What is sudden cardiac arrest (SCA)?

A term many of us will have heard before, sudden cardiac arrest (SCA) is considered a medical emergency. But what does cardiac arrest actually mean? Well, if treatment isn’t received within minutes, the result will usually be fatal. With this in mind, learning more about the causes, signs and treatment of a sudden cardiac arrest is essential not only for medical professionals, but for members of the public as well.

What is sudden cardiac arrest?

Sudden cardiac arrest refers to a problem with the heart’s electrical system that causes it to suddenly stop beating normally. When this happens, the blood has no way of reaching the brain and other vital organs. If this is sustained for longer than a few minutes, the organs will be starved of oxygen and the person will die.

Why does this happen?
Glitches with the heart’s electrical system cause irregular heartbeats called arrhythmias. During an arrhythmia, the heart can beat too quickly, slowly, or with an irregular rhythm. However, some arrhythmias can cause the heart to stop beating, resulting in sudden cardiac arrest.

Find out the difference between a sudden cardiac arrest and heart attack.

Causes and risk factors
The majority of sudden cardiac arrests are caused by ventricular fibrillation (v-fib), a type of arrhythmia. During a v-fib, the heart’s ventricles don’t contract properly and instead ‘quiver’ very rapidly and irregularly. This leads to the heart not being able to pump blood around the body.

There are a number of conditions that can result in sudden cardiac arrest including:

Coronary heart disease – this disease causes a build-up of plaque in the coronary arteries. This can result in heart attack which can then trigger an SCA. cardiac arrest.
Physical stress – intense physical activity, extremely low levels of potassium or magnesium, severe lack of oxygen and extensive blood loss can all lead to a sudden cardiac arrest.
Heart structural changes – an enlarged heart due to high blood pressure, for instance, can result in sudden cardiac arrest.
Inherited disorders – a predisposition for arrhythmias can run in the family, putting an individual at higher risk of sudden cardiac arrest.

Who’s most at risk?
Although sudden cardiac arrests can happen to anyone, no matter your age, diet or fitness, there are a few factors that can increase their likelihood. As well as suffering from any of the above conditions, sudden cardiac arrest risk factors include drug and alcohol abuse and a personal history of arrythmias.

Your risk of sudden cardiac arrest also increases as you get older, and they are more common in men. What’s more, your diet and lifestyle could increase your risk of other conditions such as coronary heart disease and heart attacks, which are known causes of sudden cardiac arrest.

Symptoms and signs

There are often no signs to indicate an SCA is about to happen. However, some people may experience a racing heartbeat and dizziness before they collapse. Sudden cardiac arrest symptoms include:

• Loss of consciousness
• Unresponsiveness
• Not breathing, or not breathing normally

If you find someone in this state, immediate treatment is needed.


If you come across someone in sudden cardiac arrest, call 999 and start CPR straight away. They’ll also need immediate defibrillation to increase their chance of survival. For every minute that passes without defibrillation, a person’s likelihood of survival decreases by 10%. On average, emergency services in the UK take eight minutes to arrive, so having a defibrillator on hand can be the difference between life and death.

Not sure how to use a defibrillator? Here’s how it works.

An automated external defibrillator (AED) will shock the patient’s heart to try and return it to a normal rhythm. It only shocks the heart if it detects a dangerous arrhythmia, meaning you can’t accidently shock someone who won’t benefit from defibrillation.

If there is no defibrillator available, continue with CPR until the emergency services arrive. A person who has been shocked by a defibrillator will still need sudden cardiac arrest treatment by medical professionals, so calling the emergency services is essential even if you have access to a defibrillator.


Knowing how to prevent sudden cardiac arrests depends on whether you’re at high or low risk. If you’re a survivor of an SCA , your doctor may suggest you have an implanted cardioverter defibrillator (ICD) fitted. This monitors your heartbeat and will shock your heart if it detects a dangerous rhythm.

If you’re at high risk of suffering from an SCA, your doctor may prescribe you medications that’ll help decrease your chance of a heart attack, lower your blood pressure and prevent blood clots. If you think you may be high risk and aren’t currently taking any medications, talk to your GP.

For those who have no known sudden cardiac arrest risk factors, a healthy lifestyle can reduce your chance of an SCA. This requires:

• A healthy diet
• Regular exercise
• Maintaining a healthy weight
• Managing stress
• No smoking

For most of us, living a healthy lifestyle is the best way to reduce our chances of sudden cardiac arrest. However, if the situation arises, having access to a defibrillator could be essential to the survival of you, your colleagues, your friends or your pupils.

To find out more

To find out more about installing a defibrillator in your home, school, workplace or community space, get in touch with us today.

Posted on December 12, 2018