Cardiac Arrest and Sudden Death Syndrome

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

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.

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.

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

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.

After the person who suffered a cardiac arrest has stabilised, their long-term treatment will depend on the cause of the cardiac arrest. If the cardiac arrest is related to a heart condition, tests will be required and treatment will depend on the underlying condition.

In some cases, the condition will be managed by medication. Some people, particularly those who experienced cardiac arrest due to SDS, may have an Implantable Cardioverter-Defibrillator (ICD) inserted – this is a device which detects abnormal heart rhythm and shocks it back to a normal rhythm when necessary.

Other people may require angioplasty (where a small balloon is inserted into obstructed blood vessels to open them up), bypass surgery, or other corrective surgeries.

A cardiac arrest occurs when the heart stops pumping blood around the body.

A heart attack, on the other hand, occurs when a coronary artery becomes blocked, preventing blood flow to part of the heart muscle.

During a heart attack a person remains conscious and keeps breathing. Sometimes, a heart attack can cause a cardiac arrest. This is because a person who is having a heart attack may develop a dangerous heart rhythm, which causes a cardiac arrest. Both a heart attack and a cardiac arrest are medical emergencies, and in both circumstances, you should call 999 or seek emergency medical help immediately.

A cardiac arrest occurs when the heart stops pumping blood around the body.

A heart attack, on the other hand, occurs when a coronary artery becomes blocked, preventing blood flow to part of the heart muscle.

During a heart attack a person remains conscious and keeps breathing. Sometimes, a heart attack can cause a cardiac arrest. This is because a person who is having a heart attack may develop a dangerous heart rhythm, which causes a cardiac arrest. Both a heart attack and a cardiac arrest are medical emergencies, and in both circumstances, you should call 999 or seek emergency medical help immediately.

The risk of cardiac arrest can be reduced by getting regular check-ups, being screened for heart disease and leading a heart-healthy lifestyle, including getting regular exercise and eating a balanced diet that is low in cholesterol and saturated fats.

For Sudden Death Syndrome, early diagnosis is an important step in preventing a fatal episode. If you have a family history of SDS, a doctor may be able to determine if you also have a syndrome that could lead to unexpected death, and subsequently take steps to prevent sudden death.

These may include: avoiding medications that trigger symptoms, such as antidepressants and sodium-blocking drugs; quickly treating fevers; exercising with caution; eating a balanced, heart-healthy diet; and maintaining regular check-ins with your doctor or cardiac specialist.