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Cardiac Arrest

What is cardiac arrest?

Cardiac arrest means the heart has stopped beating. It can be fatal. When it causes death with little or no warning, it is called sudden cardiac death.

How does it occur?

Cardiac arrest is caused by an abnormal heart rhythm. These abnormal heart rhythms are:

  • Ventricular fibrillation (VF), which is a very fast and irregular heartbeat. It causes the heart to suddenly stop pumping blood.
  • Bradycardia, which is a very slow heartbeat. The heartbeat is too slow for the heart to be able to pump enough blood to the rest of your body.

The abnormal heart rhythms can be caused by several conditions. A few examples of these conditions are:

  • Coronary artery disease. A blocked blood vessel may affect the part of the heart that carries the signal for the heart to beat. This kind of blockage is especially dangerous when the heart is scarred from a heart attack.
  • Cardiomyopathy. Cardiomyopathy is an abnormality of the heart muscle. The heart muscle may be weakened or thickened. This makes the heart less able to pump enough blood.
  • Long Q-T syndrome (LQTS). This is a form of heart disease that some people are born with. It sometimes causes heart rhythm problems, particularly when there is emotional or physical stress. LQTS can appear at any age but often occurs in children and young adults.

Several things make sudden cardiac death more likely for people who have heart disease.

  • People who do not exercise regularly and then engage in heavy physical activity have a higher risk of sudden cardiac death.
  • Stress may cause cardiac arrest in people who have heart disease.
  • Certain medicines can cause an irregular heartbeat that is life threatening.
  • Illegal drug abuse can also cause sudden cardiac death.

How is it treated?

When cardiac arrest occurs, lack of blood flow to the brain and other body tissues can cause death. The only treatment is to restore the normal rhythm of the heart before severe damage is done.


Call 911 and then start CPR (cardiopulmonary resuscitation). CPR can maintain blood flow to the brain and other organs until a normal heart rhythm is restored. You may be able to use an automatic external defibrillator (AED), available in many public places and on some airplanes. AEDs are designed to be used by people without medical training. AEDs shock the heart and can change an abnormal rhythm (VF) back to a normal rhythm. For other causes of cardiac arrest, the person may need to be treated with medicines.

How can I help prevent cardiac arrest?

The first step is to see if you have any medical problems that increase your risk of sudden cardiac death. Often these conditions can be treated with medicines or a pacemaker. It is important to treat conditions that increase your risk for cardiac arrest, prevent coronary artery disease, and make healthy lifestyle changes.


If you have had a heart attack, follow the treatment prescribed by your healthcare provider.


People at highest risk for cardiac arrest may need an implantable cardioverter defibrillator (ICD). ICDs detect abnormal heart rhythms and shock the heart back to a normal rhythm. For other people, medicines such as beta blockers can reduce the risk of sudden cardiac death.


Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.


HIA File card3609.htm Release 13/2010

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