The Atrioventricular Node in Hypertrophic Obstructive Cardiomyopathy

The cause of syncope and sudden death in hypertrophic obstructive cardiomyopathy is uncertain and the significance of hypertrophic subaortic stenosis as a cause of ventricular fibrillation is discussed. The conducting tissue in four cases was examined histo-logically and the findings in the atrioventricular node are presented. It would appear that abnormalities of muscle structure similar to those seen in the myocardium are also to be found in the conducting tissue. In cases without left outflow tract stenosis, cardiac excitability may have to be suppressed if syncope and sudden death are to be prevented.