Echocardiography in Pediatric and Adult Congenital Heart Disease, 2nd Ed.

8. Ebstein’s Malformation and Tricuspid Valve Diseases

The most common congenital malformations involving the tricuspid valve are Ebstein’s malformation and tricuspid valvar dysplasia. This chapter will primarily consider Ebstein’s malformation with concordant atrioventricular connections and biventricular circulation. Ebstein-like deformation of the morphologically tricuspid valve in association with atrioventricular discordance is discussed in Chapter 10. Isolated dysplasia of the tricuspid valvar leaflets, traumatic tricuspid regurgitation, and other right ventricular abnormalities will be briefly described, and the differences between these disorders and Ebstein’s malformation are highlighted. Echocardiography has become the procedure of choice for both the diagnosis and long-term assessment of patients with Ebstein’s malformation. In the 1980s, cross-sectional echocardiography replaced M-mode as the clinical standard. As early as 1984, cross-sectional imaging was considered sufficiently comprehensive that angiography was no longer necessary to diagnose Ebstein’s malformation.

ON THE NAMING OF THE TRICUSPID VALVAR APPARATUS

We have chosen to adopt an anatomically unambiguous system of names to describe the components of the tricuspid valvar apparatus. This will create some differences between the descriptions contained within this chapter and in many previous publications. It seems best to concretely define this system to avoid potential confusion. The three valvar leaflets will be referred to as the anterior, the septal, and the inferior leaflets (Fig. 8.1). The designations of the anterior and septal leaflets are clear. The inferior leaflet has often been called the “posterior” leaflet. This designation is anatomically incorrect. This leaflet is positioned inferiorly within the ventricular cavity, lying adjacent to the diaphragm in the normal heart. We recognize that abnormal valves often display rotation of their components away from the normal position. However, the inferior tricuspid leaflet is always associated with the ventricular free wall and is never in a posterior position. The posterior aspect of the right ventricle is the interventricular septum, not the free wall adjacent to the diaphragm. Therefore, in the human heart, it would be inappropriate to refer to the tricuspid valve leaflet nearest the free wall as being “posterior,” when it is not. This leaflet is always positioned inferior to the anterior and septal leaflet, even in the most severely distorted valves, leading to our preference for the name “inferior” leaflet of the tricuspid valve.

Ebstein’s Malformation

Ebstein’s malformation has an extremely variable natural history. The clinical course depends on the degree of abnormality manifested by the right ventricle and the tricuspid valvar apparatus. These abnormalities can range from minimal to severe. If the deformity of the tricuspid valve is severe, it may result in profound congestive heart failure in the neonatal period, or even in intrauterine death. At the other end of the spectrum, patients with a mild degree of displacement and dysfunction may remain asymptomatic until late adult life.

DEFINITION AND ANATOMIC FEATURES OF EBSTEIN’S MALFORMATION

Ebstein’s malformation is often thought of as a primary disorder of the tricuspid valve. In reality, it is a manifestation of a more global aberration in myocardial development. Those afflicted with Ebstein’s malformation invariably display abnormalities in both myocardial structure and function, as well as the characteristic valvar deformities. The right ventricle and tricuspid valve are universally involved, while changes in the left heart are less common.

The hallmark of Ebstein’s malformation is displacement of the annular attachments (hinges) of the septal and inferior leaflets, away from the atrioventricular junction (Fig. 8.2). This results from failure of these leaflets fully to separate from the underlying ventricular wall during cardiac development. The normal separation process is referred to as “delamination” (Fig. 8.3). Delamination begins at the tips of the embryonic leaflets and proceeds “back” toward the atrioventricular junction. A completely delaminated leaflet will have a hinge point at (or very near) the anatomic tricuspid valvar annulus.

This failure of delamination results in the leaflets remaining variably adherent to the underlying right ventricular and septal myocardium (Fig. 8.4). This adherence creates the characteristic displacement of the annular attachments of the valve and rotates its functional orifice away from the normal position within the right ventricular inlet. It is now appreciated that the concept of apical displacement of the tricuspid valve in Ebstein’s malformation was not anatomically precise. The displacement seen in Ebstein’s malformation is not simply a linear shift of the tricuspid valve toward the cardiac apex. The displacement is actually rotational or spiral in nature, following the contours of the right ventricular cavity. The primary orientation of the rotation is in an anterior direction, toward the right ventricular outflow tract, and only to a lesser extent toward the apex. This spiral shift in the tricuspid valve apparatus moves the functional valvar orifice to the junction of the trabecular and outlet zones of the ventricle (Figs. 8.5 and 8.6). In the most severe cases, the functional leaflets may be positioned within the outlet itself. The adherent portions of the valvar leaflets usually have little or no motion. This typically leads to tricuspid regurgitation or, more rarely, to stenosis.

Figure 8.1. These subcostal, sagittal plane images demonstrate the anatomic relationships of the three tricuspid valve leaflets. A: Normal tricuspid valve. The septal tricuspid leaflet (STL) lies parallel to the ventricular septum, and the anterior tricuspid leaflet (ATL) is positioned parallel to the anterior free wall of the right ventricle and separates the posterior inlet from the anterior outlet of the ventricle. The inferior tricuspid leaflet (ITL) is parallel to the diaphragmatic surface of the right ventricle and lies in the most inferior portion of the ventricle. This leaflet has often been referred to as the “posterior” leaflet, which is anatomically incorrect. B: From an examination of the patient with Ebstein’s malformation. The ATL remains parallel to the anterior free wall. The STL and ITL are more difficult to recognize in this diastolic image because they are adherent to the myocardium of the septum and right ventricular inferior wall. Only a small segment of the STL is seen separated from the ventricular septum near the right ventricular outflow tract (arrow). LV, left ventricle; P, posterior; S, superior.

Figure 8.2. Apical four-chamber plane of a normal heart (left) and a heart afflicted with Ebstein’s malformation (right). The hinge point (septal insertion) of the normal STL is positioned slightly more toward the cardiac apex, compared with the septal hinge point of the anterior mitral leaflet (bottom left, arrow). This displacement is exaggerated in hearts with Ebstein’s malformation, as shown by the diagram (top right) and the arrows in the echocardiographic image (bottom right). It should be noted that the valvar leaflets are also abnormal in Ebstein’s malformation. In the case shown (bottom right), the leaflets are thickened and moderately dysplastic. ASD, atrial septal defect; L, left; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; S, superior.

