ECG Level 3 Tutorial: Bundle Branch Blocks
Tutorial: Bundle Branch Blocks
Understand why a right bundle branch block and left bundle branch block pattern are created. Learn also the diagnostic criteria.
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Tutorial: Bundle Branch Blocks Advanced details
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Advanced details
Brugada syndrome:
  • is listed here because it can mimic or be associated with RBBB
  • Brugada syndrome is caused by a sodium or calcium channel mutation and is a cause of sudden onset ventricular tachycardia or ventricular fibrillation in children and adults
  • the diagnostic criteria for Brugada syndrome is
    • J point elevation with ST elevation in V1-V3
    • the ST is described as coved or saddlebacked:
      • coved = downsloping and convex upward
      • saddlebacked = flat ST elevation with initial and final parts of ST segment slightly higher
  • the ST is abnormal because the abnormal ion channels result in electrical currents during the ST segment (during which in a normal heart, there is typically little to no current movement)
There are 3 types of Brugada syndrome. Type 1 has the "coved" ST and types 2 and 3 have the saddleback morphology:

                  Coved ST                                           Saddleback ST
coved ST segment
  • Brugada syndrome does not cause a wide QRS nor an R' wave. However, the ST elevation can be misinterpretted as an R' wave. When this happens, the QRS would erroneously be seen as wide.
  • remember that the ST segment in RBBB should be isoelectric and flat (blue circle). In these 2 examples, it is actually slightly depressed in fact:

     ST segment RBBB       ST segment RBBB