Brugada syndrome is an uncommon but serious heart condition. It can cause fainting and episodes of an abnormally rapid heart rhythm, called arrhythmia.
This happens because the electrical activity of the heart is disrupted – a problem that is usually inherited (see What is the cause? below).
Not everyone with Brugada syndrome will experience arrhythmia, when when it does happen, it can be fatal.
This page covers:
How can it be fatal?
What are the signs and symptoms of Brugada syndrome?
The warning signs of Brugada syndrome usually start in adulthood (at age 30-40), but may appear as early as infancy. They include:
- cardiac arrest – when an abnormal heart rhythm causes the heart to stop beating
- (sometimes) heart palpitations
How can it be fatal?
Sometimes, the abnormal heart rhythm persists, leading to ventricular fibrillation (a rapid, uncoordinated series of heart contractions).
Most of the time, this does not revert to normal heart rhythm without being corrected electrically, and usually causes the heart to stop pumping.
Brugada syndrome is a leading cause of sudden cardiac death in young, otherwise healthy people, and usually the cause of sudden arrhythmic death syndrome. It may explain some cases of sudden infant death syndrome, which is a major cause of death in babies younger than one.
Sadly, most deaths from Brugada syndrome will have happened without any warning sign of the disorder.
Who is affected?
Brugada syndrome typically affects young and middle-aged males who are otherwise healthy, although women can also be affected.
Men are more likely than women to show signs of it, possibly because of the sex hormone testosterone, which is thought to play a role.
What is the underlying cause of Brugada syndrome?
The heart of someone with Brugada syndrome is structurally normal, however there are problems with electrical activity. To properly understand the underlying cause, it is important to know how the heart cells work.
On the surface of each heart muscle cell are tiny pores, or ion channels. These open and close to let electrically charged sodium, calcium and potassium atoms (ions) flow into and out of the cells.
This passage of ions generates the heart's electrical activity. An electrical signal spreads from the top of the heart to the bottom, causing the heart to contract and pump blood. The box on this page (above left) explains in more detail how each heartbeat happens.
Inherited Brugada syndrome
People with hereditary Brugada syndrome will have inherited a mutated (altered) gene from one of their parents.
The SCN5A gene is most often involved, but this is only found in a quarter of famillies. This particular gene provides instructions for making a sodium channel that transports positively charged sodium ions into heart muscle cells.
The mutation in this gene will affect the proteins that make up the sodium channels, so they don't work as well. There is a reduced flow of sodium ions into the heart cells, which alters the way the heart beats.
Only one copy of the altered gene in each cell is needed to cause the disorder. In most cases, an affected person has just one parent with the condition.
Acquired Brugada syndrome
Not all people with Brugada syndrome will have this gene mutation, and there is not always a family history of it.
In those who appear to have acquired Brugada syndrome, the cause is unknown. However, certain drugs may play a role, including medication used to treat some forms of arrhythmia, angina, high blood pressure and depression.
Also, abnormally high blood levels of calcium or potassium as well as abnormally low levels of potassium have been associated with acquired Brugada syndrome.
How is it diagnosed?
If your doctor thinks you have Brugada syndrome after assessing your symptoms, they may ask you to have an electrocardiogram (ECG) and refer you to a heart specialist (cardiologist). This should usually be a cardiologist who specialises in heart rhythm and genetic heart problems.
An ECG is a test that records the rhythm and electrical activity of your heart. Every time your heart beats, it produces tiny electrical signals, which an ECG machine traces onto paper.
Small stickers, called electrodes, are stuck onto your arms, legs and chest and connected by wires to the ECG machine.
If Brugada syndrome is suspected, you'll probably have a simple and safe test known as an ajmaline or flecainide challenge, to confirm your diagnosis.
Ajmaline and flecainide block sodium channels. They are given through a vein in your arm, and an ECG records how your heart responds to it. If given to someone with Brugada syndrome, they can reveal the abnormal ECG pattern that is characteristic of the syndrome.
If the ajmaline or flecainide test is negative, your doctor will consider your individual risk of Brugada syndrome and advise if further tests are needed, but you'll probably be able to go home the same day.
You may need to have an echocardiography and/or MRI scan to rule out other heart problems and causes of arrhythmia, and blood tests to measure blood potassium and calcium levels.
Genetic testing may also be carried out to identify the defective SCN5A gene that may be causing Brugada syndrome.
You and your family may be offered genetic testing if Brugada syndrome is diagnosed in a relative.
Learn more about genetic testing.
How is it treated?
The only proven effective treatment for Brugada syndrome is having an implantable cardiac defibrillator (ICD) fitted.
An ICD is similar to a pacemaker. If the ICD senses that your heart is beating at a potentially dangerous abnormal rate, it will deliver an electrical shock, which can help return your heart to a normal rhythm or get it pumping again.
An ICD will not prevent arrhythmia, but can treat ventricular tachycardia (the abnormally fast heart rate) and ventricular fibrillation (rapid heart contractions) when this happens, and will prevent sudden cardiac death.
The drugs quinidine or hydroquinidine have been proven to reduce the occurrence of ventricular tachycardia and ventricular fibrillation in patients with ICD implants. They have not been tested in patients without symptoms.