Etiology

  Mutation of SCN5A gene encoding the sodium channels of cardiac muscle cells.

  Less fruquently, mutations involving the

            - L-type calcium channel gene

            - glycerol-3-phosphate dehydrogenase-like peptide (GPD1-L)

            - transient outward potassium current

            - ATP-sensitive potassium channel

    also have been reported in patients with Brugada syndrome.




Diagnostic criteria

  ST segment elevation is observed in right precordial leads C1, C2, C3 (V1, V2, V3).

  The ST segment elevation
resembles right bundle branch block pattern.

  In patients with Brugada Syndrome, the ECG
may change over time.

  Sometimes the ECG may be normal.





Types of Brugada Syndrome according to the ECG appearance

  Type 1: 2mm or more coved (concave) ST elevation and negative T wave is seen in at least 2

      of the leads V1, V2 or V3. This pattern may be absent at rest and

      may arise only after administration of a sodium channel blocking agent.

  Type 2: Saddleback ST segment elevation is seen. The J point is elevated at least 2mm and

      the ST segment is elevated at least 1 mm. T wave may be positive (upright) or biphasic.


  Type 3: has either a saddleback or coved appearance with an ST-segment elevation of < 1 mm.



  A
Brugada-like ECG can occasionally appear for a brief period or for a period of several hours

     
after direct-current cardioversion.



For the diagnosis of Brugada Syndrome, at least one of the following should be present
in addition to the typical ECG appearance


  Documented ventricular fibrillation (VF).

  Documented polymorphic ventricular tachycardia (VT).

  A family history of sudden cardiac death before 45 years of age.

  Coved-type ECGs in family members.

  Inducibility of VT with programmed electrical stimulation.

  Syncope.

  Nocturnal agonal respiration (Video).



  Brugada Syndrome is also diagnosed if Type 2 or Type 3 ECG pattern at rest converts to Type 1

      after administration of a sodium channel blocking agent.

      (with the additional requirement of at least one of the above clinical criteria).




Other ECG abnormalities that may be observed in patients with Brugada Syndrome are

  Slight prolongation of QT interval.

  Prolongation of P wave duration.

  Prolongation of PR interval.

  Widening of the QRS.




Clinical importance

  May result in polymorphic ventricular tachycardia or ventricular fibrillation.

  These arrhythmias may result in
syncope or sudden cardiac death.

  Ventricular fibrillation in Brugada Syndrome
usually occurs during sleep at night.

  Although it may be observed at all ages, sudden cardiac death usually occurs
at ages of 35-40 years.

  About 10% of the patients may show
paroxysmal atrial fibrillation.

  Brugada syndrome is observed more frequently in
males.

  In order to decrease the risk of sudden cardiac death, some medicines should be avoided

      in patients with Brugada Syndrome.



Click here for a
list of the drugs that should be avoided in patients with Brugada syndrome.



Factors that modify the appearance of typical ECG findings of Brugada Syndrome

  Class 1a, Class 1c and Class 3 antiarhhythmic drugs increase the ST segment elevation.

 
Adrenergic stimulation decreases ST segment elevation.

     
Vagal stimulation increases ST segment elevation.

  In patients with atrial pacing, ST segment elevation increases as heart rate decreases.

 
Increased body temperature (due to any cause) increases ST segment elevation.



ECG findings similar to Brugada syndrome may also be observed in:

  Misplacement of chest electrodes

  Myotonic dystrophy

  Chagas' disease

  Pectus excavatum

  Mediastinal tumors

  Some drugs including tricyclic antidepressants, fluoxetine, lithium, trifluoperazine, antihistamines,

      and cocaine.




References

  Circulation 2005;111:659-670

  Journal of Arrhythmia 2013;29:77-82.





ECG 1. Brugada pattern Type 1.

Dr. Konstantinos Letsas (k.letsas@mail.gr, letsaskpa@yahoo.co.uk) has donated this ECG to our website.

Click here for a more detailed ECG





ECG 2. Another patient with Brugada pattern Type 1.

Dr. Konstantinos Letsas (k.letsas@mail.gr, letsaskpa@yahoo.co.uk) has donated this ECG to our website.

Click here for a more detailed ECG





ECG 3. Brugada pattern Type 2.

Dr. Konstantinos Letsas (k.letsas@mail.gr, letsaskpa@yahoo.co.uk) has donated this ECG to our website.

Click here for a more detailed ECG





ECG 4. Ajmaline Test in Brugada syndrome. The test is considered positive if an additional 1 mm ST segment elevation
appears in leads V1, V2 and V3. The ST segment elevation is measured 0.08 s after the J wave

Dr. Konstantinos Letsas (k.letsas@mail.gr, letsaskpa@yahoo.co.uk) has donated this ECG to our website.

Click here for a more detailed ECG





ECG 5. Type 1 Brugada syndrome.

Click here for a more detailed ECG






ECG 6. Brugada syndrome.

Dr. Ramon Brugada has donated this ECG to our website.

Click here for a more detailed ECG





ECG 7. Brugada syndrome.

Dr. Ramon Brugada has donated this ECG to our website.

Click here for a more detailed ECG





ECG 8. Brugada syndrome.

Dr. Ramon Brugada has donated this ECG to our website.

Click here for a more detailed ECG





ECG 9. Brugada syndrome.

Dr. Ramon Brugada has donated this ECG to our website.

Click here for a more detailed ECG



ECG 10. Brugada syndrome.

Prof. Dr. Haldun Muderrisoglu has donated this ECG to our website.

Click here for a more detailed ECG





Click here to get more information about Brugada Syndrome.






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