SymptomHeart & circulation
Signs of Cardiac Arrest and What to Do
Cardiac arrest is when the heart suddenly stops pumping blood. The person collapses, does not respond, and is not breathing normally, sometimes making gasping sounds. Without help, death follows within minutes. If you see this, call 911 or your local emergency number, start hard, fast chest compressions in the center of the chest, and use an AED (automated external defibrillator) as soon as one arrives. Immediate CPR can double or triple the chance of survival.
Also called: Sudden cardiac arrest, cardiopulmonary arrest, heart stopped, collapse with no pulse
At a glance
- What you see
- Sudden collapse, no response, no normal breathing (or only gasps), no signs of life.
- What to do
- Call 911, push hard and fast on the chest (100 to 120 per minute), use an AED.
- Time matters
- Survival falls by roughly 7 to 10% for each minute without CPR or defibrillation.
- Warning signs (sometimes)
- Chest pain, fainting, palpitations or breathlessness in the hours to weeks before.
- Not the same as
- A heart attack, where the heart keeps beating but part of the muscle loses blood supply.
When to get help
Call 911 or go to the ER
- Someone collapses and does not respond to shouting or a firm tap on the shoulders: call 911 or your local emergency number and start CPR
- Not breathing, or only occasional gasping breaths (agonal breathing), even if the person seems to be "breathing"
- A brief seizure-like jerking at the moment of collapse followed by no normal breathing
- Chest pain, pressure or tightness lasting more than a few minutes
- Fainting during exercise, or fainting preceded by a racing heart
See a doctor within a day or two
- A pounding or racing heartbeat with dizziness, near-fainting or shortness of breath
- New chest discomfort or breathlessness with exertion that is getting worse over days
Book a routine appointment
- A family member who died suddenly and unexpectedly before age 50, or has an inherited heart condition: ask about screening
- Episodes of palpitations that come and go without other symptoms
How to recognize cardiac arrest
Cardiac arrest is recognized by three things:
- Sudden collapse. The person drops, often without warning.
- No response. They do not react when you tap their shoulders and shout.
- No normal breathing. They are not breathing, or they make slow, irregular gasps, snorts or gurgles. This is agonal breathing: it is a sign of cardiac arrest, not of recovery.
You do not need to check for a pulse. Even health professionals find pulse checks unreliable under stress. If someone is unresponsive and not breathing normally, treat it as cardiac arrest.
Some people have a brief seizure-like jerking for a few seconds as the brain loses blood flow. If normal breathing does not resume straight after, start CPR.
What to do: step by step
- Check safety and approach. Tap the shoulders firmly and shout, "Are you OK?"
- Call 911 or your local emergency number, or tell a specific person to call. Put the phone on speaker; the dispatcher will coach you.
- Send someone for an AED. They are in many offices, gyms, airports, schools and malls.
- Start chest compressions immediately: - Place the heel of one hand in the center of the chest, on the lower half of the breastbone, with the other hand on top. - Keep your arms straight and shoulders over your hands. - Push down hard, at least 5 cm (2 inches) in adults, and let the chest fully rise between compressions. - Go fast: 100 to 120 compressions a minute, the beat of "Stayin' Alive".
- Rescue breaths: if you are trained and willing, give 2 breaths after every 30 compressions. If not, hands-only CPR (continuous compressions) is effective for adults who collapse suddenly.
- Use the AED as soon as it arrives. Turn it on and follow the voice instructions. Attach the pads to bare skin as shown. Stand clear when it analyzes and shocks, then restart compressions straight away.
- Keep going until the person starts breathing normally, paramedics take over, or you are too exhausted to continue. Swap with another rescuer every 2 minutes if possible.
Children and babies
For children and babies, rescue breaths matter more, because their arrests are usually caused by breathing problems. Give 30 compressions to 2 breaths if you are trained. Compress about one third of the chest depth: about 5 cm (2 inches) in children and 4 cm (1.5 inches) in babies, using two fingers or two thumbs for an infant. Hands-only CPR is still far better than doing nothing.
Cardiac arrest vs heart attack vs fainting
| Cardiac arrest | Heart attack | Fainting | |
|---|---|---|---|
| What happens | Heart stops pumping, usually from a chaotic rhythm | A blocked artery starves part of the heart muscle | Brief drop in blood flow to the brain |
| Conscious? | No | Usually yes | Briefly no, recovers within a minute |
| Breathing | Absent or gasping | Present, may be short of breath | Normal |
| What to do | Call 911, CPR, AED | Call 911, rest, chew aspirin if advised | Lay flat, raise legs, get checked |
A heart attack can trigger cardiac arrest, which is why chest pain must be treated as an emergency. Fainting is usually harmless, but fainting during exercise can be a warning sign of a heart rhythm problem.
Warning signs before cardiac arrest
About half of people have symptoms in the hours, days or weeks before, though many dismiss them:
- chest pain or pressure, particularly with exertion
- shortness of breath
- palpitations or a racing heartbeat
- fainting or near-fainting, especially during exercise or when startled
- unusual fatigue
Reporting these symptoms promptly can allow treatment that prevents an arrest.
Why it happens
Most adult cardiac arrests are caused by a sudden chaotic heart rhythm called ventricular fibrillation, usually on a background of coronary artery disease. Other causes include inherited conditions such as hypertrophic cardiomyopathy and long QT syndrome, drowning, choking, opioid overdose, severe bleeding, and pulmonary embolism. For causes, risk factors, hospital treatment and outlook, see the cardiac arrest condition page.
What happens next
Paramedics continue CPR and defibrillation, secure the airway and give medicines. If the heart restarts, the person is taken to a hospital that can open blocked arteries and provide intensive care, including controlled temperature management to protect the brain.
Frequently asked questions
What are the first signs of cardiac arrest?
The person suddenly collapses, does not respond, and is not breathing normally. They may gasp or make gurgling sounds. Some people have chest pain, palpitations, breathlessness or fainting in the days or hours beforehand.
Can you survive cardiac arrest without CPR?
Rarely. Without blood flow, brain damage begins within 4 to 6 minutes. Immediate CPR and early use of an AED are the biggest factors in survival. Hands-only CPR by a bystander buys time until a defibrillator and paramedics arrive.
Is gasping a sign of breathing?
No. Slow, irregular gasping (agonal breathing) is a reflex from a brain starved of oxygen and is a common early sign of cardiac arrest. If an unresponsive person is only gasping, call 911 and start chest compressions.
Can I hurt someone by doing CPR?
Ribs sometimes crack during CPR, but this is far less serious than the alternative: without CPR, a person in cardiac arrest will almost certainly die. Good Samaritan laws in the US protect people who give CPR in good faith.
Do I need training to use an AED?
No. AEDs are designed for anyone to use. They give spoken instructions, analyze the heart rhythm automatically, and only deliver a shock if one is needed. Training makes you faster and more confident, so a CPR course is worth taking.
Sources
This guide was written from current patient and clinical guidance, including:
- American Heart Association: Guidelines for CPR and Emergency Cardiovascular Care
- American Heart Association: Hands-Only CPR
- American Red Cross: CPR steps
- NHS: How to do CPR on an adult
- National Heart, Lung, and Blood Institute: Sudden cardiac arrest