85: Ebstein’s Anomaly

Epidemiology

• Ebstein’s anomaly occurs in 1 percent of all congenital heart defects and represents 0.3 to 0.8 percent of all cardiac malformations diagnosed during the first year of life.

Pathophysiology

• The degree of displacement and morphology of the tricuspid leaflets determine the degree of regurgitation. The attachments of the anterior leaflet to the right ventricular outflow tract may inhibit normal flow to the pulmonary artery, thus creating various degrees of outflow tract obstruction or functional/anatomical pulmonary atresia with duct-dependent pulmonary circulation. Diminishing forward output, with increasing backflow to the right atrium, leads to severe cyanosis due to right-to-left shunting at the atrial level. Right ventricular dilation can induce leftward bulging of the interventricular septum, thus compromising left ventricular function. Progressive cardiomegaly can affect the growth of the lungs, inducing lung hypoplasia.

Clinical features

• Clinical presentation can occur at any age. Newborns will often manifest cyanosis and congestive heart failure, accompanied by circulatory collapse. After infancy, the child may show limited cyanosis during exercise. With increasing age arrhythmias, cyanosis and limited exercise tolerance (with dyspnea and palpitations) become more prominent. Mild forms may not be symptomatic until adulthood.

Diagnostics

• Echocardiography is diagnostic. Cardiac catheterization is not routinely performed, unless the pulmonary artery pressure and vascular resistance require evaluation.

Treatment

• In neonates and young infants, the indications for surgery are ventilator dependence, severe cardiac failure, and severe tricuspid insufficiency with prostaglandin-dependent circulation.

• In older patients, surgery is indicated due to symptoms of poor growth, decreased exercise tolerance, cyanosis, progressive cardiomegaly (cardiothoracic ratio >0.6), reduced left ventricular function, tachyarrhythmias, and the presence of significant associated lesions. Timely operation is warranted before cardiomegaly develops and the functional status deteriorates.

• Surgical therapy should restore tricuspid valve competence and address the inadequacy of the inefficient right ventricle. In children, tricuspid valve plasty with biventricular correction should take preference over tricuspid valve replacement or single ventricle pathway. Surgical repair consists of (1) reconstruction of the tricuspid valve, (2) consideration of plication or resection of the atrialized right ventricle, (3) closure of the atrial communication and correction of any associated anomalies, (4) arrhythmia surgery, and (5) right reduction atrioplasty. In special situations, the concept of one and one-half ventricular repair or of the single ventricular pathway should be adopted.

Outcomes/prognosis

• With current surgical techniques, repair is feasible in the vast majority of patients and results in low early mortality (<5 percent); reintervention rate and survival is of >80 percent at 20 years. Newborns and small infants remain, however, still a challenge.