Obstruction of left ventricular outflow tract after mechanical mitral valve replacement.

We successfully operated on a patient with a rare complication of left ventricular outflow tract obstruction after mitral valve replacement. In a 57-year-old woman with previous mitral valve replacement, transthoracic echocardiography showed left ventricular outflow tract obstruction as a result of anterior displacement of the mitral prosthesis and local thickening of the interventricular septum. Cardiac surgery verified this rare lesion. During the operation, the anterior half of the prosthesis ring was cut away from hyperplastic tissue and sutured to the natural mitral annulus. Subaortic hyperplastic tissue was excised to enlarge the left ventricular outflow tract. The patient had an uneventful postoperative recovery, and left ventricular outflow tract obstruction disappeared on postoperative transthoracic echocardiography.