A cardiac arrest is when your heart suddenly stops pumping blood around your body, commonly because of a problem with electrical signals in your heart.

When your heart stops pumping blood, your brain is starved of oxygen. This causes you to fall unconscious and stop breathing.

There are usually no symptoms before a cardiac arrest and, without immediate treatment, it will be fatal. If someone is in cardiac arrest:

A cardiac arrest is a medical emergency. If you witness a cardiac arrest, you can increase a person’s chances of survival by calling the nearest ambulance and take to the hospital emergency. Ventricular fibrillation(VF) can sometimes be corrected by giving an electric shock through the chest wall, by using a device called a defibrillator. Cardiopulmonary resuscitation (CPR) is an emergency procedure that combines chest compressions often with artificial ventilation in an effort to manually preserve intact brain function until further measures are taken to restore spontaneous blood circulation and breathing in a person who is in cardiac arrest.