Chapter 7. Cardioversion and Defibrillation

• • Rapid termination of tachycardia that is either unresponsive to medications or pacing interventions or is hemodynamically compromising, necessitating more urgent intervention.

Cardioversion

• • Tachycardia, either supraventricular or ventricular, with regular ventricular response with mild to moderate hypotension.

  • Mechanisms of supraventricular tachycardia include the following:

  • • Atrial reentry tachycardia.

    • Reciprocating tachycardia utilizing an accessory connection.

    • Atrial flutter.

    • Atrioventricular nodal reentry tachycardia.

Defibrillation

• • The most effective treatment for ventricular fibrillation and pulseless ventricular tachycardia (Table 7–1).

  • Its effectiveness diminishes rapidly over time; therefore, early defibrillation is recommended in patients who have suffered cardiac arrest.

  • Atrial fibrillation.

  • Supraventricular tachycardia with rapid conduction via an accessory connection.

  • Ventricular fibrillation.

  • Torsades de pointes.

Absolute

• • A patient directive regarding resuscitation.

Relative

• • Cardioversion of a rhythm known to be automatic in origin is not indicated.

  • Digoxin toxicity-induced arrhythmia.

  • • With digoxin toxicity, there is a high incidence of post-cardioversion ventricular tachycardia and fibrillation.

  • Elective cardioversion of a hemodynamically stable patient with a known atrial thrombus; however, the likelihood of impending cardiovascular compromise can outweigh the risk of thromboembolism.

  • Repeated cardioversion of a rhythm where the predisposing cause is not eliminated.

• • External defibrillator, either manual or semi-automated (Figure 7–1).

• • Skin electrode patches, wires to connect to defibrillator.

  • Heart rhythm monitor.

  • Equipment to protect the airway as well as resuscitation medications to support blood pressure.

  • Do not delay cardioversion or defibrillation in a hemodynamically unstable patient while waiting for additional monitoring equipment or personnel.

• • Chest wall lesions.

  • Neurologic complications.

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