Effect of ethanol on electrogram changes and regional myocardial blood flow during acute myocardial ischaemia

Acute occlusion of the left anterior descending coronary artery in dogs produced delayed conduction and diminished amplitude of bipolar electrograms recorded from ischaemic zones. Intravenous infusion of ethanol (1.2 g . kg-1), before coronary artery occlusion, delayed conduction and reduced the amplitude of electrograms recorded in normal myocardium, but attenuated ischaemia-induced electrogram changes produced by the subsequent occlusion. Ethanol (0.6 g . kg-1 iv) did not significantly alter activation of electrograms recorded from normal myocardium, but reduced ischaemia-induced electrogram changes and decreased the incidence of ventricular fibrillation elicited by rapid ventricular pacing from five of eight to one of eight dogs. Infusion of 10 or 30% (V/V) ethanol directly into a non-occluded coronary artery significantly increased conduction time and reduced electrogram amplitude recorded in the epicardium perfused by that coronary artery. These effects were more pronounced when ethanol was infused into an occluded coronary artery distal to the site of occlusion. Ethanol did not alter regional myocardial blood flow determined by labelled microspheres during ischaemia. Thus, despite a direct depressant effect on extracellular electrical activity recorded from normal and ischaemic myocardium, ethanol reduced the severity of ischaemia-induced electrogram alterations and decreased the incidence of ventricular fibrillation when given intravenously prior to coronary artery occlusion.