[Combined therapy with glycosides and Ca++-antagonistic agents (author's transl)].
Ca-antagonistic drugs increase cardiac oxygen supply by a coronary vasodilator action whilst they simultaneously lower myocardial oxygen demand. The latter drug effect is due to a decrease in cardiac contractile energy expenditure both directly (restriction of myocardial contractility) and indirectly (reduction of arterial blood pressure resulting from systemic vasodilation). In coronary disease all these factors can contribute to an improvement of the disturbed myocardial energy balance. As to the coronary vasodilator action of Ca-antagonistic drugs in particular, it is important to note that they readily relax the smooth musculature of the major extramural stem arteries where most of the occlusive atherosclerotic intima processes (about 95%) are located. In contrast, other coronary vasodilators such as adenosine, dipyridamole, chromonar, lidoflazine, theophylline, which lack Ca-antagonistic properties, are primarily acting on the small intramural resistance vessels of the heart whereas vascular smooth musculature originating from the major extramural arteries is less affected. Therefore, in elderly atherosclerotic patients the possible risk of glycoside-induced vasoconstriction in extramural coronary stem arteries (and also in arteries of systemic circulation) can be sufficiently eliminated only with the help of Ca-antagonists.