FREE SHIPPING over $40
OVER 10000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Journal of veterinary internal medicine2025; 39(5); e70218; doi: 10.1111/jvim.70218

Multiple Catheter Recording in Horses to Investigate Atrial Depolarization Pattern During Sinus Rhythm and Induced Premature Atrial Complexes.

Abstract: Detailed characterization of arrhythmias can be performed by multiple catheter mapping; but this has not yet been explored in horses. Objective: Perform ultrasound-guided multiple catheter mapping of the right heart during sinus rhythm and right and left atrial pacing to identify activation patterns characteristic of the origin of ectopy. Obtain His signals and effective refractory periods (ERP). Methods: Eight healthy adult horses. Methods: Experimental study. Recording catheters were placed at the terminal crest, intervenous tubercle, caudal vena cava, and coronary sinus. Right atrial pacing was performed in standing, sedated horses from each catheter and from the cranial vena cava, right atrial appendage, and right atrial free wall. Left atrial pacing was performed during general anesthesia at the four pulmonary vein ostia, left atrial appendage, and interatrial septum. Atrial activation patterns were recorded from the catheters during sinus rhythm and during pacing at the different sites. During sinus rhythm, the His bundle was recorded, and ERP at different sites was determined. Results: Characteristic activation maps during sinus rhythm and pacing were identified. Late coronary sinus activation indicated ectopy originating from the right atrium or ostium III. The direction of coronary sinus electrode activation aided in differentiating left atrial ectopy locations. His signals were recorded in 5/8 horses. Atrial ERP varied between 170 and 420 ms with inter-horse and intra-horse variation. Conclusions: Performing an electrophysiological study in horses, including multiple catheter recording, was feasible. Pacing-induced ectopy resulted in characteristic activation patterns, which might aid in identifying the site of atrial ectopy.
© 2025 The Author(s). Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.
Get Full Text
Publication Date: 2025-09-18 PubMed ID: 40966305PubMed Central: PMC12445429DOI: 10.1111/jvim.70218Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • 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.

Research Overview

  • This study developed and tested a technique using multiple catheter electrophysiological mapping in horses to characterize atrial electrical activation during normal heart rhythm and induced abnormal beats.
  • The goal was to identify patterns of atrial activation that could pinpoint the origin of abnormal electrical impulses (ectopy) within the atria.

Background and Purpose

  • Atrial arrhythmias in horses can be challenging to diagnose due to limited detailed mapping techniques available compared to human cardiology.
  • Multiple catheter mapping allows simultaneous recording from different intracardiac sites to provide detailed electrical activation maps.
  • This study aimed to apply this advanced mapping method to the right heart of horses and to perform pacing from various atrial locations to observe characteristic electrical activation sequences.
  • Additional objectives included recording electrical signals from the His bundle (part of the heart’s electrical conduction system) and determining effective refractory periods (ERP), which are measures of electrical recovery times in heart tissue.

Methods

  • Eight healthy adult horses were included in this experimental study.
  • Multiple electrophysiological catheters were placed in the heart at specific anatomic landmarks in the right atrium: terminal crest, intervenous tubercle, caudal vena cava, and the coronary sinus. Ultrasound guidance was used to place these catheters accurately.
  • Right atrial pacing (electrical stimulation) was performed in sedated horses standing up, from each of these catheter sites as well as from the cranial vena cava, right atrial appendage, and right atrial free wall.
  • Left atrial pacing was done under general anesthesia at four pulmonary vein ostia, the left atrial appendage, and the interatrial septum.
  • Atrial activation patterns were recorded from the catheters during both natural sinus rhythm and during the pacing protocols.
  • The His bundle signal was recorded during sinus rhythm whenever possible, and ERP was measured at different sites to assess electrical recovery properties.

Results

  • Distinct activation maps were identified both during normal rhythm and various pacing points, revealing characteristic sequences that corresponded to specific atrial locations.
  • Late activation in the coronary sinus suggested that ectopic beats originated from the right atrium or from an anatomical area called ostium III.
  • The directional pattern of activation recorded by coronary sinus electrodes helped differentiate whether ectopy originated from the left atrium and its sublocations.
  • The His bundle electrical signals were successfully recorded in 5 out of 8 horses, demonstrating feasibility in this species.
  • Atrial effective refractory periods varied widely (170 to 420 ms), showing variability both between horses and between different atrial regions within the same horse.

