Bifascicular block is used to describe blocks of any two of the following; right bundle branch, left anterior fascicle, or left posterior fascicle.
Bifascicular Block (QRS ≥ 120 ms)
Sometimes applied to complete LBBB
Bilateral bifascicular bundle branch blocks
RBBB + LAFB (seen in large anteroseptal infarcts)
RBBB + LPFB
Learn about different types of blocks using these links:
Unifascicular Block
Trifascicular Block
Left Bundle Branch Blocks
Right Bundle Branch Blocks
Left Anterior Fascicular Block
Left Posterior Fascicular Block