Bundle branch blocks

The two main types of bundle branch blocks are right (RBBB) and left (LBBB)

Conduction disturbance within the right bundle branch causes RV activation to occur after LV activation is completed, resulting in an R' deflection in lead V1
Learn more about RBBB here
Conduction disturbance within the left bundle branch delays LV activation, resulting in a markedly prominent S wave in lead V1
Learn more about LBBB here
Activation of the ventricular Purkinje system is not recorded on the surface ECG

BBBs can cause pseudo ST deviation (especially common in aVR), don't be fooled!
- Never rely on single leads or rhythm strips to assess intervals or ST deviation
- Rhythm strips will often mislead you!
- Get a 12-lead and look in ALL leads for clues

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