Assessment of left ventricular relaxation in the diseased heart in man.

To examine the exponential nature of the left ventricular pressure (LVP) fall during isovolumic relaxation (IRP) in 59 patients (normal (N), 6; angina pectoris (AP), 13; myocardial infarction (MI), 24; and congestive (CCM, 6) and hypertrophic (HCM, 10) cardiomyopathies), LVP and dP/dt were measured by a Millar's catheter-tipped transducer. In P vs time relation during IRP was reasonably fitted by a straight line (r greater than 0.97) in all cases. Time constant (msec) in CCM (56.9 +/- 10.7), HCM (44.8 +/- 12.4) and MI (43.8 +/-7.4 higher (p less than 0.05) than in N (30.3 +/- 5.5), and peak (-) dP/dt (mmHg/sec) was lower (841 +/- 171, 1152 +/- 397 and 1270 +/- 211, respectively; p less than 0.05) than in N (1885 +/- 150), suggesting impaired LV relaxation in these groups. However, (-) dP/dt upstroke pattern was exponential only in both N and 8 of the AP. The (-) dP/dt upstroke in the remaining groups lost its exponential nature, showing rather a down ward-convex curvature which was especially prominent in CCM. This indicates non-exponential fall of LVP during IRP. Thus, the present results suggest that impaired relaxation disturbs the exponential nature of LV relaxation.