ALTERATIONS IN LEFT-VENTRICULAR RELAXATION AND DIASTOLIC COMPLIANCE IN CONGESTIVE CARDIOMYOPATHY

Summary: Elevated ventricular diastolic pressures are characteristic of congestive heart failure, and are generally thought to result from reduced ventricular emptying in systole. To determine whether other factors might contribute to the increased diastolic pressures within the left ventricle in con- gestive heart failure, we examined parameters of both left ventricular relaxation rate and diastolic compliance in eight patients with chronic congestive heart failure due to cardiomyopathy, and compared them with similar observations in a control population. Combined recordings of simultaneous left ventricular pressure and echocardiogram were obtained in each case. Left ventricular relaxation rate was assessed by measurement of the maximum rate of left ventricular pressure decline (peak negative dP/dt) and the mean velocity of circumferential fibre lengthening (VCFL) in early diastole. Both of these parameters were significantly decreased in congestive cardiomyopathy patients compared with controls (peak negative dP/dt: 138 ± 15 kPa·s-1 (1037 ± 115 mmHg·s1) versus 347 ± 22 kPa·s-1 (2607 ± 120 mmHg·s-1) for controls, P<0.0005; VCFL; 0.9 ± 0.1 s-l in congestive cardiomyopathy versus 1.3 ± 0.1 s-1 in controls, P<0.01). Left ventricular diastolic distensibility, δD/δP, and normalised distensibility, (δD/δP)/D, were significantly decreased in cardiomyopathy subjects as compared with controls (δD/δP=0.165 ± 0.03 cm (dimension) kPa-1 [0.02 ± 0.004 cm (dimension)·mmHg-1) compared with 1.28 ± 0.23cm (dimension)·kPa-1 [0.17 ± 0.03 cm (dimension)·mmHg-1] for controls, P<0.0005; (δD/δP)/D=25.6 ± 3.8 kPa-1 × 10 -3 (3.4 ± 0.5 mmHg-1 × 10-3) versus 301 ± 75 kPa-1 × 10 -3 (40 ± 10 mmHg-1 × 10 -3) for controls, P <0.0005). Linear regression analysis showed a strong correlation between peak negative dP/dt and both diastolic distensibility (r=0.89, P<0.0005) and normalised distensibility (r=0.88, P<0.0125). These data suggest that early diastolic left ventricular relaxation is impaired in congestive cardiomyopathy and that this defect occurs in association with a decrease in left ventricular diastolic compliance.