A large aneurysm of a left sinus of Valsalva invading the interventricular septum--a rare cause of syncope.

Sinus of Valsalva aneurysms are uncommon, especially those in the left sinus of Valsalva. A case of a 45-year-old woman with syncope is presented. She was in complete heart block. Auscultation revealed moderate aortic regurgitation. Transthoracic echocardiography revealed a subaortic membrane attached to the interventricular septum with expansion in diastole and collapse in systole. A diastolic flow was seen at the edge of this membrane. Transesophageal echocardiography revealed a cystic mass that was thought to be a large aneurysm with a parietal thrombus of the left coronary sinus extending into the interventricular septum. Magnetic resonance imaging confirmed the diagnosis. The aneurysm extension to the interventricular septum resulted in complete heart block, presumably through compression of normal atrioventricular nodal function. Case reports of the latter association are extremely rare. The present is a rare report describing the magnetic resonance imaging appearance of a left sinus of Valsalva aneurysm.