In the cardiac disease, idiopathic hypertrophic subaortic stenosis (IHSS) (1), there is hypertrophy of the myocardium which is often asymmetrically distributed. Although published descriptions appeared earlier, it was not until a clinical report by Brock (3) in 1957 and a pathologic report by Teare (10) in 1958 that the disease became well known. Since that time many other papers have appeared. The disease is much more common than was first realized. Most of the authors describing their cases emphasize that the often massive myocardial hypertrophy may primarily involve the ventricular septum (2, 4, 8, 10, 11), although usually the free wall of the left ventricle and sometimes the right ventricle are involved as well. Frequently the first manifestation of the disease is a heart murmur. The most common symptoms are dyspnea and angina. The patient is often asymptomatic, however. The electrocardiogram is almost always abnormal (2). At catheterization the demonstration of a pressure gradient within the left ve...