Ventricular response during lungeing exercise in horses with lone atrial fibrillation.
Abstract: Atrial fibrillation (AF) is the most important dysrhythmia affecting performance in horses and has been associated with incoordination, collapse and sudden death. Limited information is available on ventricular response during exercise in horses with lone AF. Objective: To investigate ventricular response in horses with lone AF during a standardised lungeing exercise test. Methods: A modified base-apex electrocardiogram was recorded at rest and during a standardised lungeing exercise test from 43 horses diagnosed with lone AF. During the test horses walked for 7 min, trotted for 10 min, cantered for 4 min, galloped for 1 min and recovered for 7 min. Results: Individual average heart rate during walk ranged from 42 to 175 beats/min, during trot from 89 to 207 beats/min, during canter from 141 to 269 beats/min, and during gallop from 191 to 311 beats/min. Individual beat-to-beat maximal heart rate ranged from 248 to 492 beats/min. Ventricular premature depolarisations were present in 81% of the horses: at rest (16%), during exercise (69%), and during recovery (2%). In 33% of the horses, broad QRS complexes with R-on-T morphology were found. Conclusions: Exercising horses with lone AF frequently develop disproportionate tachycardia. In addition, QRS broadening and even R-on-T morphology is frequently found. QRS broadening may originate from ventricular ectopic foci or from aberrant intraventricular conduction, for example due to bundle branch block. This might explain the high number of complexes currently classified as ventricular premature depolarisations. Conclusions: Prevalence of QRS broadening and especially R-on-T was very high in horses with AF and was found at low levels of exercise. These dysrhythmias are considered risk factors for the development of ventricular tachycardia and fibrillation and they might explain signs of weakness, collapse or sudden death that have been reported in horses with AF.
© 2012 EVJ Ltd.
Publication Date: 2012-10-23 PubMed ID: 23094848DOI: 10.1111/j.2042-3306.2012.00653.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research examined ventricular responses in horses during lungeing exercise, particularly those with lone atrial fibrillation (AF). The results showed that these horses often develop disproportionate tachycardia, along with QRS broadening and even R-on-T morphology, all of which can pose a significant risk for the development of ventricular tachycardia and fibrillation.
Objective of the Research
- The primary aim of the study was to investigate how the ventricles respond during a standardised lungeing exercise test in horses with lone atrial fibrillation (AF). This research was vital since AF is the most critical dysrhythmia that impacts horses’ performance and could lead to severe consequences such as sudden death.
Research Methodology
- The research involved recording a modified base-apex electrocardiogram at rest and during a standardised lungeing exercise test from 43 horses diagnosed with lone AF.
- The test included different stages: walk for 7 minutes, trot for 10 minutes, canter for 4 minutes, gallop for 1 minute, and recovery for 7 minutes.
Research Findings
- Horses’ heart rates varied at different stages of the test; walking ranged from 42 to 175 beats/min, trotting from 89 to 207 beats/min, cantering from 141 to 269 beats/min, and galloping from 191 to 311 beats/min. The beat-to-beat maximal heart rate ranged from 248 to 492 beats/min.
- Ventricular premature depolarisations, an abnormal heartbeat, were found in 81% of horses, with various occurrences at rest (16%), during exercise (69%), and during recovery (2%).
- 33% of the animals showed broad QRS complexes with R-on-T morphology, an abnormal heart rhythm that can be a precursory sign of cardiac arrest.
Conclusions
- The exercise triggered a disproportionate heart rate increase, known as tachycardia, in horses with lone AF. Further, many horses showed QRS broadening and R-on-T morphology, which can originate from ventricular ectopic foci or aberrant intraventricular conduction, which might be due to a bundle branch block.
- Significantly, both QRS broadening and R-on-T were prevalent in horses with AF, even at low exercise levels. These abnormal heart rhythms are potential risk factors for developing ventricular tachycardia and fibrillation. They might explain the signs of weakness, collapse, or sudden death reported in horses with AF.
Cite This Article
APA
Verheyen T, Decloedt A, van der Vekens N, Sys S, De Clercq D, van Loon G.
(2012).
Ventricular response during lungeing exercise in horses with lone atrial fibrillation.
Equine Vet J, 45(3), 309-314.
https://doi.org/10.1111/j.2042-3306.2012.00653.x Publication
Researcher Affiliations
- Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium. tinne.verheyen@ugent.be
MeSH Terms
- Animals
- Atrial Fibrillation / physiopathology
- Atrial Fibrillation / veterinary
- Electrocardiography / instrumentation
- Electrocardiography / methods
- Electrocardiography / veterinary
- Female
- Heart Rate
- Horse Diseases / diagnosis
- Horse Diseases / physiopathology
- Horses
- Male
- Physical Conditioning, Animal / methods
- Ventricular Function / physiology
Citations
This article has been cited 17 times.- Natterson-Horowitz B, Wright K, Van Steenkiste G, Decloedt A, Gagnon AL, Cai X, Mazmanian A. Arrhythmias across the tree of life: comparative insights for human electrophysiology. Front Cardiovasc Med 2025;12:1652591.
