A cardiac arrest is when your heart suddenly stops pumping blood around your body.

When your heart stops pumping blood, your brain is starved of oxygen. This causes you to fall unconscious and stop breathing. A cardiac arrest usually happens without warning. If someone is in cardiac arrest, they collapse suddenly and:

• will be unconscious
• will be unresponsive and
• won’t be breathing or breathing normally – not breathing normally may mean they’re making gasping noises.

Without immediate treatment or medical attention, the person will die. If you see someone having a cardiac arrest, phone 999 immediately and start CPR. Defibrillators are very easy to use. Although they don’t all look the same, they all function in broadly the same way. You don’t need training to use one. The machine gives clear spoken instructions – all you have to do is follow them – and it won’t shock someone unless they need it.