Double-chambered left ventricle: submitral accessory valvular tissue causing inlet and outlet obstruction.

We report a patient with a large submitral ridge of muscular and fibrous tissue that divides the left ventricle into two distinct chambers causing inlet and outlet obstruction. Doppler echocardiography revealed obstruction to both filling and ejection. Echocardiography demonstrated that the obstruction was in series with the mitral apparatus. Surgery was done with resection of much of this ring of tissue. Subsequent studies revealed morphologic and hemodynamic improvement.