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The heart has an internal electrical system that controls the rhythm of the heartbeat. Problems can cause abnormal heart rhythms, called arrhythmias. There are many types of arrhythmia. During an arrhythmia, the heart can beat too fast, too slow, or it can stop beating. Sudden cardiac arrest (SCA) occurs when the heart develops an arrhythmia that causes it to stop beating. This is different than a heart attack, where the heart usually continues to beat but blood flow to the heart is blocked.
There are many possible causes of SCA. They include coronary heart disease, physical stress, and some inherited disorders. Sometimes there is no known cause for the SCA.
Without medical attention, the person will die within a few minutes. People are less likely to die if they have early defibrillation. Defibrillation sends an electric shock to restore the heart rhythm to normal. You should give cardiopulmonary resuscitation (CPR) to a person having SCA until defibrillation can be done.
If you have had an SCA, an implantable cardiac defibrillator (ICD) reduces the chance of dying from a second SCA.
NIH: National Heart, Lung, and Blood Institute
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Diagnosis and Tests
- How Is Sudden Cardiac Arrest Diagnosed? (National Heart, Lung, and Blood Institute)
Prevention and Risk Factors
- Catheter Ablation (National Heart, Lung, and Blood Institute)
- How Can Death Due to Sudden Cardiac Arrest Be Prevented? (National Heart, Lung, and Blood Institute)
- Understand Your Risk for Cardiac Arrest (American Heart Association)
- Warning Signs of Heart Attack, Stroke and Cardiac Arrest (American Heart Association)
- Who Is at Risk for Sudden Cardiac Arrest? (National Heart, Lung, and Blood Institute)
Treatments and Therapies
- Automated External Defibrillator (National Heart, Lung, and Blood Institute)
- Automated External Defibrillators: Do You Need an AED? (Mayo Foundation for Medical Education and Research)
- How Is Sudden Cardiac Arrest Treated? (National Heart, Lung, and Blood Institute)
- MedlinePlus: CPR (National Library of Medicine)
- Coronary Artery Anomalies (Texas Heart Institute) Also in Spanish
- Heart Attack or Sudden Cardiac Arrest: How Are They Different? (American Heart Association)
- Ventricular Fibrillation (Mayo Foundation for Medical Education and Research)
- What Causes Sudden Cardiac Arrest? (National Heart, Lung, and Blood Institute)
- Genetics Home Reference: progressive familial heart block (National Library of Medicine)
Health Check Tools
- Sudden Cardiac Arrest (SCA) Risk Assessment (Heart Rhythm Society)
Journal ArticlesReferences and abstracts from MEDLINE/PubMed (National Library of Medicine)
- Sudden Death in Young People--Heart Problems Often Blamed (Mayo Foundation for Medical Education and Research)