The Effect of Digitalis on the Cardiac Output of the Normal Heart at Rest and during Exercise

Abstract
There is a prevalent feeling among physicians that digitalis is toxic to the compensated heart. As a result clinicians have frequently been reluctant to administer this drug except in the presence of overt congestive heart failure or certain atrial arrhythmias. Most textbooks of pharmacology and cardiology state that digitalis reduces the cardiac output of both the normal and the enlarged nonfailing heart (1-9) by as much as 20 to 35% (4). Examination of the literature on which this idea is based reveals that the studies were frequently done under unphysiological conditions on heart-lung preparations (10) or in animals (11-13). Some