trunk), C (through the Crista supraventricularis), and D (Dorsal to aorta). The coronaries can also take an intramyocardial course (myocardial bridging). From a structural point of view, the coronary arteries may be stenotic, hypoplastic, or atretic.

Echocardiographic Assessment

A careful assessment is fundamental to viewing these anomalies. Upper esophageal and midesophageal (aortic short-axis and long-axis) views are very useful in examining the origin and course of the vessels. Special attention needs to be paid to assess for other congenital associations, segmental wall motion abnormalities, and ventricular function.

Coronary Fistula

A coronary fistula is any abnormal communication between the coronary artery and a cardiac chamber, great vessel, or vascular structure. Fistulas result from persistence of embryonic channels between the chambers and coronary arteries, and can involve the right coronary (most common), the left coronary, or both. They tend to terminate more toward the low-pressure right-side chambers (pulmonary artery, coronary sinus, or superior vena cava). Very rarely, a fistula will drain into the left heart.19 The overall incidence of coronary fistulas is 2.1%. The clinical presentation and physiologic consequence of this lesion depend on the degree of shunting, location of the fistula, and termination site. Long-standing left-to-right shunting can produce ventricular volume overload and congestive heart failure. When the fistula diverts coronary flow, angina and, rarely, myocardial infarction can occur. Coronary fistula should not be confused with the Thebesian veins, or venae cordis minimae which are tiny cardiac venous tributaries that normally drain directly into the cardiac chambers.

Echocardiographic Assessment

The primary objective of the echocardiographic examination is to ascertain the site and dimensions of the fistula, and the receiving chamber and the degree of the shunt. Evaluation of the coronary artery fistula involves upper esophageal aortic arch, ME aortic valve short-axis, and ME long-axis views. Two-dimensional echocardiography may detect an enlarged proximal coronary artery. RV enlargement denotes the presence of left-to-right shunting. Color-flow Doppler detects a continuous flow pattern within the enlarged and tortuous coronary artery or turbulent flow patterns within the receiving chamber. Contrast echocardiography (using agitated saline solution to visualize an area of negative contrast) also can be used to detect the termination of the fistula into the right heart.

Sinus of Valsalva Aneurysm

A higher incidence of sinus of Valsalva aneurysms has been reported in Far Eastern countries than in Western countries, with a 4:1 male predominance. A weakness in the aortic media at its junction with the annulus fibrosis is thought to be the cause of the congenital aneurysm of the aortic sinuses of Valsalva. These aneurysms are associated with other lesions such as VSD (40%), bicuspid aortic valve, ASD, pulmonary stenosis, and patent ductus arteriosus. They occur most commonly in the right (69%) and noncoronary sinus (26%), but can be seen in the left coronary sinus (5%). They also may extend into other regions of the heart, most frequently the right ventricle and right atrium.20 An enlarged aneurysm can present with RV outflow tract obstruction, LV outflow tract obstruction, and compression of the main coronary arteries or tricuspid valve. It also can cause atrioventricular conduction abnormalities or VSDs by burrowing into the septum. Mild aortic regurgitation occurs due to aortic root enlargement. Clinically, symptoms typically occur when the aneurysm ruptures into the receiving chamber, which is usually the right atrium or ventricle. Patients often present with retrosternal chest pain, epigastric pain, congestive heart failure, or evidence of outflow tract obstruction.

Echocardiographic Assessment

The aortic root, sinuses of Valsalva, LV outflow tract, and the ascending aorta can be examined in detail by using the following views: ME aortic valve short axis, ME aortic valve long axis, transgastric long axis, deep transgastric long axis, upper esophageal aortic arch short and long axis, and epiaortic scanning. Two-dimensional echocardiographic findings include abnormal dilatation of one or more of the sinuses, an extended aneurysmal channel typically seen as a finger-like projection (“windsock” appearance) with echo dropout at the tip of the aneurysm (Figure 18–20), diastolic expansion of the aneurysm, aortic valve prolapse, RV volume overload (in rupture of the noncoronary or right coronary type), or LV volume overload (in rupture of the left coronary type). Doppler findings include a swirling flow pattern in an intact aneurysm and a high-velocity systolic and diastolic turbulent flow pattern into the receiving chamber, if the aneurysm has ruptured. Doppler also helps in determining the presence and severity of associated VSDs and aortic or tricuspid regurgitation. Lesions that should be differentiated from a sinus of Valsalva aneurysm include membranous ventricular septum aneurysms (originates below the plane of the aortic valve), acquired aortic fistulas (do not show the extended aneurysmal channel), and coronary artery fistulas (coronary artery origin and abnormal coronary lumen size).

