Cardiac arrest

A cardiac arrest occurs when your heart stops pumping blood around the body. Here we explain the signs, symptoms and causes of a cardiac arrest and explain what to do in the event of this medical emergency.

Cardiac arrest is a serious cardiac event that occurs when your heart stops pumping blood around the body. If you suffer a cardiac arrest you will stop breathing and lose consciousness almost immediately. Unless action is taken within minutes, cardiac arrest will be fatal.

If you believe someone has suffered a cardiac arrest call 111 immediately and, if possible, begin CPR and defibrillation [anchor to how to treat accordian].

Learn how to perform CPR with St John Medical Director, Dr Tony Smith

Find a defibrillator near you

The most common cause of a cardiac arrest is ventricular fibrillation (VF). In VF, the electrical activity of the heart becomes erratic, causing the heart to quiver or ‘fibrillate’ instead of beating normally. VF can be caused by a number of different heart-related problems, including:

Ventricular fibrillation can also happen as a result of events unrelated to heart disease such as:

  • Suffocation or choking
  • Electrocution
  • Loss of a lot of blood such as hemorrhage.

For many people, a cardiac arrest comes without any warning signs. However, some people do experience some warning signs before a cardiac arrest. These can include:

  • Chest pain
  • Dizziness
  • Palpitations
  • Fainting
  • Breathlessness

Someone who has already had a cardiac arrest will be:

  • Unconscious
  • Unresponsive
  • Not breathing

A cardiac arrest is a medical emergency which is often fatal. If you believe someone has had a cardiac arrest call 111 immediately and begin CPR and defibrillation.

CPR (cardiopulmonary resuscitation) is a combination of rescue breathing and chest compressions. It provides oxygen to the lungs and keeps oxygenated blood circulating until an effective heartbeat and breathing can be restored. By knowing and performing CPR, you may save a life.

Defibrillation is the use of an electric shock through the chest wall to correct the VF. It is carried out using a machine called a defibrillator.

Members of the public can access community defibrillators (known as Automated External Defibrillators (AEDs) at thousands of locations across New Zealand. The machines provide automated instructions on how to use them.

The charity St John offers a free app for iOS devices that provides a step by step guide to CPR and use of AEDs.

If a cardiac arrest occurs in hospital, a clinical team (often referred to as the "crash team") will be called to carry out CPR and defibrillation.

Long term treatment will depend on the cause of your cardiac arrest.

In some cases the condition will be managed by medication. Some people may have an Implantable Cardioverter-Defibrillator (ICD) inserted - a device which detects abnormal heart rhythm and shocks it back to a normal rhythm when necessary. Other people may require angioplasty, bypass surgery or other corrective surgery.

Heart attacks and cardiac arrest are frequently confused, but they are two different types of heart event.

A cardiac arrest occurs when the heart stops pumping blood around the body. Normal breathing stops and consciousness is lost. During a heart attack a person remains conscious and keeps breathing.

Sometimes a heart attack causes a cardiac arrest, but many do not. Similarly a cardiac arrest is not always caused by a heart attack.

Both cardiac arrest and heart attacks are medical emergencies. You should call 111 immediately if you suspect either.

Watch stories from survivors a cardiac arrest