Conclusions and Significance

  • This study demonstrated that it is feasible to perform detailed electrophysiological studies in horses using multiple intracardiac catheters.
  • The methodology allowed the identification of distinctive electrical activation patterns during sinus rhythm and paced ectopic beats.
  • Such activation maps can potentially aid clinicians and researchers in identifying the site of origin of atrial ectopy in horses, which is important for diagnosis and treatment of atrial arrhythmias.
  • Recording His bundle signals and measuring ERP adds valuable information about the electrical conduction properties in equine hearts.
  • Overall, the findings provide a framework for further investigations into the mechanisms of atrial arrhythmias and potentially improved therapeutic interventions in equine cardiology.

Cite This Article

APA
Buschmann E, Van Steenkiste G, Vernemmen I, Demeyere M, Schauvliege S, Decloedt A, van Loon G. (2025). Multiple Catheter Recording in Horses to Investigate Atrial Depolarization Pattern During Sinus Rhythm and Induced Premature Atrial Complexes. J Vet Intern Med, 39(5), e70218. https://doi.org/10.1111/jvim.70218

Publication

Journal of veterinary internal medicine
ISSN: 1939-1676
NlmUniqueID: 8708660
Country: United States
Language: English
Volume: 39
Issue: 5
Pages: e70218
PII: e70218

Researcher Affiliations

Buschmann, Eva
  • Equine Cardioteam Ghent, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
Van Steenkiste, Glenn
  • Equine Cardioteam Ghent, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
Vernemmen, Ingrid
  • Equine Cardioteam Ghent, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
Demeyere, Marie
  • Equine Cardioteam Ghent, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
Schauvliege, Stijn
  • Department of Large Animal Surgery, Anaesthesia and Orthopaedics, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
Decloedt, Annelies
  • Equine Cardioteam Ghent, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
van Loon, Gunther
  • Equine Cardioteam Ghent, Department of Internal Medicine, Reproduction and Population Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.

MeSH Terms

  • Animals
  • Horses
  • Male
  • Female
  • Atrial Premature Complexes / veterinary
  • Atrial Premature Complexes / physiopathology
  • Atrial Premature Complexes / diagnosis
  • Horse Diseases / diagnosis
  • Horse Diseases / physiopathology
  • Heart Atria / physiopathology
  • Cardiac Catheterization / veterinary

Grant Funding

  • 01B05818 / Bijzonder Onderzoeksfonds UGent
  • 1S71521N / Fonds Wetenschappelijk Onderzoek
  • 1SA2223N / Fonds Wetenschappelijk Onderzoek
  • 1SE9122N / Fonds Wetenschappelijk Onderzoek

Conflict of Interest Statement

Authors declare no off‐label use of antimicrobials. The authors declare no conflicts of interest.

