The digitalis glycosides, although used much less frequently now than 15-20 years ago, are still occasionally employed in the treatment of patients with heart failure and with some supraventricular arrhythmias, particularly atrial fibrillation and flutter. They have 2 major effects: 1) Increasing the heart’s sensitivity to vagal stimulation 2) Binding to a sub-unit of sodium-potassium ATPase to inhibit the activity of the sodium/potassium pump. The vagally mediated effects do not occur in transplanted hearts because theses hearts are denervated. However, the directly mediated effects of digitalis on the sodium/potassium pump occur in denervated as well as enervated hearts.