Relation between apex cardiographic and internal indices of left ventricular relaxation in man.

Abstract

In 19 patients the left apex cardiogram was recorded by a transducer with infinite time constant; at the same time left ventricular (tip, manometer) and aortic pressures were recorded during cardiac catheterization. The relation between 2 relaxation time intervals in the apex cardiogram and hemodynamic and angiocardiographic indices of left ventricular performance were studied. These apex cardiographic time intervals were: the time from the onset of the aortic component of the 2nd heart sound (S2) in the phonocardiogram to the negative peak of the 1st derivative (dA/dt) of the apex cardiogram, termed early apex cardiographic relaxation time and the time from S2 to the point where dA/dt after having reached its negative peak ascends to the zero line, termed total apex cardiographic relaxation time. In 100 normal subjects early apex cardiographic relaxation time averaged 3 .+-. 12 (.+-. 1 SD) ms and total apex cardiographic relaxation time was 93 .+-. 16 ms. In 11 patients with non-obstructive cardiomyopathy and decreased left ventricular function early and total apex cardiographic relaxation times were significantly (P < 0.001) prolonged (52 .+-. 23 ms and 152 .+-. 23 ms, respectively). In 8 patients without or with only minimal left ventricular pressure or volume overload they were within normal limits (-1 .+-. 8 ms and 94 .+-. 9 ms, respectively). Significant correlations were observed between early apex cardiographic relaxation time and internally measured indices of left ventricular performance: maximal rate of pressure fall (min dP/dt) in the left ventricle, velocity of lengthening of the contractile elements at minimum dP/dt, and ejection fraction. Correlations with several other values of left ventricular function (end-diastolic pressure, maximal dP/dt, and peak measured velocity of shortening of the contractile elements) were also observed. In the total group of subjects total apex cardiographic relaxation time correlated significantly with early apex cardiographic relaxation time. In the catheterized patients total apex cardiographic relaxation time showed less close correlation with the internal indices. The early and total relaxation time intervals in the left apex cardiogram proved to be 2 important noninvasive methods for assessing left ventricular performance in man.