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Marion-Knudsen R, Lindberg LA, Jespersen T, Saljic A. Quantitative histologic assessment of atrial fibrillation-associated fibrosis in animal models: A systematic review. Heart Rhythm 2025:S1547-5271(25)02102-2. [PMID: 40058516 DOI: 10.1016/j.hrthm.2025.03.1880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2024] [Revised: 02/17/2025] [Accepted: 03/04/2025] [Indexed: 03/25/2025]
Abstract
Atrial fibrillation (AF) is the most common sustained arrhythmia, and cardiac fibrosis is a major component in driving its progressive nature. Quantitative histologic assessment of fibrosis in animal models is crucial for understanding AF, but current published studies present various methodologies that limit comparison. This systematic review examines 195 AF studies across multiple animal models (mice, rats, goats, dogs, pigs, and horses) to summarize (1) quantified fibrosis results and (2) methodologies for histologic fibrosis assessment; and (3) evaluate antifibrotic therapies used in these studies. The fibrosis quantified across the studies ranged from 0.34%-60.2% depending on the animal, intervention model, and quantification method. The findings underscore the need for a standardized fibrosis quantification protocol in AF research, enabling comparison across studies and offering greater insight into potential pharmacologic interventions.
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Affiliation(s)
- Rikke Marion-Knudsen
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lucas Alexander Lindberg
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Jespersen
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Arnela Saljic
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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2
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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; 57:449-458. [PMID: 39031582 PMCID: PMC11807927 DOI: 10.1111/evj.14112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 05/16/2024] [Indexed: 07/22/2024]
Abstract
BACKGROUND Paroxysmal atrial fibrillation (pAF) occurs sporadically and can impair athletic performance. Gold standard for diagnosis is surface electrocardiography (ECG), however, this requires AF to be sustained. Implantable loop recorders (ILRs) are routinely used for AF detection in human medicine. While ILR placement has been studied in horses, its AF detection performance is unknown. OBJECTIVES (I) Validation of ILRs for AF detection in horses. (II) Determining pAF incidence using ILRs and estimate the positive predictive value (PPV). STUDY DESIGN (I) Experimental study; (II) Longitudinal observational study. METHODS (I) Implantation of ILRs in 15 horses with AF and 13 horses in sinus rhythm. Holter ECGs were recorded at: 1, 4, 8, 12 and 16 weeks of AF. The ILR ECGs were compared with surface ECGs to assess diagnostic sensitivity and specificity. (II) Eighty horses (43 Warmbloods, 37 Standardbreds) with ILRs were monitored for 367 days [IQR 208-621]. RESULTS (I) ILRs detected AF on all recording days, in horses with AF, with a sensitivity of 66.1% (95% CI: 65.8-66.5) and a specificity of 99.99% (95% CI: 99.97-99.99). The sensitivity remained consistent across all time points. (II) The incidence of pAF was 6.3% (5/80). In horses with pAF, the PPV ranged from 8% to 87%. Increased body condition score (BCS > 6/9) was associated with an increased number of false positive episodes (p = 0.005). MAIN LIMITATIONS (I) Horses were stabled during the ECG recordings, and AF was induced, rather than naturally occurring pAF. (II) Integrated algorithm in this ILR is optimised for AF detection in humans using remote monitors. Additionally, sensing is affected by motion artefacts. CONCLUSION The ILR reliably detected AF in resting horses, particularly in horses with normal BCS (6/9). The ILR proved useful to detect pAF and is recommended alongside Holter monitoring for diagnostic workup of horses with suspected pAF.
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Affiliation(s)
- Sofie Troest Kjeldsen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Sarah D. Nissen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Nina C. Christensen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Simon L. Haugaard
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Mélodie J. Schneider
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Zenta Vinther
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Stefan M. Sattler
- Department of CardiologyHerlev and Gentofte University HospitalGentofteDenmark
- Department of Biomedical Sciences, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Helena Carstensen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Christian Jøns
- Department of Cardiology, The Heart CentreCopenhagen University Hospital, RigshospitaletCopenhagenDenmark
| | - Charlotte Hopster‐Iversen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Rikke Buhl
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
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Hansen S, Otten ND, Nissen SD, Carstensen H, Hopster-Iversen C, Fjeldborg J, Staun SH, Fenner M, Hesselkilde EM, Buhl R. Atrial fibrillation as a risk factor for exercise-induced pulmonary haemorrhage following a standardised exercise test. Equine Vet J 2024; 56:552-561. [PMID: 37654233 DOI: 10.1111/evj.13995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 08/17/2023] [Indexed: 09/02/2023]
Abstract
BACKGROUND 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. STUDY DESIGN 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.
