An ostium primum atrial septal defect (ASD) occurs when then atrial septum near the atrioventricular valves has a communication between the two atrium causing a left to right shunt. This rarely ...

An atrial septal defect of the secundum type is relatively common and occurs from failure of the septum secundum to develop ... septal defect 5 = Ostium Primum atrial septal defect The murmur ...