Left posterior fascicular block explained

Left posterior fascicular block
Synonyms:	Left posterior hemiblock

A left posterior fascicular block (LPFB), also known as left posterior hemiblock (LPH), 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]

Definition

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

• Left anterior fascicular block
• Left bundle branch block

Further reading

• Ma FS, Ma J, Tang K, etal . Left posterior fascicular block: a new endpoint of ablation for verapamil-sensitive idiopathic ventricular tachycardia . Chin. Med. J. . 119 . 5 . 367–72 . March 2006 . 16542578 . 10.1097/00029330-200603010-00003. free .

Notes and References

1. Book: Atlas of emergency medicine. 2010. McGraw-Hill Professional. New York. 978-0071496186. 3rd. Kevin J. Koop. 23. etal.
2. Web site: Lesson VI - ECG Conduction Abnormalities . 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 . 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 . 2009 . 19281930 . 10.1016/j.jacc.2008.12.013 . free .
4. James. TN. Anatomy of the coronary arteries in health and disease.. Circulation. Dec 1965. 32. 6. 1020–33. 5846099. 10.1161/01.cir.32.6.1020 . free.
5. Rokey. R.. Chahine, R. A. . Isolated left posterior fascicular block associated with acquired ventricular septal Defect. Clinical Cardiology. June 1984. 7. 6. 364–369. 10.1002/clc.4960070608. 6744692. free.