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Affiliation(s)
- Sanni Hansen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Nina D Otten
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Sarah D Nissen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Helena Carstensen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Charlotte Hopster-Iversen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Julie Fjeldborg
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Sophie H Staun
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Merle Fenner
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Eva M Hesselkilde
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Rikke Buhl
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
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Nath LC, Elliott A, La Gerche A, Weir J, Forbes G, Thomas G, Franklin S. Associations between postrace atrial fibrillation and measures of performance, racing history and airway disease in horses. J Vet Intern Med 2023; 37:2573-2583. [PMID: 37740606 PMCID: PMC10658555 DOI: 10.1111/jvim.16878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Accepted: 09/11/2023] [Indexed: 09/24/2023] Open
Abstract
BACKGROUND Atrial fibrillation (AF) is the most common performance limiting arrhythmia in racehorses. High dose exercise and airway disease promote AF in humans. Few studies have investigated epidemiological factors associated with AF in horses. OBJECTIVES Explore variables relating to performance, exercise volume and postrace endoscopic findings in horses with AF. ANIMALS A total of 164 horses with poor race performance and postrace AF were compared to 321 horses with poor performance without AF (PP) and 314 horses performing to expectation (TE). METHODS Horse-level and race-level variables for horses racing in Australia and Hong Kong from 2009 to 2021 were compared using univariable and multivariable logistic regression. Postrace endoscopic exercise-induced pulmonary hemorrhage (EIPH) and tracheal mucus accumulation (TMA) grades for AF and PP horses were compared using chi-squared analysis. RESULTS Variables that were significant in the multivariable model of AF compared to TE were distance (lengths) behind the winner, (odds ratio [OR]; 95% confidence interval [95% CI], 1.41 [1.32-1.51], P < .0001), cumulative prize money per start before the event (OR [95% CI] 1.02 [1.01-1.03], P = .01) and age (OR [95% CI] 0.72 [0.55-0.92], P = .01). More AF horses had EIPH grade ≥ 3 (23/109; 21.1%) than PP horses (7/213; 3.3%; OR [95%CI] 7.9 [3.3-20.2], P < .0001). CONCLUSIONS AND CLINICAL IMPORTANCE Acute race performance was substantially impaired by AF but career earnings before the event were not inferior. Exercise volume did not promote AF. Higher grades of EIPH found in AF horses suggests a mechanistic relationship between these conditions.
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Carstensen H, Nissen SD, Saljic A, Hesselkilde EM, van Hunnik A, Hohl M, Sattler SM, Fløgstad C, Hopster-Iversen C, Verheule S, Böhm M, Schotten U, Jespersen T, Buhl R. Long-Term Training Increases Atrial Fibrillation Sustainability in Standardbred Racehorses. J Cardiovasc Transl Res 2023; 16:1205-1219. [PMID: 37014465 PMCID: PMC10615936 DOI: 10.1007/s12265-023-10378-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 03/14/2023] [Indexed: 04/05/2023]
Abstract
Atrial fibrillation (AF) is more prevalent in athletes, and currently, the mechanisms are not fully understood. Atrial fibrillation inducibility and stability was investigated in trained and untrained Standardbred racehorses. The horses underwent echocardiography for evaluation of atrial size. High-density mapping during AF was performed, and the presence of structural remodeling, as well as the expression of inflammatory and pro-inflammatory markers in the atria, was studied. Atrial fibrillation sustained significantly longer after tachypacing in the trained horses, whereas no difference in AF inducibility was found. The untrained horses displayed a significant difference in the AF complexity when comparing right and left atria, whereas such difference was not observed in the trained animals. No evidence of increased structural remodeling or inflammation could be identified. Left atrial dimensions were not significantly increased. The increased AF sustainability in trained horses was not related to fibrosis or inflammation as seen in other animal exercise models.
