Background
Unroofed coronary sinus (UCS) is a rare atrial septal defect (ASD) that results in an abnormal communication between the coronary sinus and the left atrium. It is usually associated with other forms of congenital heart disease, typically heterotaxy syndromes. It is frequently associated with a persistent left superior vena cava (PLSVC), which is the most common anomaly of systemic venous drainage.