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The ABCs of AEDs

Sept. 28, 2026—If you witness a cardiac arrest, knowing what to do could literally save a life—and you don't need any special medical training or superhuman strength.

Recognizing cardiac arrest

Cardiac arrest is when the heart suddenly stops beating normally, says the American Heart Association (AHA). About 350,000 adults in the U.S. have cardiac arrest outside of a hospital setting each year.

A person in cardiac arrest typically collapses and becomes unresponsive. They may breathe abnormally, gasp for air or not breathe at all for a while. Cardiac arrest also can cause sharp, sudden movements that look like a seizure.

During cardiac arrest a person is, technically speaking, deceased. But quick action can bring them back to life, according to the AHA. An automated external defibrillator (AED) makes this possible-and you can use it without advanced training.

AED facts

You may have seen AEDs mounted in boxes on the walls of airports, offices, hotels and schools. They're easy to carry and use.

An AED works by analyzing a person's heartbeat. If it detects an abnormal rhythm, it delivers an electric shock to the heart through the chest. This "shocks" the heart back into a normal rhythm.

While an AED doesn't replace professional emergency medical care, it can save a life. The AHA says that every minute a person is in cardiac arrest, their chance of survival decreases by 7% to 10%.

Another AHA statistic: 9 out of 10 people who get an AED electric shock within the first minute of cardiac arrest survive.

How to use an AED

An AED comes with easy-to-understand instructions. It also speaks to you, telling you exactly what to do.

If you see a person collapse, see if they are responsive—for example, by tapping them on the shoulder. If they don't respond, call 911 first, then ask someone to find an AED.

When the AED arrives:

• Remove all clothing covering the person's chest.
• Turn on the AED.
• Follow the voice instructions.
• Peel the backing off the two pads.
• Place the pads on the person's chest according to the illustrations included with the AED.
• If needed, plug the pads' connector into the AED.
• Wait for the AED to determine if the person needs an electric shock. While the AED is analyzing the person's heartbeat, do not touch the person.
• If a shock is necessary, first make sure no one is touching the person, then press the "shock" button.
• Start administering CPR until emergency medical help arrives. Learn how to perform hands-only CPR here.

Don't be afraid to help someone who has collapsed and is unresponsive. Good Samaritan laws protect people who are trying to save a life. Your fast action could make all the difference.

Sources

• American Heart Association. AED Fact Sheet.
• American Heart Association. What Cardiac Arrest Looks Like and Why Early Action Matters.
• American Heart Association. What Is an AED? How to Use One During a Cardiac Arrest.
• American Heart Association. What Is an Automated External Defibrillator?
• American Red Cross. What Is AED?