Cardiac arrest: recognising an immediate emergency
A person who is unresponsive and not breathing normally needs immediate emergency action.
Understanding cardiac arrest
Cardiac arrest is not the same as a heart attack, though the two are closely linked. In cardiac arrest, the heart's electrical system suddenly malfunctions, so the heart stops pumping blood effectively — it may quiver chaotically in a dangerous rhythm, or stop altogether. Without blood flow, a person collapses and loses consciousness within seconds and stops breathing normally. This is a life-threatening emergency at every stage, and outcomes depend heavily on how quickly the people nearby recognise it and start CPR, and how quickly a defibrillator and emergency care can be reached.
A heart attack, by contrast, is a blockage in an artery supplying the heart muscle — the heart usually keeps beating, though a heart attack can trigger the electrical chaos that leads to cardiac arrest. Because the two overlap, anyone who has collapsed should later be assessed for both, but the immediate bystander response is the same regardless of the underlying cause: recognise it and act at once.
Recognising cardiac arrest
Cardiac arrest can happen without warning, even in someone who seemed well moments earlier, or it can follow chest pain, palpitations or collapse. The rule for anyone nearby is simple and should never be second-guessed:
If someone is unresponsive AND not breathing normally, treat it as cardiac arrest — start CPR and call our 24/7 emergency line. Do not wait to check for other signs.
- ●Sudden collapse
- ●No response when spoken to loudly or gently shaken
- ●No normal breathing — or only occasional, irregular gasping
- ●No purposeful movement
- ●Skin may look unusually pale, grey or bluish
Occasional, irregular gasping in the first minutes is common in cardiac arrest and is not normal breathing — it should never be mistaken for a reason to wait. If you are unsure whether breathing is normal, treat it as cardiac arrest and start CPR.
Bystander action saves lives
- 01Check and call. Confirm the person is unresponsive and not breathing normally. Call Cardiocare's 24/7 emergency line and send someone to fetch an AED (automated external defibrillator) if one is nearby — but do not delay starting compressions while this happens.
- 02Start compressions. Push hard and fast in the centre of the chest, even if you are not trained. Aim for a fast, steady rhythm and let the chest rise fully between pushes.
- 03Use the AED as soon as it arrives. Switch it on and follow its voice prompts — it will guide you and will only advise a shock if the heart's rhythm needs one.
- 04Keep going. Continue compressions, following the AED's prompts, until professional help arrives and takes over. Swap with another helper if you tire, with as little interruption as possible.
You cannot make things worse for someone in cardiac arrest by attempting CPR. The greater risk is hesitating or doing nothing while waiting for someone else to act.
Call Cardiocare 24/7Why every minute matters
Without blood flow, the brain begins to be affected within minutes, so the time between collapse and the first compressions and shock strongly influences the outcome. Bystander action before professional help arrives — starting CPR and using an AED without waiting — makes a real difference.
What causes cardiac arrest
Cardiac arrest is usually the end result of an underlying heart problem reaching a critical point, though it can occasionally arise from a cause outside the heart.
Coronary artery disease and heart attack
Narrowed or suddenly blocked arteries are among the most common underlying causes, particularly in older adults — the disrupted blood supply can trigger a dangerous heart rhythm.
Cardiomyopathy and heart failure
An enlarged, thickened or weakened heart muscle, from any cause, makes dangerous rhythms more likely, even without a sudden blockage.
Inherited and structural rhythm problems
In younger people or those without obvious heart disease, an inherited electrical condition, a structural heart problem present from birth, or significant valve disease is more likely to be the cause — a reason family screening is sometimes recommended after a cardiac arrest.
Causes outside the heart
- ●Severe electrolyte disturbance (for example, dangerously abnormal potassium levels)
- ●Drowning or choking-related loss of oxygen
- ●Major trauma or severe blood loss
- ●Severe allergic reaction or a serious reaction to a medicine or substance
Who is at higher risk
These factors make cardiac arrest more likely, and are worth discussing at a cardiology review:
- ●Known coronary artery disease or a previous heart attack
- ●Heart failure or cardiomyopathy
- ●A family history of sudden cardiac death or an inherited rhythm condition
- ●Uncontrolled high blood pressure or diabetes
- ●Significant valve disease
- ●A previous dangerous heart rhythm or unexplained fainting episode
- ●Smoking or heavy alcohol use
What happens after cardiac arrest
Someone whose heart has been restarted needs close hospital monitoring — recovery and the risk of complications depend heavily on how long the brain and other organs went without blood flow, and on treating the underlying cause promptly.
