This defect is associated with ASD and is also associated with hypogenetic lung (scimitar syndrome). The defect is almost exclusively right-sided. In almost all instances, the anomalous vein is a pulmonary vein. It usually drains into the infradiaphragmatic IVC. Less commonly drainage is to hepatic, portal or azygous veins, the coronary sinus or right atrium. Occasionally, the PAPVR drains to the left atrium ("meandering pulmonary vein"). In many cases of scimitar syndrome, part of the right lung receives arterial blood supply from the descending thoracic aorta or upper abdominal aorta.