Structure of canine Bachmann's bundle related to propagation of excitation.

Published

Journal Article

Impulse propagation and histology were studied in adult and neonatal canine Bachmann's bundle. Both showed nonuniform electrical anisotropy: effective longitudinal conduction velocity (theta L) markedly exceeded effective transverse conduction velocity (theta T), and extracellular potential waveforms with transverse propagation were polyphasic. An age difference in theta L (0.80 m/s neonate, 1.31 m/s adult) was found; it could be largely accounted for by a difference in myocyte diameter (4.7 microns neonate, 17.1 microns adult). Close apposition of myocytes in the neonate and development of transverse tubules in the adult may have influenced theta L at each stage. Perimysial septa separated fascicles in both neonatal and adult bundles; however, endomysial septa between individual myocytes were completely developed only in adult bundles. Thus perimysial septa were much more responsible for nonuniform anisotropy and low theta T than endomysial septa. Fascicle diameter and length were greater in the adult, which may have affected transverse propagation. Specialized conduction system cells could not be identified.

Full Text

Cited Authors

  • Dolber, PC; Spach, MS

Published Date

  • November 1989

Published In

Volume / Issue

  • 257 / 5 Pt 2

Start / End Page

  • H1446 - H1457

PubMed ID

  • 2589500

Pubmed Central ID

  • 2589500

Electronic International Standard Serial Number (EISSN)

  • 2163-5773

International Standard Serial Number (ISSN)

  • 0002-9513

Digital Object Identifier (DOI)

  • 10.1152/ajpheart.1989.257.5.h1446

Language

  • eng