Coronary sinus septal defect associated with tricuspid atresia.

Coronary sinus septal defects are unusual congenital anomalies that may assume particular clinical importance in patients undergoing a modified Fontan procedure. Two of 10 patients with tricuspid atresia who underwent a modified Fontan procedure between January, 1984, and December, 1984, were noted to have coronary sinus septal defects in the early postoperative period. A pathologic review of 159 specimens of tricuspid atresia revealed coronary sinus septal defects in four. Although infrequent, coronary sinus septal defects may permit significant persistent right-to-left interatrial shunting after a modified Fontan procedure. Ideally, preoperative recognition allows for selective direct closure or closure of the coronary sinus orifice. Alternatively, routine baffling of the coronary sinus into the left atrium obviates this potential source of interatrial communication.