References

This article includes 46 references
  1. Buschmann E, Van Steenkiste G, Vernemmen I. Lesion Size Index‐Guided Radiofrequency Catheter Ablation Using an Impedance‐Based Three‐Dimensional Mapping System to Treat Sustained Atrial Tachycardia in a Horse. Equine Veterinary Journal 57 (2025): 1009–1016.
    pubmed: 39434506
  2. Buschmann E, Van Steenkiste G, Vernemmen I. Caudal Vena Cava Isolation Using Ablation Index‐Guided Radiofrequency Catheter Ablation (CARTO 3) to Treat Sustained Atrial Tachycardia in Horses. Journal of Veterinary Internal Medicine 39 (2025): e17251.
    pmc: PMC11638121pubmed: 39614765
  3. Van Steenkiste G, Boussy T, Duytschaever M. Detection of the Origin of Atrial Tachycardia by 3D Electro‐Anatomical Mapping and Treatment by Radiofrequency Catheter Ablation in Horses. Journal of Veterinary Internal Medicine 36 (2022): 1481–1490.
    pmc: PMC9308432pubmed: 35686355
  4. Buschmann E, Van Steenkiste G, Boussy T. Three‐Dimensional Electro‐Anatomical Mapping and Radiofrequency Ablation as a Novel Treatment for Atrioventricular Accessory Pathway in a Horse: A Case Report. Journal of Veterinary Internal Medicine 37 (2023): 728–734.
    pmc: PMC10061177pubmed: 36866668
  5. Hesselkilde E M, Isaksen J L, Petersen B V. A Novel Approach for Obtaining 12‐Lead Electrocardiograms in Horses. Journal of Veterinary Internal Medicine 35 (2021): 521–531.
    pmc: PMC7848388pubmed: 33274799
  6. van Loon G, Decloedt A. Arrhythmias and Abnormalities of the Cardiac Conduction System in Athletic Horses. in Equine Sports Medicine and Surgery, 3rd ed., ed. Hinchcliff K., Kaneps A., Geor R., and van Erck‐Westergem E. (Elsevier, 2024), 831–865.
  7. Van Steenkiste G, Delhaas T, Hermans B. An Exploratory Study on Vectorcardiographic Identification of the Site of Origin of Focally Induced Premature Depolarizations in Horses, Part I: The Atria. Animals 12 (2022): 549.
    pmc: PMC8908827pubmed: 35268117
  8. Avison A, Gelzer A R, Reef V B. Twenty‐Four Hour Continuous Transvenous Temporary Right Ventricular Pacing in Healthy Horses. Journal of Veterinary Internal Medicine 38 (2024): 1751–1764.
    pmc: PMC11099695pubmed: 38514200
  9. van Loon G, Van Steenkiste G, Vera L. Catheter‐Based Electrical Interventions to Study, Diagnose and Treat Arrhythmias in Horses: From Refractory Period to Electro‐Anatomical Mapping. Veterinary Journal 263 (2020): 105519.
    pubmed: 32928488
  10. Van Steenkiste G, De Clercq D, Boussy T. Three Dimensional Ultra‐High‐Density Electro‐Anatomical Cardiac Mapping in Horses: Methodology. Equine Veterinary Journal 52 (2020): 765–772.
    pubmed: 31954064
  11. Van Steenkiste G, Vera L, Decloedt A. Endocardial Electro‐Anatomic Mapping in Healthy Horses: Normal Sinus Impulse Propagation in the Left and Right Atrium and the Ventricles. Veterinary Journal 258 (2020): 105452.
    pubmed: 32564870
  12. Hesselkilde E, Linz D, Saljic A. First Catheter‐Based High‐Density Endocardial 3D Electroanatomical Mapping of the Right Atrium in Standing Horses. Equine Veterinary Journal 53 (2021): 186–193.
    pmc: PMC7818172pubmed: 32285961
  13. Issa Z M, Zipes D P. Conventional Intracardiac Mapping Techniques. in Clinical Arrhythmology and Electrophysiology, 3rd ed., ed. Issa J. M. (Elsevier, 2019), 125–154.
  14. Vernemmen I, Buschmann E, Demeyere M. Feasibility of Transthoracic Echocardiographic Guidance for Multi‐Catheter Electrophysiological Mapping Studies in Horses. Journal of Veterinary Internal Medicine 38 (2024): 2686–2697.
    pmc: PMC11423469pubmed: 39096119
