Atrial Septal Defect, Partial Anomalous Pulmonary Venous Connection, and Scimitar Syndrome

An atrial septal defect (ASD) is defined as an opening, or hole, in the interatrial septum. The defect within the oval fossa is one of the most common congenital heart defects to occur as an isolated lesion. In the normal heart, the atrial septum is closed. Its site is marked, when viewed from the right atrium, by the location of the oval fossa. The coronary sinus is the venous channel running within the left atrioventricular groove that serves as the confluence for the majority of the coronary veins draining the blood from the ventricular musculature. The degree of left-to-right shunting at the atrial level is determined by the size of the ASD and the relative right and left ventricular compliance. Scimitar syndrome consists of a rare constellation of anomalies, the constant being total or partial anomalous pulmonary venous connection of the right lung to the inferior caval vein.