Ostium Secundum Defect: Understanding the Most Common Type of ASD

The most common type of atrial septal defect (ASD) is the ostium secundum defect. This type of ASD occurs when there is a hole in the atrial septum, located in the centre of the atrial septum, just below the fossa ovalis. Ostium secundum defects make up approximately 70% of all ASDs and are more common in females than in males.