Ventricular fibrillation
Ventricular fibrillation is chaotic, disorganized ventricular electrical activity with no effective contraction, producing immediate loss of cardiac output and cardiac arrest. It is the leading shockable arrest rhythm, and survival depends on immediate CPR and defibrillation, followed by treatment of the cause and an ICD for secondary prevention.
- Topic reviewThe full article, organized the way the exam asks it.
- ABIM-format MCQsVignettes with an explanation for every wrong answer.
- Key factsThe numbers and thresholds worth memorizing, up front.
- AI tutorMedBrain answers the question you're stuck on.
What this article covers
- Overview
Definition: ventricular fibrillation (VF) is chaotic, disorganized ventricular electrical activity producing no coordinated contraction and no cardiac output, a form of cardiac arrest.
- Epidemiology
A leading mechanism of sudden cardiac death.
- Risk factors
Coronary disease and acute myocardial infarction (the dominant cause).
- Pathophysiology
Multiple reentrant wavelets: disorganized, continuously shifting reentry circuits prevent coordinated depolarization.
- Clinical features
Sudden collapse, apnea, and pulselessness.
- Differential diagnosis
Pulseless ventricular tachycardia: organized wide complexes, also shockable (ventricular tachycardia).
- Diagnosis
Establish clinically by cardiac arrest with a monitor or defibrillator showing chaotic activity without discrete QRS complexes: the diagnostic basis is a pulseless, unresponsive patient with an…
- Management
First-line, start CPR and defibrillate immediately: begin high-quality chest compressions and deliver an unsynchronized shock as soon as the defibrillator is available, resuming compressions at once.
- Complications
Death without prompt defibrillation. Anoxic brain injury after prolonged arrest.
- Prognosis
Survival depends on time to defibrillation and bystander CPR.
- Prevention
ICD for secondary prevention (and primary prevention when ejection fraction is 35 percent or less).
Read the whole article
Subscribing to Internal Medicine opens every article, the full question bank and MedBrain, on the web, iPhone and Android.
Related articles
- Ventricular tachycardia
Ventricular tachycardia is three or more consecutive ventricular beats at over 100 per minute, a wide-complex tachycardia that is life-threatening when sustained. Any regular wide-complex tachycardia is ventricular tachycardia until proven otherwise: unstable patients are cardioverted or defibrillated, and long-term risk is managed with an implantable defibrillator.
- Sudden cardiac arrest
Sudden cardiac arrest is the abrupt cessation of cardiac function with loss of pulse and consciousness, most often from a ventricular tachyarrhythmia on a background of coronary disease. Survival depends on immediate CPR and defibrillation of shockable rhythms, followed by treatment of the cause and secondary prevention with an ICD.
- ST-elevation myocardial infarction (STEMI)
ST-elevation myocardial infarction is acute transmural myocardial ischemia from complete coronary occlusion, diagnosed by ischemic symptoms with diagnostic ST-segment elevation and a rising troponin. It is a time-critical emergency in which immediate reperfusion, primary PCI within 90 minutes or fibrinolysis when PCI is unavailable, plus antiplatelet and anticoagulant therapy, determines survival.
- Torsades de pointes
Torsades de pointes is a polymorphic ventricular tachycardia occurring on a background of QT prolongation, with a characteristic twisting of QRS complexes around the baseline. Management is intravenous magnesium, correction of the underlying QT-prolonging cause, and rate acceleration by pacing or isoproterenol; unstable episodes are defibrillated.