Ventricular Fibrillation

Ventricular fibrillation (VF) is a very fast, chaotic heart rate in the lower chambers of the heart, resulting from multiple areas of the ventricles attempting to control the heart's rhythm. Ventricular fibrillation can occur spontaneously (generally caused by heart disease) or when ventricular tachycardia has persisted too long. When the ventricles fibrillate, they do not contract normally, so they cannot effectively pump blood. The instant VF begins, effective blood pumping stops. VF quickly becomes more erratic, resulting in sudden cardiac arrest. This arrhythmia must be corrected immediately via a shock from an external defibrillator or an ICD. The defibrillator stops the chaotic electrical activity and restores normal heart rhythm.

Normal Rhythm

Every normal heart has a normal rhythm. That rhythm varies from person to person. In most healthy people, the heart at rest beats about 60 to 100 times per minute. A small bunch of heart cells called the sinoatrial node keeps time.