Two Cases of Prenatally Diagnosed Membranous and Muscular Ventricular Septal Aneurysms.

A ventricular septal aneurysm is a rare heart defect located in the muscular or membranous part of the septum. Muscular ventricular septal aneurysms are usually isolated, with a favorable prognosis. Membranous ventricular septal aneurysms are often associated with other heart anomalies, could result in serious complications, and may require surgical treatment. We describe 2 cases of prenatally diagnosed ventricular septal aneurysms: an isolated membranous ventricular septal aneurysm with a good outcome, which was initially misdiagnosed as an atrioventricular septal defect; and a muscular ventricular septal aneurysm associated with a hypoplastic aortic arch and severe hydrocephaly, which resulted in termination of the pregnancy. To our knowledge, the combination of a muscular ventricular septal aneurysm with an extracardiac anomaly has not been reported previously.