Some general rules are available
RBBB -Morphology -LV origin
LBBB morphology -RV origin
Exceptions : Interventricular septum is electrically RV or LV ?
Electrically it is more of a LV . Septal focus often have RBBB morpholgy . Exist points do matter
Three lead approach
Rapidly looking at lead V1 , V6 and AVR can give us a clue
AVR +ve will immediately tell us the VPDs are firing towards right shoulder .
RBBB morphology points to a LV focus .
Negative VPD in V5 will further confirm LV apex is in the trailing end of VPD
Common sites for post MI VPD
- LV apex and Apical septum
- Infero posterio MI
- RV origin more common
Which VPD morphology has better localising value RBBB or LBBB ?
It is the LBBB that has more localising value . LBBB invariably fixes the right ventricle
RBBB can either be right ventricle or left ventricle .
To be continued .
Dr.S.Venkatesan MD 
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