Partial atrioventricular septal defect

A rare congenital cardiac malformation that is a variant of an atrioventricular septal defect (AVSD) with an interatrial communication (ostium primum defect) just above the common atrioventricular (AV) valve, no interventricular communication just below the atrioventricular valve, a common atrioventricular junction but separate right and left atrioventricular valvar orifices, and a three-leaflet, left-sided component of the common atrioventricular valve (''cleft''). Shunting is restricted to the atrial level because of fusion of the leaflets of the common AV valve with the crest of the ventricular septum.