Ebsteins

Ebstein's anomaly is a rare congenital heart defect characterized by downward (apical) displacement of the septal and often the posterior tricuspid valve leaflets into the right ventricle. This causes atrialization of a portion of the right ventricle and severe tricuspid regurgitation, with a disproportionately large right atrium and a small functional right ventricle. The condition may occur alone or with other defects such as an atrial septal defect. Incidence is about 1 per 200,000 live births. Most cases are sporadic; maternal use of lithium in early pregnancy is a known risk factor. Associations with arrhythmias, especially Wolff-Parkinson-White syndrome, are common.

Clinical presentation varies from asymptomatic to cyanosis and signs of heart failure in infancy; older children may have exertional dyspnea, fatigue, palpitations, or chest pain. Arrhythmias are common.

Diagnosis relies on echocardiography, which shows the apical displacement of the tricuspid leaflets by more than 8 mm per meter of body surface area from the mitral annulus, an enlarged right atrium, atrialized right ventricle, and varying degrees of tricuspid regurgitation. Chest radiography may reveal cardiomegaly with a prominent right atrium; ECG may show right bundle branch block or preexcitation if WPW is present. Cardiac MRI can provide detailed anatomy.

Management is tailored to severity. Mild cases may be observed; diuretics or afterload-reducing therapy may help symptoms. Severe disease or heart failure in infancy requires surgical repair or replacement of the tricuspid valve, with cone repair gaining prominence. Treating associated defects and arrhythmias is important. Prognosis improves with modern surgical techniques, though it depends on anatomy and comorbidity.