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Affiliation(s)
- Helena Carstensen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegaard Allé 5, 2630, Taastrup, Denmark
| | - Sarah Dalgas Nissen
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark.
| | - Arnela Saljic
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
| | - Eva Melis Hesselkilde
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
| | - Arne van Hunnik
- Department of Physiology, Maastricht University, Maastricht, Netherlands
| | - Mathias Hohl
- Department of Internal Medicine III, University Hospital, Saarland University, Homburg, Saar, Germany
| | - Stefan Michael Sattler
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
- Department of Cardiology, Herlev and Gentofte University Hospital, Herlev, Denmark
| | - Cecilie Fløgstad
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegaard Allé 5, 2630, Taastrup, Denmark
| | - Charlotte Hopster-Iversen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegaard Allé 5, 2630, Taastrup, Denmark
| | - Sander Verheule
- Department of Physiology, Maastricht University, Maastricht, Netherlands
| | - Michael Böhm
- Department of Internal Medicine III, University Hospital, Saarland University, Homburg, Saar, Germany
| | - Ulrich Schotten
- Department of Physiology, Maastricht University, Maastricht, Netherlands
| | - Thomas Jespersen
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
| | - Rikke Buhl
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Højbakkegaard Allé 5, 2630, Taastrup, Denmark
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Buhl R, Hesselkilde EM, Carstensen H, Hopster‐Iversen C, van Loon G, Decloedt A, Van Steenkiste G, Marr C, Reef VB, Schwarzwald CC, Mitchell KJ, Nostell K, Nogradi N, Nielsen SS, Carlson J, Platonov P. Atrial fibrillatory rate as predictor of recurrence of atrial fibrillation in horses treated medically or with electrical cardioversion. Equine Vet J 2022; 54:1013-1022. [PMID: 34957586 PMCID: PMC9787611 DOI: 10.1111/evj.13551] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 12/20/2021] [Indexed: 12/30/2022]
Abstract
BACKGROUND The recurrence rate of atrial fibrillation (AF) in horses after cardioversion to sinus rhythm (SR) is relatively high. Atrial fibrillatory rate (AFR) derived from surface ECG is considered a biomarker for electrical remodelling and could potentially be used for the prediction of successful AF cardioversion and AF recurrence. OBJECTIVES Evaluate if AFR was associated with successful treatment and could predict AF recurrence in horses. STUDY DESIGN Retrospective multicentre study. METHODS Electrocardiograms (ECG) from horses with persistent AF admitted for cardioversion with either medical treatment (quinidine) or transvenous electrical cardioversion (TVEC) were included. Bipolar surface ECG recordings were analysed by spatiotemporal cancellation of QRST complexes and calculation of AFR from the remaining atrial signal. Kaplan-Meier survival curve and Cox regression analyses were performed to assess the relationship between AFR and the risk of AF recurrence. RESULTS Of the 195 horses included, 74 received quinidine treatment and 121 were treated with TVEC. Ten horses did not cardiovert to SR after quinidine treatment and AFR was higher in these, compared with the horses that successfully cardioverted to SR (median [interquartile range]), (383 [367-422] vs 351 [332-389] fibrillations per minute (fpm), P < .01). Within the first 180 days following AF cardioversion, 12% of the quinidine and 34% of TVEC horses had AF recurrence. For the horses successfully cardioverted with TVEC, AFR above 380 fpm was significantly associated with AF recurrence (hazard ratio = 2.4, 95% confidence interval 1.2-4.8, P = .01). MAIN LIMITATIONS The treatment groups were different and not randomly allocated, therefore the two treatments cannot be compared. Medical records and the follow-up strategy varied between the centres. CONCLUSIONS High AFR is associated with failure of quinidine cardioversion and AF recurrence after successful TVEC. As a noninvasive marker that can be retrieved from surface ECG, AFR can be clinically useful in predicting the probability of responding to quinidine treatment as well as maintaining SR after electrical cardioversion.
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Affiliation(s)
- Rikke Buhl
- Department of Veterinary Clinical SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Eva M. Hesselkilde
- Department of Veterinary Clinical SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Helena Carstensen
- Department of Veterinary Clinical SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Charlotte Hopster‐Iversen
- Department of Veterinary Clinical SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Gunther van Loon
- Equine CardioteamDepartment of Large Animal Internal MedicineGhent UniversityMerelbekeBelgium
| | - Annelies Decloedt
- Equine CardioteamDepartment of Large Animal Internal MedicineGhent UniversityMerelbekeBelgium
| | - Glenn Van Steenkiste
- Equine CardioteamDepartment of Large Animal Internal MedicineGhent UniversityMerelbekeBelgium
| | | | - Virginia B. Reef
- Department of Clinical Studies New Bolton CenterUniversity of Pennsylvania School of Veterinary MedicineKennett SquarePennsylvaniaUSA
| | | | | | - Katarina Nostell
- Department of Clinical SciencesFaculty of Veteirnary SciencesSwedish University of Agricultural SciencesUppsalaSweden
| | | | - Søren S. Nielsen
- Department of Veterinary SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
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7
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Burns JJ, MacMillan KM, John EE. Retrospective review of atrial fibrillation in Standardbred racehorses at a tertiary care facility in Atlantic Canada. THE CANADIAN VETERINARY JOURNAL = LA REVUE VETERINAIRE CANADIENNE 2022; 63:1051-1056. [PMID: 36185789 PMCID: PMC9484198] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Atrial fibrillation (AF) is the most clinically relevant cardiac arrhythmia identified in the Standardbred racehorse. However, there is limited literature regarding athletic ability in Standardbred racehorses following AF conversion. To investigate this issue, the objectives of this review were to: i) determine the success rate in using quinidine sulphate to treat AF in a population of hospitalized equine patients in Atlantic Canada between January 2008 and December 2019; and ii) measure return to athletic ability (using racetrack earnings and top-3 finishes) following cardioversion with quinidine sulphate in a population of Standardbred racehorses. Overall, 73% (16/22) of AF instances in this study were successfully treated with enteral quinidine sulphate. No significant difference was detected in racetrack earnings or number of top-3 finishes for each horse that raced at least 5 times pre- and post-conversion. Key clinical message: To the authors' knowledge, this is the first published review to assess the athletic ability of Standardbred racehorses following cardioversion with enteral quinidine sulphate. Based on the current information, it does not appear that treatment of AF with quinidine sulphate affects future athletic performance in horses that achieved cardioversion.
