Myocardial protective effect and negative inotropic effect of verapamil in potassium cardioplegia
Suzuki, Y.
Nihon Kyobu Geka Gakkai 32(6): 903-912
1984
ISSN/ISBN: 0369-4739 PMID: 6491404 Document Number: 241259
The additive effect of verapamil (V) in cold K (28 meq/l) cardioplegia solution on myocardial protection during hypothermic (22.degree. C) 120 min. aortic occlusion was examined hemodynamically and ultrastructurally. Dogs (25) were divided into 4 groups according to V concentration: group I (0 mg/l, n = 6), group II (0.1 mg/l, n = 6), group III (0.5 mg/l, n = 7), group IV (2 mg/l, n = 6). The dogs were placed on a right heart bypass model with the constant mean aortic pressure and heart rate. Left ventricular (LV) function recovery calculated from the preischemic and postischemic sarnoff curves were 29.9 .+-. 10.2 (mean .+-. SD)% in group I, 43.8 .+-. 18.9% in group II, 48.3 .+-. 1.20% in group III and 52.9 .+-. 23.4% in group IV. Group III demonstrated a significantly higher recovery than group I (P < 0.05). Recovery of max dp/dt and t-peak dp/dt which were indices of myocardial contractility demonstrated the tendency of dose-dependent negative inotropic effect of V. However, recovery of % shortening of LV segmental length which was an index of myocardial contraction was preserved even in the V groups. Duration of A-V block was prolonged in the early reperfusion period, while spontaneous recovery of bearing was increased in the V groups. EM demonstrated well preserved myocardial tissue during reperfusion in all groups, and there were no significant differences between groups. V (0.5 mg/l) has additive myocardial protective effect during hypothermic K cardioplegia, improving LV function recovery. Concomitantly V has also negative inotropic effect depressing myocardial contractility. EM study demonstrated well preserved myocardial tissue in all groups.