Left posterior fascicular block

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Left posterior fascicular block
Classification and external resources
Specialty cardiology
ICD-10 I44.5

A left posterior fascicular block (LPFB) is a condition where the left posterior fascicle, which travels to the inferior and posterior portion of the left ventricle,[1] does not conduct the electrical impulses from the atrioventricular node. The wave-front instead moves more quickly through the left anterior fascicle and right bundle branch, leading to a right axis deviation seen on the ECG.[2]

The American Heart Association has defined a LPFB as:[3]

  • Frontal plane axis between 90° and 180° in adults
  • rS pattern in leads I and aVL
  • qR pattern in leads III and aVF
  • QRS duration less than 120 ms

The broad nature of the posterior bundle as well as its dual blood supply[4] makes isolated LPFB rare.[5]

See also[edit]


  1. ^ Kevin J. Koop; et al., eds. (2010). "23". Atlas of emergency medicine (3rd ed.). New York: McGraw-Hill Professional. ISBN 0071496181. 
  2. ^ "Lesson VI - ECG Conduction Abnormalities". Retrieved 2009-01-07. 
  3. ^ Surawicz B, Childers R, Deal BJ, Gettes LS, Bailey JJ, Gorgels A, Hancock EW, Josephson M, Kligfield P, Kors JA, Macfarlane P, Mason JW, Mirvis DM, Okin P, Pahlm O, Rautaharju PM, van Herpen G, Wagner GS, Wellens H (2009). "AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part III: intraventricular conduction disturbances: a scientific statement from the American Heart Association Electrocardiography and Arrhythmias Committee, Council on Clinical Cardiology; the American College of Cardiology Foundation; and the Heart Rhythm Society. Endorsed by the International Society for Computerized Electrocardiology". J. Am. Coll. Cardiol. 53 (11): 976–81. doi:10.1016/j.jacc.2008.12.013. PMID 19281930. 
  4. ^ James, TN (Dec 1965). "Anatomy of the coronary arteries in health and disease.". Circulation 32 (6): 1029. doi:10.1161/01.cir.32.6.1020. PMID 5846099. 
  5. ^ Rokey, R.; Chahine, R. A. (June 1984). "Isolated left posterior fascicular block associated with acquired ventricular septal Defect". Clinical Cardiology 7 (6): 364–369. doi:10.1002/clc.4960070608. 

Further reading[edit]