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8
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Ellis KL, Contino EK, Nout‐Lomas YS. Poor performance in the horse: Diagnosing the non‐orthopaedic causes. EQUINE VET EDUC 2022. [DOI: 10.1111/eve.13712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Katherine L. Ellis
- Gail Holmes Equine Orthopedic Research Center, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences Colorado State University Fort Collins Colorado USA
| | - Erin K. Contino
- Gail Holmes Equine Orthopedic Research Center, Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences Colorado State University Fort Collins Colorado USA
| | - Yvette S. Nout‐Lomas
- Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences Colorado State University Fort Collins Colorado USA
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9
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Nissen SD, Weis R, Krag-Andersen EK, Hesselkilde EM, Isaksen JL, Carstensen H, Kanters JK, Linz D, Sanders P, Hopster-Iversen C, Jespersen T, Pehrson S, Buhl R. Electrocardiographic characteristics of trained and untrained standardbred racehorses. J Vet Intern Med 2022; 36:1119-1130. [PMID: 35488721 PMCID: PMC9151491 DOI: 10.1111/jvim.16427] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 04/01/2022] [Accepted: 04/02/2022] [Indexed: 11/28/2022] Open
Abstract
Background Long‐term exercise induces cardiac remodeling that potentially influences the electrical properties of the heart. Hypothesis/objectives We assessed whether training alters cardiac conduction in Standardbred racehorses. Animals Two hundred one trained and 52 untrained Standardbred horses. Methods Cross‐sectional study. Resting ECG recordings were analyzed to assess heart rate (HR) along with standard ECG parameters and for identification of atrial and ventricular arrhythmias. An electrophysiological study was performed in 13 horses assessing the effect of training on sinoatrial (SA) and atrioventricular (AV) nodal function by sinus node recovery time (SNRT) and His signal recordings. Age and sex adjustments were implemented in multiple and logistic regression models for comparison. Results Resting HR in beats per minute (bpm) was lower in trained vs untrained horses (mean, 30.8 ± 2.6 bpm vs 32.9 ± 4.2 bpm; P = .001). Trained horses more often displayed second‐degree atrioventricular block (2AVB; odds ratio, 2.59; P = .04). No difference in SNRT was found between groups (n = 13). Mean P‐A, A‐H, and H‐V intervals were 71 ± 20, 209 ± 41, and 134 ± 41 ms, respectively (n = 7). We did not detect a training effect on AV‐nodal conduction intervals. His signals were present in 1 horse during 2AVB with varying H‐V interval preceding a blocked beat. Conclusions and Clinical Importance We identified decreased HR and increased frequency of 2AVB in trained horses. In 5 of 7 horses, His signal recordings had variable H‐V intervals within each individual horse, providing novel insight into AV conduction in horses.
