It is an arrhythmia characterized by such rapid and uncoordinated contractions of the individual muscle fibers of the ventricles that the heart is effectively stopped and unable to pump blood into the body. It is the most dramatic event for the heart responsible for cardiac arrest.

A person with ventricular fibrillation loses consciousness rapidly due to lack of blood to the brain and needs immediate medical assistance to live. If it is not interrupted it leads rapidly to death and if it lasts a long time before being interrupted it can lead to very serious disorders of the brain that remains for too long without blood and oxygen.

The only treatment for this arrhythmia is an electric shock that passes through the heart or, very rarely, resuscitation maneuvers. Patients affected by this pathology or at high risk of developing it are subjected to the implantation of an automatic defibrillator, a life-saving device that emits an electric shock from inside the heart and restores normal cardiac rhythm.