"Diverticula" of anterior mitral valve leaflet as a cause of subvalvular aortic stenosis.

A 77-year-old male patient presented with symptoms of shortness of breath, fatigue, chest pain on exertion and dizziness. Transthoracic echocardiography suggested the presence of a diaphragmatic type of obstruction in the subaortic area of the left ventricular outflow tract. The systolic peak gradient at rest was 34 mmHg with a mean of 23 mmHg. Cardiac catheterization demonstrated rounded radiolucencies in the left ventricular outflow tract in the form of two "pouches" that moved back and forth causing subaortic stenosis. There was also a 70% stenosis of the left anterior descending coronary artery. Left ventricular function was normal. At surgery, a transesophageal echocardiogram demonstrated two distinct pouches arising from the anterior leaflet of the mitral valve. The larger of the two originated near the free edge of the leaflet and was attached via a chord to the membranous septum traversing the subaortic area of the left ventricular outflow tract. The patient underwent a left internal mammary to left anterior descending bypass graft, excision of the larger pouch and over-sewing of the smaller pouch. The excision and repair were performed through the aortic root and aortic valve. The patient made an uncomplicated recovery and on follow up his symptoms disappeared. This case shows the excellent results that can be obtained by surgery of diverticula of the mitral valve causing intermittent subaortic stenosis, a rare pathologic entity, morphologically different from the classical diaphragmatic subaortic stenosis.