Congenital anomalies involving the coronary sinus.

A classification is presented of anomalies involving the coronary sinus. These anomalies are classified into four anatomic groups on the basis of (1) enlargement of the coronary sinus, (2) absence of the coronary sinus, (3) atresia of the right atrial coronary sinus ostium, and (4) hypoplasia of the coronary sinus. Anomalies involving the coronary sinus often are associated with other venous anomalies, either of the systemic or the pulmonary circulation. In some there is no basic disturbance of the circulation. Those conditions involving the coronary sinus which are of major functional significance participate in shunts, either left-to-right or right-to-left in nature. Enlargement of the coronary sinus in the absence of a shunt usually indicates that a systemic venous channel joins the coronary sinus anomalously.