Ventricular Function and Indications for Digitalis
The digitalis glycosides have been employed widely in clinical medicine for nearly two centuries as the principal drug in the treatment of congestive heart failure. Many important advances in the past few years have considerably improved our understanding of their physiologic and subcellular mechanisms of action and their pharmacodynamics and application in patients (1). The beneficial effects of digitalis in patients with congestive heart failure result from its direct stimulation of the depressed contractile state. Digitalis augments the low cardiac output and reduces the elevated ventricular end-diastolic pressure of the dysfunctioning heart (Fig. 1). Thus, the glycoside improves the fundamental physiologic defect causing ventricular failure (2), depressed contractility, and this increase in contractile state allows a lesser need for Frank-Starling preload compensation, so that a normal cardiac output can be delivered at a substantially less elevated ventricular filling pressure. Although there is now general agreement that digitalis stimulates the force of contraction of the failing myocardium, there has been considerable confusion about its effects on the nonfailing heart. This problem has recently been resolved by evidence that the glycoside directly elevates the contractile state of the normal ventricle (3), although the increased contractile state is not translated into a rise of cardiac output.
KeywordsCardiac Output Myocardial Oxygen Consumption Constrictive Pericarditis Contractile State Digitalis Glycoside
Ventrikelfunktiori und Indikationen für Digitalis
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