Figure 8.3. Delamination. Normal delamination process that gives rise to the tricuspid valve leaflets (top). During embryonic valve formation, the inner layer of endomyocardium separates (delaminates) from the underlying cardiac muscle and gradually loses its myocardial components. As development progresses (left to right), we begin to recognize the supportive chordal structures and leaflet of the mature valve. When a failure of delamination occurs (bottom), it results in adherence of the “tricuspid valve” tissues to the right ventricular myocardium. This is the hallmark of Ebstein’s malformation. The four diagrams (bottom), progressing from mild to severe (left to right), demonstrate the spectrum of abnormality that can be associated with failed delamination. EC, endomyocardial layer; RA, right atrium; RCA, right coronary artery; RV, right ventricle; TV, tricuspid valve.

In hearts with Ebstein’s malformation, the septal and inferior leaflets are most dramatically involved and show the largest change in the anatomic position of their hinge points. In contrast, the anterior leaflet forms at a different developmental stage. As a result, its junctional hinge usually retains a normal position near the atrioventricular groove and it can become very large and “sail-like.” Mild cases can be encountered in which only the hinge of the septal leaflet is displaced away from the atrioventricular junction. Such cases are found most frequently in the setting of pulmonary atresia with an intact ventricular septum. In the absence of pulmonary atresia, it is unlikely that such minimal changes would produce the typical, if indeed any, symptomatology.

Clinically, it is important to distinguish pathologic displacement of the septal leaflet from the typical valvar offsetting found in the normal heart (see Fig. 8.2). It is in making this distinction that the apical component of the displacement associated with Ebstein’s malformation is most useful. The normal tricuspid septal leaflet hinges at a point on the ventricular septum that is slightly apical to the hinge point of the anterior mitral leaflet, when both are displayed in the apical four-chamber view. Although the two septal hinges are offset, this does not represent displacement of the tricuspid valve. When the septal leaflet is abnormally adherent to the myocardium, as in Ebstein’s malformation, the distance separating the two septal valvar hinge points becomes exaggerated. This exaggerated separation can be quantitated by measuring the linear distance between the two septal hinges in the four-chamber plane. (See discussion of the apical displacement index later in this chapter.)

The abnormalities associated with Ebstein’s malformation also cause the leaflets to adopt a “bileaflet” configuration, with a plane of closure at the junction of the trabecular and the outlet components of the right ventricle (Figs. 8.68.7, and 8.8).

The keys to understanding this malformation and its anatomic consequences are appreciating the developmental etiology of failed delamination and recognizing that the abnormal, displaced location of the valve represents a complex rotational or spiral deformity (Figs. 8.5 and 8.6), rather than the more simplistic linear “apical” displacement that has received attention in the past.

Figure 8.4. Anatomic specimen from a patient with a severe case of Ebstein’s malformation (A) and a segment of right ventricular wall from a patient with Ebstein’s malformation (B). The anatomic atrioventricular junction is marked (asterisks). The failure of the tricuspid valve to delaminate in the specimen not only displaced the valve away from the junction but also produced extensive adherence of the valve tissue to the ventricular myocardium (A, arrows). No mobile segments of valve are appreciated within the right ventricular inlet. The remnant of tricuspid valve tissue (B) is also nearly completely adherent to the underlying myocardium. Only a small tag of tissue shows any separation from the wall (near the solid arrow). The segment of “valve” between the dashed and solid arrows is seen as the dense, white inner lining of the cavity (clearly different from normal endocardial tissue, which can be seen below the level of the solid arrow). The adherence of the tricuspid valve creates a zone of the right ventricular cavity that is “atrialized.” This zone has walls composed of ventricular myocardium, but its cavity is proximal to the tricuspid valvar orifice. aRV, atrialized right ventricle; LA, left atrium; LV, left ventricle; RV, right ventricle; TV, tricuspid valve.

CLINICAL PRESENTATION OF EBSTEIN’S MALFORMATION

Patients with Ebstein’s malformation may present at any age. The most severe cases present prenatally or as newborns. Prenatal diagnosis is dependent on ultrasonic screening examinations. Fetal presentation is accompanied by increased heart size, a significant incidence of fetal hydrops, and, in the most severe cases, pulmonary parenchymal hypoplasia secondary to marked cardiac enlargement. Prenatal arrhythmia is not common. Newborns most often present with cyanosis, while slightly older infants present with a combination of desaturation and symptoms of cardiac failure. Murmurs and arrhythmias are more frequently encountered as presenting complaints in older patients. Although some patients remain asymptomatic, most will have some cardiovascular symptoms. Beyond infancy, the majority will display abnormal fatigability, dyspnea, palpitations, or cyanosis with exertion. Palpitations in a cyanotic child should raise the possibility of Ebstein’s malformation (Table 8.1).

Figure 8.5. Rotation of the functional tricuspid orifice in Ebstein’s anomaly. Rotational shift of the functional tricuspid orifice away from the atrioventricular junction to the plane that divides the trabecular and outlet zones of the ventricle (Aheavy dashed line). The observed planes of the effective valvar orifices of the hearts with Ebstein’s malformation studied by Schreiber and colleagues are shown (Bovals). The effective displacement of the functional tricuspid valve (heavy dashed line) away from the atrioventricular junction (marked by the dotted line) is rotational, not linear. This rotation is spiral in nature and is directed both toward the apex and, more important, anteriorly toward the outflow tract. aRV, atrialized right ventricle; RA, right atrium; RV, right ventricle.

Echocardiography has significantly influenced the age at which patients with Ebstein’s malformation are diagnosed. In 1979, Giuliani and colleagues found that just under one-third of patients were diagnosed before 4 years of age. Another two-fifths were diagnosed before the age of 19, with the remainder presenting in adulthood, some at 80 years of age. In contrast, in the experience reported by Celermajer et al. in 1994 (see Table 8.1), three-fifths came to clinical attention before the age of 1 year, with half diagnosed prenatally or as newborns. One-tenth presented between 1 and 12 months of age, with only three-tenths presenting as children or adolescents. Despite the increased availability of echocardiographic examination in this more recent cohort, one-tenth remained undiagnosed until adulthood.

ASSOCIATED CARDIOVASCULAR ABNORMALITIES

Nearly all patients with Ebstein’s malformation will have an interatrial communication, with the most frequent being a patent foramen ovale or secundum atrial septal defect. Venosus and partial atrioventricular septal defects do coexist with Ebstein’s malformation but are much less common. A large spectrum of other lesions has been described, including ventricular septal defects, tetralogy of Fallot, aortic coarctation, noncompaction of the left ventricular myocardium, and patency of the ductus arteriosus. The most common nonatrial cardiac abnormality is pulmonary stenosis or atresia, which is found in up to one-third of those presenting in infancy. Obstruction of the right ventricular outflow tract is commonly associated with Ebstein’s malformation when diagnosed in fetal life. In this setting, it may be difficult to distinguish structural from functional pulmonary valve atresia using echocardiography, especially in the presence of severe tricuspid regurgitation. When there is no systolic flow from the right ventricle to the pulmonary artery, the presence of pulmonary regurgitation is the most reliable marker of functional pulmonary atresia (Fig. 8.9). The regurgitant flow can be detected by either color flow or spectral Doppler echocardiography. Doppler detectable pulmonary regurgitation has been reported in more than 80% of series with ductal-dependent neonatal Ebstein’s malformation. In the setting of anatomic pulmonary valve atresia, there is no flow detectable during either phase of the cardiac cycle. In cases of Ebstein’s malformation with either stenosis or atresia, the pulmonary valvar abnormality is probably secondary to the malformation of the tricuspid valve, with hypoplasia of the outflow tract resulting from reduced anterograde flow through the right heart. When severe Ebstein’s malformation is associated with fetal and neonatal distress, or death, both lungs are usually hypoplastic. The markedly enlarged heart compresses the lungs, leading to the pulmonary hypoplasia seen in these cases.

