What are Defibrillators?


Defibrillators are devices that send an electric pulse or shock to the heart to restore a normal heartbeat. They are used to prevent or correct an arrhythmia, an uneven heartbeat that is too slow or too fast. If the heart suddenly stops, defibrillators can also help it beat again. Different types of defibrillators work in different ways. Automated external defibrillators (AEDs), which are now found in many public spaces, are used to save the lives of people experiencing cardiac arrest. Even untrained bystanders can use these devices in an emergency.

Other defibrillators can prevent sudden death among people who have a high risk of a life-threatening arrhythmia. They include implantable cardioverter defibrillators (ICDs), which are surgically placed inside your body, and wearable cardioverter defibrillators (WCDs), which rest on the body. It can take time and effort to get used to living with a defibrillator, and it is important to be aware of possible complications.

Who needs an AED?

AEDs can save the life of someone having cardiac arrest, when the heart suddenly and unexpectedly stops beating.

AEDs can be used for adults, as well as for children as young as 1 year old. Some devices have pads and cables sized especially for children.


Doing cardiopulmonary resuscitation, or CPR, on someone having cardiac arrest also can improve his or her chance of survival.

Who needs an ICD?

ICDs can correct a dangerous arrhythmia or keep an irregular heartbeat from causing cardiac arrest. Life-threatening arrhythmias can develop for many reasons and can affect people of any age, from newborns to older adults. Your doctor may recommend an ICD if you have a type of arrhythmia that causes your heart’s ventricles to shake instead of pumping blood. This type of arrhythmia is most likely to cause cardiac arrest.

If you have the following conditions, you may be at risk for a life-threatening arrhythmia and your doctor may recommend an ICD:

  • You survived cardiac arrest.
  • You developed an arrhythmia during or after treatment for a heart attack.
  • You have a condition passed down from your parents that causes arrhythmia. This includes having congenital heart disease or an inherited conduction disorder.
  • You have a neuromuscular disorder. For example, the progression of muscular dystrophy can damage the heart and cause unpredictable heart rhythms. This can lead to unexplained fainting and a high risk of death.
  • You have an abnormally slow heart rate or other problem with the heart’s electrical signals.
  • You have cardiac sarcoidosis.
  • You have poor heart function following a procedure to improve blood flow.
  • Your doctor detected an arrhythmia during an electrocardiogram (EKG) or stress test. If this happened several times, you may be at increased risk.

Who needs a WCD?

WCDs are used to protect against cardiac arrest in certain circumstances, such as if you are at risk of arrhythmia for just a short time. This might occur under these conditions:

  • You are recovering from a heart attack.
  • You are waiting for a heart transplant.
  • You are fighting an infection.
  • You are removing or waiting to replace your ICD.

When to use an AED in an Emergency

Fainting is usually the first sign of cardiac arrest. If you think someone may be in cardiac arrest, try the following steps:

  • If you see a person faint or if you find a person already unconscious, first confirm that the person cannot respond. The person may not move, or his or her movements may look like a seizure.
  • You can shout at or gently shake the person to make sure he or she is not sleeping, but never shake an infant or young child. Instead, you can gently pinch the child to try to wake him or her up.
  • Check the person’s breathing and pulse. If the person is not breathing and has no pulse or has an irregular heartbeat, prepare to use the AED as soon as possible.

Where to find an AED

You often find AEDs in places where large numbers of people gather, such as shopping malls, golf courses, gyms and swimming pools, businesses, airports, hotels, sports venues, and schools. You can also purchase a home-use AED.

The AED is in a case about the size of a large first-aid kit. Many AEDs have a heart logo in red or green. Large letters on the case or the wall where it is stored might spell out A–E–D.

How to use an AED

Even someone without special training can respond in an emergency by following the instructions relayed by the device. The information below can help you use an AED correctly.

  • Call 9-1-1 or have someone else call 9-1-1. If two rescuers are present, one can provide CPR while the other calls 9-1-1 and gets the AED.
  • Make sure the area around the person is clear. Touching the person could interfere with the AED’s reading of the person’s heart.
  • Listen for voice prompts that tell you when and how to give an electric pulse or shock
     if one is needed to restore a normal rhythm. Electrodes deliver the shock, and some deliver more than one shock with increasing.
  • Start CPR again after delivering the shock, if the device instructs you to do so.



Leave a Reply

%d bloggers like this: