The purpose of this study is to investigate the effects of reversible left stellate ganglion blockade on cardiac electrical activity, myocardial blood flow and norepinephrine kinetics in a selected group of symptomatic patients with hypertrophic cardiomyopathy (IHSS) who are shown to have inducible malignant ventricular arrhythmias during electrophysiologic studies and who are at high risk of sudden cardiac death. Presently we are awaiting the first patient.