Prenatal diagnosis of an aneurysm of the mitral-aortic intervalvular fibrosa.

Aneurysm of the mitral-aortic intervalvular fibrosa (A-MAIVF) is a rare but potentially fatal condition. The aneurysm is located between the mitral and aortic valves and communicates with the left ventricular outflow tract, and the differential diagnoses include dilated coronary sinuses and coronary arteriovenous fistula. We describe the first reported case of an A-MAIVF diagnosed in the fetus.