Electrical cardioversion

Guideline describing the indications, contraindications and procedure of DC electrical cardioversion of tachyarrhythmias

Electrical Cardioversion

An electrical current applied across the chest, which is synchronised with the R wave of the ECG to reduce the risk of precipitating VF if the shock was delivered in the relative refractory period of the cardiac cycle (i.e. with the T wave).


  • Emergency treatment of haemodynamically unstable patients with tachyarrhythmia (hypotension, SOB, chest pain)
  • Elective treatment of stable patients with a tachyarrhythmia.


  • Sinus tachycardia
  • Multifocal atrial tachycardia.

Procedural Technique

  • Explain the procedure to the patient. Enquire about allergy to anaesthetic agents and confirm fasting status.
  • Use low-dose propofol or fentanyl plus midazolam for conscious patients undergoing elective cardioversion.
  • The procedure is similar to that for defibrillation, except that the defibrillator is set to ‘Synchronous’ mode so that the shock is delivered with the R wave.
  • Energy requirements are less than those required for defibrillation to terminate VF.
    • Atrial fibrillation (AF)
      • Biphasic waveform: 120–150 J
      • Monophasic dampened sinusoidal (MDS): commence with 200 J increasing to 360 J as necessary.
    • Atrial flutter and paroxysmal SVT other than AF
      • Biphasic: 70–120 J
      • MDS: commence with 100 J, increasing to 200 J and 360 J if required.
    • Stable monomorphic VT
      • Biphasic: 120–150 J for the initial shock
      • MDS: commence with 200 J, increasing to 360 J if required.

Date implemented – 05/2009
Review date – currently being revised
Author – Mike Cadogan  

Dr James Wheeler
Dr James Wheeler

Emergency Physician, SCGH, WA, Australia

Articles: 498

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