Ventricular Fibrillation

Ventricular Fibrillation is a topic covered in the 5-Minute Emergency Consult.

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  • Ventricular fibrillation (VF) is completely disorganized depolarization and contraction of small areas of the ventricle without effective cardiac output.
  • Cardiac monitor displays absence of QRS complexes and T-waves with the presence of high-frequency, irregular undulations that are variable in both amplitude and periodicity.


  • Damaged myocardium creates sites for re-entrant circuits:
    • Myocardial damage may be caused by multiple factors including ischemia, necrosis, reperfusion, healing, and scar formation
  • Most often a result of severe myocardial ischemia:
    • 7% of patients with STEMI develop sustained VF, 80–85% occurring in the 1st 24 hr
  • Complication of cardiomyopathy:
    • Up to 50% of patients with dilated cardiomyopathy suffer an episode of VF.
    • In hypertrophic cardiomyopathy, unexpected sudden death occurs with reported frequency of up to 3%/yr.
  • Nonischemic causes of ventricular tachycardia may evolve into VF:
    • Drug toxicities (cyclic antidepressants, digitalis)
    • Electrolyte or acid–base abnormalities
    • Congenital and acquired prolonged QT syndromes.
    • Short QT syndrome
    • Brugada syndrome
  • Premature ventricular complexes (PVCs) with R-on-T phenomenon
  • Other less common causes of VF:
    • Electrocution
    • Hypoxia
    • Hypothermia
    • Blunt chest trauma
    • Iatrogenic myocardial irritation from pacemaker placement or pulmonary artery catheter
  • Idiopathic VF (5–10%)

Pediatric Considerations
  • Primary ventricular dysrhythmias are extremely rare in children.
  • VF usually results from a respiratory arrest, hypothermia, or near drowning.

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