Sudden Cardiac Arrest (SCA) is the unexpected cessation of an organised heartbeat — the heart stops, without warning, in anyone, at any time, anywhere. It is potentially reversible, with a high likelihood of successful resuscitation if defibrillation and CPR are provided quickly.
What Causes Sudden Cardiac Arrest?
There are many causes. Common ones include:
- Heart disease — the most common underlying cause
- Coronary artery blockage (“heart attack”) — a blocked artery cutting off blood supply to the heart muscle
- Electrical arrhythmia — a fault in the heart’s electrical conduction system causing a chaotic or absent rhythm
- Lack of oxygen — for example, severe asthma, drowning or airway obstruction
- Electrocution
- Trauma
Importantly, Sudden Cardiac Arrest is not the same as a heart attack, although a heart attack can trigger one. A heart attack is a circulation problem — a blockage. Cardiac arrest is an electrical problem — the heart stops pumping altogether.
What Does It Look Like?
When the heart stops suddenly, the victim rapidly becomes unresponsive and unconscious. Signs to look for:
| Sign | What You May See |
|---|---|
| Unresponsive | Does not respond to voice or touch — unconscious |
| Absent or gasping breathing | Not breathing normally — may have occasional gasps (agonal breathing). This is not normal breathing. Treat as cardiac arrest. |
| No signs of life | No movement, no response to stimulation |
| Colour change | May appear pale, grey or blue — particularly around the lips |
| Fitting-like movement | May appear to be fitting or convulsing — this can be mistaken for a seizure |
Time is critical.
After approximately three minutes without circulation, the brain and vital organs begin to die. Without prompt treatment, survival is unlikely. Every minute without defibrillation reduces the chance of survival by approximately 10%.
What Should You Do?
If you witness a Sudden Cardiac Arrest, act immediately:
- Follow DRSABCD — the standard emergency action plan
- Call 000 immediately — see our tips for calling an ambulance
- Begin CPR — push hard and fast on the centre of the chest
- Apply the nearest AED / defibrillator as soon as it arrives and follow its instructions
- Continue until paramedics take over
The combination of early CPR and early defibrillation gives the patient the best possible chance of survival. Neither alone is as effective as both together.
Have questions about Sudden Cardiac Arrest?
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