Cardiac arrest: symptoms, causes, CPR and recovery

The BHF explains that a cardiac arrest happens when your heart’s electrical system does not work properly and your heart starts beating too quickly, too slowly or irregularly. This abnormal heart rhythm is called an arrhythmia. Not all abnormal rhythms are life-threatening, but some mean that the heart cannot pump blood around the body. Rhythms that can lead to cardiac arrest include ventricular fibrillation (VF), ventricular tachycardia (VT) and supraventricular tachycardia (SVT).

The BHF says a cardiac arrest is an emergency that usually happens without warning. Without immediate treatment, the person will die.

If someone is in cardiac arrest, the BHF says they collapse suddenly and will be unconscious, unresponsive and not breathing or not breathing normally, and they may make gasping noises. St John Ambulance advises ignoring occasional, irregular gasps, as these are common in the early stages of cardiac arrest.

For an adult who is unresponsive and not breathing normally, you need to call 999 or 112 for emergency help and start CPR straight away.

The two are often confused. The NHS says that cardiac arrest is when your heart stops suddenly and causes you to lose consciousness; it is life-threatening but different to a heart attack and needs different treatment. A heart attack can be a cause of cardiac arrest.

The BHF says some conditions can cause abnormal heart rhythms and in turn a cardiac arrest if they are severe or left untreated: cardiomyopathies (diseases of the heart muscle), inherited heart conditions that affect the heart’s electrical system such as Brugada syndrome, congenital heart disease, heart failure, heart valve disease, and severe or untreated myocarditis.

Other causes it lists are a heart attack, often caused by coronary artery disease, losing a large amount of blood (severe haemorrhage), a sudden drop in oxygen levels (hypoxia), being electrocuted and a drug overdose.

The BHF says that if you are with someone having a cardiac arrest you should call 999 and start CPR immediately, following the instructions of the 999 operator until the emergency services arrive. If someone is with you, ask them to go and get a defibrillator, which gives a controlled electric shock to try to get the heart beating normally. You do not need training to use one, because the machine talks you through the steps.

St John Ambulance describes the steps for an adult in the table. The ambulance controller can tell your helper where the nearest defibrillator is. If you are on your own, use the hands-free speaker on a phone so you can start CPR while speaking to ambulance control.

The BHF says that after a cardiac arrest you are looked after in a coronary care or intensive care unit where you can be closely monitored, and you may be kept asleep (induced coma) to allow your body to recover. Doctors then want to work out what caused the arrest and can recommend medicines and treatments to reduce the risk of it happening again, such as an implantable cardioverter defibrillator (ICD) or ablation, and may refer you to cardiac rehabilitation.

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

The BHF says a lack of oxygen to the brain during a cardiac arrest can sometimes have long-term effects, including personality changes, memory problems, tiredness, dizziness or balance issues, problems with speech and language, involuntary muscle movements (myoclonus) and permanent brain injury. Specialist support such as speech and language therapists or an occupational therapist can help.

It is normal to have no memory of a cardiac arrest, and you may feel low, angry, confused or a mix of emotions. It can also be difficult for family members who saw it happen. The BHF suggests speaking to your doctor about counselling and refers people to Sudden Cardiac Arrest UK for peer support.

The BHF says your doctor may suggest lifestyle changes to reduce your risk of another cardiac arrest, including a healthy diet, quitting smoking, cutting down on alcohol, being physically active and taking medicines and following treatments from your doctor. It says that in England you can get an NHS Health Check to assess your risk of heart disease, kidney disease and stroke, and that elsewhere in the UK you should contact your GP.

Learning CPR matters because many of us will witness a cardiac arrest. The BHF offers a free online CPR training course that takes around 15 minutes.

Cardiac arrest is an emergency handled through 999, ambulance and hospital care. The BHF says that after a cardiac arrest doctors work out what caused it, can recommend medicines and treatments such as an implantable cardioverter defibrillator (ICD) or ablation, and may refer you to cardiac rehabilitation.

Private cardiology services can offer follow-up tests and consultations, but initial emergency treatment is always through the NHS. Ask your team who will organise family screening if an inherited heart condition is suspected.