Cardiac arrest

A cardiac arrest happens when your heart suddenly stops beating. Here we explain the signs and symptoms of a cardiac arrest and explain what to do in the event of this medical emergency.

Key points

  • A cardiac arrest is a medical emergency when the heart stops beating.
  • A person in cardiac arrest will collapse, be unresponsive and stop breathing normally.
  • If you see a cardiac arrest call 111, start CPR and use an AED as soon as possible.
  • Minutes count in a cardiac arrest – starting CPR and using an AED increases someone’s chances of survival. You could save their life.

What is a cardiac arrest?

Cardiac arrest is when your heart stops beating. This stops oxygenated blood reaching your brain and other vital organs.

It can happen in people of any age, including children and teens.

If someone has a cardiac arrest, they will collapse and become unresponsive almost immediately. They won’t respond to touch or sound and they’ll stop breathing normally. Unless action is taken immediately, a cardiac arrest will cause death.

If you see someone having a cardiac arrest, you can increase their chance of survival by:

  • calling 111 immediately
  • doing CPR (cardiopulmonary resuscitation)
  • using an AED (automated external defibrillator).

Someone having a cardiac arrest outside of hospital is 2.8 times more likely to survive if a bystander performs CPR. CPR alone is not enough to save the life of someone in cardiac arrest; an AED is required to restart the heart.

What causes cardiac arrest?

A cardiac arrest can be caused by a range of heart-related problems.

  • Coronary artery disease - The most common cause, coronary artery disease, involves blockages that restrict blood flow to the heart, which can lead to a heart attack and cardiac arrest.
  • Heart attack - A heart attack can damage the heart muscle and disrupt its electrical signals, leading to cardiac arrest.
  • Heart muscle conditions - Conditions like cardiomyopathy (an enlarged or stiff heart) and other structural changes can cause abnormal heartbeats.
  • Heart rhythm disorders - Some rhythm conditions, such as Long QT syndrome, can cause electrical signalling problems that lead to cardiac arrest.

Cardiac arrest can also happen as a result of issues not related to heart disease, including things like electrocution and drug overdose.

What are the signs and symptoms of cardiac arrest?

A cardiac arrest can occur without any warning signs. When someone is in cardiac arrest they:

  • will collapse suddenly
  • will be unresponsive
  • won’t respond to touch or sound
  • will stop breathing normally – or may make gasping, snorting, gurgling or moaning sounds.

Immediate treatment for cardiac arrest

Emergency cardiac arrest response steps showing call 111 for help, begin CPR with chest compressions, and use an AED, presented with simple icons and instructions

A cardiac arrest is a medical emergency. If not treated quickly, it will cause death.

If you see someone having a cardiac arrest, follow these steps:

  • CALL 111 immediately
  • Start CPR
  • Use an AED as soon as available

It doesn’t matter if you haven’t been trained in CPR. The 111 operator will provide instructions until emergency services take over.

Minutes count in a cardiac arrest – starting CPR and using an AED as soon as possible gives someone the best chance of survival.

What is CPR?

CPR (cardiopulmonary resuscitation) is a combination of rescue breathing and chest compressions.

It involves pushing hard and fast in the middle of the chest.

CPR keeps oxygen moving from the lungs to the brain and other vital organs.

CPR won’t get the heart beating normally again, but it can support the heart, brain and other vital organs until an AED can reset the heart rhythm.

How to do CPR

What is an AED?

An AED (automated external defibrillator) is a safe and simple to use machine that gives an electric shock to restore the heart’s normal rhythm when someone is in cardiac arrest.

You can use an AED without any training. The machine will give you step-by-step instructions on what to do. It will increase someone’s chance of survival.

You cannot accidentally shock someone; an AED guides you through CPR and decides when a shock is required.

Where can I find an AED?

AEDs are usually located in public places such as community centres, supermarkets and sports facilities.

There are thousands of them across New Zealand. The website AED Locations shows you the closest available defibrillator.

You can also download the AED Locations app:

Another app, GoodSAM, can alert people trained in CPR to a nearby cardiac arrest.

What happens after a cardiac arrest?

Longer term treatment for a cardiac arrest will depend on the cause.

Most people will go on heart medication. Some people may get an ICD (implantable cardioverter defibrillator).

Other people may have angioplasty, bypass surgery or other corrective surgery.

What’s the difference between a heart attack and a cardiac arrest?

Illustration comparing cardiac arrest as an electrical problem causing unresponsiveness, and heart attack as a plumbing problem with blocked arteries, both requiring immediate medical attention

A heart attack is not the same as a cardiac arrest. They are two different types of heart event.

A cardiac arrest is when the heart stops beating. It is caused by a problem with the heart’s ‘electrical system’. The person will collapse, be unresponsive and won’t breathe normally.

During a heart attack, a blockage cuts off blood flow to the heart muscle, but the heart will continue to beat. It is a problem with the heart’s ‘plumbing’.

Sometimes a heart attack can cause a cardiac arrest.

Although they are different, heart attacks and cardiac arrests are both medical emergencies. Call 111 immediately.

Stories from people who’ve had a cardiac arrest

Heart conditions