Brugada syndrome: what is it, symptoms, causes, treatment

What is Brugada Syndrome?

Brugada syndrome Is a rare hereditary disorder of the electrical system of the heart that can lead to ventricular fibrillation and sudden death in practically healthy young people. Unlike most other diseases that cause sudden death in young people, arrhythmiacaused by Brugada syndrome usually occurs during sleep rather than during physical activity or exercise.

The heart has its own electrical (conductive) system, consisting of an electrical impulse generator - the main driver rhythm (sinus node) - and pathways (atrio-ventricular junction, bundle of His and its branches) connecting the entire electrical chain.

The majority of people diagnosed with Brugada syndrome are middle-aged young adults, with an average age of 41 at the time of diagnosis. Brugada syndrome is much more common in men than in women - in some studies, the prevalence in men is nine times higher than in women.

In the United States, Brugada syndrome is believed to affect about one in 10,000 people. However, it is more common in people of Southeast Asian descent (approximately 1 in 100 people). The only cardiac abnormality is electrical; the hearts of people with Brugada syndrome are structurally normal.

Symptoms

The most devastating problem caused by Brugada syndrome is sudden death while sleeping. However, people with Brugada syndrome may experience episodes of dizziness, loss of balance or fainting (loss of consciousness) to fatal outcome. If the first signs come to the attention of a physician before death, a diagnosis and treatment can be made to prevent subsequent sudden death.

At first, Brugada syndrome was identified as a mysterious "sudden syndrome unexpected / unexplained nocturnal death ”, the condition was first described decades ago as a condition affecting young men in Southeast Asia. It has since been recognized that these young Asian men have Brugada syndrome, which is much more common in this part of the world than in most other places.

Causes and risk factors

Brugada syndrome appears to be caused by one or more genetic abnormalities that affect the cells of the heart, specifically in the genes that control the sodium channel. It is inherited in an autosomal dominant mannerbut not everyone with an abnormal gene or SCN5A genes is affected in the same way.

The electrical signal that controls the heart rate is generated by channels in the membranes heart cells, which allow charged particles (called ions) to flow back and forth through membrane. The flow of ions through these channels produces an electrical signal from the heart. One of the most important channels is the sodium channel, which allows sodium to enter the heart cells. In Brugada syndrome, the sodium channel is partially blocked so that the electrical signal generated by the heart is altered. This change leads to electrical instability, which in some circumstances can lead to ventricular fibrillation.

In addition, people with Brugada syndrome can take the form of dysautonomy - an imbalance between sympathetic and parasympathetic tone. It has been suggested that the normal increase in parasympathetic tone during sleep may be exaggerated in people with Brugada, and that this strong parasympathetic tone can cause instability of abnormal channels and lead to sudden of death.

Other factorsthat can cause fatal arrhythmias in people with Brugada syndrome include fever, cocaine use, and the use of various medications, especially some antidepressants.

Diagnostics

Electrical abnormalities caused by Brugada syndrome can result in a characteristic ECG pattern - the pattern named Brugada pattern. This circuit consists of a pseudo-right bundle branch block followed by ST elevations in leads V1 and V2.

Not everyone with Brugada syndrome has a "typical" Brugada ECG pattern, although they are likely to have other subtle changes. Thus, if Brugada syndrome is suspected (for example, due to fainting or sudden death of a family member while sleeping), any ECG abnormalities should be referred to an electrophysiologist to assess whether the person may have an “atypical” pattern Brugada.

If the person's ECG displays Brugada pattern, and if he had episodes of unexplained severe dizziness or fainting, the person suffered stopping there have been cases of sudden death in the heart or in the family before the age of 45, the risk of sudden death is high. However, if the Brugada pattern is present on the ECG, but none of the above signs and symptoms are present, the risk of sudden death is much lower.

People with Brugada Syndrome who are at high risk of sudden death should be treated aggressively. However, for those with Brudad's ECG pattern but no other risk factors, the decision about how aggressive the treatment should be is not so straightforward.

Electrophysiological research is used to help with more aggressive treatment by clarifying the risks of a person's sudden death. The ability of electrophysiological research to accurately assess risks is far from ideal. However, mainstream professional societies now support this study in people with Brugada ECG pattern without additional risk factors.

Genetic testing may help confirm the diagnosis of Brugada syndrome, but usually does not help in assessing a patient's risk of sudden death. In addition, genetic testing for Brugada syndrome is quite complex and often not clear-cut answers. Therefore, most experts do not recommend routine genetic testing in people with this condition.

Because Brugada syndrome is a genetic disorder that is often inherited, current recommendations require screening of all first-degree relatives of anyone diagnosed with it condition. Screening should consist of an ECG examination and a thorough medical history looking for episodes of fainting or severe and frequent dizziness.

Treatment

The only proven method of preventing sudden death in Brugada syndrome is to set implantable defibrillator. In general, antiarrhythmic drugs should be avoided. Because of the way these drugs act on channels in the membranes of heart cells, not only do they not reduce the risk of ventricular fibrillation in Brugada syndrome, but they may actually increase that risk.

Whether someone with Brugada Syndrome should have an implantable defibrillator installed depends on whether their risk of sudden death is definitively assessed as high or low. If the risk is high (based on symptoms or electrophysiologic testing), a defibrillator is recommended. But implantable defibrillators are expensive and carry their own complications, so if the risks of sudden death are assessed as low, these devices are not currently recommended.

Exercise recommendations

Whenever a young person is diagnosed with a heart condition that can lead to stopping it suddenly, it is necessary to ask the question of whether it is safe to perform various exercise. This is because most arrhythmias that lead to sudden death in young people are more likely to occur during exercise.

In contrast, in Brugada syndrome, fatal arrhythmias are much more likely to occur during sleep than during exercise. However, it has been suggested (with little or no objective evidence) that strenuous exercise may pose an increased risk of cardiac arrest than usual in people with this condition. For this reason, Brugada syndrome is included in the formal guidelines developed by expert groups, addressing exercise guidelines for young athletes with medical conditions hearts.

Initially, guidelines for sports with Brugada syndrome were rather restrictive. At the 36th 2005 Bethesda Conference on Recommendations for Athletes with Cardiovascular disorders, it was recommended that people with Brugada syndrome avoid high-intensity physical activity altogether. loads.

However, this absolute limitation was subsequently deemed too strict. Because the arrhythmias seen with Brugada syndrome do not usually occur during exercise, these recommendations were liberalized in 2015 in line with new guidelines from the American Heart Association and the American College cardiologists.

According to the latest 2015 guidelines, if young athletes with Brugada Syndrome did not have symptoms associated with physical activity, it is advisable for them to participate in competitive types sports if:

• They, their doctors, parents or guardians understand the risks involved and have agreed to take the necessary precautions.
• An automatic external defibrillator (AED) is a normal part of their personal sports equipment.
• Team officials are able and willing to use an automated external defibrillator and perform CPR (cardiopulmonary resuscitation) as needed.

To summarize

Brugada syndrome is a rare genetic disorder that causes sudden death, usually during sleep, in healthy young adults. The importance is to diagnose this condition before an irreversible event occurs. This requires doctors to be vigilant - especially for those who have had fainting spells or unexplained episodes of dizziness - of the delicate ECG data that is seen in Brugada syndrome.

People diagnosed with Brugada syndrome can almost always avoid death with appropriate treatment and expect to live a normal life.