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

To determine the usefulness of the time intervals obtained from the first derivative of apexcardiogram (dA/dt) in assessing contraction and relaxation in cardiomyopathy, 11 patients with hypertrophic obstructive cardiomyopathy (HOCM) and 9 patients with congestive cardiomyopathy (COCM) with hemodynamically and angiographically documented diagnosis were studied. As a control group 50 normal subjects were used. Since contraction and relaxation is dependent on preload and afterload, the time interval from R wave of electrocardiogram to the positive peak of dA/dt (R to dA/dt) and 2 relaxation parameters derived from negative peak dA/dt, early relaxation index (ERI) and total relaxation index (TRI) were investigated. In HOCM the R to dA/dt were shortened (55 +/- 13 msec versus 76 +/- 14 msec in controls, P less than 0.01) and both ERI and TRI were augmented (ERI: 12.5 +/- 9 versus 4.3 +/- 5 in controls, p less than 0.001; TRI: 147 +/- 29 versus 70 +/- 18 in controls, p less than 0.02). In COCM the R to dA/dt were elongated (124 +/- 14 msec versus 76 +/- 14 msec in controls, P less than 09.001) and both ERI and TRI were decreased (ERI: 2.1 +/- 4 versus 4.3 +/- 5 in controls, p less than 0.005; TRI: 41 +/- 17 versus 70 +/- 18 in controls, p less than 0.002)., Significant correlation between these indices and some internal parameters of myocardial performance were observed. These findings indicate that systolic and diastolic time intervals measured from the first derivative of apexcardiogram may be used as a reliable indices for evaluation of contraction and relaxation independently of preload and afterload.