What is Brugada Syndrome?
Brugada syndrome is an inherited condition that increases the risk of serious heart rhythm disorders. It was first identified by Josep and Pedro Brugada in 1992. The disease can be recognized by two specific signs in an electrocardiogram (ECG), a test that measures the electrical activity of the heart. These are a right bundle branch block, which is a delay or obstruction along the pathway that electrical currents travel to make the heart beat, and ST-segment elevations in the right precordial leads (V1-V3), which are specific areas on the ECG.
What Causes Brugada Syndrome?
The first genetic link found with Brugada syndrome was a change in the gene responsible for the sodium channels in the heart, called SCN5A. This change, which affects how the gene functions, is thought to be present in 15-30% of Brugada syndrome cases.
Other genetic changes have also been discovered related to Brugada syndrome, particularly those affecting calcium and potassium channels, proteins related to these channels, and proteins located in cell junctions.
The syndrome is typically inherited in a pattern where one copy of the changed gene in each cell is enough to cause the condition. However, people who inherit the gene don’t always exhibit symptoms or they exhibit differing severity of symptoms. This could be due to a variety of influences from both genes and environment, such as temperature, medications, electrolyte imbalances, and substance use like cocaine.
Risk Factors and Frequency for Brugada Syndrome
Brugada Syndrome is a condition that affects about 3 to 5 in every 10,000 people. It is usually 8 to 10 times more prevalent in adult men compared to women, however, this difference is not seen in children. The reason behind this could be related to changes in hormone levels after puberty and varying electrical currents in the body based on sex. People of Southeast Asian descent tend to be more affected by this syndrome. The average age of those impacted by Brugada Syndrome is 41 years old. Surprisingly, it causes 4% of all sudden deaths due to heart-related issues.
Signs and Symptoms of Brugada Syndrome
Brugada syndrome is a condition that affects the heart’s rhythm. Its symptoms can vary from person to person. Some people may not experience any symptoms at all. Others may experience severe symptoms, such as sudden cardiac death, which often happens during sleep. This could be due to an increase in the ‘vagal tone’, which helps control the heart rate. It’s also been observed that about 80% of people with Brugada syndrome who have issues with irregular heart rhythms or rapid heartbeats may experience fainting. Other possible symptoms include heart palpitations and dizziness.
People with Brugada syndrome might also see an increase in symptoms when they have a fever because it can trigger these irregular heart rhythms. Interestingly, 10 to 30% of patients with Brugada syndrome may have an irregular heartbeat that starts in the atria (the upper chambers of the heart); this is higher than the general population. Nevertheless, it’s important to note that 72% of people diagnosed with Brugada syndrome won’t show any symptoms, and 28% won’t have a family history of sudden cardiac death.
Testing for Brugada Syndrome
To identify and create a treatment plan for Brugada syndrome, a type of heart rhythm disorder, a comprehensive 12-lead electrocardiogram (ECG) is necessary. This test can present three different patterns: a curved ST elevation more than 2 mm with an inverted T wave (type 1); a saddleback-shaped ST elevation more than 2 mm (type 2); and a saddleback-shaped ST elevation less than 2 mm (type 3).
In some cases, individuals who have a regular ECG but display high-risk factors may need to undertake a drug challenge test. In this method, typical ECG findings are revealed by encouraging ST elevations in the heart readings from V1 to V3. High-risk factors that could trigger this test include having a family history of Brugada syndrome or sudden heart failure and symptoms similar to Brugada syndrome along with questionable ECG abnormalities.
The medications used in the drug challenge test are Class IA antiarrhythmics (like procainamide and ajmaline) and IC antiarrhythmics (such as flecainide and propafenone), which are sodium channel blockers. ECG readings indicating Brugada syndrome can also come about after cocaine usage or the toxicity of tricyclic antidepressants. Furthermore, certain abnormalities in chemicals in the body, namely high levels of potassium and calcium, can prompt ST elevations in the right heart readings.
When performing drug challenge tests on children, it may be necessary to repeat the process once the child reaches puberty due to hormonal changes that could affect Brugada syndrome characteristics. Another method to expose the ST elevations of Brugada syndrome is the full stomach test. This involves obtaining ECGs before and after having a big meal, which results in an enhancement in the vagal tone. In some cases, further tests like genetic testing for certain mutations and invasive electrophysiology could prove beneficial.
Treatment Options for Brugada Syndrome
An implantable cardioverter-defibrillator (ICD), a type of device that can correct an irregular heartbeat, is often used to treat patients with Brugada syndrome. It’s generally recommended for those who’ve survived a cardiac arrest, patients showing certain abnormalities on their ECG results associated with Brugada syndrome, and those who can exhibit these ECG changes during drug tests.
Pharmacological treatment, using a drug called quinidine, is another option for treating Brugada syndrome. However, there’s some disagreement on whether quinidine should replace ICD placement altogether. In some cases, quinidine is beneficial, especially for patients with Brugada syndrome who have an ICD and experience multiple shocks. It’s also a good option for people who can’t have an ICD for medical reasons.
There’s a new treatment option on the horizon too: radio frequency ablation of the front part of the right ventricular outflow tract, an area in the heart. This shows promising results for Brugada syndrome patients.
Things get a bit more complex when it comes to treating individuals who don’t show any symptoms but have ECG findings indicative of Brugada syndrome. In these cases, it’s crucial to personalize the treatment plan based on the patient’s specific risk factors. This involves a team of medical professionals and requires careful monitoring and regular check-ups.
What else can Brugada Syndrome be?
Several health issues that share similar symptoms with Brugada syndrome can often lead to confusion during diagnosis. A common symptom among these conditions is fainting (syncope). To properly evaluate this, doctors usually perform a 12-lead ECG (electrocardiogram). This test helps them identify diseases that may appear like Brugada syndrome. Some of these conditions include:
- QT prolongation (a heart rhythm disorder)
- Wolff-Parkinson-White syndrome (another type of heart condition)
- Pulmonary embolism (a blockage in the lungs)
- Sick sinus syndrome (an irregular heartbeat)
- Early repolarization syndrome (a rarely dangerous heart rhythm disturbance)
- Electrolyte imbalances (abnormal levels of minerals in the body)
- Atrial fibrillation (irregular and often rapid heart rate)