Bifascicular block

1. Right bundle branch block (RBBB) + left anterior fascicular block (LAFB) 
2. RBBB + left posterior fascicular block (LPFB)
3. Complete left bundle branch block (LBBB)

Incomplete Trifascicular block

1. Bifascicular block w/1^st degree AV block    *classically referred to as “trifascicular block”*
2. Bifascicular block w/2^nd degree AV block
3. Alternating LBBB + RBBB

Complete Trifascicular block

1. Bifascicular block w/3^rd degree AV block 

References

1. Surawicz B, Knilans T. Chou’s Electrocardiography in Clinical Practice (6th edition), Saunders 2008. 
2. Wagner, GS. Marriott’s Practical Electrocardiography (11th edition), Lippincott Williams & Wilkins 2007.
3. Levis J, Garmel G. Clinical Emergency Medicine Casebook, Cambridge University Press 2009.