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Cardiac Arrest

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What is a cardiac arrest?

Contrary to popular belief, a cardiac arrest is not a heart attack. A heart attack occurs when the blood supply to the heart is cut off. This is often caused by a clot in a coronary artery. During a heart attack, the heart is still pumping blood around the body and the person will continue to be conscious and breathing. This can lead to a cardiac arrest and if you’re experiencing heart attack symptoms, it’s vital that you immediately call 999 for an ambulance.

However, a cardiac arrest usually happens without any signs or warning. If somebody is in cardiac arrest, they will collapse suddenly, be unconscious/unresponsive, and will either not be breathing or be struggling to breathe, i.e., making gasping noises.

Without immediate treatment or medical attention, the person will die. If you see somebody having a cardiac arrest or suspect that they may be, call 999 immediately and perform CPR.

What causes a cardiac arrest?

The main causes of cardiac arrest are:

  • Ventricular fibrillation (an abnormal heart rhythm where the electrical activity of the heart is so erratic that the heart stops pumping and just quivers)
  • heart attack (caused by coronary heart disease)
  • cardiomyopathy
  • congenital heart disease
  • heart valve disease
  • inflammation of the heart muscle

However, cardiac arrest can also happen as a result of electrocution, a drug overdose, severe haemorrhage (internal bleeding), or hypoxia (low oxygen levels).

How is a cardiac arrest treated?

If you witness somebody going into cardiac arrest, immediately call 999. Perform CPR on them as soon as possible if you are trained to do so. If you are not trained in CPR, look for someone with first aid or medical training who can perform CPR. CPR keeps oxygen and blood travelling to the brain, which slows brain damage and makes it more likely that the person will survive. Despite what you may have seen on TV, CPR will not stop the cardiac arrest – but it will keep the person alive until the medical team can arrive, and can reduce the lasting damage they experience.

A defibrillator can then be used to deliver a controlled electric shock, which helps towards getting the heart beating regularly again. Defibrillators are used by ambulance staff, but increasingly, many public buildings have defibrillators for emergency use too. You should only use a defibrillator on someone if you are confident that you know how to use it properly.

Cardiac arrest recovery

Recovery from cardiac arrest depends on:

  • How bad the arrest was
  • The symptoms since your arrest
  • The root cause of your cardiac arrest
  • Recovery can be a long, complicated process with many changes and decisions to make along the way. You may be fitted with a pacemaker, enter rehabilitative care, or even be placed into an induced coma.

    Your treatment team will guide you through your care plan and help you to make the best choices for you and your health.

We’re here to help

Such a lifechanging experience can be very daunting and frightening. Remember: you are not alone. CHSS offer trained nurses and care providers who can support you through the months following leaving hospital.

We also have support groups, so that people who have experienced a cardiac arrest can help one another come to terms with the trauma, and can learn to live a life that they love again.

If you’d like to learn more about us and what we can do to support you, give our Advice Line nurses a call on 0808 801 0899 for free, confidential advice and support.

Visit our Living with a Heart Condition section for more information about how to manage your condition at home, how to stay well, and how to reduce your risk of future heart problems.

This page was last updated on May 2, 2023 and is under regular review. If you feel anything is missing or incorrect, please contact to provide feedback.

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