Ebstein Anomaly and Malformation

Excerpt

Ebstein anomaly is a rare congenital cardiac abnormality involving the tricuspid valve and the right ventricle (RV). Ebstein anomalies comprise < 1% of congenital heart defects. The anomaly was initially described by the pathologist Wilhelm Ebstein in 1866 after performing an autopsy on a 19-year-old cyanotic male with exertional dyspnea and palpitations who died of a sudden cardiac arrest. Ebstein anomaly is defined by the following characteristics:

1. Apical displacement of the tricuspid valve

2. Adherence of the septal and posterior tricuspid leaflets to the myocardium

3. Apical displacement and dilatation of the tricuspid annulus

4. Dilatation of the atrialized portion of the right ventricle

5. Redundancy, fenestrations, and tethering of the anterior tricuspid leaflet

Abnormalities commonly associated with Ebstein anomaly include a secundum atrial septal defect and a variable degree of RV outflow tract obstruction. Some neonates with Ebstein anomaly may present with functional or anatomical pulmonary atresia; both are ductal-dependent lesions. Less commonly associated cardiac defects include ventricular septal defects, tetralogy of Fallot, transposition of the great arteries, and atrioventricular canal defects. In general, the clinical manifestations of Ebstein anomaly can range from asymptomatic to severe, depending on the degree of tricuspid valve displacement and severity of regurgitation, the effective right ventricular volume, and the associated malformations.

Atrial tachycardias, including atrial fibrillation, atrial flutter, or ectopic atrial tachycardia, can occur in 25% to 65% of patients with Ebstein anomaly. Additionally, 10% to 25% of patients have one or more accessory pathways, which increase the risk of protracted arrhythmias that can produce cardiac failure and sudden cardiac death.