Abstract
Interatrial communications are the most frequent congenital heart malformation in adulthood. Four different types of atrial defect are identified: the ostium secundum, ostium primum, sinus venosus and unroofed coronary sinus types. The unroofed coronary sinus defect is the rarest form of interatrial communication accounting for <1% overall. The presence of a persistent left superior vena cava is frequent in this form of atrial defect and associated anomalous pulmonary venous return has been described. The sinus venosus form – accounting for 5 to 10% of atrial defects – is a communication between the two atria localised within the mouth of the caval vein, which has a biatrial connection. It most frequently involves the superior vena cava and anomalous pulmonary venous return (usually the right upper pulmonary vein) and is associated with 85% of atrial defects. We report typical examples of sinus venosus and unroofed coronary sinus defects associated with anomalous pulmonary venous return.