Total anomalous pulmonary venous return

In total anomalous pulmonary venous return (TAPVR), the pulmonary veins incorrectly send blood to the heart's upper right chamber (atrium). In a normal heart (shown on the left), oxygen-rich blood flows from the pulmonary veins to the upper left chamber (left atrium). In a type of TAPVR called supracardiac TAPVR, oxygen-rich blood from the pulmonary veins goes into the wrong chamber on the other side (right atrium). As a result, the blood mixes with oxygen-poor blood.