Systolic anterior motion of the mitral valve without asymmetric septal hypertrophy.

This report describes a patient with echocardiographic systolic anterior motion of the mitral valve causing the anterior mitral leaflet to contact the septum in systole. At necropsy a normal nonhypertrophied heart with normal-sized ventricular cavities and a normal outflow tract and mitral valve was found. Thus, asymmetric septal hypertrophy and abnormal mitral valvular placement are not requisites for systolic anterior motion of the mitral valve. During systole, a marked forward movement of the anterior mitral leaflet developed in our patient in the setting of hypovolemia and continuous intravenous administration of pressor drugs, suggesting, rather, that systolic anterior motion reflects a small, vigorously contracting ventricular cavity and that such dynamic subaortic obstruction is not pathognomonic of idiopathic hypertrophic subaortic stenosis.