Figure 8.6. Patient with Ebstein’s malformation. A: Anatomic specimen shows the atrial aspect of the deformed valve. It illustrates how the anterior leaflet retains its normal attachment at the atrioventricular junction (light blue dotted line), but the conjoined septal and inferior leaflets have their hinge points attached well away from the atrioventricular junction (compare the dark blue dashed and black dotted lines). The separation of the inferior and septal hinge points from the true annulus is also highlighted by the curved red arrow. The portion of the right ventricle between the darker blue and black linesis said to be “atrialized” and in this case has a very thin wall. Note that the leaflets of the deformed valve will close in “bileaflet” fashion. B: Subcostal, coronal echocardiographic image displays some of the same features. Remnants of the anterior (near the white arrow) and the ITLs (black arrow) are seen. The hinge point of the anterior leaflet (white arrow) retains a normal position, while the insertion of the inferior leaflet is displaced into the ventricular cavity away from the anatomic atrioventricular junction, which is marked (asterisk). Similar to the anatomic image on B, this echocardiogram confirms that the displacement of the tricuspid apparatus associated with Ebstein’s malformation actually rotates the valve anteriorly, as well as apically (curved red arrows). ATL, anterior tricuspid leaflet; ITL, inferior tricuspid leaflet; RA, right atrium; RV, right ventricle; RVOT, right ventricular outflow tract; STL, septal tricuspid leaflet.

ECHOCARDIOGRAPHIC RECOGNITION AND EVALUATION OF EBSTEIN’S MALFORMATION

Imaging of the internal cardiac crux, the components of the abnormal tricuspid valve, and the right ventricular myocardium reveals several features that are reliably used to identify patients with Ebstein’s malformation. The single most sensitive and specific diagnostic feature is the displacement of the annular hinge of the septal leaflet. This displacement is most easily appreciated by comparison to the annular hinge of the mitral leaflet as seen in the apical four-chamber view. One must recall that the normal septal tricuspid leaflet inserts at a position that is slightly apical to the insertion of the anterior mitral valve leaflet. In patients with Ebstein’s malformation, this displacement is exaggerated. The distance between the valvar hinge points can easily be measured in systole (Fig. 8.10A). This distance, when divided by the body surface area in square meters, is known as the displacement index. In a heart with evidence of failed delamination, an index value greater than 8 mm/m2 reliably distinguishes those with Ebstein’s malformation from both normals and from patients with other disorders associated with enlargement of the right ventricle. In cases with severely adherent and displaced septal leaflets, the hinge of the septal tricuspid leaflet may not be seen in the four-chamber plane. In these cases, the first septal structure seen on the right ventricular septal surface (apical to the insertion of the anterior mitral leaflet) will be the moderator band (Fig. 8.10B). The apical displacement index is essentially infinite in these hearts, and recognition of the presence of Ebstein’s malformation is straightforward.

Figure 8.7. Patient with Ebstein’s malformation. A: Four-chamber echocardiographic image. B: Systolic frames in a parasternal long-axis format. The tricuspid valve’s functional orifice does not lie in the “four-chamber” plane but rather has been rotated anteriorly and apically. A cross section of the orifice, as the valve closes, can be appreciated in the long-axis images (arrows). These frames highlight the bileaflet nature of the functional tricuspid valve in Ebstein’s malformation. There is just a single, vertically oriented, line of closure between the functional segments of valve tissue. C: Coaptation gap that allows regurgitant flow. aRV, atrialized right ventricle; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle.

Occasionally, it can be difficult to assess the offset between the valvar hinges at the internal crux. In these unusual situations, other echocardiographic features that can assist in making an accurate diagnosis include elongation of the anterior leaflet, tethering of any of the leaflets to the underlying myocardium, shortened chordal supports, attachment of the leading edge of the anterior leaflet to the right ventricular myocardium, displacement of the annular attachment of the anterior leaflet, absence of the septal or inferior leaflets, congenital fenestration of the leaflets, and enlargement of the valvar annulus.

Echocardiography is also used to define associated cardiovascular abnormalities and myocardial function. In addition, preoperative examinations are used to define anatomic features that relate to potential for surgical repair. Over the past decade, circumferential tricuspid valve reconstruction (“cone” repair) has replaced the monoleaflet repair as the preferred surgical approach. Several of the anatomic features that indicated potential success of the monoleaflet repair remain helpful prior to cone reconstructions. The most important feature predictive of a durable repair is the mobility of the anterior leaflet. When 50% or more of the leaflet is freely mobile, there is no major tethering to the myocardium; and due to the leading edge that moves freely within the inlet of the right ventricle, repairs are not only more likely to succeed, but also retain good function longer. These assessments are based primarily on images from the apical four-chamber view (Fig. 8.11), but both subcostal and short-axis views can provide important information as well. Extensive adherence of the anterior leaflet to the ventricular myocardium (see Fig. 8.10B) makes a successful repair less likely. A single central jet of regurgitation (Fig. 8.12) is more easily eliminated than are multiple regurgitant orifices (Fig. 8.13). Even when there is a significant amount of leaflet tissue present, direct muscular insertions from the ventricular free wall into the leading edge of the anterior leaflet can make cone repairs more difficult and often lead to failure of the monoleaflet approach (Fig. 8.14). Figures 8.15 and 8.16 demonstrate the results of successful monoleaflet repairs.

Figure 8.8. Three-dimensional echocardiographic image, from a transthoracic examination, has been cropped to show a view analogous to an apical long-axis image. It is focused on the abnormally positioned, functional tricuspid orifice (FTO) within the right ventricle. This valve not only shows how the functional orifice is rotated anteriorly in Ebstein’s malformation but also is a good example of the “bileaflet” configuration of the functioning valve leaflets seen in this disorder. The large anterior leaflet (ATL) functions as one part of the coaptation mechanism, while the remnants of the inferior and septal leaflets (ITL and STL) combine with the ventricular septum to provide the surface against which the ATL can close (or attempt to close). Ao, aorta; LV, left ventricle; RA, right atrium; S, septum.

