Left Ventricular Volumes and Compliance in Hypertrophic Cardiomyopathy

¹ Cardiac Unit, Department of Medicine, University of Natal, Wentworth Hospital, Durban, South Africa

Left ventricular (LV) function, volumes and compliance were studied in 14 patients with hypertrophic cardiomyopathy. Systolic function of the left ventricle was normal. Angiocardiographic LV end-diastolic volume was normal but end-systolic volume was reduced so that angiographic stroke index was large and ejection fraction greatly increased (87 ± 6 percent). Mean left ventricular wall mass was increased (428 ± 165 gram/M²). The left ventricular diastolic pressures were elevated and the `a' wave was important. The distensibility indices V/P and dV/dP at end-diastole were reduced, and the passive elastic modulus of the LV was increased. Analysis of the exponential pressure-volume relationship in diastole based on real, measured points at beginning and end-diastole, showed that the relationship is shifted upward so that "m" was normal or slightly reduced, but the initial diastolic tension was greatly increased. The major problem in hypertrophic myopathy appears to be a disorder of compliance.