What is a cardiac arrest?

A cardiac arrest happens when your heart stops pumping blood around the body.

The most common cause of a cardiac arrest is a life threatening abnormal heart rhythm called ventricular fibrillation.  Ventricular fibrillation occurs when the electrical activity of the heart becomes so chaotic that the heart stops pumping and quivers, or 'fibrillates' instead.

Other reasons why you might have a cardiac arrest are:

  • if you lose a large amount of blood or fluid
  • lack of oxygen
  • your body being very hot or very cold
  • a blood clot in the lung or coronary arteries

A cardiac arrest is different from a heart attack

A heart attack usually happens because you have coronary heart disease.  If you have a heart attack, you do not always experience the life threatening rhythms that can lead to a cardiac arrest.

A cardiac arrest does not always happen because you have a heart condition. If a person has a cardiac arrest, they become unresponsive and lose consciousness almost at once. There are no other signs of life - such as normal breathing - and the person may turn grey very quickly.

A cardiac arrest is the ultimate medical emergency.  If someone has a cardiac arrest, it is sometimes possible to shock the heart back into a normal heart rhythm by giving the heart an electrical shock using a defibrillator.

This is an emergency and if you witness a cardiac arrest you should call 999 immediately.

Links to the Original paper on chain of survival:

The Chain of Survival

Sudden Cardiac Arrest