Cardioversion

Cardioversion or electrical conversion refers to giving electrical shock to a patient with an arrhythmia to restore sinus rhythm. It can be done acutely in case of emergencies, or electively in cases where pharmacological treatment of the arrhythmia hasn’t had satisfactory effect.

Cardioversion is, unlike defibrillation, synchronised. This means that the device gives a shock exactly when the cardiac cycle is at the R wave of a QRS complex. This prevents the shock from occurring during the T wave, which could induce the “R on T phenomenon”, which can cause VF.

Cardioversion is indicated for:

• Emergency management of any haemodynamically unstable tachyarrhythmias, like AVNRT, AVRT, pre-excited atrial fibrillation, ventricular tachycardia with a pulse
• Elective management of atrial fibrillation or flutter

Cardioversion may be used for Afib or flutter in cases where the onset is very recent, or if pharmacological treatment has not induced conversion to sinus rhythm. Cardioversion becomes less and less likely to succeed as the duration of the Afib or flutter increases.