Assessment of left ventricular contraction and relaxation by systolic and diastolic time intervals measured from the first derivative of apex cardiogram in cardiomyopathy.

To determine the usefulness of the time intervals obtained from the first derivative of apex cardiogram (dA/dt) in assessing contraction and relaxation in cardiomyopathy, 11 patients with hypertrophic obstructive cardiomyopathy (HOCM) and 9 with congestive cardiomyopathy (COCM) with hemodynamically and angiographically documented diagnosis were studied. The control group numbered 50 normal subjects. Since contraction and relaxation are dependent on preload and afterload, the time interval from R wave of the electrocardiogram to the positive peak of dA/dt (R to dA/dt) and two relaxation parameters derived from the negative peak dA/dt, as well as early apex cardiographic relaxation index EARI) and total apex cardiographic relaxation index (TARI) were determined in all the subjects investigated. In HOCM the R to dA/dt were shortened (55 +/- 13 msec vs. 76 + 14 msec for controls, p less than 0.01) and both EARI and TARI were augmented (EARI: 11.5 +/- 9 vs. 4.3 +/- 5 in controls, p less than 0.001; TARI: 127 +/- 29 vs. 70 +/- 18 in controls p less than 0.02). In COCM the R to dA/dt were elongated (124 +/- 14 msec vs. 76 +/- 14 msec in controls, p less than 0.001) and both EARI and TARI were decreased (EARI: 2.4 +/- 4 vs. 4.3 +/- 5 in controls, p less than 0.005; TARI; 43 + 17 vs. 70 +/- 18 for controls, p less than 0.02). A significant correlation between these indices and some internal indices of myocardial performances was demonstrated. These findings indicate that the interval R to dA/dt, EARI and TARI may be used as reliable indices for the evaluation of contraction and relaxation in cardiomyopathy, independently of preload and afterload.