Cardiac arrest

What are the symptoms of a cardiac arrest?

A cardiac arrest is an emergency that usually happens without warning. If someone is in cardiac arrest, they collapse suddenly and:

• will be unconscious
• unresponsive, and
• not breathing or not breathing normally – this may mean they’re making gasping noises.

Without immediate treatment, the person will die. If you see someone having a cardiac arrest, phone 999 immediately and start CPR.

What causes a cardiac arrest?

A cardiac arrest is caused by a dangerous abnormal heart rhythm (arrhythmia), which happens when the electrical system in the heart isn’t working properly. Not all abnormal heart rhythms are life-threatening, but some mean that the heart cannot pump blood around the body.

Ventricular fibrillation (VF) is an example of a dangerous heart rhythm that can lead to a cardiac arrest. This is when the heart quivers or ‘fibrillates’ instead of pumps. Common arrhythmias like atrial fibrillation aren’t life-threatening although they cause irregular, fast heart rhythms.

Some conditions can cause abnormal heart rhythms and in turn, a cardiac arrest if they're severe or left untreated:

• cardiomyopathies (disease of the heart muscle) and inherited heart conditions which affect the electrical system of the heart, such as Brugada syndrome
• congenital heart disease – a heart condition or defect you get before you’re born
• heart valve disease – when one or more of your heart valves don’t work properly
• severe or untreated myocarditis - inflammation of the heart muscle.

Other causes of cardiac arrest include:

• a heart attack (often caused by coronary heart disease)
• a severe haemorrhage (losing a large amount of blood)
• hypoxia - a severe drop in oxygen levels
• electrocution
• a drug overdose

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

A heart attack happens when the blood supply to the heart muscle is cut off. This is often caused by a clot in one of the coronary arteries. The heart is still pumping blood around the body during a heart attack. The person will usually be conscious and breathing.

A heart attack can lead to a cardiac arrest as you’re at higher risk of having ventricular fibrillation. It's important to get medical attention immediately by calling 999 for an ambulance if you have heart attack symptoms.

How is a cardiac arrest treated?

A cardiac arrest is an emergency. If you're with someone who's having a cardiac arrest, call 999, start CPR and use a defibrillator if there’s one nearby. Follow instructions from the 999 operator until emergency services take over.

Starting immediate CPR is vital as it keeps blood and oxygen moving to the brain and around the body. A defibrillator will then deliver a controlled electric shock to try and get the heart beating normally again.

Public access defibrillators are often in places like train stations and shopping centres. Anyone can use one and you don't need training to do so.

Recovery after a cardiac arrest

Immediate recovery

After a cardiac arrest, you’ll be looked after in a coronary care or intensive care unit. This is where people who need special monitoring go so a close eye can be kept on them. You may be put in an induced coma and kept asleep to allow your body to recover.

Mid-term recovery

Doctors will want to work out what caused the cardiac arrest. They can then recommend medication and treatment, such as a pacemaker or implantable cardioverter defibrillator (ICD), to reduce the risk of it happening again.

They may also refer you to cardiac rehabilitation to help rebuild your confidence, fitness and strength levels. Each programme is different, but it usually involves regular assessments such as checking your pulse and blood pressure, psychological support, health education talks and exercise sessions.

Long-term recovery

The time it takes to recover depends on what caused your cardiac arrest and how long it took for your heart to beat on its own again after the arrest. It could take several weeks, a few months or longer if you need more rehab for things like learning to walk and caring for yourself again.

However long it takes, your doctor will support you during this time. Talk to family and doctors about what will happen once you go home and practical matters, like driving and returning to work.

• Read what Sarah, a nurse, learned after suffering a cardiac arrest when she was 50. 

Are there long-term effects after a cardiac arrest?

A lack of oxygen to the brain during a cardiac arrest can sometimes have long-term effects on your brain. Effects can include:

• personality changes
• problems with memory
• feeling tired
• dizziness or balance issues
• aphasia/dysphasia (problems with speech and language)
• myoclonus (involuntary movements)
• permanent brain injury.

If you have some of these long-term problems, your doctor can help you get specialist support like speech and language therapists or an occupational therapist.

It’s normal to have no memory of a cardiac arrest and you may feel low, angry, confused or a combination of lots of different emotions due to the shock of the experience. It can also be difficult for your family members who may have seen it happening. Speak to your doctor if you’re concerned about your mental health as they may be able to refer you to counselling.

Our emotional wellbeing webpages also have information about topics such as anxiety and depression, caring for someone who's had a cardiac arrest and life after you’ve given someone CPR.

How can I reduce my risk of having a cardiac arrest?

Your doctor may suggest making lifestyle changes to reduce your risk of another cardiac arrest. This can include:

• eating a healthy diet
• quitting smoking
• cutting down on alcohol
• taking medications and following treatments from your doctor
• being physically active.

You’re able to get an NHS Health Check for your risk of heart disease, kidney disease, stroke and other issues if you live in England. If you live elsewhere in the UK, contact your GP about getting checked for your risk of heart disease.

Heart Helpline and other support

• speak to our cardiac nurses by phone, callback, email or online chat on Heart Helpline (Monday to Friday, 9am to 5pm)
• contact us to talk to our customer care advisors, find your local BHF shop and for any comments, compliments and complaints you may have
• sign up to our Heart Matters magazine for online information packed with health and lifestyle advice
• find more support from Sudden Cardiac Arrest UK, including meeting people who've had a cardiac arrest.