Ebstein Anomaly

Ebstein anomaly is a congenital malformation of the tricuspid valve. During cardiac development, the septal and posterolateral (inferior) leaflets fail to delaminate completely from the underlying right ventricular myocardium. Their functional hinge points therefore sit below the true atrioventricular junction, displaced toward the apex. The anterior leaflet may be large, elongated, and unusually mobile, but the defining abnormality is the apical displacement of the septal leaflet. The portion of right ventricle between the true tricuspid annulus and the displaced leaflet becomes atrialized. It has a thin wall and contracts poorly, so it contributes little effective forward flow. The remaining functional right ventricle is smaller than usual. The malformed leaflets often fail to meet properly during systole, producing tricuspid regurgitation (TR). Blood then moves backward into the right atrium instead of forward into the pulmonary artery. This creates a linked physiological problem: 1. TR enlarges and pressure-loads the right atrium. 2. The atrialized RV and regurgitant valve reduce effective right-sided forward output. 3. The functional RV may dilate and eventually lose systolic performance. 4. A stretched annulus or atrial-level communication can...