Stanford Cardiac Arrhythmia Service

Brugada Syndrome and other inherited Arrhythmia Disorders

Brugada Syndrome is a heredity condition which affects the electrical conduction system of the heart, causing an abnormal heart rhythm. In some cases, Brugada Syndrome can be life-threatening, and may come about with little warning.

With every normal heartbeat, an electrical signal courses through the heart in a highly controlled fashion. Each portion of the heart must electrically activate, then reset to allow the next beat to follow. The proteins that regulate this process, called ion channels, regulate the flow of sodium, potassium, chloride, calcium, magnesium, and other molecules across heart cells. When an electrocardiogram (ECG or EKG) is performed on a patient, the heart’s electrical activation and reset are being recorded and evaluated.  Activation of each section of the heart is seen on the ECG: the P wave represents atrial activation, the QRS represents left and right ventricular activation, and the QT interval and T wave represent the resetting of the left and right ventricles.

The electrical signal that triggers activation of the ventricles is controlled by specific ion channels that regulate sodium. These sodium channels, like most other ion channels, need to activate and then reset with every single heartbeat.  In Brugada syndrome, a genetic mutation in these sodium channels causes them to not quite be able to reset reliably. These sodium channel abnormalities usually can be seen on a patient’s ECG. In specific portions of the ECG, called leads V1, V2, and V3, the “ST segment” has abnormalities in it’s pattern.  As a result, ventricular tachycardia (VT) may result. An episode of VT may lead to symptoms ranging from palpitations, dizziness, to fainting, to cardiac arrest. 

Diagnosis of Brugada syndrome is most often made based on findings on the ECG, as described above. Genetic testing is available, but it is not highly sensitive at this point, although it may be useful in particular for screening family members of patients with a known diagnosis. Oftentimes the ECG may not be clearly consistent with the diagnosis. If there is sufficient clinical suspicion of Brugada syndrome, a “drug challenge” test may be performed. In a drug challenge, a patient is monitored in the hospital and given a medication that may bring out the ECG findings of Brugada syndrome, making the diagnosis more certain. Moreover, in patients with an “incidental” ECG that shows the pattern of Brugada syndrome, or when the diagnosis is still uncertain, an electrophysiology study (EP study) may be recommended. During an EP study, catheters are placed through the leg veins into the heart using an x-ray camera (fluoroscopy). Those catheters are then used to electrically stimulate the heart to try to start a ventricular arrhythmia. If an arrhythmia is started, the diagnosis of Brugada syndrome is highly likely.

Currently, the only reliable treatment of Brugada syndrome is an implanted defibrillator (ICD) . The ICD will treat and cut short arrhythmia episodes, but it does not prevent the episode. Some medications are being evaluated for treating Brugada syndrome, but these are currently experimental.

In addition to Brugada syndrome and Long QT syndrome , there are several quite rare genetic or inherited arrhythmia conditions. These include short QT syndrome, which almost always comes to attention in childhood.   Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT) results from a genetic mutation in a protein that regulates calcium called the ryanodine receptor, leading to adrenaline-induced arrhythmias. In addition, there are inherited forms of atrial fibrillation . Finally, several inherited cardiomyopathies in rare families are associated with specific arrhythmias. 

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