Coronary sinus ostial atresia: A rare associated anomaly that should be remembered in patients undergoing univentricular palliation

Coronary sinus ostium atresia associated with congenital heart diseases with single ventricular physiology is rare and detection of this anomaly is very important (1-3). In coronary sinus ostial atresia, the coronary sinus usually drains into an unroofed coronary sinus and the left atrium. However, it may drain into the right atrium via the Thebesian veins or, as presented in our case, drainage may only be present into the left persistent superior vena cava (SVC) (4-7). A case of a patient with tricuspid atresia who was diagnosed to have coronary sinus ostium atresia with retrograde drainage of the coronary veins into the left superior vena cava during diagnostic heart catheterization prior to the Fontan procedure is presented.