True congenital aneurysm of the septum primum not associated with obstructive right- or left-sided lesions: identified by two-dimensional echocardiography and angiography in a newborn.

Aneurysms of the interatrial septum are unusual anomalies that have been demonstrated by (M-mode and 2-dimensional) echocardiography in patients with complex congenital heart defects. They have also been found at autopsy in adults without heart defects. Complications have resulted from these aneurysms in adults. A true aneurysm of the septum primum was an incidental finding identified by 2-dimensional echocardiography and angiography in a newborn with an atrial septal defect.