Idiopathic hypertrophic subaortic stenosis.

IHSS is a familial illness with a significant and frequently lethal effect on cardiac function. Diagnosis can be made on clinical grounds and by echocardiography, and is confirmed by cardiac catheterization. High-dose beta -adrenergic blockade may control symptoms but does not give complete protection against fatal arrhythmias. Surgery may be required. A new class of drugs, calcium antagonists, will soon be marketed in this country and could provide more effective therapy for IHSS.