Reviewed by Jonathan Melamed, M.D. NYU Medical CenterVentricular fibrillation (also known as “V-Fib”) is a very rapid, uncoordinated series of contractions throughout the lower chambers of the heart caused by
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chaotic electrical impulses. In this case, the rhythm is very fast and irregular causing the heart to effectively stop beating. Ventricular fibrillation is the worst kind of abnormal heart rhythm, and is a form of cardiac arrest.
Damaged heart muscle due to a heart attack or other acute reduction of oxygen supply to the heart can cause ventricular fibrillation. It may be seen immediately following a heart attack. It may also develop during hypoxia, atrial fibrillation, or improper grounding of electrical devices. An extremely low level of potassium in the blood can also cause ventricular fibrillation. Ventricular fibrillation is electrically similar to atrial fibrillation, but has a much graver prognosis. In ventricular fibrillation, the ventricles merely quiver and don’t carry out coordinated contractions. The first, and usually the only, symptom of ventricular fibrillation is sudden unconsciousness. The person usually may convulse and develop irreversible brain damage after about 5 minutes, followed by death.
Prognosis: Early and effective cardiopulmonary resuscitation (CPR) may provide the time necessary for medical personnel to arrive with a defibrillator. Drugs are then given to help maintain the normal heart rhythm. If a defibrillator is able to promptly restore a normal rhythm, up to 25% of victims are able to leave the hospital without evidence of brain damage. If ventricular fibrillation occurs in the hospital in conjunction with a heart attack, defibrillation has a 95% success rate.
Prevention: Ventricular fibrillation is treated the same way as ventricular tachycardia. A complete electrophysiologic evaluation is necessary, along with testing for coronary insufficiency. If ventricular fibrillation is caused by blockages in the coronary arteries, fixing those blockages with bypass surgery or with balloon angioplasty can decrease the risk of recurrence. An implantable cardioverter-defribrillator or ICD can rescue a patient from recurrent ventricular fibrillation and thus save his or her life.
