Cardioversion and Defibrillation

Abstract

Cardioversion and defibrillation are both techniques of terminating cardiac arrhythmias. Direct current (DC) cardioversion uses the discharge of electrical energy through the myocardium to terminate certain arrhythmias. In DC cardioversion shock delivery is synchronized with the QRS complex to avoid provoking ventricular fibrillation (VF). If a shock is given during the vulnerable refractory period of ventricular repolarization, VF may result [1]. In comparison defibrillation uses no synchronization and the shock is given randomly in the cardiac cycle. Monophasic and biphasic waveforms have been shown to be effective in cardioversion and defibrillation. In the use of biphasic waveforms current polarity becomes reversed which more consistently terminates arrhythmias with less energy delivered.