Synchronised DC Cardioversion
All patients underwent synchronised DC cardioversion of their arrhythmia’s according to standard protocol. In brief, pre-procedural electrocardiogram was obtained for confirmation of the presenting arrhythmia and participants received general anesthesia. A Phillips HeartStart biphasic Defibrillator XL (Phillips, Amsterdam, Netherlands) was used for the procedure with pad placed in the anterior-posterior position. Adhesive gel pads were used for all procedures. Once sedated, a shock of 150J was delivered to the patient. If this was sufficient energy to cardiovert to sinus rhythm the procedure was complete. If the patient remained in arrhythmia, a subsequent shock of 200J was delivered up to two more times. Following the third overall attempt, pads were changed and a fourth and final attempt was made with an energy of 200J. The exact energy of the shock delivered and measured impedance was recorded from the rhythm strip of the defibrillator. A successful cardioversion was defined as at least three consecutive beats of sinus rhythm on the rhythm strip following cardioversion.