Effects of Acetylstrophanthidin on Coronary Vascular Resistance and Myocardial Oxygen Consumption.

• The primary clinical indication for digitalis therapy is congestive heart failure and the inotropic effect of digitalis preparations has been demonstrated in both experimental animals and man. However, studies by Ross et al.' have shown that digitalis affects not only myocardial contractility but also total peripheral resistance. In view of the latter effects, we have to consider the possibility that digitalis may have a direct action on the coronary vascular bed. Since coronary artery disease frequently accompanies or directly causes congestive heart failure, any action of digitalis on the coronary vascular bed might be of clinical importance. Previous studies of the effects of digitalis preparations on coronary flow have been inconclusive. Frank et al. found that strophanthin decreased coronary blood flow in the intact anesthetized dog; whereas, in a similar experiment acetyldigitoxin increased flow and digitoxin had no effect. Dearing et al. found no change of coronary flow in the dog with therapeutic doses of digitalis. Page et al. demonstrated an increase of coronary resistance following administration of ouabain. Cardiac oxygen consumption was maintained at the expense of a decrease in coronary