Sudden Cardiac Arrest

Sudden cardiac arrest (SCA) occurs when the lower chambers of the heart (the ventricles) suddenly stop beating normally and develop what is called ventricular fibrillation (VF). VF is a very fast, chaotic heart rate in the lower chambers of the heart. 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. If this arrhythmia is not corrected immediately via a shock from an external defibrillator or an , death will follow. The defibrillator stops the chaotic electrical activity and restores normal heart rhythm.

A 2002 study—Multi-center Automatic Defibrillator Implantation Trial II (MADIT II)—found that people who have survived a heart attack, yet who have extensive muscle damage, may be at risk for sudden cardiac death due to the heart’s inability to pump enough blood. For many of these patients, physicians are recommending an implantable cardioverter defibrillator (ICD).

Learn more about heart attack and sudden cardiac arrest.

Are you at risk for sudden cardiac arrest? Find out at: Inside Cardiac Arrest.

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.