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Ventricular fibrillation

Ventricular fibrillation (VF) is a severely abnormal heart rhythm (arrhythmia) that is life threatening.


The heart pumps blood to the lungs, brain, and other organs. If the heartbeat is interrupted, even for a few seconds, it can lead to fainting (syncope) or cardiac arrest.

Fibrillation is an uncontrolled twitching or quivering of muscle fibers (fibrils). When it occurs in the lower chambers of the heart, it is called ventricular fibrillation. During ventricular fibrillation, blood is not pumped from the heart. Sudden cardiac death results.

The most common cause of VF is a heart attack. However, VF can occur whenever the heart muscle does not get enough oxygen for any reason. Conditions that can lead to VF include:

Most people with VF have no history of heart disease. However, they often have heart disease risk factors, such as smoking, high blood pressure, and diabetes.


A person who has a VF episode can suddenly collapse or become unconscious. This happens because the brain and muscles are not receiving blood from the heart.

The following symptoms may occur within minutes to 1 hour before the collapse:

  • Chest pain
  • Dizziness
  • Nausea
  • Rapid heartbeat
  • Shortness of breath

Exams and Tests

A cardiac monitor will show a very disorganized ("chaotic") heart rhythm.

Tests will be done to look for the cause of the VF.


Ventricular fibrillation is a medical emergency. It must be treated immediately to save a person's life.

Call for emergency help (such as 911) if a person who is having a VF episode collapses at home or becomes unconscious.

  • While waiting for help, place the person's head and neck in line with the rest of the body to help make breathing easier. Start CPR by doing chest compressions ("push hard and push fast").
  • Continue to do this until the person becomes alert or help arrives.

VF is treated by delivering a quick electric shock through the chest. It is done using a device called an external defibrillator. The electric shock can immediately restore the heartbeat to a normal rhythm, and should be done as quickly as possible. Many public places now have these machines.

Medicines may be given to control the heartbeat and heart function.

An implantable cardioverter defibrillator (ICD) is a device that can be implanted in the chest wall of people who are at risk for this serious rhythm disorder The ICD detects the dangerous heart rhythm and quickly sends a shock to correct it. It is a good idea for family members and friends of people who have had VF and heart disease to take a CPR course. CPR courses are available through the American Red Cross, hospitals, or the American Heart Association.

Outlook (Prognosis)

VF will lead to death within a few minutes unless it is treated quickly and properly. Even then, long-term survival for people who live through a VF attack outside of the hospital is low.

People who have survived VF may be in a coma or have long-term damage.

Possible Complications


Alternative Names

VF; Fibrillation - ventricular


Epstein AE, DiMarco JP, Ellenbogen KA, et al. 2012 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2013 Jan 22;61(3):e6-75.

Myerburg RJ, Castellanos A. Approach to cardiac arrest and life-threatening arrhythmias. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 63.

Olgin JE, Zipes DP. Specific arrhythmias: diagnosis and treatment. In: Bonow RO, Mann DL, Zipes DP, Libby P, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 9th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 39.

Stevenson WG. Ventricular arrhythmias. In: Goldman L, Schafer AI, eds. Goldman's Cecil Medicine. 24th ed. Philadelphia, PA: Elsevier Saunders; 2011:chap 65.

Meaney PA, Bobrow BJ, Mancini ME, et al. AHA Consensus Statement: Cardiopulmonary Resuscitation Quality: Improving Cardiac Resuscitation Outcomes Both Inside and Outside the Hospital. Circulation.

Update Date 5/13/2014

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