What is Cardiac Arrest, and how serious is it?

A cardiac arrest is when your heart suddenly stops pumping blood around your body. When your heart stops pumping blood, your brain is starved of oxygen, causing you to fall unconscious and stop breathing. A cardiac arrest usually happens without warning; if someone is in cardiac arrest, they will collapse suddenly, will be unconscious, unresponsive and will not be breathing normally – they may make gasping noises.

Without immediate treatment or medical attention, a person in cardiac arrest will die.

What are the signs and symptoms of Cardiac Arrest?

Aside from the immediate signs mentioned above, other signs and symptoms that can occur before cardiac arrest include:

• Chest discomfort
• Shortness of breath
• Weakness
• Heart palpitations
• Unexplained wheezing
• Light-headedness or dizziness

If you or anyone you are with experiences any of these signs or symptoms, call 999 or seek emergency medical help immediately.

What causes a Cardiac Arrest?

A common cause of a cardiac arrest is a life-threatening abnormal heart rhythm called ventricular fibrillation (VF). VF happens when the electrical activity of the heart becomes so chaotic that the heart stops pumping efficiently and quivers or ‘fibrillates’ instead.

The main causes of cardiac arrest related to the heart are:

• Heart attacks (caused by coronary heart disease)
• Cardiomyopathy
• Congenital heart disease
• Heart valve disease
• Acute myocarditis (which is an inflammation of the heart muscle)

Other causes of cardiac arrest include:

• Electrocution
• Drug overdose
• Severe blood loss (haemorrhage)
• Hypoxia



What is Sudden Death Syndrome (SDS)?

Sudden death syndrome (SDS) is a loose umbrella term for a series of cardiac syndromes that cause sudden cardiac arrest and can cause death if untreated. Some of these syndromes are the result of structural problems in the heart. Others may be the result of irregularities within the electrical channels in the heart – all may cause unexpected and abrupt cardiac arrest, even in people who are otherwise healthy, and some people may die as a result.

What are the signs and symptoms of Sudden Death Syndrome?

Unfortunately, the first symptom or sign of SDS can be sudden and unexpected death. However, SDS can cause the following red-flag symptoms:

• Chest pain, especially during exercise
• Loss of consciousness
• Difficulty breathing
• Dizziness
• Heart palpitations or fluttering feeling
• Unexplained fainting, especially during exercise

If you or anyone you are with experiences any of these symptoms, seek immediate medical attention. A doctor can conduct tests to determine what is the likely cause of these unexpected symptoms.

What causes Sudden Death Syndrome?

Unfortunately, it’s unclear what causes Sudden Death Syndrome. Genetic mutations have been linked to many of the syndromes that fall under the SDS umbrella, but not every person with SDS has these genetic mutations. It is possible other genes are connected to SDS, but these are yet to be identified, and some causes of SDS aren’t genetic at all.

Additionally, some medications can cause the syndromes that may lead to sudden death. For example, long QT syndrome may result from using:

• Antihistamines
• Decongestants
• Antibiotics
• Diuretics
• Antidepressants
• Antipsychotics

How is Cardiac Arrest and SDS treated?

A cardiac arrest is a medical emergency which is often fatal if not treated quickly with a combination of cardiopulmonary resuscitation (CPR) and defibrillation. If your heart stops beating due to SDS, the same measures should be taken as above.

Starting immediate CPR is vital as it keeps blood and oxygen circulating to the brain and around the body until an effective heartbeat and breathing can be restored. A defibrillator will then deliver a controlled electric shock to try and get the heart beating normally again. Public access defibrillators are often in locations like train stations and shopping centres – anyone can use one and you do not need training to do so.