Ectopic pulmonary veins are a congenital heart defect that occurs when the pulmonary veins do not drain into the left atrium but instead drain into another location, either the right atrium or an accessory vein. This condition causes increased pressure on the right side of the heart and reduces the amount of oxygen-rich blood reaching the left side of the heart to nourish the body. The basic treatment is to correct the anatomical abnormality, bringing the pulmonary veins into the left atrium.