Intracardiac phonocardiography in experimental left ventricular cavity obliteration: potential clinical applicability for the distinction of obliterating left ventricle from hypertrophic obstructive cardiomyopathy

Intracardiac sound was measured in six dogs, four with left ventricular cavity obliteration induced by isoproterenol, and two with catheter entrapment. In left ventricular cavity obliteration, no murmur occurred within the left ventricle. Whenever a systolic murmur occurred, it was distal to the aortic valve. In entrapment, no murmur occurred within the left ventricle or distal to the aortic valve. Previous studies in patients with hypertrophic obstructive cardiomyopathy showed that the systolic murmur was of greatest intensity within the left ventricular outflow tract. Therefore, intracardiac phonocardiography may assist in differentiating these conditions which produce an intraventricular pressure gradient.