Supravalvular Obstruction

Supravalvular aortic obstruction is a narrowing of the ascending aorta. This type of stenosis is uncommon and often associated with Williams syndrome or congenital rubella, or it may be familial. The three major types of obstruction are the hourglass type (an infolding of the aorta at the sinotubular junction producing an hourglass deformity), membranous type (a membranous web-like obstruction), and tubular type (diffuse tubular hypoplasia of the ascending aorta). Supravalvular obstruction is usually progressive and aortic regurgitation is common. The origins of the coronary arteries become dilated and tortuous secondary to exposure to high pressures from the more distal aortic obstruction. With Williams syndrome, there often are associated peripheral pulmonary or systemic arterial stenoses. Patients with supravalvular aortic obstruction are at an increased risk for sudden death.

Echocardiographic Assessment

Echocardiographic detection of supravalvular stenosis relies on careful inspection of the sinotubular junction and the proximal ascending aorta in the ME long-axis view of the aorta. In a normal aorta, the diameter at the sinotubular junction equals or slightly exceeds that of the aortic annulus, and the tubular portion of the ascending aorta should never be smaller than the aortic annulus. Imaging of the proximal branch pulmonary arteries also should be attempted in patients with Williams syndrome.

Coarctation of the Aorta

Coarctation of the aorta accounts for 8% of all cases of congenital heart disease (CHD). The anatomic lesion most commonly found is a discrete ridge or diaphragm comprised of localized medial thickening, infolding of the media, and superimposed neointimal tissue that narrows the aortic segment just below the left subclavian artery and opposite the ductus arteriosus or ligamentum arteriosum. Coarctation of the aorta can be one of the causes of left ventricular outflow obstruction in the very young. In the older age group, coarctation is most often diagnosed after the identification of incidental hypertension during a routine physical examination or after the detection of diminished or absent pulses in the lower extremities. Coarctation is categorized as preductal, juxtaductal, or postductal depending on the position relative to the ligamentum arteriosum, and may be discrete or involve a long segment of the aorta. The lesion may also occur at the level of the abdominal aorta. Associated defects include bicuspid aortic valve (80% to 85%), patent ductus arteriosus (50%), VSDs, valvular aortic stenosis, subaortic stenosis, and Turner syndrome. It also can occur as a part of Shone complex (supravalvular mitral valve ring, parachute mitral valve, subaortic stenosis, and coarctation). Clinically, patients with coarctation present with a history of systemic hypertension (33%), headache, epistaxis, and congestive heart failure. Physical examination findings include elevated systolic blood pressure in the upper extremity when compared with the lower extremity (systolic blood pressure differential in arm vs leg of 20 mm Hg or more), radial to femoral pulse delay, diminished femoral pulses, and cyanosis with exercise (in preductal). The primary physiologic consequence of this defect is an increased LV afterload.

Echocardiographic Assessment

A detailed examination can be conducted by using the short- and long-axis views of the aortic arch and descending aorta. Two-dimensional findings include a long, tubular narrowing of the descending thoracic aorta usually distal to the left subclavian artery, increased systolic pulsation of the aorta proximal to the lesion, decreased systolic pulsation of abdominal aorta, poststenotic dilatation of the aorta, enlarged intercostal arteries distal to coarctation, and increased diameter of the left subclavian artery. Evaluation of the associated defects is also important. The severity of coarctation is assessed by measuring the narrowest diameter of the coarctation and comparing it with the descending thoracic aorta diameter (a ratio of 0.4 or less indicates severe coarctation). Pulsed-wave Doppler may detect increased velocity and turbulent flow at the site of obstruction. Continuous-wave Doppler through the coarctation demonstrates the characteristic flow pattern of increased systolic flow velocity and continuous flow in diastole. The profile of the abdominal aortic flow is typically damped and has a delay in the systolic upstroke, turbulence in systole, and variable degrees of diastolic antegrade flow.21 Color-flow Doppler demonstrates flow acceleration proximal to and turbulent flow through the site of obstruction (Figure 18–21).

