Brugada Syndrome
Brugada Syndrome Definition
The Brugada syndrome is a genetic disease that is marked by abnormal electrocardiogram (ECG) findings and an increased risk of sudden cardiac death. It is also known as Sudden Unexpected Death Syndrome (SUDS), and is the most commonly found cause of sudden death in young men without known underlying cardiac disease in Thailand and Laos. Although the ECG findings of Brugada syndrome were first reported among survivors of cardiac arrest in 1989, it was only in 1992 that the Brugada brothers recognised it as a distinct clinical entity, causing sudden death by resulting to ventricular fibrillation (a lethal arrhythmia) in the heart.
Brugada Syndrome Pathophysiology
An estimated 20% of the cases of Brugada syndrome have been shown to be associated with mutation(s) in the gene that encodes for the sodium ion channel in the cell membranes of the muscle cells of the heart (the myocytes). The gene, called SCN5A, is located on the short arm of the third chromosome (3p21). Loss-of-function mutations in this gene result to a loss of the action potential dome of some epicardial areas of the right ventricle. This leads to transmural and epicardial dispersion of repolarization. The transmural dispersion underlies ST-segment elevation and the development of a vulnerable window across the ventricular wall, whereas the epicardial dispersion of repolarization aids in the development of phase 2 reentry, which generates a phase 2 reentrant extrasystole that captures the vulnerable window to precipitate ventricular tachycardia and/or fibrillation that often results in sudden cardiac death. However, at present time, all the reported patients died because of the disease and submitted to detailed necropsy study, have shown a structural right ventricular pathology underlying the syndrome.
Brugada Syndrome Prevalence
In Asia (like the Philippines, Thailand, Japan), Brugada syndrome seems to be the most common cause of natural death in males younger than 50 years. It is known as Bangungut (Philippines), Lai Tai (Thailand), and Pokkuri (Japan). In Northeast Thailand, the mortality rate from Lai Tai is an estimated 30 per 100,000 population per year.
Brugada Syndrome Treatment
The death in Brugada syndrome is caused by ventricular fibrillation. The episodes of syncope (fainting) and sudden death (aborted or not) are results of fast polymorphic ventricular tachycardias or ventricular fibrillation. These arrhythmias show up with no warning. While there is no exact treatment modality that reliably and wholly prevents ventricular fibrillation from occurring in this syndrome, treatment lies in termination of this lethal arrhythmia before it causes death. This is done via implantation of an implantable cardioverter-defibrillator (ICD), which then continuously monitors the heart rhythm and will defibrillate an individual if ventricular fibrillation is seen.