Emergency Central is a collection of disease, drug, and test information including 5-Minute Emergency Medicine Consult, Davis’s Drug, McGraw-Hill Medical’s Diagnosaurus®, Pocket Guide to Diagnostic Tests, and MEDLINE Journals created for emergency medicine professionals. Explore these free sample topics:
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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:
- Blunt chest trauma
- Iatrogenic myocardial irritation from pacemaker placement or pulmonary artery catheter
- Idiopathic VF (5–10%)
- Primary ventricular dysrhythmias are extremely rare in children.
- VF usually results from a respiratory arrest, hypothermia, or near drowning.