Patent Ductus Arteriosus

An inevitable part of fetal life, the ductus arteriosus usually closes within the first 24 to 48 hours of life. Patent ductus accounts for about 2% to 10% of cases of CHD. The ductus arises from the pulmonary artery bifurcation near the left pulmonary artery and connects to the descending aorta just opposite the left subclavian artery (Figure 18–22). It can occur as an isolated anomaly or in association with other defects such as VSDs and coarctation. In later life, the ductus can become calcified, friable, or even aneurysmal. Patients may present with symptoms of infective endocarditis, chest pain, palpitations, congestive heart failure, or pulmonary hypertension. The nature and severity of symptoms is dependent on the size of the ductus and the difference between the systemic and pulmonary vascular resistances.

Echocardiographic Assessment

The main goals in the evaluation include morphologic portrayal of the ductus and surrounding structures, appraisal of the shunt magnitude, estimation of pulmonary artery pressures, and exclusion of associated anomalies. The ductus is best viewed where the left pulmonary artery crosses the descending thoracic aorta. A full evaluation of this lesion often requires a combination of the upper esophageal aortic arch, descending aorta long- and short-axis views, and the deep transgastric long-axis views. Two-dimensional findings include left atrial and ventricular dilatation, LV volume overload, dilated pulmonary artery, and signs of pulmonary hypertension. The length and diameter of the ductus also should be measured. Color-flow Doppler is probably the best aid in diagnosing the ductus. The continuous ductal flow presents as a jet entering the main pulmonary artery near the origin of the left pulmonary during diastole, but the systolic component of the shunt flow usually is eclipsed by the systolic flow in the main pulmonary artery. As pulmonary artery pressures rise, the shunt velocity and flow decrease, making visualization of even the diastolic component more difficult. In a similar fashion, pulsed Doppler with an accurate recording of the electrocardiogram helps to differentiate shunt flow from normal pulmonary artery flow. Continuous-wave Doppler measurement of the peak systolic velocity of the shunt jet can be used to calculate the systolic gradient between the aorta and the pulmonary artery (by using the simplified Bernoulli equation). Subtracting this gradient from the systemic systolic blood pressure yields the systolic pulmonary artery pressure. In patients with a patent ductus arteriosus, the shunt occurs after the pulmonary valve, so Qp is measured at the level of the left ventricular outflow tract and Qs is measured at the level of the right ventricular outflow tract.

The Univentricular Heart

The definition of univentricular heart encompasses a broad group of congenital cardiac malformations. Specifically, it includes double-inlet left ventricle or double-inlet right ventricle, mitral atresia, tricuspid atresia, and unbalanced atrioventricular canal defects. All are characterized by both atria being related entirely to one functional ventricle. In most univentricular hearts there are two ventricular chambers—one well-developed ventricle (the functional ventricle) and a second rudimentary ventricle. The well-developed ventricle may be designated left, right, or indeterminate.22 The dominant ventricle has a left ventricular morphology in 80% of cases. Ventricular morphology can be established by the unique features of each ventricle as listed in Table 18–1. The univentricular circulation is inherently inefficient because of the recirculation of the pulmonary and systemic venous return; therefore, the palliative plan for patients with single ventricle physiology is diversion of all the systemic venous blood directly into the pulmonary arteries. Adult patients with single ventricle physiology would have undergone a systemic to pulmonary artery shunt, followed by a Glenn shunt, and finally a Fontan procedure.

