Intraoperative diagnosis of unroofed coronary sinus after aortic valve replacement.

A patient with combined aortic insufficiency and stenosis underwent aortic valve replacement. After weaning off cardiopulmonary bypass, a new shunt into the left atrium was noted that had not been apparent on multiple previous echocardiographs. Using an agitated saline test, we confirmed a shunt between the coronary sinus and left atrium. The assumption was made that there had been an iatrogenic fistula created with placement of the retrograde catheter; however, upon opening the left atrium it was realized that the patient had a previously undiagnosed, congenitally unroofed coronary sinus. It was repaired primarily and the patient had an uneventful recovery.