Double orifice right atrioventricular valve in atrioventricular septal defect: morphology and extension of the concept of fusion of leaflets.

A rare observation of a double orifice right atrioventricular valve in a partial form of atrioventricular septal defect is reported. The concept of leaflet fusion along part of their anticipated zones of apposition is used to explain the formation of this anomaly. We show that this concept can account for the different morphologic presentations of atrioventricular septal defect.