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Synchronised DC cardioversion [advanced]

Please note this information is for educational purposes only and procedures should not conducted based on this information. OSCEstop and authors take no responsibility for errors or for the use of any content.

Routine indications: AF/atrial flutter after 4 weeks anticoagulation

Emergency indications: tachyarrhythmia with adverse signs (shock, syncope, myocardial ischaemia, heart failure)

Synchronised DC cardioversion is used for patients with a pulse (shock synchronises with R wave to avoid inducing VF)

Unsynchronised DC cardioversion (defibrillation) is used for patients without a pulse (cardiac arrest) – see ALS


Skip this section if it is being performed as an emergency.

  • Read referral letter
  • Check potassium >4mmol/L
  • Check ECG still shows AF/flutter
  • Consent patient
    • Risks: stroke (<1%), pain or burns from pads, failure (1/3), ventricular arrhythmias (may require further shocks/CPR), bradycardia or asystole (may require external pacing)
  • Check anticoagulation has been taken for >4 weeks
    • NOAC – check no missed doses
    • Warfarin – check INRs in last 3 weeks are >2
  • Check patient is clinically well and fit for anaesthetic



  • Anaesthetist must be present to sedate patient
  • Apply 3-lead cardiac monitoring (clockwise from right arm Ride Your Green Bicycle) and connect lead to external cardiac monitor or defibrillator machine
    • Red: anterior aspect of right shoulder
    • Yellow: anterior aspect of right shoulder
    • Green: left anterior superior iliac spine
    • Black: not present on defibrillation machine
  • Apply defibrillator pads (in AP position) after shaving chest if required
    • β€˜Right’ pad: place longitudinally on left sternal edge
    • β€˜Left’ pad: place longitudinally on left paraspinal muscles (in line with anterior pad)
  • Connect pads lead to defibrillator machine


  • Set defibrillator machine monitoring trace to β€˜pads’
  • Set defibrillator to synchronised mode (synchronises shock with R wave to avoid inducing VF)
  • Set energy level (increase as shown if unsuccessful)
    • Broad-complex tachycardia or AF: 150J β†’ 200J β†’ 200J  (biphasic)
    • Narrow complex tachycardia or atrial flutter: 70J β†’ 120J β†’ 200J  (biphasic)
  • Ask anaesthetist to sedate patient and wait until they are happy to proceed
  • Ask everybody to move away from the patient and ask for the oxygen to be moved away
  • Press charge (then move hand away from button)
  • Re-check everybody and oxygen is away from the patient, announce you are about to shock and press and hold the shock button until shock is delivered (it will wait for the R wave)
  • Re-assess the rhythm
  • If unsuccessful, repeat at next energy (maximum 3 attempts)

Dealing with complications

  • Asystole or bradycardia with haemodynamic compromise (SBP<90) β†’ if sustained, proceed to transcutaneous pacing
  • Bradycardia without haemodynamic compromise β†’ monitor, reduce Ξ²-blockers
  • Ventricular tachycardia with pulse β†’ repeat synchronised DC shock as above
  • Pulseless arrhythmia β†’ unsynchronised DC shock if shockable rhythm (VT/VF); if ongoing or not shockable rhythm, start chest compressions and manage as cardiac arrest (see ALS)


  • Document procedure
  • Complete discharge letter
    • Continue all medications (except digoxin if taking and successfully cardioverted)
    • Continue anticoagulation until patient has been reviewed at least 4 weeks post-cardioversion
  • Book for clinic follow up
  • Re-check ECG and observations
  • Advise patient not to drive for 24 hours and stay with someone overnight
DC cardioversion set up

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