- Dufourni A, Demeyere M, Vernemmen I, Van Steenkiste G, Verhaeghe LM, van Loon G, Decloedt A. Effect of N-Butylscopolammonium Bromide and Metamizol Sodium on Heart Rate, Blood Pressure, and Echocardiographic Measurements in Warmblood Horses With Aortic and Mitral Valve Regurgitation. J Vet Intern Med 2025 Nov-Dec;39(6):e70254.
- Kjeldsen ST, Nissen SD, Christensen NC, Haugaard SL, Schneider MJ, Vinther Z, Sattler SM, Carstensen H, Jøns C, Hopster-Iversen C, Buhl R. Validation and clinical application of implantable loop recorders for diagnosis of atrial fibrillation in horses. Equine Vet J 2025 Mar;57(2):449-458.
- Kenchaiwong W, Sangpo P, Kusol A, Pontaema T, Lerdweeraphon W. The position of ground electrode affects electrocardiographic parameters in horses. Vet World 2022 Apr;15(4):1107-1112.
- Vernemmen I, Paulussen E, Dauvillier J, Decloedt A, van Loon G. Three-dimensional and catheter-based intracardiac echocardiographic characterization of the interatrial septum in 2 horses with suspicion of a patent foramen ovale. J Vet Intern Med 2022 Jul;36(4):1535-1542.
- Huang YH, Lyle JV, Ab Razak AS, Nandi M, Marr CM, Huang CL, Aston PJ, Jeevaratnam K. Detecting paroxysmal atrial fibrillation from normal sinus rhythm in equine athletes using Symmetric Projection Attractor Reconstruction and machine learning. Cardiovasc Digit Health J 2022 Apr;3(2):96-106.
- Alberti E, Stucchi L, Lo Feudo CM, Stancari G, Conturba B, Ferrucci F, Zucca E. Evaluation of Cardiac Arrhythmias before, during, and after Treadmill Exercise Testing in Poorly Performing Standardbred Racehorses. Animals (Basel) 2021 Aug 16;11(8).
- Vitale V, Vezzosi T, Tognetti R, Fraschetti C, Sgorbini M. Evaluation of a new portable 1-lead digital cardiac monitor (eKuore) compared with standard base-apex electrocardiography in healthy horses. PLoS One 2021;16(8):e0255247.
- Nath LC, Elliott AD, Weir J, Curl P, Rosanowski SM, Franklin S. Incidence, recurrence, and outcome of postrace atrial fibrillation in Thoroughbred horses. J Vet Intern Med 2021 Mar;35(2):1111-1120.
- Corradini I, Fernández-Ruiz A, Barba M, Engel-Manchado J. Stall-side screening potential of a smartphone electrocardiogram recorded over both sides of the thorax in horses. J Vet Intern Med 2020 Sep;34(5):2101-2108.
- Broux B, De Clercq D, Vera L, Ven S, Deprez P, Decloedt A, van Loon G. Can heart rate variability parameters derived by a heart rate monitor differentiate between atrial fibrillation and sinus rhythm?. BMC Vet Res 2018 Oct 25;14(1):320.
- McGurrin MKJ. The diagnosis and management of atrial fibrillation in the horse. Vet Med (Auckl) 2015;6:83-90.
- Buhl R, Carstensen H, Hesselkilde EZ, Klein BZ, Hougaard KM, Ravn KB, Loft-Andersen AV, Fenner MF, Pipper C, Jespersen T. Effect of induced chronic atrial fibrillation on exercise performance in Standardbred trotters. J Vet Intern Med 2018 Jul;32(4):1410-1419.
- Decloedt A, Broux B, De Clercq D, Deprez P, Van Steenkiste G, Vera L, Ven S, van Loon G. Effect of sotalol on heart rate, QT interval, and atrial fibrillation cycle length in horses with atrial fibrillation. J Vet Intern Med 2018 Mar;32(2):815-821.
- Decloedt A, Schwarzwald CC, De Clercq D, Van Der Vekens N, Pardon B, Reef VB, van Loon G. Risk factors for recurrence of atrial fibrillation in horses after cardioversion to sinus rhythm. J Vet Intern Med 2015 May-Jun;29(3):946-53.
- Van Der Vekens N, Decloedt A, Ven S, De Clercq D, van Loon G. Cardiac troponin I as compared to troponin T for the detection of myocardial damage in horses. J Vet Intern Med 2015 Jan;29(1):348-54.
- Reef VB, Bonagura J, Buhl R, McGurrin MK, Schwarzwald CC, van Loon G, Young LE. Recommendations for management of equine athletes with cardiovascular abnormalities. J Vet Intern Med 2014 May-Jun;28(3):749-61.
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