Acquired partially flail leaflet causing severe mitral regurgitation in a congenital double-orifice mitral valve.

Double orifice mitral valve is a rare congenital malformation. We report a 48-year-old woman with new onset congestive heart failure and mitral regurgitation. Transesophageal echocardiography showed a partially flail mitral valve and severe mitral regurgitation. A deep transgastric view showed a double orifice mitral valve with a smaller accessory anterolateral orifice, and identified the origin of the regurgitant jet from the larger posteromedial orifice.