Right Ventricular Diastolic Function in Patients With Hypertrophic Cardiomyopathy

To assess diastolic function of the right ventricle (RV) in patients with hypertrophic cardiomyopathy (HCM), biplane RV angiograms and RV pressures were analyzed in 19 HCM patients and in 13 normal subjects. RV and left ventricle (LV) pressures were measured using catheter-tip manometers. RV volumes were obtained from frame-by-frame tracings of angiograms. Ventricular relaxation was assessed by the time constant of isovolumic pressure decay (T). The peak filling rate (PFR) and the time to PFR (TPFR) were used as parameters of early diastolic filling, and the right atrial contribution to RV filling (%AF) was used as a parameter of late diastolic filling. The T for the RV was significantly prolonged in HCM patients. However, there was no significant correlation between the T for the RV and LV, nor did the T for the RV correlate with the RV ejection fraction or interventricular septal wall thickness. The TPFR, but not PFR, was significantly greater in HCM patients, and the %AF tended to be increased in HCM, but not significantly. The RV diastolic pressure-volume relations in the HCM patients shifted upward. In conclusion, impaired isovolumic relaxation and delayed diastolic filling and decreased diastolic distensibility are present in the RV of HCM patients.