This site is intended for healthcare professionals
Login | Register (NOW FREE)

Medical search

more detailed information about left posterior fascicular block

FREE subscriptions for doctors and students... click here
You have 3 open access pages.

  • the normal left ventricular activation proceeds first down the left bundle branch, and then simultaneously through its two fascicles (left anterior fascicle and left posterior fascicle)
  • left posterior fascicular block (LPFB), also known as left posterior hemiblock, is much less common than left anterior fascicular block (LAFB) - this is due to a number of factors:
    • the posterior fascicle is a thicker structure than the anterior fascicle
    • posterior fascile has a dual blood supply
    • the anatomic location of the posterior fascicle is away from more turbulent ventricular blood flow
  • ECG changes in LPFB:
    • QRS interval <0.12 seconds
    • right axis deviation
    • rS pattern in the lateral limb leads (I and aVl)
    • qR complex in the inferior leads (II, III, and aVf)
    • no evidence of right ventricular hypertrophy
  • LPFB is a rare finding
    • LPFB is nonspecific for cardiac disease - however coronary artery disease is the most common cause
    • other associations for LPFB include hypertensive heart disease, aortic valvular pathology, and fibrocalcific disease of the cardiac skeleton
    • LPFB is the least common intraventricular conduction block seen in acute myocardial infarction
  • data on established LPFB are insufficient assess prognostic significance


  1. Harrigan RA et al. Electrocardiographic manifestations: bundle branch blocks and fascicular blocks. The Journal of Emergency Medicine 2003;25(1):67–77
  2. Rowlands DJ.Left and right bundle branch block, left anterior and left posterior hemiblock. Eur Heart J. 1984 Mar;5 Suppl A:99-105.

Last reviewed 01/2018

The information provided herein should not be used for diagnosis or treatment of any medical condition. A licensed medical practitioner should be consulted for diagnosis and treatment of any and all medical conditions. Copyright 2016 Oxbridge Solutions Ltd®. Any distribution or duplication of the information contained herein is strictly prohibited. Oxbridge Solutions Ltd® receives funding from advertising but maintains editorial independence. GPnotebook stores small data files on your computer called cookies so that we can recognise you and provide you with the best service. If you do not want to receive cookies please do not use GPnotebook.