Cardiology In Critical Care

Arrhythmia Recognition

Bundle Branch Block (BBB)

Impulses originate in the SA node and spread normally through the atria and AV junction, however, the conduction through the right (R) or left (L) branches of the bundle of His is blocked.  In RBBB the right ventricle is activated late through the septum this being reflected by M-shaped QRS complex or wide notched or slurred R in V1-V2 and wide slurred S in V5-V6.  In LBBB the left ventricle is activated late through the septum this being relected by M-shaped QRS or wide notched or slurred R in V5-V6 and wide slurred S or QS in V1-V6.  QRS duration 0.11 sec or more.  ST segment depressed and T inverted in leads with M-shaped QRS.


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