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Home / Equine Research Bank / Acta Physiol (Oxf) / Intramural Purkinje fibers facilitate rapid ventricular acti...
Acta physiologica (Oxford, England)2023; 237(3); e13925; doi: 10.1111/apha.13925

Intramural Purkinje fibers facilitate rapid ventricular activation in the equine heart.

Abstract: The Purkinje fibers convey the electrical impulses at much higher speed than the working myocardial cells. Thus, the distribution of the Purkinje network is of paramount importance for the timing and coordination of ventricular activation. The Purkinje fibers are found in the subendocardium of all species of mammals, but some mammals also possess an intramural Purkinje fiber network that provides for relatively instantaneous, burst-like activation of the entire ventricular wall, and gives rise to an rS configuration in lead II of the ECG. To relate the topography of the horse heart and the distribution and histology of the conduction system to the pattern of ventricular activation as a mechanism for the unique electrical axis of the equine heart. The morphology and distribution of the cardiac conduction system was determined by histochemistry. The electrical activity was measured using ECG in the Einthoven and orthogonal configuration. The long axis of the equine heart is close to vertical. Outside the nodal regions the conduction system consisted of Purkinje fibers connected by connexin 43 and long, slender parallel running transitional cells. The Purkinje fiber network extended deep into the ventricular walls. ECGs recorded in an orthogonal configuration revealed a mean electrical axis pointing in a cranial-to-left direction indicating ventricular activation in an apex-to-base direction. The direction of the mean electrical axis in the equine heart is determined by the architecture of the intramural Purkinje network, rather than being a reflection of ventricular mass.
© 2023 The Authors. Acta Physiologica published by John Wiley & Sons Ltd on behalf of Scandinavian Physiological Society.
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Publication Date: 2023-01-18 PubMed ID: 36606541DOI: 10.1111/apha.13925Google Scholar: Lookup
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  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

This study investigates the structure of the equine heart’s Purkinje fibers network—an intricate system that conveys electrical impulses—and its implication on ventricular activation patterns. The research further points out the importance of these fibers’ distribution in determining the unique electrical axis of a horse’s heart.

Research Objective

  • The study aims to analyze the topography of the horse heart, specifically, the distribution and histology of the conduction system, and relate it to the pattern of ventricular activation. The objective was to comprehend how this influences the singular electrical axis of the equine heart.

Morphology and Distribution of Cardiac Conduction System

  • The researchers carried out a detailed examination of the horse heart’s morphology using histochemistry—a technique to identify the chemical components of the cells.
  • According to their findings, outside the nodal areas, the conduction system comprised Purkinje fibers linked by connexin 43—proteins integral to heart function—and long, slender parallel running transitional cells.

Purkinje Fiber Network

  • Part of the study also revealed that the Purkinje fiber network extended deep into the ventricular walls, more than commonly observed in other mammals.
  • The presence of this intramural (within the walls) Purkinje fiber network contributes to rapid, ‘burst-like’ activation of the entire ventricular wall, enhancing the coordination of ventricular activation.

Electrical Activity Analysis

  • In addition to histochemistry, the researchers also measured the heart’s electrical activity using electrocardiograms (ECGs) in the Einthoven and orthogonal configuration.
  • The results showed that ECGs configured orthogonally registered a mean electrical axis pointing from the cranial to the left direction which suggests ventricular activation in an apex-to-base direction.

Conclusion

  • The research concludes that the direction of the mean electrical axis in a horse’s heart is influenced by the design of the intramural Purkinje network rather than reflecting the ventricular mass. It means this unique architecture could play a significant role in their ability to deliver high-speed performances for extended periods.

Cite This Article

APA
Elbrønd VS, Thomsen MB, Isaksen JL, Lunde ED, Vincenti S, Wang T, Tranum-Jensen J, Calloe K. (2023). Intramural Purkinje fibers facilitate rapid ventricular activation in the equine heart. Acta Physiol (Oxf), 237(3), e13925. https://doi.org/10.1111/apha.13925

Publication

Acta physiologica (Oxford, England)
ISSN: 1748-1716
NlmUniqueID: 101262545
Country: England
Language: English
Volume: 237
Issue: 3
Pages: e13925

Researcher Affiliations

Elbrønd, Vibeke S
  • Section for Pathobiological Sciences, Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg C, Denmark.
Thomsen, Morten B
  • Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
Isaksen, Jonas L
  • Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
Lunde, Ester D
  • Section for Pathobiological Sciences, Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg C, Denmark.
Vincenti, Stefano
  • Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark.
Wang, Tobias
  • Section for Zoophysiology, Department of Biology, Aarhus University, Aarhus C, Denmark.
Tranum-Jensen, Jørgen
  • Department of Cellular and Molecular Medicine, The Panum Institute, University of Copenhagen, Copenhagen, Denmark.
Calloe, Kirstine
  • Section for Pathobiological Sciences, Department of Veterinary and Animal Sciences, University of Copenhagen, Frederiksberg C, Denmark.

MeSH Terms

  • Horses
  • Animals
  • Purkinje Fibers / physiology
  • Heart Ventricles
  • Electrocardiography
  • Myocytes, Cardiac
  • Mammals

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