How is an atrioventicular septal defect diagnosed in an adult? echo? reliable? or often missed?

Yes: An av septal defect is diagnosed by history, listening for a murmur on examination, echocardiography, electrocardiogram, chest x-ray, and possibly MRI and/or cardiac catheterization.

Physical and Echo: A cardiac echo (ultrasound) combined with doppler flow signal analysis can be very reliable to diagnose atrial (ASD) as well as ventricular septal defects (vsd). However, it does require that the person performing the study is trained and knowledgeable in congenital heart. Both defects have associated clincial findings. Defects however, can be missed on echo if a poor study is performed.

Echocardiogram: An atrioventricular septal defect (more commonly called a common av canal defect) should be diagnosable by echocardiogram. Sometimes the vsd component is very small or absent, which makes it trickier. Other clues are a cleft in the left av valve, no offset between the right and left av valves or a primum type asd. If echo pictures aren't clear enough, a transesophageal echo would help.