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).

Indications

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

Contraindications

• 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