Echocardiographic Assessment

TEE should delineate details of the atrioventricular connection, the ventriculoarterial connection, and ventricular morphology. When more than 50% of both AV valves open into a single ventricle, it is considered an echocardiographic hallmark of a double-inlet ventricle. Similarly, the hallmark of an unbalanced atrioventricular canal defect is more than 75% of a common AV valve opening into one ventricular chamber.22 Tricuspid atresia is characterized by the lack of a direct connection between the right atrium and ventricle, and mitral atresia by the lack of direct connection between left atrium and ventricle. AV valve insufficiency is common in these hearts and also a marker for adverse prognosis. Abnormalities of the ventriculoarterial connections form an integral part of univentricular hearts.17 Most often, the ventriculoarterial connection is discordant, with the pulmonary artery arising from the main left ventricle and the aorta arising from a rudimentary right ventricle. TEE definition of the ventricular morphology may be difficult, but as a rule, anterior rudimentary chambers are of right ventricular morphology and posterior rudimentary chambers are usually of left ventricular morphology.17 The evaluation on an adult post–Fontan-type operation is discussed in the section below on surgical procedures.

Truncus Arteriosus

Truncus arteriosus is a rare anomaly characterized by a single arterial trunk arising from the normally formed ventricles by means of a single semilunar valve (ie, truncal valve) and accounts for 1% to 2% of the congenital heart disease. This anomaly is thought to result from incomplete or failed septation of the distal conus, truncus arteriosus, and the aortic sac. A large VSD usually coexists with the truncus defect, essentially making the right and left ventricles into a single chamber. The pulmonary arteries originate from the common arterial trunk distal to the coronary arteries and proximal to the first brachiocephalic branch of the aortic arch. Pulmonary arteries may arise from the common trunk in one of several patterns, which often are used to classify subtypes of truncus arteriosus. In type I (most common), an aortopulmonary septum is recognized and a single main pulmonary artery is identified to originate from the posterior wall of the truncus. In type II the aortopulmonary septum is absent and separate right and left pulmonary arteries arise from the posterior truncal wall. Type III has only one pulmonary artery arising from the lateral wall of the truncal vessel and the blood supply to the other lung is from either the base of the aortic arch or the systemic arteries. In type IV (rare), the pulmonary arteries arise from the descending aorta, and this type often is called a pseudotruncus (probably a severe tetralogy of Fallot with pulmonary atresia and large bronchial collaterals). A variety of abnormalities may be associated with truncus arteriosus such as structural abnormalities of the truncal valve, including dysplastic and supernumerary leaflets,23 significant regurgitation (moderate or severe) through the truncal valve, abnormal proximal coronary arteries, interruption of the aortic arch (which almost always occurs between the left common carotid and subclavian arteries), right aortic arch, left superior caval vein, aberrant subclavian artery, ASD, atrioventricular septal defect, double aortic arch, and various forms of functionally univentricular heart. The physiologic sequelae of this anomaly depend on the degree of cyanosis and ventricular volume overload. The single most important issue in the description of truncus arteriosus is whether a right ventricular to pulmonary artery conduit can be performed as a primary repair. The surgical management of this condition involves removal of the pulmonary arteries from the truncal root, closure of the root defect, patch closure of the ventricular septal defect, and reconstruction of the right ventricular outflow.

Echocardiographic Assessment

A full set of echocardiographic views is necessary to guarantee complete and precise definition of the anatomy and associated anomalies. The primary objectives are to identify and confirm the conotruncal abnormalities, the number of VSDs, the morphology of the truncal valve, anomalies of the coronary arteries, size of the aortic arch, and location of the pulmonary artery orifices. The most characteristic finding is the identification of the truncal root, which overrides a ventricular septal defect and deficiency of the infundibular septum. The midesophageal and aortic arch views demonstrate the single arterial trunk arising from the ventricles, with variable override of the ventricular septum. The single trunk is also seen to be in continuity with the mitral valve. The left atrium is large due to increased pulmonary blood flow. These views also demonstrate the thickness and mobility of the truncal valve leaflets, and origins and course of the proximal coronary arteries. The aortic arch view allows delineation of the pulmonary arterial origin(s) from the common trunk, although additional views are helpful to more completely characterize the pulmonary arterial anatomy. Demonstration of pulmonary arteries arising from the truncus is necessary to distinguish this anomaly from pulmonary atresia with VSD.

