Editing Cardioversion (section)

==Electrical==
To perform synchronized electrical cardioversion, two [[electrode]] pads are used (or, alternatively, the traditional hand-held "paddles"), each comprising a metallic plate which is faced with a saline based conductive gel.  The pads are placed on the chest of the patient, or one is placed on the chest and one on the back.  These are connected by cables to a machine which has the combined functions of an [[electrocardiogram|ECG]] display screen and the electrical function of a [[defibrillator]]. A synchronizing function (either manually operated or automatic) allows the cardioverter to deliver a reversion shock, by way of the pads, of a selected amount of [[electric current]] over a predefined number of [[millisecond]]s at the optimal moment in the [[cardiac cycle]] which corresponds to the R wave of the [[QRS complex]] on the [[electrocardiogram|ECG]].

Timing the shock to the R wave prevents the delivery of the shock during the vulnerable period (or relative refractory period) of the [[cardiac cycle]], which could induce [[ventricular fibrillation]].  If the patient is conscious, various drugs are often used to help sedate the patient and make the procedure more tolerable.  However, if the patient is hemodynamically unstable or unconscious, the shock is given immediately upon confirmation of the [[Heart arrhythmia|arrhythmia]]. When synchronized electrical cardioversion is performed as an elective procedure, the shocks can be performed in conjunction with drug therapy until [[sinus rhythm]] is attained. After the procedure, the patient is monitored to ensure stability of the sinus rhythm.

Synchronized electrical cardioversion is used to treat hemodynamically unstable supraventricular (or narrow complex) [[tachycardia]]s, including [[atrial fibrillation]] and [[atrial flutter]]. It is also used in the emergent treatment of wide complex tachycardias, including [[ventricular tachycardia]], when a pulse is present. Pulseless [[ventricular tachycardia]] and [[ventricular fibrillation]] are treated with unsynchronized shocks referred to as [[defibrillation]]. Electrical therapy is inappropriate for [[sinus tachycardia]], which should always be a part of the [[differential diagnosis]].