Figure 8.9. Functional pulmonary valve atresia. This parasternal color flow echocardiographic image is focused on the right ventricular outflow tract, pulmonary valve, and main pulmonary artery (PA). It was taken during the examination of a newborn with severe Ebstein’s malformation. No systolic forward flow, crossing the pulmonary valve, could be demonstrated. However, this diastolic frame clearly shows a jet of pulmonary regurgitation (arrow). This transvalvar flow reveals that the pulmonary valve is patent, not atretic in an anatomic sense. The lack of forward flow is due to the inability of the right ventricle to generate a systolic pressure greater than the systolic pressure in the PA. Such echocardiographic confirmation of pulmonary valve patency is critical to therapeutic planning. A, anterior; L, left; LV, left ventricle; RV, right ventricle.

Figure 8.10. Four-chamber, systolic images obtained from two different patients with Ebstein’s malformation. A: Modest displacement of the tricuspid valve apparatus and excellent mobility of the valve leaflets. Both the anterior and septal leaflets remain visible in this plane because the degree of anterior rotation in this heart was minimal. The small white arrows highlight the separation between the septal insertions of the anterior mitral and STLs. The absolute distance between the insertions was 13 mm. Patient’s body surface area was 1.0 m2. Therefore, the displacement index in this case was equal to 13 mm/m2B: A more severe example of Ebstein’s malformation. The remnant of the septal leaflet (and its hinge point) was found near the right ventricular outflow tract, far anterior to the plane demonstrated in this image. The anterior leaflet is significantly tethered and was immobile in this plane; it remains parallel to the right ventricular free wall, even though this frame was taken at peak systole. Apically, it was also adherent to the moderator band (apical red arrow). In this situation, the apical displacement index is clearly large but cannot be accurately measured because no septal leaflet tissue is visualized in this plane. Nonetheless, the exaggerated separation between the septal insertion of the anterior mitral leaflet and the displaced tricuspid septal remnant clearly identifies this as a case of Ebstein’s malformation. ADI, apical displacement index; aRV, atrialized right ventricle; L, left; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; S, superior.

The additional surgical “delamination” performed during circumferential tricuspid reconstructions results in a larger percentage of successful repairs than was possible with the monoleaflet approach. A simplistic description of this complex repair is provided by Fig. 8.17. Unlike the monoleaflet repair, during a cone reconstruction the surgeon is able to recruit or “artificially delaminate” additional tricuspid valve tissue by dissecting the adherent components away from the underlying myocardium (see Fig. 8.17A). This increases the amount of mobile tissue available to assist in the reconstruction of the valve and results in a sheet of valve tissue separate from the myocardium and the atrioventricular junction (see Fig. 8.17B). Chordal support between the leading edge of this “surgically delaminated” valve tissue and the right ventricular walls must be preserved, or occasionally supplemented with Gore-Tex sutures. Fenestrations in the neotricuspid tissue must be closed. The tissue is then sutured into a “cone” and the base of the cone is anchored near the atrioventricular junction, avoiding the areas containing the conduction pathways (see Fig. 8.17C). Thus, a cone reconstruction not only decreases the amount of tricuspid regurgitation, but also restores the hinge points of the repaired valve to a more normal position near the atrioventricular junction. Figure 8.18shows an echocardiographic example of a cone reconstruction. It seems likely that valves such as those shown in Figures 8.10A8.13, and 8.14 would now be candidates for cone reconstructions, if they had presented after its introduction. Additional experience with and follow-up after the cone reconstruction of the tricuspid valve are needed before we can confidently define the anatomic features associated with favorable results from this procedure. Early impressions suggest that the amount of mobility in the native anterior leaflet and its leading edge will have an influence on the success and durability of these repairs. However, valves with even major degrees of tethering have been successfully repaired using this approach (Fig. 8.19). The presence of septal leaflet tissue within the right ventricular inlet also seems to relate to better function of the “cone” postoperatively.

Figure 8.11. Apical four-chamber inflow images demonstrate a case of Ebstein’s malformation with excellent anterior leaflet mobility. A: Mid-diastole. B: Peak systole. Features that suggest favorable anatomy for monoleaflet repair are that the anterior leaflet in this patient is freely mobile, including its leading edge. There are no muscular insertions that limit or distort the motion of the valve. The regurgitant jet originated only from the gap in coaptation seen between the anterior leaflet and the remnant of the septal leaflet. The leading edge of the valve reaches a point near enough to the septum that, given the degree of annular dilation, an annuloplasty can “advance” it to a position where it will coapt with the septum and the vestiges of the septal leaflet. L, left; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; S, superior.

Regardless of the patient’s operative status (preoperative or postoperative) or even the type of valve (native, repaired, or prosthetic), the functional impact of the malformation on overall cardiac performance should be determined. Anatomical and functional severities are usually similar, but they are not always the same. For example, a patient can have a severe anatomic displacement with Ebstein’s malformation but only mild functional impairment. This can occur if the myocardium is only mildly dysfunctional, the interatrial communication is small, and the displaced valve leaflets allow little transvalvar regurgitation. Both anatomic and functional aspects of severity play an important role in determining functional state, prognosis, and, to a certain extent, the reparability of the tricuspid valve.

Figure 8.12. Severe tricuspid regurgitation in Ebstein’s malformation. The anterior leaflet of this tricuspid valve is freely mobile (A) and color flow mapping (B) revealed that there was only a single, central jet of regurgitation (red arrow on A). There is a coaptation gap between the anterior leaflet and the remnant of the septal leaflet in this case (Bred arrow). The vena contracta of the tricuspid regurgitant jet was greater than 50% of the normal tricuspid annulus diameter, consistent with very severe regurgitation. This patient subsequently had a successful monoleaflet repair, with only mild residual tricuspid regurgitation and no stenosis. L, left; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; S, superior.

Figure 8.13. Large muscular insertion to the middle of the anterior leaflet (A) and multiple fenestrations and associated jets of regurgitation (B). The tethering and multiple origins of regurgitant flow dramatically decrease the chance for successful monoleaflet repair, and a tricuspid valve replacement was performed. Although a monoleaflet repair was not possible, if this patient presented today the amount of leaflet tissue present suggests that a cone reconstruction would be possible, although each individual fenestration would need to be closed as a part of the repair. L, left; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; S, superior.

Figure 8.14. Apical four-chamber image showing (arrows) significant, direct muscular insertions from the right ventricular free wall into the mid-section of the anterior leaflet of the tricuspid valve. Even though this valve leaflet has separated from the underlying myocardium, its mobility was quite limited by these attachments to the ventricular free wall. Although a monoleaflet repair would not be possible, the surgical “delamination” that occurs during a cone reconstruction has made even this type of valve a candidate for repair. aRV, atrialized right ventricle; L, left; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; S, superior.

