LEFT VENTRICULAR CINEANGIOGRAPHIC OBSERVATIONS IN MUSCULAR SUBAORTIC STENOSIS

Left ventricular cineangiographic studies in 35 patients with muscular subaortic stenosis demonstrated a definite sequence of events in systole in this condition. Early systole was characterized by a rapid, convulsive ejection into the aorta, during which time, in the left anterior oblique view, the anterior ventricular septum began to encroach on the outflow tract and the basal attached portion of the anterior mitral leaflet moved out of the outflow tract in the direction of normal mitral valve closure. By mid-systole, either anterior septal encroachment or a radiolucent area, or both, developed in the outflow tract. This radiolucent area indicated the site of obstruction caused by the mid-systolic apposition of the anterior ventricular septum with the lower (free) half of the anterior mitral valve leaflet. The latter was observed to move actively into the outflow tract in some instances. After the early aortic ejection and the development of the outflow tract obstruction, late systolic mitral regurgitation occurred and appeared to be the principal determinant of the end-systolic size of the left ventricle. Postoperative cineangiograms demonstrated the site of the ventriculomyotomy in the left ventricular outflow tract and lessening or abolition of the outflow tract obstruction and the mitral regurgitation. © 1969.