Introduction Atrial septal defects (ASD) account for 7–10% of congenital heart anomalies., ASD are classified as three anatomical types: ostium secundum (OS) (70% of cases), ostium primum (15–20% of cases), and sinus venosus (5–10% of cases) defects. OS involves the fossa ovalis region and results from poor embryological development of septum secundum or excessive absorption of septum primum resulting in the lack of a septum in the fossa ovalis. Affected patients are usually asymptomatic. Exercise intolerance in the form of […]