Synchronized cardioversion

See critical care quick reference for doses by weight.

Background

• Low energy shock synchronized with peak of QRS complex
• Machine leads synchronized with patient's EKG rhythm

Indications

It is important to note that the procedure and indications differ between defibrillation and cardioversion

Defibrillation (Unsynchronized Cardioversion)

• Ventricular fibrillation
• Pulseless ventricular tachycardia
• Polymorphic ventricular tachycardia

Synchronized Cardioversion

• Supraventricular tachycardia (SVT)
• Atrial fibrillation
• Atrial flutter
• Ventricular tachycardia with a pulse

Contraindications

• None

Equipment Needed

• Defibrillator
• Consider sedation medication in conscious patient (e.g. etomidate, ketamine), but do not delay procedure in unstable patient
  • Give fentanyl 1 μg/kg before sedation, and consider slow 0.5 mg/kg lidocaine IV 1 min before sedative
  • Etomidate superior to propofol in terms of recovery and hemodynamic stability
    • Etomidate 0.1 mg/kg, followed by etomidate second dose of 0.05 mg/kg just prior to shock
    • VS propofol 1 mg/kg, followed by propofol second dose of 0.5 mg/kg just prior to shock

Procedure

Cardioversion

• Apply pads
  • Anterior-Posterior placement is preferred but may not be as important as previously thought and most studies are for atrial fibrillation or flutter
    • Avoid placing in close proximity to implanted devices if possible
• Select appropriate energy (Joules)
• Ensure machine is "synced" before each discharge
  • Most machines show an indicator (arrow or dot) above each beat if appropriately synchronized
• Ensure R or S wave is bigger than T wave
  • Machine may read T wave as depolarization and shock during an actual repolarization phase
  • May induce shock on T and subsequent VT/VF
  • Move leads to avoid this
• Give sedation, if indicated
  • All awake and hemodynamically stable patients
• Ensure safety of environment prior to cardioversion
  • Nobody touching patient
  • Nobody touching equipment that is touching patient
  • Consider removing supplemental oxygen
• Cardiovert
  • Hold 'Shock' button until shock discharged
    • Shock delayed until peak of QRS complex in synchronized cardioversion (keep holding button down)
• Repeat PRN
  • May require escalating energy

Doses

Initial recommendations:

• Tachycardia with pulse
  • Narrow regular (SVT): 50-100 J
  • Narrow irregular (A fib, A flutter)
    • Biphasic: 120-200 J (may start as low as 50 - 100 J for A flutter)
    • Monophasic: 200 J
  • Wide regular (VT with pulse): 100 J
  • Wide irregular: defibrilate (NOT synchronized)

See Also

• ACLS (Main)
• PALS (Main)
• Defibrillation
• In-Training Exam Review

External Links

• Merk Manual - Direct-Current Cardioversion-Defibrillation

Videos

• Larry Mellick-live demonstration (https://www.youtube.com/watch?v=uCETUw0Bssw)

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References

• AHA 2010 ACLS Recommendations