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Home / Equine Research Bank / Sci Rep / Morphological variations of the interatrial septum and poten...
Scientific reports2025; 15(1); 16500; doi: 10.1038/s41598-025-01387-3

Morphological variations of the interatrial septum and potential implications in equine cardiology.

Abstract: The interatrial septum morphology, shaped by the septum primum and secundum fusion, results in the formation of the fossa ovalis (FO) and its limbus. Incomplete fusion can lead to a patent foramen ovale (PFO), while complete fusion may produce septal ridges and pouches (SPs), with SPs in humans linked to ischemic stroke and atrial arrhythmias. In horses, atrial tachycardia and fibrillation often originate near the FO. This study examines adult equine interatrial septum morphology to enhance understanding the region and guide electrophysiological interventions for equine cardiac arrhythmias. Post-mortem examinations of 62 adult equine hearts, assessed the interatrial septum morphology from both right and left sides, measuring the dimensions of the FO and the craniocaudal length, and dorsoventral height of the SPs. Histological analysis at selected septal locations evaluated the wall's thickness and composition. Significant morphological variations were observed, particularly the consistent presence of right-sided SP. The septum wall comprises three layers, with the central layer containing cardiomyocytes in varied orientations, interspersed with fibroadipose tissue, features potentially contributing to atrial arrhythmias. Understanding the equine interatrial septum morphology is important for optimizing transseptal puncture outcomes, by facilitating accurate intracardiac echocardiography interpretation, guiding precise puncture site selection and improving procedural safety and efficacy.
© 2025. The Author(s).
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Publication Date: 2025-05-12 PubMed ID: 40355652PubMed Central: PMC12069587DOI: 10.1038/s41598-025-01387-3Google Scholar: Lookup
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Summary

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Researchers investigate the structure of the interatrial septum in horses and how its variations could affect the understanding of and intervention for equine cardiac arrhythmias.

Morphology of the Interatrial Septum

  • The study primarily focused on the morphology of the interatrial septum in horses, which includes the fossa ovalis and potentially, the patent foramen ovale and septal ridges and pouches, depending on whether the septums primum and secundum fuse completely or not.
  • These morphological details were explored to understand their potential connection to ischemic stroke, atrial arrhythmias, atrial tachycardia, and atrial fibrillation, conditions that have been linked to these structures in humans and horses.
  • In order to examine these structures, the researchers conducted post-mortem examinations on 62 adult equine hearts. This involved assessing the septum’s morphology from the right and left sides, noting the dimensions of the fossa ovalis and other structures.

Wall Composition and Potential Role in Atrial Arrhythmias

  • Alongside the morphology, the researchers also conducted a histological analysis of the septum. This involved examining the thickness and composition of the wall at selected locations.
  • The septum wall was found to consist of three layers: the central layer was of particular interest as it contained cardiomyocytes (heart muscle cells) arranged in various orientations within a matrix of fibroadipose tissue (a combination of fat and fibrous/connective tissue).
  • The presence of this specialized tissue could potentially contribute to the manifestation of atrial arrhythmias in horses. This variation in the composition of the wall was noted as a significant finding and suggests the need for further study.

Significance for Electrophysiological Interventions

  • The study suggests that a better understanding of the morphology and tissue composition of the interatrial septum could help optimize procedures for equine cardiac patients.
  • Knowledge of these factors could help improve the interpretation of intracardiac echocardiograms, making for a more accurate diagnosis and selection of electrophysiological intervention strategies.
  • Being able to select a precise puncture site could enhance the safety and efficacy of transseptal punctures in equine patients, potentially leading to better patient outcomes.

Cite This Article

APA
Ibrahim L, Vernemmen I, Buschmann E, van Loon G, Cornillie P. (2025). Morphological variations of the interatrial septum and potential implications in equine cardiology. Sci Rep, 15(1), 16500. https://doi.org/10.1038/s41598-025-01387-3

Publication

Scientific reports
ISSN: 2045-2322
NlmUniqueID: 101563288
Country: England
Language: English
Volume: 15
Issue: 1
Pages: 16500

Researcher Affiliations

Ibrahim, Lara
  • Department of Morphology, Imaging, Orthopedics, Rehabilitation and Nutrition, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium. Lara.ibrahim@ugent.be.
Vernemmen, Ingrid
  • Equine Cardioteam Ghent, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
Buschmann, Eva
  • Equine Cardioteam Ghent, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
van Loon, Gunther
  • Equine Cardioteam Ghent, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.
Cornillie, Pieter
  • Department of Morphology, Imaging, Orthopedics, Rehabilitation and Nutrition, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium.

MeSH Terms

  • Animals
  • Horses / anatomy & histology
  • Atrial Septum / anatomy & histology
  • Atrial Septum / pathology
  • Atrial Septum / diagnostic imaging
  • Female
  • Male

Conflict of Interest Statement

Declarations. Competing interests: The authors declare no competing interests.

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