An atrial septal defect of the secundum type is relatively common and occurs from failure of the septum secundum to develop. This results in a communication between the left and right atrium ...

Less common than the secundum type atrial septal defect, a primum ASD is usually small and less commonly requires intervention when it occurs in isolation. Frequently it is considered as a part of ...

A radiogram may show enlargement of the right chambers in the lateral view and pulmonary artery dilation: even significant ASD often has a normal cardiac silhouette and normal pulmonary vascularity.