Transposition of the Great Arteries (TGA)

Also known as D-transposition, with this lesion there is atrioventricular concordance and ventriculoarterial discordance. The aorta arises in an anterior position from the right ventricle, and the pulmonary artery arises from the anatomic left ventricle (Figure 18–23). Systemic venous blood returns to the right atrium, from where it goes to the morphologic right ventricle and then to the aorta. Pulmonary venous blood returns to the left atrium, from where it goes to the morphologic left ventricle and then to the pulmonary artery. Therefore, there is complete separation of the pulmonary and systemic circulation and survival depends on a communication such as ASD, VSD, or patent ductus arteriosus between the two circuits, allowing for intracardiac mixing. Other associated cardiac anomalies include obstruction to pulmonary outflow, atrioventricular valve abnormalities, anomalous origin and course of the coronary arteries, and aortic arch anomalies. Most patients who are currently adults with D-transposition have undergone surgery to redirect blood at an atrial level by using a baffle (Mustard procedure) or atrial flaps (Senning procedure). These so-called physiologic procedures correct cyanosis, but the right ventricle continues to function as the systemic ventricle and late dysfunction and dilatation are not uncommon. The Jatene procedure, also described as anatomic repair, has supplanted the atrial switch procedures and involves transection of the pulmonary artery and ascending aorta and switching of the arteries, so that the left ventricle supports the systemic circulation. The coronary arteries are also translocated to the neo-aorta, formerly the pulmonary artery.

Echocardiographic Assessment

TEE is valuable in the assessment of these patients in the perioperative period. Preoperatively, a variety of transesophageal planes including long- and short-axis views are used to view the anomalies. The aortic long-axis view can be used to visualize the parallel relationship of the outflow tracts and great vessels with a posterior course of the pulmonary artery. The pulmonary artery (LVOT in this anomaly) should be viewed for the presence of obstruction or valve regurgitation in the long-axis, apical, and transgastric views. The deep transgastric view demonstrates the discordant ventriculoarterial connections. Evaluation of the tricuspid valve (systemic atrioventricular valve) for regurgitation is fundamental because the severity of ventricular dysfunction and the extent of tricuspid regurgitation may have long-term and short-term prognostic implications.

Echocardiographic evaluation after the arterial switch procedure should focus on detection of RV outflow tract obstruction (the most common problem), neo-pulmonary stenosis, neo-aortic root dilatation, neo-aortic valve regurgitation, and assessment of RV function and coronary ostial patency.

Congenitally Corrected Transposition of the Great Arteries (ccTGA)

Also known as L-transposition, congenitally corrected transposition of the great arteries is characterized by inversion of the ventricles and transposition of the great arteries (discordant atrioventricular connections plus discordant ventriculoarterial connections). Systemic venous blood returns to the right atrium, and flows across the mitral valve and into the morphologic left ventricle, which is connected to the pulmonary artery. Pulmonary venous blood returns to the left atrium, and flows across the tricuspid valve and into the morphologic right ventricle, which is connected to the aorta. Therefore, the systemic and pulmonary circulations are in series and physiologically corrected, but the morphologic right ventricle supports the systemic circulation.

This lesion is a rare form of CHD. Associated abnormalities occur in most cases and consist of VSD, pulmonary or subpulmonary stenosis, and tricuspid valve anomalies. Patients with no associated abnormalities may have undetected L-transposition until problems arise in the sixth or seventh decade. Surgery is complex but may be feasible in certain patients and involves an atrial baffle procedure plus an arterial switch operation—the so-called double switch operation.

Echocardiographic Assessment

The ME four-chamber view confirms the diagnosis by demonstrating the abnormal inferiorly placed atrioventricular valve (tricuspid valve) in the left-side morphologic right ventricle (Figure 18–24). The tricuspid valve is often ebsteinoid in character in this form of CHD. The aortic valve is located leftward, anterior, and superior to the pulmonic valve. The great vessels connection can be appreciated from a variety of views as previously described. With advancing age, RV dilatation is common and is accompanied by decreased systolic function. The TEE examination should include a search for associated abnormalities of the left-side tricuspid valve (present in 90%), VSD (70%), LV outflow obstruction (40%, usually subvalvular), RV outflow tract obstruction, and subaortic stenosis.

