Brugada syndrome is a rare genetic disorder that disrupts the heart’s normal rhythm, leading to irregular heartbeats. The condition is a channelopathy, involving a malfunction in the ion channels that coordinate the heart’s electrical impulses. This electrical abnormality increases the risk of dangerous heart rhythms and can occur in a structurally normal heart.
Causes and Risk Factors
The primary cause of Brugada syndrome is a genetic mutation inherited from a parent. A child has a 50% chance of inheriting the condition if one parent carries the affected gene. The most commonly identified gene mutation is in the SCN5A gene, which is responsible for creating a protein that forms part of the sodium channels in heart muscle cells. These channels are responsible for the proper flow of sodium ions, which initiate the heart’s electrical signals. Mutations in the SCN5A gene can lead to a decrease in this sodium ion flow, disrupting normal heart rhythm.
While genetics play a large role, mutations in the SCN5A gene are found in only about 20-30% of cases, indicating that other genes are also involved. For many people with the syndrome, the underlying genetic cause is never identified. In some individuals, the condition may arise from a new genetic mutation not present in their parents.
Certain external factors can unmask or trigger the dangerous heart rhythms associated with Brugada syndrome in individuals who have a genetic predisposition. A high fever is a well-documented trigger. Additionally, specific medications, such as certain types of anesthetics, antidepressants, and antipsychotics, can induce symptoms. Electrolyte imbalances and excessive alcohol consumption have also been identified as potential triggers.
Symptoms and Warning Signs
Many individuals with Brugada syndrome are asymptomatic and may be unaware they have the condition. The first indication of the disorder can sometimes be a life-threatening cardiac event. When symptoms do occur, they can manifest at any age but often begin around the age of 40.
Common symptoms are a result of abnormal heart rhythms, such as ventricular fibrillation, where the lower chambers of the heart beat erratically instead of pumping blood effectively. This can lead to sudden cardiac arrest. Warning signs include:
- Fainting spells, known as syncope
- Heart palpitations, which can feel like a fluttering in the chest
- Dizziness or seizures
- Labored or gasping breathing, particularly at night
The Diagnostic Process
The diagnosis of Brugada syndrome often begins with an electrocardiogram (ECG or EKG), a test that records the heart’s electrical activity. A specific abnormality known as the “Brugada pattern” on the ECG is the primary diagnostic marker. This pattern, characterized by a particular type of ST-segment elevation in the leads that record activity from the right side of the heart (V1-V3), is the primary diagnostic marker. There are different types of Brugada ECG patterns, but only the “Type 1” pattern is considered definitively diagnostic.
Because the characteristic ECG pattern may not always be present, its absence does not rule out the syndrome. If a doctor suspects Brugada syndrome but the initial ECG is inconclusive, a drug challenge test may be performed. This procedure is conducted in a controlled hospital environment where a patient is given a medication that blocks sodium channels, such as ajmaline or flecainide. These drugs can provoke and reveal the hidden Brugada ECG pattern, helping to confirm the diagnosis.
Genetic testing can be a useful tool to identify a mutation in the SCN5A gene or other associated genes. A positive genetic test can confirm the diagnosis and is particularly helpful for screening family members. However, a negative genetic test does not exclude Brugada syndrome, as not all causative genetic mutations have been identified. Diagnosis relies on a combination of ECG findings, clinical symptoms, and family history of sudden cardiac death.
Treatment and Management
There is no cure for Brugada syndrome, so treatment focuses on managing the condition and preventing sudden cardiac death. For high-risk individuals—such as those who have previously survived a cardiac arrest or experienced fainting spells—the primary treatment is an implantable cardioverter-defibrillator (ICD). An ICD is a small device surgically placed in the chest that continuously monitors the heart’s rhythm. If it detects a life-threatening arrhythmia, the ICD delivers an electrical shock to restore a normal heartbeat.
Beyond the ICD, management strategies involve lifestyle adjustments and avoiding known triggers. Individuals with Brugada syndrome should aggressively manage fevers with medication, as fever can provoke dangerous heart rhythms. Patients are also advised to avoid a specific list of medications known to exacerbate the condition, including certain anesthetics and drugs used to treat depression. Avoiding excessive alcohol intake is also recommended.
In some cases, medications may be used as part of a long-term management plan. For instance, a drug called quinidine can help suppress abnormal heart rhythms in some patients. For those who experience frequent arrhythmias, a procedure known as cardiac ablation may be considered. This involves identifying and destroying the small area of heart tissue that is causing the electrical problem.