Antiarrhythmic Effect of Regional Myocardial Chemical Sympathectomy in the Early Phase of Coronary Artery Occlusion in Dogs

Abstract

To investigate the importance of local noradrenaline (NA) release in initiating early ventricular extrasystoles (VES) and primary ventricular fibrillation (VF) after acute myocardial ischemia, a special form of regional myocardial chemical sympathectomy (RMCS) has been performed in dogs. After RMCS the tissue content of NA within the denervated region was reduced below 1.5% of normal, whereas the residual myocardium retained its functional state almost unchanged. After acute left circumflex coronary artery (LCX) occlusion (30 min), all control animals with normal circumflex circulation and without functionally effective collaterals died of VF. In contrast, after RMCS none of the dogs had VF and very few had VES. After RMCS the rise in myocardial extracellular K+ activity ([K+]e) during coronary occlusion is slightly slower, but the same [K+]e are reached at 8 min of occlusion. Therefore, the effect of RMCS cannot be explained by changes in myocardial K+ liberation. These results, obtained from RMCS experiments, are supported by the preliminary results of experiments using a special perfusion technique to wash out blood from the acutely occluded myocardial region, and show an ischemia-induced raise of the locally released NA in the early arrhythmic phase 1a with a further increase in phase 1b.