II. Indications
III. Protocol: Sedation Prior to Cardioversion
- See Procedural Sedation
- Combination Protocol: Etomidate and Fentanyl
- Combination Protocol: Midazolam and Fentanyl
- Midazolam 1 mg IV every 3-5 minutes up to adequate sedation or to maximum 5 mg cummulative dose and
- Fentanyl 50 mcg increments
- Hypotension risk
-
Propofol Protocol
- Considered superior agent if patient stable
- Short induction
- Rapid awakening and recuperation
- Minimal adverse effects (although risk of Hypotension)
- Anesthesia or second provider supervision is recommended
- References
- Considered superior agent if patient stable
IV. Technique: Electrode (paddle) position
- Anteroposterior electrodes most effective in Atrial Fib
- Anteroposterior placement conversion rate: 96%
- Anterolateral placement conversion rate: 78%
- Kirchhof (2002) Lancet 360:1275-9 [PubMed]
- Avoid placing directly over implanted device (internal Defibrillator or Pacemaker)
- Contrast with Defibrillation, where paddles may be positioned over implanted device to prevent delays
- In refractory cases, electophysiologists may apply pressure to the anterior electrode during cardioversion shock
- This may increase cardioversion efficacy by reducing distance between the anterior and posterior electrode
- Place 2 towels on the anterior pad, stand on a step stool and apply pressure to the anterior pad
- Biphasic devices appear to be safe despite contact with examiner as they apply pressure to the pads
V. Dosing
- Pediatric
- Initial: 0.5 Joule per kg
- Subsequent: 1 Joule per kg
- Adult
- Background
- Cardioversion is often performed at maximal biphasic joules (e.g. 200 J) to limit number of shocks
- Joules listed below are a historical guideline, but starting at lower joules may require additional attempts
- Myocardium is "stunned" after each shock, and this adverse effect increases with cummulative shocks
- Narrow regular Tachycardia (PSVT, Atrial Flutter)
- Initial: 50-100 J (monophasic or biphasic)
- Narrow irregular Tachycardia (Atrial Fibrillation)
- See Atrial Fibrillation Cardioversion
- Initial Monophasic: 200 J synchronized (up to 360 J synchronized)
- Initial Biphasic: 150 J synchronized (up to 200 J synchronized)
- Consider Amiodarone 150 mg prior to cardioversion if stable
- Anecdotal evidence of improved success in electrical cardioversion of Atrial Fibrillation
- Unfractionated Heparin or Low Molecular Weight Heparin indications
- Atrial Fibrillation of unknown duration or >48 hours (emergent, unstable cases requiring immediate cardioversion) or
- High risk of Cerebrovascular Accident (e.g. prior TIA or CVA, Rheumatic Heart Disease, Mechanical Heart Valve)
- Wide regular Tachycardia (Ventricular Tachycardia)
- Initial: 100 J (monophasic or biphasic)
- Wide irregular Tachycardia
- Defibrillation (non-synchronized)
- Background
VI. Precautions: Digoxin
- Do not use electrical cardioversion in Digoxin Toxicity (risk of malignant ventricular Arrhythmia)
- Modified electrical cardioversion dosing in patients on Digoxin
- Start at 10-20 Joules biphasic
- Increase in 10-20 Joule increments until cardioversion