Interatrial communication through coronary sinus orifice

**Definition:** A congenital cardiovascular malformation in which there is a communication between the left atrium and the coronary sinus allowing interatrial communication through the coronary sinus ostium.

Additional information: 'Interatrial communication through coronary sinus orifice' may or may not be associated with a persistent left superior caval vein (superior vena cava). This occurs in the absence of the coronary sinus (total unroofing of the coronary sinus) or partial unroofing of the coronary sinus.