The degree of right atrial and ventricular enlargement and functional state of the right ventricular myocardium should be specifically defined. The largest right-sided chambers are associated with the most functional impairment and have less satisfactory clinical, as well as surgical, outcomes. Other important features include the degree of dilation of the right ventricular outflow tract, the presence and size of any atrial septal defect, and the degree of transvalvar regurgitation. Tricuspid regurgitation should not only be described but also be quantified. The most common scheme used to grade tricuspid regurgitation is trivial (grade 0), mild (grade 1), moderate (grade 2), moderate–severe (grade 3), or severe (grade 4). The left ventricular myocardium has also been described as being abnormal in a significant fraction of the patients with Ebstein’s malformation. Noncompacted segments of left ventricular myocardium can be seen in 10% to 20% of cases. Therefore, quantitative evaluation of left ventricular performance (as described in Chapter 3) should also be a routine component of the echocardiographic evaluation of the patient with Ebstein’s malformation. When ventricular septal defects and/or pulmonary stenosis coexist with Ebstein’s malformation, standard echocardiographic assessments are required to define their impact on the patient’s physiology.

The techniques used to assess tricuspid regurgitation and right ventricular function deserve some additional discussion. Tricuspid regurgitation, in particular, can be difficult to accurately assess in Ebstein’s malformation. This is due to the rotational displacement of the functional valvar orifice away from the expected position within the right ventricular inlet. As a result, the origin of the transvalvar regurgitation is often not visualized in the usual views and can be oriented in unusual directions (Fig. 8.20). In these cases, the plane of sound must be angled more anteriorly toward the functional valvar orifice, typically at the junction of the body and outlet of the right ventricle (see Fig. 8.6). The subcostal acoustic window often provides the optimal visualization of this area in young patients. In older patients, either transthoracic parasternal short-axis, anteriorly angled apical views, or transgastric transesophageal imaging planes can provide similar information.

Figure 8.15. Postoperative examination of the patient shown in Figure 8.11. A: Echocardiographic anatomy after a monoleaflet repair. The right ventricular cavity and right atrioventricular junction have been significantly reduced in size. This allows the anterior leaflet (arrow) to coapt with the ventricular septum in systole. B: Magnified color flow images showing no stenosis or regurgitation. L, left; LV, left ventricle; RA, right atrium; RV, right ventricle; S, superior.

Figure 8.16. Two apical four-chamber images show the anatomy of a patient with Ebstein’s malformation before and after a monoleaflet repair. The anterior leaflet (arrow) was successfully advanced to coapt with the ventricular septum and the remnant of the tricuspid septal leaflet, eliminating the tricuspid regurgitation. L, left; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; S, superior.

Figure 8.17. Concept of the cone reconstruction in Ebstein’s malformation. A: Adherent segments of tricuspid valve tissue being separated from the anatomic annulus and the underlying right ventricular myocardium. B: Sheet of tricuspid of tissue after it has been released. This tissue is used to create a cone, often attaching the anterior leaflet to the remnants of the septal leaflet (see suture line, C). Once the cone is created, the base is attached to the atrioventricular junction, restoring the hinge points to a nondisplaced position (C). When dilated, thin, or significantly dyskinetic, the atrialized right ventricle can be reduced in size by either elliptical resection or plication (C). The annuloplasty reduces the size of the intraventricular junction to what is appropriate to the size of the reconstructed cone.

Figure 8.18. Apical four-chamber images taken 1 year after cone reconstruction for Ebstein’s malformation. A: Two-dimensional anatomy of the reconstructed tricuspid valve in diastole. Both the septal and lateral hinge points are now near the anatomic atrioventricular junction. B, C: Color flow images in diastole (B) and systole (C). The reconstructed valve shows no signs of stenosis and minimal regurgitation with virtually no color flow disturbance during either phase of the cardiac cycle. L, left; LA, left atrium; LV, left ventricle; R, right; RA, right atrium; RV, right ventricle.

In cases with a single regurgitant orifice, the width of the regurgitant jet at its origin is often the best quantitative indicator of the regurgitant volume (Figs. 8.218.22, and 8.23). The diameter of the vena contracta provides a convenient and reproducible method for defining this width. In the adult, with only one tricuspid regurgitation jet present, a vena contracta width of less than 3 mm is associated with mild regurgitation. A single diameter of 8 to 10 mm represents severe transvalvar regurgitation. The combination of multiple jets is more difficult to assess. In this situation, the examiner must mentally combine the size of the regurgitant orifices in order to determine the overall degree of tricuspid regurgitation. The vena contracta guidelines listed for single jets can only be used in a general way when assessing multiple regurgitant orifices. One must remember that simply adding the jet diameters together will slightly overstate the amount of regurgitant volume.

These adult guidelines cannot be directly applied to smaller patients. However, given the large annular diameters associated with Ebstein’s malformation, these cut points are useful even in the school-aged child. To avoid underestimating the degree of regurgitation in an infant or small child, the vena contracta diameter should be compared with the patient’s expected normal diameter of the tricuspid valve. Vena contracta diameters that are less than 10% of the normal annulus would usually be considered mild. Jet origins measuring more than 25% to 30% of the normal annular dimension would be classified as severe. The density of the tricuspid regurgitant signal when examined by continuous-wave Doppler can also provide a semiquantitative marker of regurgitant severity. A very dense, easily obtained signal suggests a larger regurgitant volume than a faint signal.

Figure 8.19. Series of apical four-chamber images from examinations of a 3-year-old girl with Ebstein’s malformation. A: Preoperative examination, demonstrating no remnants of tricuspid septal leaflet tissue within the anatomic right ventricular inlet. The anterior leaflet is severely tethered by multiple attachments to the right ventricular free wall. Red arrows outline the anterior leaflet. Even though this is a frame from peak systole, the leaflet tissue remains parallel to and very near the right ventricular free wall. The patient underwent a cone reconstruction of her tricuspid valve a short time later. B–D: Postoperative, predischarge echocardiogram. B and C: Reconstructed valve in diastole and systole, respectively. By attaching the “annulus” of the reconstructed “cone” to a plane near the anatomic atrioventricular junction, the surgeon has completely eliminated the large atrialized portion of the right ventricle, as well as the regurgitation. Despite the severe deformity of the native valve, the color flow image in the postreconstruction echocardiogram (D) showed only mild tricuspid regurgitation. There was no obstruction (mean gradient = 4 mm Hg). aRV, atrialized right ventricle; L, left; LA, left atrium; LV, left ventricle; R, right; RA, right atrium; RV, right ventricle.

