Thebundle branches,orTawara branches,[1]transmitcardiac action potentials(electrical signals) from thebundle of HistoPurkinje fibersinheart ventricles.They are offshoots of the bundle of His and are important to theelectrical conduction system of the heart.[2]
| Bundle branches | |
|---|---|
 The left bundle branch (4) and the right bundle branch (10) | |
| Anatomical terminology |
Structure
editThere are two branches of the bundle of His: theleft bundle branchand theright bundle branch,both of which are located along theinterventricular septum.The left bundle branch further divides into theleft anterior fascicleand theleft posterior fascicle.These structures lead to a network of thin filaments known as Purkinje fibers. They play an integral role in the electrical conduction system of the heart by transmitting cardiac action potentials to the Purkinje fibers.[2]
Clinical significance
editWhen a bundle branch or their fascicles becomes injured (by underlying heart disease, myocardial infarction, or cardiac surgery), it may cease to conduct electrical impulses appropriately, resulting in altered pathways for ventricular depolarization. This condition is known as abundle branch block.[3]
History
editThe bundle branches were separately described by Retzer and Braeunig as early as 1904, but their physiological function remained unclear and their role in the electrical conduction system of the heart remained unknown untilSunao Tawarapublished his monograph onDas Reizleitungssystem des Säugetierherzens(English:The Conduction System of the Mammalian Heart) in 1906.[4]Although Tawara's monograph had demonstrated that the branches of the bundle of His may transmit cardiac action potentials to the ventricles, the functional proof for his observation was not provided until 1910, whenHans EppingerandCarl Julius Rothbergershowed that cutting off both branches to induce a bilateral bundle branch block results in a completeheart block.[5]
References
edit- ^Kullmann T, Baráth Z, Csiszér E (January 2009). "Remission of left Tawara-branch block under treatment for systemic sarcoidosis".International Journal of Cardiology.131(2): e83–4.doi:10.1016/j.ijcard.2007.07.063.PMID17935802.
- ^abTusscher KH, Panfilov AV (2008)."Modelling of the ventricular conduction system".Progress in Biophysics and Molecular Biology.96(1–3): 152–70.doi:10.1016/j.pbiomolbio.2007.07.026.PMID17910889.
- ^Kumar V, Venkataraman R, Aljaroudi W, et al. (January 2013)."Implications of left bundle branch block in patient treatment".The American Journal of Cardiology.111(2): 291–300.doi:10.1016/j.amjcard.2012.09.029.PMID23111137.
- ^Silverman ME, Grove D, Upshaw CB (June 2006)."Why does the heart beat? The discovery of the electrical system of the heart".Circulation.113(23): 2775–81.doi:10.1161/CIRCULATIONAHA.106.616771.PMID16769927.
- ^Hollman A (1985)."The history of bundle branch block".Medical History Supplement(5): 82–102.PMC2557404.PMID3915526.
Further reading
edit- Massing GK, James TN (April 1976)."Anatomical configuration of the His bundle and bundle branches in the human heart".Circulation.53(4): 609–21.doi:10.1161/01.CIR.53.4.609.PMID1253382.
- Widran J, Lev M (December 1951)."The dissection of the atrioventricular node, bundle and bundle branches in the human heart".Circulation.4(6): 863–7.doi:10.1161/01.CIR.4.6.863.PMID14879494.