Left posterior fascicular block LPFB (left posterior hemiblock), impulses are conducted to the left ventricle via the left anterior fascicle
Trifascicular block (TFB) refers to the presence of conducting disease in all three fascicles: RBBB, LAFB, LPFB. LITFL ECG Library
Bifascicular block is the combination of RBBB with either LAFB or LPFB. Conduction to the ventricles is via the single remaining fascicle.