Cardiovascular Medicine Book

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Synchronized Cardioversion

Aka: Synchronized Cardioversion, Synchronized Shock
  1. See Also
    1. Defibrillation
  2. Indications
    1. Paroxysmal Supraventricular Tachycardia
    2. Atrial Fibrillation
    3. Atrial Flutter
    4. Ventricular Tachycardia
  3. Protocol: Sedation prior to cardioversion
    1. Combination Protocol: Etomidate and Fentanyl
      1. Etomidate 0.15 to 0.2 mg/kg and
      2. Fentanyl: 1 mcg/kg/dose up to 50 mcg/dose every 3 minutes, titrating to effect
    2. Combination Protocol: Midazolam and Fentanyl
      1. Midazolam 1 mg IV every 3-5 minutes up to adequate Sedation or to maximum 5 mg cummulative dose and
      2. Fentanyl 50 mcg increments
      3. Hypotension risk
    3. Propofol Protocol
      1. Considered superior agent if patient stable
        1. Short induction
        2. Rapid awakening and recuperation
        3. Minimal adverse effects (although risk of Hypotension)
      2. Anesthesia or second provider supervision is recommended
      3. References
        1. Coll-Vinent (2003) Ann Emerg Med 42:767-72 [PubMed]
        2. Basset (2003) Ann Emerg Med 42:773-82 [PubMed]
  4. Technique: Electrode (paddle) position
    1. Anteroposterior electrodes most effective in Atrial Fib
      1. Anteroposterior placement conversion rate: 96%
      2. Anterolateral placement conversion rate: 78%
      3. Kirchhof (2002) Lancet 360:1275-9 [PubMed]
    2. Avoid placing directly over implanted device (internal Defibrillator or Pacemaker)
      1. Contrast with Defibrillation, where paddles may be positioned over implanted device to prevent delays
  5. Doses
    1. Pediatric
      1. Initial: 0.5 Joule per kg
      2. Subsequent: 1 Joule per kg
    2. Adult
      1. Narrow regular Tachycardia (PSVT, Atrial Flutter)
        1. Initial: 50-100 J (monophasic or biphasic)
      2. Narrow irregular Tachycardia (Atrial Fibrillation)
        1. See Atrial Fibrillation Cardioversion
        2. Initial Monophasic: 200 J synchronized (up to 360 J synchronized)
        3. Initial Biphasic: 150 J synchronized (up to 200 J synchronized)
        4. Consider Amiodarone 150 mg prior to cardioversion if stable
          1. Anecdotal evidence of improved success in electrical cardioversion of Atrial Fibrillation
        5. Unfractionated Heparin or Low Molecular Weight Heparin indications
          1. Atrial Fibrillation of unknown duration or >48 hours (emergent, unstable cases requiring immediate cardioversion) or
          2. High risk of Cerebrovascular Accident (e.g. prior TIA or CVA, Rheumatic Heart Disease, Mechanical Heart Valve)
            1. See CHADS2-VASc Score
      3. Wide regular Tachycardia (Ventricular Tachycardia)
        1. Initial: 100 J (monophasic or biphasic)
      4. Wide irregular Tachycardia
        1. Defibrillation (non-synchronized)
  6. Precautions: Digoxin
    1. Do not use electrical cardioversion in Digoxin Toxicity (risk of malignant ventricular arrhythmia)
    2. Modified electrical cardioversion dosing in patients on Digoxin
      1. Start at 10-20 Joules biphasic
      2. Increase in 10-20 Joule increments until cardioversion

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