ENHANCEMENT OF VENTRICULAR GRADIENT VARIABILITY DURING ACUTE MYOCARDIAL-ISCHEMIA

We evaluated the influence of local myocardial ischemia induced by exp erimental coronary stenosis on the ventricular gradients (VGs) and det ermined whether changes of VG were related to the alterations of monop hasic action potentials (MAPs). The coronary flow was reduced to 50% i n the left anterior descending coronary artery for 30 min in nine dogs . The VG and MAP of consecutive heartbeats over a 20-s interval were o btained from McFee and Parungao body surface leads and a suction elect rode on the ischemic and non-ischemic regions. The coefficients of var iation of VG and MAP parameters were calculated as indices of variabil ity. The coefficients of variation of the VG magnitude and the MAP are a in the ischemic region were greater at 5 min after partial occlusion than in the control period (P<0.05, P<0.01, respectively). There was a significant correlation between the coefficient of Variation of the VG magnitude and the coefficient of variation of the MAP area in the i schemic region (r=0.707, P<0.0001) but not in the non-ischemic region. VG variability was enhanced during acute regional ischemia of the ven tricular myocardium. VG variability may be caused by enhanced electric al alteration of the MAP in ischemic myocardium. (C) 1998 Elsevier Sci ence Ireland Ltd.