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Affiliation(s)
- Sarah D Nissen
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rikke Weis
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Elisabeth K Krag-Andersen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Eva M Hesselkilde
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Jonas L Isaksen
- Laboratory of Experimental Cardiology, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Helena Carstensen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Jørgen K Kanters
- Laboratory of Experimental Cardiology, Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Dominik Linz
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.,Department of Cardiology, Maastricht University Medical Center, Cardiovascular Research Institute Maastricht, Maastricht, The Netherlands.,Department of Cardiology, Radboud University Medical Center, Nijmegen, The Netherlands.,Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Prashanthan Sanders
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, South Australia, Australia
| | - Charlotte Hopster-Iversen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Thomas Jespersen
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Steen Pehrson
- Department of Cardiology 2142, The Heart Centre, Copenhagen University Hospital, Rigshospitalet, Denmark
| | - Rikke Buhl
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
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10
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Paroxysmal Atrial Fibrillation in Horses: Pathophysiology, Diagnostics and Clinical Aspects. Animals (Basel) 2022; 12:ani12060698. [PMID: 35327097 PMCID: PMC8944606 DOI: 10.3390/ani12060698] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/03/2022] [Accepted: 03/08/2022] [Indexed: 02/07/2023] Open
Abstract
Atrial fibrillation (AF) is the most common arrhythmia in horses causing poor performance. As in humans, the condition can be intermittent in nature, known as paroxysmal atrial fibrillation (pAF). This review covers the literature relating to pAF in horses and includes references to the human literature to compare pathophysiology, clinical presentation, diagnostic tools and treatment. The arrhythmia is diagnosed by auscultation and electrocardiography (ECG), and clinical signs can vary from sudden loss of racing performance to reduced fitness or no signs at all. If left untreated, pAF may promote electrical, functional and structural remodeling of the myocardium, thus creating a substrate that is able to maintain the arrhythmia, which over time may progress into permanent AF. Long-term ECG monitoring is essential for diagnosing the condition and fully understanding the duration and frequency of pAF episodes. The potential to adapt human cardiac monitoring systems and computational ECG analysis is therefore of interest and may benefit future diagnostic tools in equine medicine.
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11
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Huang YH, Lyle JV, Razak ASA, Nandi M, Marr CM, Huang CLH, Aston PJ, Jeevaratnam K. Detecting Paroxysmal Atrial Fibrillation from Normal Sinus Rhythm in Equine Athletes using Symmetric Projection Attractor Reconstruction and Machine Learning. CARDIOVASCULAR DIGITAL HEALTH JOURNAL 2022; 3:96-106. [PMID: 35493267 PMCID: PMC9043370 DOI: 10.1016/j.cvdhj.2022.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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12
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Luethy D, Robinson MA, Stefanovski D, Haughan J, Torcivia C, Kowalski A, Ford M, You Y, Missanelli J, Slack J. Pharmacokinetics and pharmacodynamics of oral and intravenous metoprolol tartrate in clinically healthy horses. J Vet Pharmacol Ther 2021; 45:177-187. [PMID: 34913168 DOI: 10.1111/jvp.13037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 11/17/2021] [Accepted: 12/04/2021] [Indexed: 11/30/2022]
Abstract
Cardiac drugs with defined pharmacological parameters in horses are limited. The objective of this study was to characterize the pharmacokinetic properties and cardiovascular effects of intravenous and oral metoprolol tartrate (MET) in horses. In a 2-period randomized cross-over design, MET was administered IV (0.04 mg/kg) and PO (6 mg/kg) once to six healthy adult horses. Horses were monitored via continuous telemetry and non-invasive blood pressure (NIBP). Blood samples were serially collected for 72 h post-administration, and concentrations were determined by LC-MS/MS. Pharmacokinetics were modeled using a 3-compartment model and non-linear least squares regression. Median (range) MET concentration was 110 (40.1-197) ng/ml collected 1 min (0.0167 h) after a bolus IV administration. Maximum concentration (Cmax ) after PO administration was 2135 (1590-4170) ng/ml at 0.5 (0.25-0.5) hours. Oral bioavailability was 54% (17-100%). Median apparent volume of distribution was 0.39 (0.17-0.58) l/kg, clearance was 12.63 (11.41-18.94) ml/kg/min, and elimination half-life was 21.1 (7.46-34.36) minutes. No clinically relevant effects of IV or PO metoprolol were noted on cardiac rhythm or NIBP. Sweating was the most common side effect. The metoprolol doses used in this study achieve plasma concentrations reported to achieve ß-blockade in humans.