The large and compliant right atrium often absorbs even tremendously large regurgitant volumes. Therefore, analysis of systemic venous flow reversals is less helpful in Ebstein’s malformation than in patients with a normal right atrium and ventricle. The evaluation of tricuspid regurgitation must, therefore, focus more heavily on direct visualization of the color flow disturbance caused by the systolic flow, as described earlier. Qualitatively, the size of the right atrial chamber also reflects the degree of regurgitation. However, right atrial size is of limited utility, because it is also strongly influenced by the presence of right ventricular dysfunction and the ineffective contractions of the atrial component of the right ventricle.

Figure 8.20. Subcostal position during examination of an infant with severe Ebstein’s malformation displaying the right atrium (RA), atrialized right ventricle (aRV), and the trabecular right ventricle (RV) beyond the functional tricuspid valvar orifice (asterisk). The functional orifice is also the origin of a single broad jet of regurgitation (right, red arrow). This jet begins near the right ventricular outflow tract and is oriented in inferiorly and toward the diaphragm, near the inferior vena cava–right atrial connection. aRV, atrialized right ventricle; L, left; RA, right atrium; RV, right ventricle; S, superior.

The anatomy of the tricuspid valvar apparatus in the area of the regurgitant origin must be carefully assessed. Accurate definition of the leaflet deficiencies leading to transvalvar regurgitation simplifies surgical planning tremendously. High-quality two-dimensional surface and transesophageal images are required. Real-time three-dimensional imaging, especially during transesophageal echocardiography, can provide even more insight into the mechanisms underlying valvar dysfunction (Fig. 8.24).

Figure 8.21. Echocardiographic images examination of an 8-year-old patient with relatively mild Ebstein’s malformation. A: Characteristic displacement of the septal insertion of the tricuspid valve (two arrows). B: Color flow disturbance caused by the resulting tricuspid regurgitation (arrow). The vena contracta (VC) measured 4 mm. In an adult, this would be consistent with relatively mild regurgitation, but in this young child, it represented a moderate degree of regurgitation. In addition to the absolute VC diameter, the diameter should be compared to the patient’s expected normal diameter of the tricuspid valve to avoid underestimating the degree of regurgitation in pediatric patients. L, left; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; S, superior.

Figure 8.22. Apical four-chamber echocardiographic images from the examination of a 21-year-old, displaying features consistent with severe Ebstein’s malformation, as well as severe tricuspid regurgitation. A: Components of the tricuspid valve do not coapt in systole. B: Color flow image confirms the presence of severe tricuspid regurgitation (arrow). The VC diameter was 21 mm. L, left; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; S, superior.

Virtually no patient with Ebstein’s malformation has truly normal right ventricular performance. Quantitative assessment of right ventricular systolic function is a challenge in all forms of congenital heart disease, and Ebstein’s malformation is no exception. It is often difficult to visualize the entire right ventricle in one imaging plane. When evaluating right ventricular systolic performance qualitatively, one compares the systolic area occupied by the ventricular cavity with a diastolic area in that same plane. Better systolic function is associated with a smaller systolic cavity relative to the diastolic “starting point.” Experienced observers can generally classify these ventricles into groups displaying mild, moderate, or severe dysfunction, but interobserver variables can be significant.

It is often helpful to add a quantitative component to the assessment of right ventricular function in these patients. The can be done by obtaining an ejection fraction with magnetic resonance scanning or in the echocardiographic laboratory by determining the fractional area change (FAC) of the right ventricle. FAC can be determined by either a monoplane or biplane technique. Because right ventricular shortening is primarily a longitudinal process, the apical four-chamber view must be included as one of the planes. Systolic and diastolic areas are traced in the apical four-chamber view or, more optimally, from the apical and one other orthogonal plane. Parasternal or subcostal short-axis views at the mid-ventricular level complement the apical view well. FAC is then calculated by subtracting the systolic area from the diastolic area and dividing the result by the original diastolic area ([diastolic ventricular area – systolic ventricular area]/diastolic ventricular area). If more than one plane of imaging is used, two resulting FAC values are averaged. This measurement (FAC) is analogous to calculating ventricular shortening fraction, but it uses two-dimensional rather than M-mode data. In our laboratory, normal right ventricles show FACs equal to or greater than 40%. Other non-geometrically based methods of assessing ventricular performance such as the myocardial performance index, annular tissue Doppler velocities, and myocardial deformation imaging have been applied to the right ventricle and may be helpful in following these patients over time.

Figure 8.23. Apical four-chamber echocardiographic images from the examination of a 5-year-old, displaying features consistent with extremely severe Ebstein’s malformation and severe tricuspid regurgitation. A: Anterior leaflet has limited mobility and remains parallel to the ventricular septum in systole. No remnant of the septal leaflet can be seen. The components of the tricuspid valve do not coapt in systole. B: Color flow image confirms the presence of massive tricuspid regurgitation (arrow). The marked tethering of the tricuspid valve in this case produced a nearly unguarded tricuspid valve orifice. The vena contracta diameter was 20 mm, similar to that in the case presented in Figure 8.17 but representing even more regurgitation given the patient’s younger age and smaller body size. L, left; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; S, superior.

Figure 8.24. Preoperative transesophageal echocardiographic examination of a 16-year-old boy. A: Two-dimensional, four-chamber view demonstrating features typical of Ebstein’s malformation. B: Transgastric images oriented in a short-axis plane at the mid-ventricular level: diastolic image (left) and the systolic position of the valve leaflets (right). In this case, the septal leaflet (red arrow) is rudimentary. The inferior leaflet (blue arrow) is unusually large and mobile. Despite this, there is a large coaptation gap visible in the systolic frame (right), between the red and blue arrowsC: Three-dimensional images from the same examination that are focused on the right ventricular cavity and tricuspid valve. The volumes were cropped so that the resulting images would correspond to those shown in B. The tricuspid valve is displayed as if the examiner is standing in the apex of the right ventricle looking toward the right atrium. The leaflet texture, thickening of the leading edges, and a direct muscular insertion into the middle of the anterior leaflet (C left, white arrow) were more easily appreciated in the three-dimensional scan. A coaptation gap was also easily appreciated three-dimensionally (C right, between the red and blue arrows). The abnormal papillary muscle attachment to the anterior leaflet and the rudimentary nature of the septal leaflet combined to create a single, posterior regurgitant orifice in this case. L, left; LA, left atrium; LV, left ventricle; P, posterior; RA, right atrium; RV, right ventricle; S, superior.

Echocardiography also plays an important role intraoperatively and postoperatively in assessing the adequacy of tricuspid valvar repair or replacement (Fig. 8.25). The most important use of intraoperative echocardiography is in the immediate evaluation of the repaired valve. A repair that is not functioning can be revised, or else the valve can be replaced without a repeat operation. The postoperative examination must also be used to assess prosthetic valvar function, to determine changes in right and left ventricular function, and to exclude significant residual atrial level shunting. Transthoracic echocardiography remains important both early and late after surgical procedures. It is the primary diagnostic mortality used to assess the ongoing adequacy of a surgically repaired valve, to assess the function of a prosthetic valve, to exclude residual intracardiac shunts, to assess ventricular performance, and to exclude less common postoperative complications, such as effusions and intracardiac thrombi.

Figure 8.25. Ebstein’s malformation after tricuspid valve replacement. A 29-mm porcine bioprosthesis can be seen in the tricuspid valve position (yellow arrow). A, B: Two-dimensional images show that the sewing ring of the valve has been placed at an angle to the anatomic atrioventricular junction. This was done to avoid injury to the conduction system. As a result, the coronary sinus orifice is on the ventricular side of the prosthesis (red arrowhead). This seems to be well tolerated in patients with Ebstein’s malformation, probably due to the relatively low ventricular pressures, which are usually present. C, D: Normal excursion of the prosthetic leaflets, becoming parallel to the supporting struts in diastole (D). The lower color flow Doppler images show no evidence of regurgitation (C; note the trivial mitral regurgitation [red arrow] confirming that this is a systolic frame). The diastolic color “wavefront” fills the prosthetic annulus with little evidence of turbulence. The average mean Doppler gradient was 3 mm Hg. L, left; LV, left ventricle; RA, right atrium; RV, right ventricle; S, superior.

The degree of residual tricuspid regurgitation and tricuspid stenosis should be determined during every examination after a tricuspid valve repair or replacement. Regurgitation of a prosthesis or a repaired valve would be evaluated as described previously. The mean Doppler inflow gradient provides the most satisfactory assessment of tricuspid stenosis. Due to the prominence of respiratory variation in right ventricular filling signals, multiple consecutive cycles should always be measured and the results averaged. Most tricuspid valve bioprostheses will display a small pressure gradient. Normal bioprosthetic valves have mean gradients that are usually less than 6 mm Hg. An average mean gradient greater than 10 mm Hg generally indicates significant valve dysfunction. If a large volume of regurgitation is present or a residual left–to–right atrial shunt exists, the excess volume crossing the tricuspid annulus will artificially increase the gradient measured. These confounding conditions must be accounted for in the final assessment of the valve. Rarely, right coronary flow can be compromised by manipulation of the right atrioventricular groove by tricuspid annuloplasty or right ventricular plication. Therefore, both global and regional assessments of wall motion and function play an important role in the immediate postoperative evaluation of these patients.

PRENATAL DETECTION OF EBSTEIN’S MALFORMATION

Echocardiography can accurately define the features of Ebstein’s malformation in the fetus. Characteristics that have been associated with early neonatal mortality include marked enlargement of the right heart, severe tethering of the anterior leaflet, left ventricular compression, and associated lesions such as pulmonary atresia. Pulmonary hypoplasia develops secondary to severe cardiomegaly (Fig. 8.26) and hydrops with pleural and pericardial effusions. Definition of the fetal cardiac rhythm should occur routinely because, although uncommon in the prenatal patient with Ebstein’s malformation, tachyarrhythmias can contribute to the development of hydrops. Finding the ratio of the combined right atrial and atrialized ventricular area compared with the combined area of the functional right ventricle and left heart (Celermajer index) to be greater than 1 was shown to be associated with very poor fetal or neonatal outcome. Other fetal or neonatal findings that were associated with increased risk of mortality were a larger atrial septal defect, functional or anatomic pulmonary atresia, or reduced left ventricular function.

Figure 8.26. Two horizontal plane images of the thorax from a fetal echocardiogram performed at a gestational age of 26 weeks. A: Two-dimensional image shows not only massive cardiac enlargement but also an exaggerated offset between the tricuspid (solid red arrow) and mitral (dashed arrow) valves. The outer boundary of the fetal thorax has been defined by the yellow line, highlighting the tremendous degree of cardiac enlargement present in this fetus. The entire heart is shifted, with the right atrium and right ventricle “pushing” the left ventricle posteriorly, away from its normal position. The cardiac apex is actually posterior to the mid-axillary line on the B. The black arrow indicated the position of the atrial septum, which has also been shifted posteriorly and to the left. The heart in this case occupies the majority of the thoracic volume and also compresses the lung tissue posteriorly. This resulted in significant pulmonary hypoplasia and contributes to the extremely poor prognosis associated with a prenatal presentation of severe Ebstein’s malformation. B: Color flow disturbance (white arrow) consistent with severe tricuspid regurgitation. LA, left atrium; LV, left ventricle; R, right; RA, right atrium; RV, right ventricle; S, superior.

Other Tricuspid Valve Disorders

Ebstein’s malformation is not the only congenital disorder that afflicts the right ventricle and tricuspid valve. Apart from Ebstein’s malformation, congenital dysplasia of the tricuspid valve leaflets is the most common abnormality leading to congenital tricuspid regurgitation. There is no displacement of the annular hinge points in these valves. Rather, the leaflet tissue is thickened and the chordal supports shortened, causing significant gaps in systolic coaptation (Fig. 8.27). The degree of tricuspid regurgitation is often severe, but the right ventricular myocardium is relatively normal, especially in contrast to patients with Ebstein’s malformation. Surgical annuloplasty for symptomatic young patients can improve valvar function. Unfortunately, the improvements achieved are often temporary, leading to eventual tricuspid valve replacement later in life. Tricuspid annular dilation secondary to other congenital heart diseases, like tetralogy of Fallot or atrial septal defects, is a common cause of tricuspid regurgitation evaluated in the congenital echocardiographic laboratory. When intervention is required, this type of regurgitation is almost always amenable to surgical repair. When chordal support to the tricuspid valvar leaflets is interrupted or insufficient, the unsupported segment will “flail” past the plane of the atrioventricular junction and into the right atrium and systole (Fig. 8.28). This is a common manifestation of traumatic rupture of a tricuspid valve papillary muscle. The regurgitation caused by such flail segments is nearly always severe, but may not produce symptoms for decades. This long presymptomatic natural history is a consequence of the fact that these hearts were normal with normal pulmonary pressure and resistance prior to the trauma that induced the regurgitation. The low-pressure volume load associated with isolated tricuspid regurgitation is tolerated reasonably well in the setting of normal myocardial function. The injury that led to traumatic tricuspid regurgitation is often in the distant past and sometimes can be difficult to clearly identify. As with annular dilatation, regurgitation due to chordal rupture can be successfully repaired in most patients.

Figure 8.27. Congenital dysplasia of the tricuspid valve. There was severe tricuspid regurgitation and a large central gap in coaptation. The tricuspid leaflets are thickened and chordae are shorter than normal (red arrow), restricting the motion of all three leaflets. Despite the restricted mobility, these leaflets are not adherent to the underlying myocardium and the apical displacement index, representing the offset of the mitral and tricuspid valve septal insertions (white arrow), with only 6 mm/m2. These features confirm the fact that this was not a case of Ebstein’s malformation. L, left; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; S, superior.

