Ventricular fibrillation (VF) is a type of cardiac arrhythmia where the heart's ventricles twitch randomly rather than contracting in a co-ordinated fashion, due to aberrant electrical activity in the ventricles.
VF results in cardiac arrest with loss of consciousness and no pulse, as the ventricles fail to pump blood around the body.
Prompt CPR and defibrillation are needed to survive VF.