the right ventricle as the functional orifice is displaced apically relative to the anatomic anulus. Ebstein anomaly is a spectrum of abnormalities, depending on the extent of apical displacement of the valve, the distal attachments of the leaflets, the size and function of the remaining right ventricle, the degree of tricuspid regurgitation, and the presence of right ventricular outflow tract obstruction (usually from the redundant anterior tricuspid valve leaflet).
The best echocardiographic view for the evaluation of Ebstein anomaly is the four-chamber view. The characteristic features identified in this plane are shown schematically in Figure 18.7. Of principal importance is the accurate recording of the level of insertion of the septal leaflet of the tricuspid valve relative to the anulus. Apical displacement of this insertion site is optimally assessed in this view and is the key to diagnosis (Fig. 18.8). Because the tricuspid valve is normally positioned more apically than the mitral valve, abnormal apical displacement is relative, and some investigators have suggested measuring the distance between insertion sites of the two atrioventricular valves. When normalized for body surface area, a distance of greater than 8 mm/m2 is indicative of Ebstein anomaly. Other investigators have advocated a maximal displacement of more than 20 mm as the diagnostic criterion in adults.
The four-chamber and medially angulated parasternal views may be used to assess the severity of Ebstein anomaly and to determine surgical options. The degree of atrialization of the ventricle, the extent of leaflet tethering, and the magnitude of deformity or dysplasia of the valve leaflets are important features with implications for surgical repair (Fig. 18.9). The extent of chordal attachments between the anterior leaflet and the anterior free wall should be assessed in multiple views. If tethering is significant, valve replacement rather than repair may be required. The greater the degree of atrialization is, the worse the prognosis. If the area of the functional right ventricle is less than one-third of the total right ventricular area, overall prognosis is poor. Because of the complexity of right ventricular geometry, an accurate measure of the size of the functional right ventricle is difficult, and all available views should be used (Fig. 18.10). Doppler echocardiography should be used to detect tricuspid regurgitation, which is commonly seen in patients with Ebstein anomaly (Fig. 18.11). A redundant anterior tricuspid valve leaflet may cause functional right ventricular outflow tract obstruction, which can also be detected with Doppler imaging. In severe cases, pulmonary atresia may be present, although it is rarely seen in adults.
FIGURE 18.7. Schematic of anatomic abnormalities in Ebstein anomaly. RA, right atrium; LA, left atrium; LV, left ventricle; MV, mitral valve; MVA, mitral valve anulus; TVA, tricuspid valve anulus; AnRV, anatomic right ventricle; FRV, functional right ventricle; AtRV, atrialized right ventricle
The four-chamber and medially angulated parasternal views may be used to assess the severity of Ebstein anomaly and to determine surgical options. The degree of atrialization of the ventricle, the extent of leaflet tethering, and the magnitude of deformity or dysplasia of the valve leaflets are important features with implications for surgical repair (Fig. 18.9). The extent of chordal attachments between the anterior leaflet and the anterior free wall should be assessed in multiple views. If tethering is significant, valve replacement rather than repair may be required. The greater the degree of atrialization is, the worse the prognosis. If the area of the functional right ventricle is less than one-third of the total right ventricular area, overall prognosis is poor. Because of the complexity of right ventricular geometry, an accurate measure of the size of the functional right ventricle is difficult, and all available views should be used (Fig. 18.10). Doppler echocardiography should be used to detect tricuspid regurgitation, which is commonly seen in patients with Ebstein anomaly (Fig. 18.11). A redundant anterior tricuspid valve leaflet may cause functional right ventricular outflow tract obstruction, which can also be detected with Doppler imaging. In severe cases, pulmonary atresia may be present, although it is rarely seen in adults.
FIGURE 18.8. A four-chamber view from a patient with Ebstein anomaly is shown. The arrows indicate the degree of apical displacement of the tricuspid valve (TV), which had restricted motion. Note that the functional portion of the right ventricle (RV) is fairly well preserved. LV, left ventricle; RA, right atrium.
FIGURE 18.9. A more extreme form of Ebstein anomaly is demonstrated. The tricuspid valve (arrows) is markedly abnormal, and there is tethering of the leaflets, which prevented normal coaptation and resulted in significant tricuspid regurgitation. The right atrium (RA) is severely dilated. LV, left ventricle
FIGURE 18.9. A more extreme form of Ebstein anomaly is demonstrated. The tricuspid valve (arrows) is markedly abnormal, and there is tethering of the leaflets, which prevented normal coaptation and resulted in significant tricuspid regurgitation. The right atrium (RA) is severely dilated. LV, left ventricle
Ebstein anomaly may be associated with a variety of other abnormalities that can be detected with echocardiography, namely, atrial septal defect, mitral valve prolapse, and left ventricular dysfunction. The etiology of the left ventricular dysfunction is not known, but its presence is associated with a poor prognosis. Surgical options in patients with Ebstein anomaly include tricuspid valve repair or replacement. After surgical repair, echocardiography plays a role in assessing the success of the procedure and the function of the tricuspid valve.
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