A defibrillator is a device that gives a high energy electric shock to the heart through the chest wall to someone who is in cardiac arrest.

This high energy shock is called defibrillation, and it's an essential life saving step in the chain of survival. If you come across someone who has had a cardiac arrest, it’s vital to call 999 and start CPR. Then you should find out if there is a defibrillator nearby.

There are many defibrillators available in public places such as train stations, shopping centres, airport and leisure centres. These defibrillators are often known as public access defibrillators (PAD) as anyone can use them in an emergency. You shouldn’t be afraid of using a defibrillator if someone has had a cardiac arrest.