Brugada syndrome

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  • In the context of arrhythmia (including atrial fibrillation !), any transient ECG with complete or incomplete right bundle branch block and ST segment elevation in V1-V3 is potentially significant.

Brugada syndrome is a group of channelopathies that cause of sudden cardiac death (often in young men) with no evidence of structural heart disease. The original paper by the Brugada brothers was a report of 8 cases.[1]

Occasionally, there may be dilation of the right ventricular outflow tract (RVOT) in life and localised histopathological changes (at post mortem)[2]. The electrocardiogram shows complete or incomplete right bundle branch block, early coved ST segment elevation in the anterior praecordial leads.

It is caused by abnormality of the genes coding for ion channels and results in increased risk of sudden death from arrhythmia. Can be classified according to electrocardiographic repolarization into three types.[3] Alternatively, classified according to gene defects:

  1. Type 1 (BRS1) due to defects in the SCN5A gene which encodes for a component of the the cardiac sodium channel
    • Seen in southeast Asia. Affects males 9 times more frequently than females.
    • Over 300 mutations known
  2. Type 2 (BRS2) due to defects in the GPD1L gene at 3p22.3 resulting in a 50% reduction in inward current of the sodium channel
  3. Type 3 (BRS3) due to defects in the CACNA1C gene at 12p13.3
  4. Type 4 (BRS4) due to defects of the CACNB2 gene
  5. Type 5 (BRS5) due to defects in the SCN1B gene which encodes for a component of the cardiac sodium channel
  6. Type 6 (BRS6) due to defects in the KCNE3 gene at 11q13-q14 which encodes for a potassium channel beta subunit
  7. Type 7 (BRS7) due to defects in the SCN3B gene which encodes for a component of the cardiac sodium channel. It can be more fully unmasked to induce ST changes with procainamide
  8. Type 8 (BRS8) due to defects in the HCN4 gene which codes for a component of the hyperpolarization-activated potassium channel

The characteristic ECG is unmasked by[2]:

References

References

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