Figure 8.28. Traumatic tricuspid regurgitation. The patient was 40 years old at the time of this examination and had been involved in a motor vehicle accident as a teenager. Subsequent to the accident, he was described as having a heart murmur, but no further investigation was pursued until he complained of palpitations and exercise limitation at age 39. The echocardiogram showed severe tricuspid regurgitation due to rupture of several chordal supports to the ATL. As a result, a significant segment of the anterior leaflet “flailed” into the RA during systole (red arrows). This valve was completely delaminated as evidenced by the normal relationship between the tricuspid and mitral septal insertions (white arrows). L, left; LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle; S, superior.

All of these causes of tricuspid regurgitation are reliably distinguished from Ebstein’s malformation using the anatomic criteria and the apical displacement index described earlier in this chapter.

Acknowledgments

I gratefully acknowledge the mentorship and guidance provided by Drs. Gordon K. Danielson, Joseph A. Dearani, William D. Edwards, and James B. Seward, as well as Professor Robert H. Anderson, in our studies of patients with Ebstein’s malformation. Professor Anderson, Dr. Dearani, and Dr. Edwards have also generously contributed images to better illustrate this chapter (RHA, Figures 8.5 and 8.6; JAD, Figures 8.38.5, and 8.17; and WDE, Figure 8.4). Thank you all very much.

SUGGESTED READING

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Questions

1.Ebstein malformation is a result of:

A.incomplete delamination of the mitral leaflets.

B.incomplete delamination of the tricuspid valve leaflets.

C.premature closure of the ductus arteriosus.

D.incomplete development of the sinus venosus.

2.The _____ is displaced toward the right ventricular outflow tract in patients with Ebstein malformation.

A.the right atrioventricular groove

B.the moderator band

C.the hinge point of the tricuspid anterior leaflet

D.the functional orifice of the tricuspid valve

3.An apical displacement index greater than ___ mm/m2 separates normally delaminated tricuspid valves from those with Ebstein malformation.

A.5

B.8

C.12

D.20

4.The most common additional anomaly found in patients with Ebstein malformation is:

A.atrial septal defect.

B.ventricular septal defect.

C.pulmonary valve stenosis.

D.aortic coarctation.

5.Prenatal presentation of Ebstein malformation:

A.has the same prognosis as a postnatal presentation.

B.is associated with a worse prognosis than postnatal presentation.

C.is frequently associated with complete heart block.

D.has no impact on fetal lung development.

6.Which of the following is associated with Ebstein malformation of the tricuspid valve, but not with congenital tricuspid dysplasia?

A.Tethering of the valve leaflets by shortened chords

B.A large, sail-like, anterior leaflet

C.Reduced mobility of the tricuspid valve leaflets

D.Tricuspid valve regurgitation

7.Which mean diastolic gradient is consistent with normal tricuspid bioprosthetic valve function?

A.4 mmHg

B.8 mmHg

C.12 mmHg

D.16 mmHg

8.In patients with Ebstein malformation, systolic flow reversal in the hepatic vein occurs:

A.only when there is coexisting pulmonary stenosis.

B.only when there is coexisting tricuspid stenosis.

C.more often than in those with other causes of severe tricuspid regurgitation.

D.less often than in those with other causes of severe tricuspid regurgitation.

9.A circumferential tricuspid valve reconstruction (cone repair) results in:

A.coaptation of the anterior leaflet with the ventricular septum.

B.restoration of the normal anular hinge position.

C.a lower frequency of valve repair than the monoleaflet approach.

D.tricuspid stenosis.

10.Left ventricular abnormalities, such as myocardial noncompaction, occur in what percentage of patients with Ebstein malformation?

A.Less than 10%

B.10-20%

C.20-30%

D.More than 30%

Answers

1.Answer: B. Ebstein malformation is a disorder that impacts right heart development far more than the left heart, and incomplete delamination of the tricuspid leaflets is the hallmark of the disorder. The mitral valve and ductus are usually not affected and atrial/venous (sinus venosus) development is only impacted secondarily.

2.Answer: D. The functional tricuspid valve orifice is spirally displaced toward the infundibulum (RVOT) in Ebstein malformation. The anatomic right AV groove and moderator band are not altered. The hinges of the tricuspid septal and inferior leaflets are displaced as well, but the anterior TV hinge point usually retains a normal position.

3.Answer: B. The apical displacement index (distance between the septal insertions of the mitral and tricuspid valves divided by the body surface area) is a useful marker of the abnormal TV delamination that occurs in Ebstein malformation. Values greater than 8 mm/m2 reliably distinguish patients with Ebstein malformation from other forms of TV diseases.

4.Answer: A. Although all of these abnormalities can co-exist with Ebstein malformation, ASD is the most common.

5.Answer: B. Prenatal presentation of Ebstein malformation usually carries a worse prognosis, presumably because those who present later in life have less severe disease. Options C and D are incorrect because congenital heart block is actually uncommon in patients with Ebstein malformation and the significant cardiac enlargement associated with severe prenatal Ebstein malformation is associated with lung hypoplasia (since the heart and lungs are competing for space in the chest).

6.Answer: B. Valves affected by both Ebstein malformation and dysplasia can have short chords, reduced mobility, and regurgitation. However, only Ebstein valves have excessive anterior leaflet tissue, described as sail-like. Dysplastic valve leaflets seem to retain normal relative sizes, while the inferior and septal leaflets of Ebstein malformation are small.

7.Answer: A. All valves will have a detectable inflow Doppler gradient, but mean diastolic gradients greater than 6 mmHg are associated with dysfunction (either stenosis or regurgitation or both).

8.Answer: D. The large right atrium of patients with Ebstein malformation is very compliant and can absorb extra volume (from regurgitation) more easily than the non-Ebstein atrium. As a result, the hepatic venous reversal seen in other forms of severe tricuspid regurgitation is often absent in patients with Ebstein malformation. While reversal may occur in patients with situations like options A and B, these are not the “only” instances in which this can occur.

9.Answer: B. Option A describes the situation associated with a monoleaflet repair. Option C is not correct because cone reconstruction is successful in more patients than monoleaflet reconstruction. Option D is not correct because although stenosis is a possible complication of any repair, it is not a universal result and successful cone repairs are not stenotic.

10.Answer: B. Ebstein malformation is an abnormality of myocardial development. When present, it universally affects the right ventricle, but left ventricular abnormalities (noncompaction, bicuspid aortic valve, mitral valve prolapse, etc.) are more frequently seen in these patients than in the general population at rates between 10-20%.