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Affiliation(s)
- Daniela Luethy
- Department of Clinical Studies-New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA.,Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, Florida, USA
| | - Mary A Robinson
- Department of Clinical Studies-New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA.,Pennsylvania Equine Toxicology and Research Lab, School of Veterinary Medicine, University of Pennsylvania, West Chester, Pennsylvania, USA
| | - Darko Stefanovski
- Department of Clinical Studies-New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA
| | - Joanne Haughan
- Department of Clinical Studies-New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA
| | - Catherine Torcivia
- Department of Clinical Studies-New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA
| | - Alycia Kowalski
- Department of Clinical Studies-New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA
| | - Matthew Ford
- Department of Clinical Studies-New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA
| | - Youwen You
- Pennsylvania Equine Toxicology and Research Lab, School of Veterinary Medicine, University of Pennsylvania, West Chester, Pennsylvania, USA
| | - Jaclyn Missanelli
- Pennsylvania Equine Toxicology and Research Lab, School of Veterinary Medicine, University of Pennsylvania, West Chester, Pennsylvania, USA
| | - Joann Slack
- Department of Clinical Studies-New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA
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13
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Nath LC, Forbes G, Elliott AD, Tomren V, Ryan A, Franklin SH. Application of an electrocardiography device (iECG) for heart rhythm analysis after exercise in Thoroughbred horses. Aust Vet J 2021; 100:114-120. [PMID: 34859419 DOI: 10.1111/avj.13137] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 10/08/2021] [Accepted: 11/14/2021] [Indexed: 12/01/2022]
Abstract
AliveCor is a smartphone electrocardiography device (iECG) providing automated heart rate (HR) and rhythm determination. Atrial fibrillation (AF) in horses often is paroxysmal and rapid ECG acquisition is needed for diagnostic confirmation. iECGs were collected post-race from 15 horses with AF and 64 horses in sinus rhythm (SR). Results of manual assessment were compared to 3 commercial algorithms for HR and rhythm. Agreement between manually derived HR (HRM ) and HR derived by the AliveECG Vet (HRVET ) and Kardia version-1 (KV1 HR) and Kardia advanced (KADV HR) algorithms was quantified by the Bland-Altman limits of agreement test. Agreement between manual rhythm classification and KV1 and KADV algorithms for AF and SR was calculated by the Kappa statistical coefficient. The agreement (bias, 95% limits), between HRM and HRVET was 7.1 BPM (-29 to 43) in AF and -4.2 BPM (-38 to 30) in SR, between HRM and KV1 HR, was -0.3 BPM (-31 to 30) in AF and 0.2 BPM (-3 to 4) in SR, and between HRM and KADV HR was 7.0 BPM (-29 to 43) in AF and 0.2 BPM (-3.9 to 4.2) in SR. Agreement between manual rhythm classification and KV1 was 0.36 (0.13-0.59), and KADV was 0.84 (0.68-0.99). Sensitivity and specificity for identification of AF and SR of the KV1 algorithm were 60, 100% and 83, 100%, respectively, and of KADV was 87, 100% and 93, 100% respectively. The Kardia algorithms improved precision for HR determination in SR but not AF. The advanced algorithm accurately distinguished between AF and SR. The iECG is suitable for recording episodes of AF following exercise.
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Affiliation(s)
- L C Nath
- University of Adelaide, Roseworthy, South Australia, Australia
| | - G Forbes
- Racing Victoria, Flemington, Victoria, Australia
| | - A D Elliott
- University of Adelaide, Adelaide, South Australia, Australia
| | - V Tomren
- Racing Victoria, Flemington, Victoria, Australia
| | - A Ryan
- University of Adelaide, Roseworthy, South Australia, Australia
| | - S H Franklin
- University of Adelaide, Roseworthy, South Australia, Australia
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14
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Premont A, Balthes S, Marr CM, Jeevaratnam K. Fundamentals of arrhythmogenic mechanisms and treatment strategies for equine atrial fibrillation. Equine Vet J 2021; 54:262-282. [PMID: 34564902 DOI: 10.1111/evj.13518] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 09/13/2021] [Accepted: 09/16/2021] [Indexed: 11/26/2022]
Abstract
Atrial fibrillation (AF) is the most common pathological arrhythmia in horses. Although it is not usually a life-threatening condition on its own, it can cause poor performance and make the horse unsafe to ride. It is a complex multifactorial disease influenced by both genetic and environmental factors including exercise training, comorbidities or ageing. The interactions between all these factors in horses are still not completely understood and the pathophysiology of AF remains poorly defined. Exciting progress has been recently made in equine cardiac electrophysiology in terms of diagnosis and documentation methods such as cardiac mapping, implantable electrocardiogram (ECG) recording devices or computer-based ECG analysis that will hopefully improve our understanding of this disease. The available pharmaceutical and electrophysiological treatments have good efficacy and lead to a good prognosis for AF, but recurrence is a frequent issue that veterinarians have to face. This review aims to summarise our current understanding of equine cardiac electrophysiology and pathophysiology of equine AF while providing an overview of the mechanism of action for currently available treatments for equine AF.
