Abstract
Sinus venosus atrial septal defect (SVASD) with partial anomalous pulmonary venous return is a rare congenital heart defect that may present in adulthood when right heart enlargement has already occurred. We describe a case of unrepaired sinus venosus atrial septal defect and partial anomalous pulmonary venous return with massive right heart enlargement and recurrent atrial arrhythmias.