The pulmonary veins are the four blood vessels (two on each side) that return oxygen-rich blood from the lungs to the left atrium (left upper chamber) of the heart.

Total anomalous pulmonary venous return (TAPVR) is a rare congenital malformation in which all four pulmonary veins do not connect normally to the left atrium. Instead the four pulmonary veins drain abnormally to the right atrium (right upper chamber) by way of an abnormal (anomalous) connection.