A cardiac arrest is when the heart suddenly stops pumping blood around the body. The person collapses and becomes unconscious, and stops breathing or breathing normally. It is a medical emergency and the person will die without urgent medical help. Without help, the brain quickly becomes starved of oxygen and will be damaged.

The most common cause of a cardiac arrest is an abnormal heart rhythm called ventricular fibrillation (VF). This means that the electrical activity of the heart is chaotic and so the heart muscle does not contract in the normal ordered way. It can be triggered by various heart conditions, for example heart valve disease, heart attack and cardiomyopathy. There are other causes of cardiac arrest including electrocution and drug overdose.


When someone suffers a cardiac arrest, they need immediate cardiopulmonary resuscitation (CPR) and defibrillation to have the best chance of survival. Performing CPR keeps blood and oxygen flowing to the brain and body until the emergency services arrive. In some cases, CPR can more than double the chance of survival. A defibrillator delivers a controlled electric shock to try and to restore a normal rhythm.


A heart attack is not the same as a cardiac arrest. A heart attack is when the blood supply to the heart muscle is cut off and a cardiac arrest is when the heart suddenly stops beating. However, a heart attack can lead to a cardiac arrest.

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