THE FIRST DERIVATIVE OF APEX CARDIOGRAM AND ITS UTILIZING FOR DETERMINING SOME SYSTOLIC AND DIASTOLIC TIME INTERVALS IN MAN

Abstract

To determine the usefulness of the time intervals obtained from the first derivative of apex cardiogram (dA/dt) in assessing contraction and relaxation, 20 hemodynamically and angiographical1y investigated patients with coronary artery disease and 29 patients with hypertensive heart disease were studied.
As a control group there were used 50 normal subjects. 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 two relaxation parameters derived from negative peak dA/dt were investigated, early relaxation index (ERI) and total relaxation index (TRI). In patients with coronary artery disease all of these parameters were augmen- -- ted (R to dA/dt: 121 + 14 controls; ERI: 13.1 149 + 30 Versus + 8 - msec versus 76 + 14 msec for versus 4.3 + 5 in controls; TRI 71 + 18 for controls) and also pat ients with hypertensive heart disease s howed similar change s ( ~ to dA/ cant c orrelatio ns between these indexes a nd some i nternally par ame t e r s of myocar d i a l performance were ob s erved . These findings indicate that s ystolic and diastolic time intervals me a s ured f rom the firs t de r i v a t i v e o f apex ca r d iogr am may be used a s a reliable indices for evaluation o f contraction and relaxation independently of p r e loa d and afterload.

dt : 115 -+ 15 ms ec ; ERI: 9 . 5 +- 6 ; TRI: 81 +- 19) .Signi f I Measurement o f sustolic and diastolic time interval Is for c a rd i ac evaluation, such as isovolumetric c ont r a ction, preejection period, l eft ventricular ejection time and isovolumetric r elaxation time has been emphasized
by many authors. However, these intervals are infl- •
uenced by factors extraneous to contractility and rela1,2 xation, such as variations in preload and afterload To ov e r c ome the latter d i f f i cu l t y , Reale 3 proposed t o determine the time interval fr om ons et of ventricular depolarisation to the positive peak of the first derivative o f left apex cardiogram (dA/dt). because he established the similarity in timing and contour between the first derivative of left ve nt r i cu l a r pressure and dA/dt .
In order t o avoid the influence of a f t e r load on r elaxation, we divided a s suggest ed by Manolas et al. 4 time
intervals derived from negative peak dA/dt by mean aortic pressure. The first purpose of this study was t o investigate the average value of interval R t o positive peak dA/dt and indices derived from negative pea k dA/dt in patients with various cardiac disea se and to compare the value obt a i ned with those in a control group. The s ec ond purpose was to investigate in man the relationship between above mentioned parameters and some internal indexes obtained by heart ca t he t e r i zat i on .