Atrioventricular septal defect with two separate atrioventricular valves. (A): Internal view of right chambers, left (1) and right (2) atrioventricular valves, ostium primum (asterisk) and arrow pointing to the insertion of the septal leaflets of the left valve in the crest of the interventricular septum. Note the confluence of the ostium primum with the atrioventricular septal defect (upper asterisk), the commissure that separates those leaflets, the ample commissure between the septal leaflets and the anterior leaflet of the right atrioventricular valve (lower asterisk). (B): The two separate atrioventricular valves (1 and 2) and the fusion of the septal leaflets to the crest of the interventricular septum that closes the ventricular septal defect (arrow) can be seen. IAS: Interatrial septum. Other abbreviations as before.