Partial anomalous pulmonary venous connection (PAPVC) results the malformation of the heart during fetal development. Anatomically a PAPVC involves overcirculation of blood to the lungs through malconfigured pulmonary veins.

Anatomically, partial anomalous pulmonary venous connection (PAPVC) can involve a wide variety of connections. PAPVC from the right lung is twice as common as PAPVC from the left lung. The most common form of PAPVC is one in which a right upper pulmonary vein connects to the right atrium or the superior vena cava (SVC). This form is almost always associated with a sinus venosus type of atrial septal defect (ASD).

In addition to draining into the right atrium, the anomalous right pulmonary veins can also drain into the inferior vena cava. Similarly, the left pulmonary veins can drain into the innominate vein, the coronary sinus. More rarely, the left pulmonary vein can drain into the cavae, the right atrium, or the left subclavian vein.