Atrioventricular septal defect with two separate atrioventricular valves. (A): Internal view of left chambers, left (1) and right (2) atrioventricular valves, ostium primum (asterisk), and the arrow pointing to the insertion of the anterior septal leaflet in the crest of the interventricular septum. (B): The 4-chamber transesophageal image shows the same characteristics as in the anatomic specimen. IVS: Interventricular septum. Other abbreviations as before.