Cardiac arrest means that the heart suddenly stops beating. This is because of a problem with the heart's electrical system. When cardiac arrest occurs, emergency medical care needs to be provided right away. If it is not, the person can quickly die since blood is not being pumped throughout the body.
Cardiac arrest is not the same as a heart attack. When a person has a heart attack, the blood flow to the heart is interrupted. This may be due to problems with the coronary arteries, such as a build-up of plaque, a blood clot, or a thickening of the artery walls.
Electrical System of the Heart
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Cardiac arrest may be caused by:
Factors that may increase the risk of cardiac arrest include:
Prior to cardiac arrest, some people report the following symptoms or warning signs in the weeks before the event:
The first person to respond to a cardiac arrest should check if the person is responsive. If the person does not respond, call for emergency medical services right away or have someone else call. If there is an automated external defibrillator (AED) available, you or someone else should get it and follow the steps on the machine.
After calling emergency medical services, CPR will be started if the person is not breathing normally. If no AED is available or while you are waiting for it, begin doing CPR by giving chest compressions. Push the chest in at least two inches at a fast rate of at least 100 compressions per minute. If you are trained in CPR, after 30 compressions, open the person's airway and give two rescue breaths. Then, continue with the chest compressions. If you feel more comfortable, you can give the compressions without the breaths until the ambulance arrives.
Prompt treatment improves the chance of survival. The 4 steps in the cardiac chain of survival are:
Call for emergency medical services right away, especially if you notice cardiac warning signs or suspect cardiac arrest has occurred.
Defibrillation sends an electrical shock through the chest. The surge of electricity aims to stop the ineffective, irregular heart rhythm. This may allow the heart to resume a more normal electrical pattern. AEDs check the heart rhythm before instructing the rescuer to give the shock.
CPR helps keep blood and oxygen flowing to the heart and brain until other treatment can be given. The heart and brain are very susceptible to low oxygen levels. Permanent damage can occur, even with successful resuscitation.
Emergency medical personnel at the scene and doctors at the hospital will provide essential medical care and intensive monitoring. They will give drugs, insert a tube to maintain an open airway, and manage emergency care. Epinephrine is often given early to make the heart more receptive to electrical impulses and to improve blood flow to the heart and brain. The patient will receive oxygen.
Therapeutic hypothermia is another type of treatment that may be used at the hospital. This involves lowering the person's body temperature to 89°-93°F (32°-34°C) by using cold blankets, ice packs, and infusions of cool saline. This cooling of the body is done in an effort to aid brain function and recovery. The person's body may remain at this temperature for an extended period of time (12-24 hours).
Even in cases where an effective heart rhythm has been restored, low oxygen levels can cause serious damage to the heart, brain, and other vital organs.
You may be able to lower your risk of cardiac arrest by:
American Heart Association
Sudden Cardiac Arrest Association
Canadian Cardiovascular Society
The College of Family Physicians of Canada
About cardiac arrest. American Heart Association website. Available at:
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Updated March 10, 2017. Accessed September 13, 2017.
Cardiac arrest in adults. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T116814/Cardiac-arrest-in-adults . Updated September 1, 2017. Accessed September 13, 2017.
Explore sudden cardiac arrest. National Heart Lung and Blood Institute website. Available at: https://www.nhlbi.nih.gov/health/health-topics/topics/scda. Updated June 22, 2016. Accessed September 13, 2017.
Sudden cardiac arrest. Heart Rhythm Society website. Available at:
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Accessed September 13, 2017.
Last reviewed September 2018 by
EBSCO Medical Review Board
Michael J. Fucci, DO, FACC
Last Updated: 9/9/2014