Direct effects of ethanol on myocardial performance and coronary resistance

Ethanol has been infused into an isolated heart-lung type preparation in which the "isotonically" contracting left ventricle pumps blood and does work at a lower than normal value while afterload is maintained constant. The isotonic contraction permits observation of the influence of a drug or other agent on the coronary vasculature independent of the compressive effects of the musculature. Infusions of ethanol to concentrations of approximately 210 mg/100 ml over a 30- to 60-min period resulted in significant increases in coronary blood flow, decreases in coronary vascular resistance and depression of myocardial performance. Cardiac work increased concomitantly with the increase in coronary blood flow and cardiac output without significant alterations in tension-time index and oxygen consumption. A second group of animals received a smaller amount of ethanol over a 5-min period, accompanied by injection of 86Rb and 125I for nutritional flow measurements and of radioactive microspheres for flow distribution. Extraction increased slightly after alcohol but flow distribution was not significantly altered. Small concentrations of ethanol are concluded to have a direct vasodilating effect on the coronary vasculature.