Altered intracardiac conduction after acute administration of ethanol in the dog

Varying concentrations of ethyl alcohol were injected either into the left main coronary artery or intravenously in anesthetized intact dogs. Effects of alcohol on intracardiac conduction (by His bundle electrogram) were examined at spontaneous and paced (atrial) heart rates. Alcohol by the intracoronary route prolonged atrioventricular node and intraventricular conduction times by approximately 5 to 15%. These changes preceded a depression of left ventricular systolic pressure and of the rate of rise of left ventricular pressure and an elevation of left ventricular end-diastolic pressure. Intracoronary injections of contrast medium (sodium diatriozoate) or iso-osmolar solutions of sucrose and injections of similar amounts of alcohol in the ascending or descending aorta did not affect intracardiac conduction. Increasing atrial pacing rates resulted in prolongation of atrioventricular nodal conduction intervals, but did not influence intraventricular conduction time. At each pacing rate, alcohol depressed both atrioventricular nodal and intraventricular conduction. The data suggest that alcohol has a direct depressant effect on intracardiac conduction.