External Cardiac Stimulation

Abstract

In resuscitation from cardiac arrest effective circulation of oxygenated blood must be re-stored in the brief time interval available before anoxic brain damage is suffered. Circulation may be effected temporarily without cardiac contractions by emergency mechanical compression of the heart (“cardiac massage”), either externally through the closed chest or by direct manual compression of the heart wall when the chest or abdomen is opened. The essential task of producing cardiac contractions is accomplished by artificial excitation of ectopic ventricular beats or by the arousal, acceleration, and maintenance of an intrinsic ventricular rhythm. Ventricular tachycardia or fibrillation, which prevent effective ventricular beats, must be terminated, usually by external electric countershock before cardiac contractions can be effected. Pharmacologic agents are given in the course of cardiac resuscitation to improve cardiac contractility, increase peripheral vascular resistance, and suppress ventricular tachycardia and fibrillation. The whole program of artificial ventilation is applied to provide adequate gas exchange of circulating blood in the lungs.