What is ventricular fibrillation?

A: Ventricular fibrillation (VF) is the abnormal heart rhythm that is most often seen in sudden cardiac arrest. In VF, the heartbeat is chaotic, disorganized and very fast.  The heart cannot effectively pump blood and if untreated, the heart will stop. 
 
The only effective treatment for ventricular fibrillation is an electrical shock called defibrillation. The goal of defibrillation is to reset the heart to a normal rhythm.  But, it the shock must be provided before the heart stops. Automated external defibrillators (AEDs) are devices that analyze a heart rhythm for VF, and if VF is present, they deliver a shock.

Ventricular fibrillation is not the only rhythm in cardiac arrest. However, an AED will only shock VF. 
 
You can learn more about AED's in the article "AEDs Save Lives, But Not When They Don't Work" from West Palm Beach heart attack injury lawyer Craig Goldenfarb.