  15. Vernemmen I, Buschmann E, Van Steenkiste G. Intracardiac Ultrasound‐Guided Transseptal Puncture in Horses: Outcome, Follow‐Up and Peri‐Operative Anticogulant Treatment. Journal of Veterinary Internal Medicine 38 (2024): 2707–2717.
    pmc: PMC11423474pubmed: 39086137
  16. Ibrahim L, Buschmann E, van Loon G, Cornillie P. Morphological Evidence of a Potential Arrhythmogenic Substrate in the Caudal and Cranial Vena Cava in Horses. Equine Veterinary Journal 57 (2024): 256–264.
    pubmed: 38391272
  17. van Loon G, Duytschaever M, Tavernier R, Fonteyne W, Jordaens L, Deprez P. An Equine Model of Chronic Atrial Fibrillation: Methodology. Veterinary Journal 164 (2002): 142–150.
    pubmed: 12359469
  18. Vernemmen I, Van Steenkiste G, Buschmann E. Development of an Atrial Transseptal Puncture Procedure in Horses to Access the Left Heart: An Ultrasound‐Guided Jugular Vein and Transhepatic Approach. Equine Veterinary Journal 57 (2025): 243–255.
    pubmed: 38522423
  19. Murgatroyd F D, Krahn A D. Handbook of Cardiac Electrophysiology. Remedica, 2002, 250.
  20. Dauvillier J, Tricaud M C, Hermange T. Falsely Increased Troponin I Values in Horses With No Evidence of Myocardial Disease. 2023, In Cardio Retreat – International Meeting on Equine Cardiology, New Bolton, Pensylvannia, USA.
  21. Deen V R, Morton J B, Vohra J K. Pulmonary Vein Paced Activation Sequence Mapping: Comparison With Activation Sequences During Onset of Focal Atrial Fibrillation. Journal of Cardiovascular Electrophysiology 13 (2002): 101–107.
    pubmed: 11900282
  22. Kistler P M, Sanders P, Fynn S P. Electrophysiological and Electrocardiographic Characteristics of Focal Atrial Tachycardia Originating From the Pulmonary Veins – Acute and Long‐Term Outcomes of Radiofrequency Ablation. Circulation 108 (2003): 1968–1975.
    pubmed: 14557361
  23. Tracy C M, Swartz J F, Fletcher R D. Radiofrequency Catheter Ablation of Ectopic Atrial Tachycardia Using Paced Activation Sequence Mapping. Journal of the American College of Cardiology 21 (1993): 910–917.
    pubmed: 8450159
  24. Bishop S P, Cole C R. Morphology of the Specialized Conducting Tissue in the Atria of the Equine Heart. Anatomical Record 158 (1967): 401–415.
    pubmed: 6055082
  25. Josephson M E, Scharf D L, Kastor J A, Kitchen J G. Atrial Endocardial Activation in Man – Electrode Catheter Technique for Endocardial Mapping. American Journal of Cardiology 39 (1977): 972–981.
    pubmed: 141203
  26. Hariman R J, Hoffman B F, Naylor R E. Electrical‐Activity From the Sinus Node Region in Conscious Dogs. Circulation Research 47 (1980): 775–791.
    pubmed: 7418135
  27. Schuessler R B, Boineau J P, Bromberg B I. Origin of the Sinus Impulse. Journal of Cardiovascular Electrophysiology 7 (1996): 263–274.
    pubmed: 8867301
  28. Roithinger F X, Cheng J, SippensGroenewegen A. Use of Electroanatomic Mapping to Delineate Transseptal Atrial Conduction in Humans. Circulation 100 (1999): 1791–1797.
    pubmed: 10534466
  29. Haissaguerre M, Jais P, Shah D C. Spontaneous Initiation of Atrial Fibrillation by Ectopic Beats Originating in the Pulmonary Veins. New England Journal of Medicine 339 (1998): 659–666.
    pubmed: 9725923
  30. Linz D, Hesselkilde E, Kutieleh R, Jespersen T, Buhl R, Sanders P. Pulmonary Vein Firing Initiating Atrial Fibrillation in the Horse: Oversized Dimensions but Similar Mechanisms. Journal of Cardiovascular Electrophysiology 31 (2020): 1211–1212.
    pubmed: 32108401
  31. Kjeldsen S T, Nissen S D, Saljic A. Structural and Electro‐Anatomical Characterization of the Equine Pulmonary Veins: Implications for Atrial Fibrillation. Journal of Veterinary Cardiology 52 (2024): 1–13.
    pubmed: 38290222
