According to Medscape, defibrillation is a process that delivers electrical energy to the heart during any phase of the cardiac cycle, whereas electrical cardioversion is synchronized to deliver electrical energy on the R wave, or the QRS complex. Medscape states that cardioversion is usually not emergent and is performed using sedation. Conversely, Medscape reveals that defibrillation is an emergent maneuver and sedation is usually not given beforehand.
The indications for cardioversion and defibrillation also differ. Medscape states that a cardioversion may be performed when a person has atrial fibrillation, atrial flutter, stable ventricular tachycardia or supraventricular tachycardia. In addition, Medscape states cardioversion may be performed on any unstable person that has a reentrant tachycardia with a rate greater than 150 beats per minute. Medscape defines the person as unstable if chest pain, hypotension or pulmonary edema are present. Defibrillation may occur if a patient has pulseless ventricular tachycardia, ventricular fibrillation or cardiac arrest resulting in ventricular fibrillation, as stated by Medscape.
Similar complications may occur during or after defibrillation and cardioversion. Medline Plus, Medscape and the American Heart Association state that a person may have burning or pain where the electrodes are placed, worsening of the arrhythmia or thromboembolism. Thromboembolism is the release of a blood clot which can travel to the brain, causing a stroke.