Sudden cardiac arrest (SCA) is an abrupt loss of pulse and consciousness caused by an unexpected failure in the heart's ability to effectively pump blood to the brain and around the body. It is usually caused by life-threatening arrhythmias, abnormalities in the heart's electrical system.

Heart beating normally (48 KB)

Heart in Ventricular Fibrillation (48 KB)

The sudden cardiac arrest victim first loses his or her pulse, then consciousness, and finally the ability to breathe. All of this happens quickly - within a few seconds. Without immediate treatment, 90-95 percent of SCA victims will die.

The only definitive treatment for SCA is defibrillation - an electric current that "shocks" the heart so that a normal rhythm may resume. This "shock" must be delivered within minutes of the arrest to successfully prevent death. (See video about defibrillation)

Last updated: 20 January 2005