Double-Outlet Right Ventricle

DORV represents a continuum of congenital heart disease that ranges from VSD with significant override of the aorta, to both great arteries arising from the right ventricle, to transposition of the great arteries with pulmonary override of the VSD. DORV lesions are classified according to the anatomic relation of the VSD to the great vessels. The VSD is usually large and may be subaortic, which is most common, or subpulmonary (Taussig-Bing form), noncommitted (VSD is remote from the great vessels), or doubly committed (VSD is shared equally by the aorta and pulmonary artery). Pulmonary or aortic stenosis, valvular or subvalvular, is present in up to 50% of patients. Coarctation of the aorta is a common associated lesion, and interrupted aortic arch also may be present. The location of the VSD determines the physiologic picture, and the presence of pulmonary stenosis or increased pulmonary vascular resistance restricting flow across the VSD determines outcome in these patients. A subaortic VSD with pulmonary stenosis resembles the hemodynamic picture of tetralogy of Fallot, whereas a subpulmonary VSD resembles complete transposition with blood from the LV flowing through the VSD to the pulmonary artery and blood from the RV flowing mainly to the aorta. Surgical approach varies according to the type of DORV.

Echocardiographic Assessment

The principal diagnostic feature is the appearance of both great arteries primarily committed to the right ventricle (Figure 18–25). Deep TG views and ME LAX views are helpful in delineating the spatial relationship between the great arteries, the outflow tract of each artery, and the type of VSD and its location relative to the great arteries. Associated cardiac lesions also need to be excluded.

Adult patients who have had a Rastelli repair for DORV with subaortic VSD and pulmonary stenosis require careful TEE evaluation to exclude kinking or obstruction along these conduits. Patients with DORV of a tetralogy of Fallot type usually have had the VSD closed with a septal patch and primary repair of the pulmonic stenosis site. Residual defects in the ventricular septum or around the patch may frequently occur. Color-flow imaging confirms the residual shunt.

Cavopulmonary Connections

Glenn Shunt

A Glenn shunt is typically used as the initial palliative procedure for single ventricle physiology. It consists of an anastomosis between the end of the superior vena cava to the side of the right pulmonary artery, which is divided from the main pulmonary artery in the classic form; alternatively, superior vena cava flow is directed to both (undivided) pulmonary arteries in the bidirectional form (Figure 18–26). The shunt improves arterial saturation, although cyanosis remains because blood draining from the inferior vena cava still mixes with pulmonary venous return at the atrial level. The Glenn shunt is performed at about 6 months of age followed by the Fontan procedure between 18 months and 4 years of age.

Echocardiographic Assessment. TEE imaging in a vertical plane alignment at the level of the right atrium identifies the upper part of the superior vena cava, and then, with rotation of the probe rightward, the upper to middle superior anastomosis to the right pulmonary artery can be visualized. Combined color-flow and pulsed Doppler imaging rules out stenosis or thrombus at the level of anastomosis. Agitated saline solution injected peripherally may be used to exclude pulmonary arteriovenous fistula. Doppler findings of low-velocity, biphasic, and laminar flow with an inspiratory increase (spontaneous ventilation) in the velocity of flow within the shunt are normal. Turbulent flow, on the other hand, may indicate obstruction at the superior vena cava to pulmonary artery anatomosis.

Fontan Procedure

The Fontan procedure has evolved over many years. The objective of this procedure is to direct inferior venal caval flow into the pulmonary arteries, bypassing the right ventricular chamber. Previously this was achieved by a direct right atrial to pulmonary arteries connection, whereas more recently a total cavopulmonary connection is performed as a staged procedure. Stage I is a bidirectional Glenn shunt (as discussed above), and stage II is a technique in which inferior vena cava blood is directed through a lateral tunnel within the right atrium or a tube graft external to the right atrium into the pulmonary artery (extracardiac Fontan; Figure 18–27). Once complete, all of the systemic venous return is diverted directly into the pulmonary arteries. Pulmonary blood flow is passive without an intervening ventricular chamber to propel it across the lungs. The transpulmonary gradient (systemic venous pressure–left atrial pressure) becomes the driving pressure across the pulmonary bed. Consideration of pulmonary vascular resistance, systemic atrioventricular valve competency, and systemic ventricular function determine whether the procedure can be performed. Outcome in these patients is determined by systemic ventricular function and atrioventricular valve competency.

