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Cardioversion for specific arrhythmias

Bradley P Knight, MD, FACC
Section Editor
Richard L Page, MD
Deputy Editor
Brian C Downey, MD, FACC


Electrical cardioversion and defibrillation have become routine procedures in the management of patients with cardiac arrhythmias. Cardioversion is the delivery of energy that is synchronized to the QRS complex, while defibrillation is asynchronous delivery of a shock randomly during the cardiac cycle.

Early defibrillators delivered energy in a monophasic waveform, meaning that electrons flowed in a single direction. The newer defibrillators deliver a biphasic waveform, meaning that during the shock, polarity and electron flow reverse. In addition to reversing polarity, biphasic defibrillators also deliver a more consistent magnitude of current (figure 1). In general, biphasic defibrillators successfully terminate arrhythmias at lower energies than monophasic defibrillators. The relative efficacy of biphasic and monophasic defibrillators has been compared in a number of settings and is discussed in detail separately. (See "Basic principles and technique of electrical cardioversion and defibrillation", section on 'Monophasic versus biphasic waveforms'.)

This topic will review the clinical settings in which electrical cardioversion and defibrillation are used, along with a brief discussion of the complications that can occur independent of the arrhythmia that is being treated. The basic principles and technique of electrical cardioversion and defibrillation, the specific indications for external cardioversion and defibrillation, and the use of the automated external defibrillator are presented separately. (See "Basic principles and technique of electrical cardioversion and defibrillation" and "Automated external defibrillators".)


Preparation and personnel — Nonemergency electrical cardioversion should ideally be performed in a controlled environment with monitoring capabilities and the nearby availability of emergency equipment should complications arise. The following are considered part of the routine preparation and monitoring involved in electrical cardioversion:

Standard cardiorespiratory monitoring, including blood pressure, pulse, oxygen saturation, and cardiac telemetry


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Literature review current through: Aug 2017. | This topic last updated: Aug 24, 2017.
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