Ventricular Fibrillation



  • Ventricular fibrillation (VF) is completely disorganized depolarization and contraction of small areas of the ventricle without effective cardiac output
  • Cardiac monitor displays rapid grossly irregular electrical activity with electrocardiographic waveforms that are variable in length, morphology, and amplitude; ventricular rate is usually >300 bpm. There are no recognizable P, QRS complexes or T-waves


  • 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:
    • ∼50% of VF-OHCA patients who survive to hospital admission have evidence of AMI
  • Complication of cardiomyopathy:
    • Patients with structural heart disease are at a higher risk of sustained VT and VF
  • 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

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

There's more to see -- the rest of this topic is available only to subscribers.