Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 22 4 1980 12 15 303 316 NIKOLAI KOLEV 2015 09 28 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 .   https://acta.tums.ac.ir/index.php/acta/article/view/141 https://acta.tums.ac.ir/index.php/acta/article/download/141/137