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Anatomical science international2020; 96(2); 212-220; doi: 10.1007/s12565-020-00575-7

Morphological variations of the conduction system in the atrioventricular zone and its clinical relationship in different species.

Abstract: Atrioventricular node is responsible for delaying the passage of the electrical impulse to ventricles in order to protect them from fast depolarizations coming from the atria. The importance of this study is to identify the morphological variations of the components of atrioventricular zone that affect the conduction system and its clinical relationship in different species of mammals. We analyzed ten human hearts, nine from horses, eight from pigs, and five from dogs without a clinical history of cardiac pathologies. Histological section thickness of 5 μm were obtained with a microtome and stained with hematoxylin-eosin and Masson's trichrome. We observed both an increase in collagen fibers and a decrease in the size of P cells (nodal pacemaker cells) within the atrioventricular node in dogs, horses and pigs in cases that presented cartilage in fibrous body. The percentage of fundamental substance in atrioventricular node was significantly higher in dogs and the percentage of collagen fibers was higher in pigs, both than in humans. The presence of cartilaginous metaplasia in cardiac fibrous skeleton from different species decreases the size of atrioventricular node and its cells and increases the percentage of collagen fibers within the node, which can reduce the transmission of the electrical impulse to ventricles and therefore predispose to the presentation of ventricular arrhythmias. Morphometric analysis has allowed us to objectively quantify each of the components of AV node and compare them in the different species.
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Publication Date: 2020-09-30 PubMed ID: 32997266PubMed Central: 4425021DOI: 10.1007/s12565-020-00575-7Google Scholar: Lookup
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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 research investigated the differences in the structure and makeup of the atrioventricular zone in various mammals—humans, horses, pigs, and dogs—and how these differences can impact the conduction of electrical impulses in the heart, potentially resulting in heart rhythm abnormalities.

Research Methodology

  • The researchers studied ten human hearts, nine horse hearts, eight pig hearts, and five dog hearts, all without recorded history of cardiac diseases.
  • They gathered histological sections of 5µm from the specimens using a microtome—an instrument used to cut extremely thin sections of tissue.
  • For analysis, they used hematoxylin-eosin and Masson’s trichrome staining methods—a common technique in histology used to distinguish different elements of tissue.

Findings and Observations

  • The study found that when cartilage was present in the fibrous body, there was a marked increase in collagen fibers and a decrease in the P cells (nodal pacemaker cells) within the atrioventricular node in dogs, horses, and pigs.
  • It was observed that the proportion of fundamental substance—or the non-cellular component of the tissue—in the atrioventricular node was significantly higher in dogs than in humans.
  • On the contrary, the percentage of collagen fibers was found to be higher in pigs compared to humans.

Implications of findings

  • The observed increase in collagen and decrease in P cells due to the presence of cartilage, which implies a change in the firmness or flexibility of the heart’s fibrous skeleton, could potentially reduce the conduction of electrical impulses from the atria to the ventricles. This, in turn, could predispose these species to ventricular arrhythmias–irregular heart rhythms originating from the lower chambers of the heart.
  • The researchers concluded that morphometric analysis—measurement of the form of structures—allows for more objective comparison and quantification of each component of the AV node in different species.
  • This research could provide insights into the morphological variations that impact cardiac conduction in various mammalian species and could contribute to an improved understanding of cardiac physiology across species.

Cite This Article

APA
Gómez-Torres F, Ballesteros-Acuña L, Ruíz-Sauri A. (2020). Morphological variations of the conduction system in the atrioventricular zone and its clinical relationship in different species. Anat Sci Int, 96(2), 212-220. https://doi.org/10.1007/s12565-020-00575-7

Publication

Anatomical science international
ISSN: 1447-073X
NlmUniqueID: 101154140
Country: Japan
Language: English
Volume: 96
Issue: 2
Pages: 212-220

Researcher Affiliations

Gómez-Torres, Fabián
  • Department of Pathology, Faculty of Medicine, 1st floor, Universitat de Valencia, Av. de Blasco Ibáñez, 15, 46010, Valencia, Spain.
  • Department of Basic Sciences, School of Medicine, Universidad Industrial de Santander, Cra 32 # 29-31, 68002, Bucaramanga, Colombia.
Ballesteros-Acuña, Luis
  • Department of Basic Sciences, School of Medicine, Universidad Industrial de Santander, Cra 32 # 29-31, 68002, Bucaramanga, Colombia.
Ruíz-Sauri, Amparo
  • Department of Pathology, Faculty of Medicine, 1st floor, Universitat de Valencia, Av. de Blasco Ibáñez, 15, 46010, Valencia, Spain. Amparo.Ruiz-Sauri@uv.es.
  • INCLIVA Biomedical Research Institute, Av. de Blasco Ibáñez, 17, 46010, Valencia, Spain. Amparo.Ruiz-Sauri@uv.es.

MeSH Terms

  • Animals
  • Atrioventricular Node / anatomy & histology
  • Dogs
  • Heart Atria / anatomy & histology
  • Heart Conduction System / anatomy & histology
  • Heart Ventricles / anatomy & histology
  • Horses
  • Humans
  • Species Specificity
  • Swine

Grant Funding

  • PI14/00271 / Instituto de Salud Carlos III
  • pie15/00013 / Federaciu00f3n Espau00f1ola de Enfermedades Raras
  • PROMETEO2013/007 / Conselleria d'Educaciu00f3, Investigaciu00f3, Cultura i Esport

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Citations

This article has been cited 4 times.
  1. Faber JW, Trainini JC, Cohen M. The examination of the atrio-ventricular node region should be a routine practice in all cases of sudden unexpected death in infancy (SUDI) and childhood (SUDC). Forensic Sci Med Pathol 2026 Mar 4;.
    doi: 10.1007/s12024-026-01205-wpubmed: 41779355google scholar: lookup
  2. Avison A, Physick-Sheard PW, Pyle WG. Performance horses as a model for exercise-associated cardiac arrhythmias and sudden cardiac death. J Mol Cell Cardiol Plus 2025 Jun;12:100452.
    doi: 10.1016/j.jmccpl.2025.100452pubmed: 40475708google scholar: lookup
  3. Kubale V, Best A, Mai S, Smale T, Alibhai A, Perez W, El-Gendy SAA, Alsafy MAM, Sturrock CJ, Rutland CS. Anatomy, Histology, Aetiology, Development and Functions of Cartilago Cordis: A Systematic Review. Cells Tissues Organs 2025;214(5):366-390.
    doi: 10.1159/000544776pubmed: 40168957google scholar: lookup
  4. Gómez-Torres F, Ballesteros-Acuña LE, Molina-Aguilar P, Ríos-Navarro C, Ruíz-Sauri A. Morphometric and histological changes in cardiac nodes after acute spontaneous myocardial infarction in humans and pigs. Vet World 2024 Dec;17(12):2880-2888.
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