Effect of Ethanol on Regional Myocardial Blood Flow and Hemodynamics, before and after Coronary Artery Ligation in Dogs

The effects on regional myocardial blood flows (RMBF) and hemodynamics due to ethanol administered before and after acute coronary artery ligation (CAL) in 18 anesthetized dogs were studied. Ethanol was administered to seven dogs (group I) prior to CAL and to six dogs (group II) after CAL; five dogs (group III, control) received only saline before and after CAL. Uniform blood ethanol levels (180 +/- 30 mg/dl) were maintained in groups I and II after initial ethanol administration. In these groups the heart rate and rate-pressure product (which reflects myocardial oxygen consumption) remained stable, but pulmonary arterial pressures were elevated. Other hemodynamic parameters remained stable in all groups. Ethanol caused a significant transmural increase of RMBF (p less than 0.001) in both groups I and II. In group II the increase was significant in both nonischemic and ischemic tissues, with no apparent redistribution of flow among the myocardial layers. The percentage increase of RMBF due to ethanol was highest in group II nonischemic tissue (95-107%) compared to the corresponding ischemic tissue (57-60%) and the group I myocardial tissue (36-47%) prior to CAL (p less than 0.001). The observed differences between ethanol pre- and posttreatments suggest different interactions between ethanol and catecholamines. The results also confirm that vasodilatory reserve is present in the acutely ischemic myocardium and that the local availability of ethanol is important for coronary vasodilatation.