[Double mitral orifice. An anatomical case]

A double mitral orifice was discovered at autopsy in a 74 year old woman. Death resulted after several episodes of cardiac failure complicating mixed mitral and aortic valve disease. A vertical limbus bridged the mitral annulus separating it into two distinct right and left orifices, with oblique long axes aligned towards the lower part of the limbus perpendicular to each other from the left atrial view. After opening the left ventricle, both orifices were observed to have their own sets of chordae tendinae attached to normal papillary muscles: the right orifice to the posterior and the left to the anterior papillary muscle. The inferior end of the limbus was attached to a supplementary papillary muscle. Echocardiography and CT scanning were performed before dissection. This malformation results from symphysis of the mid parts of the two mitral leaflets during embryonic stages 15 and 16 (8-10 mm vertex-coccyx, 31st-33rd days).