Cardiac Arrest

What is a cardiac arrest?

A sudden cardiac arrest is an electrical problem in the heart and occurs when the heart suddenly stops pumping blood. If a sudden cardiac arrest is not treated properly and quickly, it will cause sudden death within 10 minutes.

What are the symptoms of a cardiac arrest?

The symptoms of sudden cardiac arrest are immediate and drastic. They include:

Other signs and symptoms may occur before a sudden cardiac arrest, such as fatigue, fainting, blackouts, dizziness, chest pain, shortness of breath, weakness, palpitations or vomiting. However sudden cardiac arrest often occurs with no warning.

Urgent treatment is required to ensure blood flow around the body is restored, and the heart begins beating again.

What to do if you think someone is having a cardiac arrest?

  1. Call Triple Zero (000) or your local emergency service
    A heart attack is a medical emergency, do not ignore the signs. If you suspect someone is having a heart attack, do not delay, call Triple Zero (000) immediately if you are in Australia. The sooner a person can get to a hospital, the better the chance of survival. Do not attempt to drive if you are suffering an arrest. If an ambulance is not available, ask a neighbour or bystander to drive you to hospital.
  2. Begin CPR
    If the person is unconscious or not breathing, call for emergency assistance then immediately begin CPR. Push hard and fast in the centre of the person's chest. CPR can save lives.
  3. Use an AED
    If the person is unconscious and an automated external defibrillator (AED) is immediately available, follow the device instructions and voice prompts until emergency assistance arrives.

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

A sudden cardiac arrest differs from a heart attack. A heart attack occurs when one of the coronary arteries in the heart becomes blocked. Without adequate blood supply, the heart muscle is starved of oxygen and if left untreated it will begin to die. A cardiac arrest is the sudden loss of heart function, breathing and consciousness. It is typically caused by an electrical disturbance in the heart which stops the heart from pumping entirely.

What are the causes of a cardiac arrest?

The immediate cause of sudden cardiac arrest is usually an abnormality in your heart rhythm, known as an arrhythmia.

The most common cause of cardiac arrest is ventricular fibrillation, an arrhythmia where rapid, erratic electrical impulses, cause your heart chambers or ventricles, to quiver uselessly instead of pumping blood.

Deadly arrhythmias do not usually occur on their own. People with normal, healthy hearts may suffer a cardiac arrest due to an outside trigger such as an electrical shock, the use of illegal drugs or trauma to the chest at the wrong time of the heart’s cycle. 

However a cardiac-arrest-inducing arrhythmia usually develops in someone with a pre-existing heart condition. These include:

How is a cardiac arrest diagnosed?

Sudden cardiac arrest often occurs with no warning and there is a 90% chance of death if it occurs outside a hospital. If you survive a sudden cardiac arrest, your doctor will want to investigate what caused it to identify the underlying cause. Tests may include:

  • Electrocardiogram
  • Blood tests
  • Imaging tests such as chest x-rays, echocardiogram, nuclear scan
  • Electrical system (electrophysiological) testing and mapping
  • Coronary catheterization (angiogram)
  • Genetic tests

How is a cardiac arrest treated? 

Immediate action is required in order to survive a sudden cardiac arrest.  The first 3-5 minutes are the key to survival. The following steps must be taken urgently:

  • Cardiopulmonary resuscitation (CPR) – urgent CPR is critical. By maintaining a flow of oxygen-rich blood to the body’s vital organs, CPR can provide a vital link until more-advanced emergency care is available.
  • Defibrillation – A portable device which momentarily stops the heart and the chaotic rhythm, often allowing the normal heart rhythm to resume. The procedure delivers a therapeutic dose of electric currents to the heart. If a defibrillator is available, it should be used as soon as possible.

Long term treatment includes:

  • Anti-arrhythmic medication
  • Implantable cardioverter defibrillator (ICD)
  • Coronary angioplasty
  • Coronary bypass surgery
  • Radiofrequency catheter ablation
  • Corrective heart surgery

Can a cardiac arrest be prevented? 

There is no definite way to know your absolute risk of sudden cardiac arrest, so reducing your overall risk is the best strategy. This includes regular check-ups at your GP, screening for heart disease and living a healthy lifestyle, for example:

If you have a pre-existing heart condition and are at high risk of a sudden cardiac arrest, you may need the following treatment/s:

  • Anti-arrhythmic drugs
  • Implantable cardioverter-defibrillator (ICD)
  • Purchase an automated external defibrillator (AED)
  • Ensure people around you (family, at work) know CPR

How common are cardiac arrests?

  • Around 20,000 Australians suffer a cardiac arrest outside a hospital every year. Only 10% of people will survive an out of hospital cardiac arrest.

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Acknowledgement of Country

The Victor Chang Cardiac Research Institute acknowledges the traditional custodians of the land, the Gadigal of the Eora nation, on which we meet, work, and discover.
Our Western Australian laboratories pay their respect to the Whadjuk Noongar who remain as the spiritual and cultural custodians of their land.