What Is Sudden Cardiac Arrest?

Sudden cardiac arrest (SCA) is a condition in which the heart suddenly and unexpectedly stops beating. When this happens, blood stops flowing to the brain and other vital organs.

SCA usually causes death if it's not treated within minutes.

Overview

To understand SCA, it helps to understand how the heart works. The heart has an internal electrical system that controls the rate and rhythm of the heartbeat. Problems with the electrical system can cause abnormal heart rhythms called arrhythmias (ah-RITH-me-ahs).

There are many types of arrhythmias. During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm. Some arrhythmias can cause the heart to stop pumping blood to the body. These are the type of arrhythmias that cause SCA.

SCA is not the same as a heart attack. A heart attack occurs when blood flow to part of the heart muscle is blocked. During a heart attack, the heart usually doesn't suddenly stop beating. SCA, however, may happen after or during recovery from a heart attack.

People who have heart disease are at increased risk for SCA. However, most SCAs happen in people who appear healthy and have no known heart disease or other risk factors for SCA.

Outlook

Ninety-five percent of people who have SCA die from it—most within minutes. Rapid treatment of SCA with a defibrillator can be lifesaving. A defibrillator is a device that sends an electric shock to the heart to try to restore its normal rhythm.

Automated external defibrillators (AEDs), which often are found in public places like airports and office buildings, can be used by bystanders to save the lives of people who are having SCA.

February 2009