230px-EKG VF

ECG lead showing VF


Ventricular fibrillation (V-fib or VF) is a condition in which there is uncoordinated contraction of the cardiac muscle of the ventricles in the heart, making them quiver rather than contract properly. While there is activity, it is undetectable by palpation (feeling) at major pulse points of the carotid and femoral arteries especially by the lay person. Such an arrhythmia is only confirmed by electrocardiography. Ventricular fibrillation is a medical emergency that requires prompt Basic Life Support interventions because should the arrhythmia continue for more than a few seconds, it will likely degenerate further into asystole ("flatline"). The condition results in cardiogenic shock, cessation of effective blood circulation, and sudden cardiac death (SCD) will result in a matter of minutes. If however the patient is revived after a sufficient period (at room temperature, roughly 5 minutes) of cerebral hypoxia, the patient could sustain irreversible brain damage and possibly be left brain dead (death often occurs if normal sinus rhythm is not restored within 90 seconds of the onset of VF, especially if it has degenerated further into asystole).


Ventricular fibrillation is a medical emergency and must be treated immediately to save a person's life. If a person having a VF episode collapses at home or becomes unconscious, call the local emergency number (such as 911). 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 with mouth-to-mouth breathing and chest compressions. Continue to do this until the person becomes alert or help arrives. VF is treated by delivering a quick electric shock through the chest using a device called an external defibrillator. The electrical shock can immediately restore the heartbeat to a normal rhythm. Medicines may be given to control the heartbeat and heart function. People with heart muscle damage may need additional procedures, including a heart transplant. A cardiologist will look for potential causes of the VF. An implantable cardioverter defibrillator (ICD) may be recommended for those who survive a VF attack and are at risk for future ones. The ICD can help prevent sudden cardiac death. Moderate hypothermia therapy may be used on people who remain in a coma after treatment. This involves keeping the person slightly below normal body temperature for several hours. Such therapy has been shown to improve the outcome and reduce death. [1]


Electric defibrillator[]

The condition can often be reversed by the electric discharge of direct current from a defibrillator. Although a defibrillator is designed to correct the problem, and its effects can be dramatic, it is not always successful.

Implantable electric defibrillator[]

In patients at high risk of ventricular fibrillation, the use of an implantable cardioverter defibrillator has been shown to be beneficial.

Precordial thump[]

If no defibrillator is available, a precordial thump can be delivered at the onset of VF for a small chance to regain cardiac function. However, research has shown that the precordial thump releases no more than 30 joules of energy[citation needed]. This is far less than the 200–360 J typically used to bring about normal sinus rhythm. Consequently, in the hospital setting, this treatment is not used.

Antiarrhythmic agents[]

Anti-arrhythmic agents like amiodarone or lidocaine can help, but, unlike atrial fibrillation, ventricular fibrillation rarely reverses spontaneously in large adult mammals. Drug therapy with anti-arrhythmic agents in ventricular fibrillation does not replace defibrillation and is not the first priority, but is sometimes needed in cases where initial defibrillation attempts are not successful.


  1. PubMed Health. "Ventricular fibrillation". June 1, 2010. [1]


See also[]

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