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Affiliation(s)
- Antoine Premont
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Samantha Balthes
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, UK
| | - Celia M Marr
- Rossdales Equine Hospital and Diagnostic Centre, Newmarket, UK
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15
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Buhl R, Hesselkilde EM, Carstensen H, Fenner MF, Jespersen T, Tfelt‐Hansen J, Michael Sattler S. Detection of atrial fibrillation with implantable loop recorders in horses. Equine Vet J 2021; 53:397-403. [PMID: 32506470 PMCID: PMC7891449 DOI: 10.1111/evj.13301] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 04/16/2020] [Accepted: 05/18/2020] [Indexed: 11/28/2022]
Abstract
BACKGROUND Cardiac arrhythmias in horses are diagnosed by auscultation or electrocardiogram (ECG), which results in a low sensitivity for detecting arrhythmias that occur sporadically. Implantable loop recorders (ILRs) are small ECG devices placed subcutaneously, to automatically detect arrhythmias in human patients. OBJECTIVES To test ILRs ability to detect atrial fibrillation (AF) in horses. Furthermore, we hypothesised that anatomical location of the implant site might influence signal quality. Signal quality was evaluated both during exercise and over time. STUDY DESIGN Experimental study. METHODS In five Standardbred mares, eleven ILRs were implanted subcutaneously in up to three different positions (Front: pectoral region, Left-6: sixth left intercostal space and Ventral: xiphoid region) and AF induced. The R- and T-wave amplitudes were measured in all positions over time during AF. AF burden automatically registered by the ILRs over a 2-month period was compared with selected Holter ECG recordings. RESULTS All three positions had stable R- and T-wave amplitudes during the study period and were of sufficient quality to allow AF detection at rest. The position Left-6 showed significantly higher R- and T-wave amplitudes compared with the other positions. During submaximal exercise only the Left-6 position was able to record ECG signals of diagnostic quality. No position yielded diagnostic signals at maximum exercise due to artefacts. MAIN LIMITATIONS Few horses and ILRs included and no spontaneous AF episodes were studied. CONCLUSIONS This preliminary study indicates that ILRs can be used for AF detection in horses, but the anatomical location is important for optimal ECG quality. Despite insufficient quality during exercise, ILRs were suitable for AF detection at rest. Therefore, the ILR may be a valuable diagnostic tool for detecting paroxysmal AF in horses.
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Affiliation(s)
- Rikke Buhl
- Department of Veterinary Clinical SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Eva M. Hesselkilde
- Department of Veterinary Clinical SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Helena Carstensen
- Department of Veterinary Clinical SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Merle F. Fenner
- Department of Veterinary Clinical SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Thomas Jespersen
- Department of Biomedical SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Jacob Tfelt‐Hansen
- Department of CardiologyThe Heart CentreCopenhagen University HospitalCopenhagenDenmark
- Department of Forensic MedicineFaculty of Medical SciencesUniversity of CopenhagenCopenhagenDenmark
| | - Stefan Michael Sattler
- Department of Biomedical SciencesFaculty of Health and Medical SciencesUniversity of CopenhagenCopenhagenDenmark
- Department of CardiologyThe Heart CentreCopenhagen University HospitalCopenhagenDenmark
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16
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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; 35:1111-1120. [PMID: 33604980 PMCID: PMC7995445 DOI: 10.1111/jvim.16063] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Revised: 01/25/2021] [Accepted: 02/02/2021] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Atrial fibrillation (AF) impacts performance and horse and jockey safety. Understanding the outcomes of AF identified postrace will better inform regulatory policy. HYPOTHESIS/OBJECTIVES To investigate the outcomes after episodes of AF identified postrace and determine whether affected horses are at increased risk of additional episodes compared to the general racing population. ANIMALS Total of 4684 Thoroughbred racehorses. METHODS Race records for Thoroughbred horses racing in Hong Kong from 2007 to 2017 were reviewed. Horses that performed below expectation were examined by cardiac auscultation and ECG. Incidence and recurrence of AF were compared between horses with and without a history of AF and between horses with paroxysmal and persistent episodes using Fisher's exact test. RESULTS There were 96 135 race starts during the study. Atrial fibrillation was identified in 4.9% of horses, with an overall incidence of 2.7 episodes per 1000 starts. The incidence of AF in horses after any previous episode (12.8 per 1000 starts) was higher than for horses with no previous episode (2.4 per 1000 starts; odds ratio [OR], 5.3; 95% confidence interval [CI], 3.8-7.6). Recurrence was seen in 64% of horses previously treated for persistent AF, which was higher than recurrence in horses with paroxysmal AF (23%; OR, 5.9; 95% CI, 1.6-21.2). Median duration between episodes was 343 days (range, 34-1065). CONCLUSIONS AND CLINICAL IMPORTANCE Thoroughbreds are at increased risk of recurrent AF after both paroxysmal and persistent episodes, but the duration of time between episodes varies widely. These findings support a substantial burden of AF among individual Thoroughbred racehorses.