Brain and organ effects. A period without blood flow can affect memory, thinking or physical function; the extent varies widely between individuals and often improves with time and rehabilitation.
Intensive monitoring. Admission to intensive or high-dependency care is usual, to support breathing, blood pressure and rhythm while the underlying cause is identified and treated.
Risk of recurrence. Without identifying and treating the underlying cause, cardiac arrest can recur — this is why thorough investigation after resuscitation matters as much as the emergency response itself.
Emotional impact. Surviving cardiac arrest, or witnessing one in a loved one, is frightening and can affect confidence and mood long afterwards; support and honest information help.
How Cardiocare investigates after resuscitation
Once a person is stabilised, finding the underlying cause guides how future risk is managed:
- 01Emergency stabilisation and ICU/HDU care. Continuous monitoring of breathing, circulation and heart rhythm while the immediate cause is assessed.
- 0212-lead ECG and continuous rhythm monitoring. Records the heart's electrical activity and watches for further dangerous rhythms.
- 03Blood tests. Checking electrolytes, heart-muscle markers, kidney function and other factors that may have contributed.
- 04Echocardiogram. A painless ultrasound scan showing the heart's structure and pumping function.
- 05Coronary angiography. Using Cardiocare's on-site cardiac catheterisation ("cath") laboratory to look for blocked or narrowed arteries.
- 06Electrophysiology (EP) study. For selected cases, a catheter-based test maps the heart's electrical pathways to find the source of a dangerous rhythm.
- 07Screening for inherited conditions. Where no other cause is found, especially in younger patients, assessment for inherited heart conditions, sometimes extending to close family members.
Treating the cause and preventing recurrence
Treatment is directed at whatever caused the cardiac arrest, alongside measures to reduce the risk of it happening again.
Treating the immediate cause
Blocked arteries may be treated with angioplasty and stenting or bypass surgery; abnormal electrolyte levels are corrected; other underlying conditions are treated directly.
Medicines, by class
Where medicine is needed to reduce future risk, your clinician will discuss the right option for you:
- ●Beta blockers — reduce the heart's tendency toward dangerous rhythms
- ●Rhythm-control medicines — help stabilise the heart's electrical activity
- ●Medicines for the underlying condition — such as heart failure or coronary artery disease treatment
Implantable cardioverter-defibrillator (ICD)
For many survivors, and for some people at high future risk who have not yet had a cardiac arrest, a small device implanted under the skin can continuously monitor the heart's rhythm and deliver an internal shock automatically if a dangerous rhythm recurs.
Family screening
Where an inherited condition is suspected, close family members may be offered assessment, since the same risk can run in families without previously causing symptoms.
Living well after cardiac arrest
Recovery continues well beyond hospital discharge:
- ✓Take all prevention medicines consistently, even when feeling completely well
- ✓Attend cardiac rehabilitation and follow-up appointments as arranged
- ✓If an ICD has been fitted, learn its basic care and what to do if it activates, and keep device follow-up appointments
- ✓Discuss driving, work and activity with your clinician before resuming them
- ✓Allow time for emotional adjustment, and ask for support if anxiety, low mood or flashbacks persist
- ✓Encourage close family members to learn CPR — it is a skill anyone can use in an emergency
Preparing for your appointment
What to bring
- ✓Any hospital discharge summary or records from the emergency admission
- ✓A list of all medicines you currently take
- ✓Details of family history of sudden cardiac death or heart rhythm problems, if known
- ✓Your HMO card or payment details
- ✓A valid means of identification
What we will ask
What is known about the event itself, any symptoms beforehand, past medical history, medicines, and family history of sudden cardiac death or inherited heart conditions.
Questions worth asking us
- ●Has a cause been found, and what does it mean for the future?
- ●Do I need a defibrillator device?
- ●Should my family be screened or trained in CPR?
- ●When can I return to work, driving or my usual activities?