Echocardiographic Assessment. Complications of the Fontan circulation such as cavoatrial shunting, thrombus formation, and obstruction within the systemic venous pathways must be excluded. The inferior venous pathway may be best visualized with a transgastric view. A normal flow profile through the venopulmonary anastomosis or in the conduit has a biphasic forward pattern of moderate velocity (0.2 to 0.5 m/s). A flow profile with a velocity of greater than 1.5 m/s is suggestive of obstruction.4 Pulsed-wave Doppler in the pulmonary artery should show increase in flow with inspiration during spontaneous ventilation.

Ross Procedure

The Ross procedure is used in patients who require aortic valve replacement. It consists of excision of the aortic valve and placement of the native pulmonary valve and trunk into the aortic position with reimplantation of the coronary arteries. On the pulmonary side, a homograft conduit is placed between the right ventricle and the pulmonary artery.

Preoperatively, comparison of aortic annulus and pulmonic annulus diameters, and detection of presence and severity of pulmonary regurgitation determines the feasibility of the procedure. Postoperative and follow-up evaluations should focus on visualization of the pulmonary autograft for aneurysmal dilatation and presence of regurgitation.

Atrial Switch Operations

Several decades ago the atrial switch operation was the standard surgical approach for transposition of the great arteries. Intra-atrial baffles that redirect blood at an atrial level were fashioned from pericardial tissue in the Mustard procedure and from right atrial flaps in the Senning procedure. Systemic venous blood from the caval veins is then directed through the baffle across the mitral valve into the left ventricle and out the pulmonary artery (Figure 18–28). Pulmonary venous return is rerouted through the tricuspid valve into the right ventricle and the aorta. This results in a physiologic correction but not an anatomic correction, as the right ventricle remains the chamber ejecting into the systemic circulation. Long-term complications include tricuspid regurgitation, atrial rhythm disturbances, right ventricular dysfunction, and sudden death.

Echocardiographic Assessment. Typical echocardiographic findings include right ventricular hypertrophy and a convex appearance of the interventricular septum towards the left ventricle as right ventricular pressure exceeds left ventricular pressure. TEE is extremely valuable in patients who have undergone a Mustard or Senning procedure because the systemic venous baffle and pulmonary venous confluence are posterior structures.24 The combination of the transverse, longitudinal, and modified planes allows for visualization of the caval junctions, the entrance of the pulmonary veins, and the midportion of the baffle. The baffle is typically seen as an oblique, linear echo within the left atrium. Color and spectral Doppler interrogation of venous inflows aids in the detection of turbulence, increased velocity (faster than 1 m/s), and abnormal flow patterns due to baffle obstruction. Baffle leaks are best assessed by using contrast echocardiography and the ME four-chamber view. Baffle obstruction results in the generation of collaterals from the superior to the inferior vena cava. Hence, imaging of the inferior vena cava during injection of agitated saline solution through a peripheral or superior central vein will confirm baffle obstruction by detecting microbubbles in the inferior vena cava. Careful evaluation of RV function, the systemic ventricle, and the tricuspid valve (the systemic atrioventricular valve) for regurgitation completes the examination.

The Rastelli Procedure

The Rastelli procedure is used to correct certain combinations of congenital heart defects. Transposition of the great arteries (d-TGA) with a VSD and right ventricular outflow tract obstruction (RVOTO), or overriding aorta plus VSD and RVOTO, or double-outlet right ventricle with a VSD and RVOTO are all indications for a Rastelli repair. In this repair, a Gore-Tex patch is used as an intraventricular baffle to direct oxygenated blood from the left ventricle to the aorta, while at the same time closing the VSD. The pulmonary valve is surgically closed and an artificial conduit and valve is placed from the right ventricle to the pulmonary artery bifurcation, allowing oxygen-depleted blood to travel to the lungs for reoxygenation.

Echocardiographic Assessment. Satisfactory postoperative hemodynamics are dependent upon free, unobstructed egress of blood from both the left ventricle and the right ventricle. Obstruction to either outflow tract will contribute to ventricular failure. TEE is useful for assessing both the proximal and distal ends of the conduit for stenosis at the anatomosis to the right ventricle or pulmonary artery. Continuous-wave Doppler directed into the conduit promotes detection of high-velocity jets, indicating the presence of an obstruction.