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Equine veterinary journal2023; 56(3); 552-561; doi: 10.1111/evj.13995

Atrial fibrillation as a risk factor for exercise-induced pulmonary haemorrhage following a standardised exercise test.

Abstract: Atrial fibrillation (AF) has been proposed as a risk factor for exercise-induced pulmonary haemorrhage (EIPH) due to increased pressure in the left atrium. Objective: To evaluate if AF was associated with EIPH following a standardised exercise test (SET) to fatigue. Methods: Two-arm controlled experiment. Methods: Ten untrained Standardbred mares mean (standard deviation [SD]) age 6 (2) years performed a SET on the treadmill in sinus rhythm (SR) (SET1) and 25-44 days after induction of self-sustained AF (SET2). AF was induced by tachypacing using a pacing device. Endoscopy, including tracheal wash and bronchoalveolar lavage (BAL), was performed 48-72 h before and 24 h after the two SETs. In addition, endoscopic grading of tracheal blood was performed 2 h after each SET. Results: After SET1, none of the horses showed blood in the trachea, and two horses showed erythrophagocytosis. Following SET2, two horses had grade 1 blood in the trachea and free erythrocytes and erythrophagocytosis in the BAL, while another two horses had erythrophagocytosis in the BAL. In SET2, the overall performance on the treadmill was decreased with a lower maximum velocity (SET1 10.3 ± 0.8 m/s vs. SET2 8.9 ± 0.9 m/s, p = 0.004), a higher heart rate (284 ± 21 vs. 221 ± 18 bpm, p = 0.003) and more abnormal QRS complexes (p < 0.001) compared with SET1. Conclusions: Two horses showed signs of EIPH, resulting in visible blood in the trachea, when exercising in AF compared with SR. However, a possible link between EIPH, pulmonary pressure and AF needs to be further elucidated.
© 2023 The Authors. Equine Veterinary Journal published by John Wiley & Sons Ltd on behalf of EVJ Ltd.
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Publication Date: 2023-09-01 PubMed ID: 37654233DOI: 10.1111/evj.13995Google 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 article investigates the proposed link between Atrial Fibrillation (AF), a heart-related disorder, and exercise-induced pulmonary haemorrhage (EIPH), a lung-related disorder, in horses, using a standardized exercise test (SET). The study found signs of EIPH in horses that were induced with AF, indicating that AF might be a risk factor for EIPH.

Objective and Methods

The aim of the research was to test if AF could be associated with increased risk of EIPH in horses after they undergo a SET to fatigue. AF is a cardiovascular disorder where the heart rhythms become irregular and sometimes rapid, leading to poor blood flow. EIPH, on the other hand, is a condition that often occurs in racehorses when they exercise, and it results in bleeding into the lungs.

  • The study involved a controlled two-arm experiment with ten untrained Standardbred mares of average age six years.
  • Each horse performed a SET on a treadmill in sinus rhythm (ordinary heart rhythm) (SET1), and then another SET 25-44 days later after the induction of AF, labelled as SET2. AF was artificially induced in the horses through a method called tachypacing, which was done using a pacing device.
  • Endoscopic examinations, consisting of both tracheal wash and bronchoalveolar lavage (BAL), were performed 48-72 hours before and 24 hours after the SETs. This also included an endoscopic grading of tracheal blood taken 2 hours after each SET.

Results and Conclusion

After the first SET (SET1), no horses showed blood in the trachea, and only two showed erythrophagocytosis (a process in which red blood cells are ingested). However, following the second SET (SET2), two horses had grade 1 blood in the trachea and showed signs of both free erythrocytes and erythrophagocytosis in the BAL.

  • In the AF-induced SET2, it was observed that the overall performance on the treadmill was reduced compared to the sinus rhythm SET1, with a lower maximum velocity, a higher heart rate, and more abnormal QRS complexes (wave patterns observed in an electrocardiogram).
  • Interestingly, two horses in the AF-induced SET showed signs of EIPH, visible as blood in the trachea, when compared to the SET in sinus rhythm.

Despite the observed signs of EIPH in AF-induced horses, the researchers concluded that more studies are required to conclusively link EIPH, pulmonary pressure, and AF. The findings nonetheless indicated preliminary evidence that AF might be a possible risk factor for EIPH in horses.

Cite This Article

APA
Hansen S, Otten ND, Nissen SD, Carstensen H, Hopster-Iversen C, Fjeldborg J, Staun SH, Fenner M, Hesselkilde EM, Buhl R. (2023). Atrial fibrillation as a risk factor for exercise-induced pulmonary haemorrhage following a standardised exercise test. Equine Vet J, 56(3), 552-561. https://doi.org/10.1111/evj.13995

Publication

Equine veterinary journal
ISSN: 2042-3306
NlmUniqueID: 0173320
Country: United States
Language: English
Volume: 56
Issue: 3
Pages: 552-561

Researcher Affiliations

Hansen, Sanni
  • Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark.
Otten, Nina D
  • Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark.
Nissen, Sarah D
  • Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark.
Carstensen, Helena
  • Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark.
Hopster-Iversen, Charlotte
  • Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark.
Fjeldborg, Julie
  • Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark.
Staun, Sophie H
  • Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark.
Fenner, Merle
  • Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark.
Hesselkilde, Eva M
  • Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark.
Buhl, Rikke
  • Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark.

MeSH Terms

  • Animals
  • Horses
  • Female
  • Atrial Fibrillation / diagnosis
  • Atrial Fibrillation / veterinary
  • Exercise Test / veterinary
  • Exercise Test / adverse effects
  • Bronchoalveolar Lavage Fluid
  • Lung Diseases / etiology
  • Lung Diseases / veterinary
  • Hemorrhage / etiology
  • Hemorrhage / veterinary
  • Physical Conditioning, Animal / adverse effects
  • Risk Factors
  • Horse Diseases / etiology

Grant Funding

  • Brdr. Hartmann Foundation
  • Augustinus Foundation
  • Kustos Foundation
  • 675351 / European Union's Horizon 2020

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Citations

This article has been cited 2 times.
  1. Aeri A, Gorla M, Sharma GT. Veterinary Regenerative Medicine: The Evolving Role of Stem Cell-Based Therapies. Stem Cell Rev Rep 2025 Nov;21(8):2484-2510.
    doi: 10.1007/s12015-025-10963-zpubmed: 40900287google scholar: lookup
  2. Lendl L, Barton AK. Equine Asthma Diagnostics: Review of Influencing Factors and Difficulties in Diagnosing Subclinical Disease. Animals (Basel) 2024 Dec 4;14(23).
    doi: 10.3390/ani14233504pubmed: 39682469google scholar: lookup
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