A case of biatrial drainage of the right superior vena cava.

Biatrial drainage of the right superior vena cava resulting from a sinus venosus defect is a rare congenital malformation. It can result in severe desaturation although a sinus venosus defect usually presents as a left-to-right shunt. A male baby was noted to have cyanosis while nursing and was referred to us for medical treatment on his second day of life. Echocardiography showed that most of the blood flowing through the superior vena cava drained into the left atrium. He underwent successful surgery to correct this defect at the age of 2 years.