  32. Vandecasteele T, Van den Broeck W, Tay H. 3D Reconstruction of the Porcine and Equine Pulmonary Veins, Supplemented With the Identification of Telocytes in the Horse. Anatomia, Histologia, Embryologia 47 (2018): 145–152.
    pubmed: 29314148
  33. Buschmann E, Van Steenkiste G, Duytschaever M. Successful Caudal Vena Cava and Pulmonary Vein Isolation in Healthy Horses Using 3D Electro‐Anatomical Mapping and a Contact Force‐Guided Ablation System. Equine Veterinary Journal 56 (2023): 1068–1076.
    pubmed: 38151793
  34. Koulouris S, Cascella M. Electrophysiologic Study Interpretation. StatPearls StatPearls, 2025.
    pubmed: 32809619
  35. Nissen S D, Weis R, Krag‐Andersen E K. Electrocardiographic Characteristics of Trained and Untrained Standardbred Racehorses. Journal of Veterinary Internal Medicine 36 (2022): 1119–1130.
    pmc: PMC9151491pubmed: 35488721
  36. Noujaim S F, Lucca E, Muñoz V. From Mouse to Whale: A a Universal Scaling Relation for the PR Interval of the Electrocardiogram of Mammals. Circulation 110 (2004): 2802–2808.
    pubmed: 15505092
  37. McAnulty J H, Nichol W P, Morris C, Nichol L, Rahimtoola S H. Measurement of the AH and HV Interval and His Bundle Duration: Interobserver and Intraobserver Variation. American Journal of Cardiology 57 (1986): 960–963.
    pubmed: 3962896
  38. Issa Z M, Zipes D P. Electrophysiological Testing: Tools and Techniques. Clinical Arrhythmology and Electrophysiology, 3rd ed., ed. Issa J. M. (Elsevier, 2019), 81–124.
  39. De Clercq D, Van Loon G, Tavernier R. Atrial and Ventricular Electrical and Contractile Remodeling and Reverse Remodeling Owing to Short‐Term Pacing‐Induced Atrial Fibrillation in Horses. Journal of Veterinary Internal Medicine 22 (2008): 1353–1359.
    pubmed: 19000247
  40. Carstensen H, Nissen S D, Saljic A. Long‐Term Training Increases Atrial Fibrillation Sustainability in Standardbred Racehorses. Journal of Cardiovascular Translational Research 16 (2023): 1205–1219.
    pmc: PMC10615936pubmed: 37014465
  41. Schwarzwald C C, Hamlin R L, Bonagura J D, Nishijima Y, Meadows C, Carnes C A. Atrial, SA Nodal, and AV Nodal Electrophysiology in Standing Horses: Normal Findings and Electrophysiologic Effects of Quinidine and Diltiazem. Journal of Veterinary Internal Medicine 21 (2007): 166–175.
    pubmed: 17338165
  42. Fenner M F, Carstensen H, Dalgas Nissen S. Effect of Selective I(K,ACh) Inhibition by XAF‐1407 in an Equine Model of Tachypacing‐Induced Persistent Atrial Fibrillation. British Journal of Pharmacology 177 (2020): 3778–3794.
    pmc: PMC7393200pubmed: 32436234
  43. Haugaard M M, Pehrson S, Carstensen H. Antiarrhythmic and Electrophysiologic Effects of Flecainide on Acutely Induced Atrial Fibrillation in Healthy Horses. Journal of Veterinary Internal Medicine 29 (2015): 339–347.
    pmc: PMC4858114pubmed: 25328012
  44. Haugaard M M, Hesselkilde E Z, Pehrson S. Pharmacologic Inhibition of Small‐Conductance Calcium‐Activated Potassium (SK) Channels by NS8593 Reveals Atrial Antiarrhythmic Potential in Horses. Heart Rhythm 12 (2015): 825–835.
    pubmed: 25542425
  45. Carstensen H, Kjær L, Haugaard M M. Antiarrhythmic Effects of Combining Dofetilide and Ranolazine in a Model of Acutely Induced Atrial Fibrillation in Horses. Journal of Cardiovascular Pharmacology 71 (2018): 26–35.
    pmc: PMC5768216pubmed: 29068807
  46. Kim I B, Rodefeld M D, Schuessler R B. Relationship Between Local Atrial Fibrillation Interval and Refractory Period in the Isolated Canine Atrium. Circulation 94 (1996): 2961–2967.
    pubmed: 8941127

Citations

This article has been cited 0 times.
Subscribe to our newsletter
Join 100,129 horse owners like you who receive our email updates on horse health and nutrition.