Left-ventricular inflow obstruction due to a dilated coronary sinus mimicking Cor Triatriatum

Persistence of the left superior vena cava with drainage to the coronary sinus is a common congenital anomaly. We report an infant with such a malformation associated with marked enlargement of the coronary sinus, which produced partial supramitral obstruction and consequently impairment to the left-ventricular inflow. The patient pre-sented with cardiac failure in infancy and features mimicking cor triatriatum. Surgical relief of the supramitral obstruction resulted in immediate reversal of the pulmonary hypertension, with clinical improvement. This rare entity, only once previously reported, is an unusual cause of pulmonary hypertension in infancy.