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Affiliation(s)
- Laura C. Nath
- School of Animal & Veterinary SciencesUniversity of AdelaideRoseworthySouth AustraliaAustralia
| | - Adrian D. Elliott
- Centre for Heart Rhythm Disorders, Adelaide Medical SchoolUniversity of AdelaideAdelaideSouth AustraliaAustralia
| | - Joe Weir
- Hong Kong Jockey Club, Veterinary Clinical ServicesEquine HospitalHong Kong SARHong Kong
| | - Peter Curl
- Veterinary RegulationHong Kong Jockey ClubHong Kong SARHong Kong
| | | | - Samantha Franklin
- School of Animal & Veterinary SciencesUniversity of AdelaideRoseworthySouth AustraliaAustralia
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17
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Saljic A, Jespersen T, Buhl R. Anti-arrhythmic investigations in large animal models of atrial fibrillation. Br J Pharmacol 2021; 179:838-858. [PMID: 33624840 DOI: 10.1111/bph.15417] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 02/10/2021] [Accepted: 02/11/2021] [Indexed: 12/13/2022] Open
Abstract
Atrial fibrillation (AF) constitutes an increasing health problem in the aging population. Animal models reflecting human phenotypes are needed to understand the mechanisms of AF, as well as to test new pharmacological interventions. In recent years, a number of large animal models, primarily pigs, goats, dog and horses have been used in AF research. These animals can to a certain extent recapitulate the human pathophysiological characteristics and serve as valuable tools in investigating new pharmacological interventions for treating AF. This review focuses on anti-arrhythmic investigations in large animals. Initially, spontaneous AF in small and large mammals is discussed. This is followed by a short presentation of frequently used methods for inducing short- and long-term AF. The major focus of the review is on anti-arrhythmic compounds either frequently used in the human clinic (ranolazine, flecainide, vernakalant and amiodarone) or being promising new AF medicine candidates (IK,Ach , ISK,Ca and IK2P blockers).
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Affiliation(s)
- Arnela Saljic
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Jespersen
- Laboratory of Cardiac Physiology, Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rikke Buhl
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
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18
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Decloedt A, Van Steenkiste G, Vera L, Buhl R, van Loon G. Atrial fibrillation in horses Part 2: Diagnosis, treatment and prognosis. Vet J 2020; 268:105594. [PMID: 33468306 DOI: 10.1016/j.tvjl.2020.105594] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 10/27/2020] [Accepted: 12/10/2020] [Indexed: 10/22/2022]
Abstract
Atrial fibrillation (AF) is suspected by an irregularly irregular rhythm during auscultation at rest and should be confirmed by electrocardiography. Heart rate monitoring is potentially interesting for AF detection by horse owners, based on the disproportionally high heart rate during exercise or increased heart rate variability. Echocardiography and laboratory analysis are useful to identify underlying cardiac disease. Horses with severe cardiac disease should not undergo cardioversion due to the risk of recurrence. Cardioversion is recommended especially in horses performing high intensity exercise or showing average maximal heart rates higher than 220 beats per min or abnormal ventricular complexes during exercise or stress. Pharmacological cardioversion can be performed using quinidine sulphate administered orally, with an overall mean reported success rate around 80%. Other therapeutic drugs have been described such as flecainide, amiodarone or novel atrial specific compounds. Transvenous electrical cardioversion (TVEC) is performed by delivering a shock between two cardioversion catheters positioned in the left pulmonary artery and right atrium, with a success rate of >95%. After cardioversion, most horses return to their previous level of performance. However, the recurrence rate after pharmacological or electrical cardioversion is up to 39%. Recurrence has been related to previous unsuccessful treatment attempts, valvular regurgitation and the presence of atrial premature depolarisations or low atrial contractile function after cardioversion. Large atrial size and long AF duration have also been suggested as risk factors. Different approaches for preventing recurrence have been described such as the administration of sotalol, however, large clinical studies have not been published.
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Affiliation(s)
- Annelies Decloedt
- Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Belgium.
| | - Glenn Van Steenkiste
- Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Belgium
| | - Lisse Vera
- Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Belgium
| | - Rikke Buhl
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Gunther van Loon
- Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Belgium
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19
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Buhl R, Nissen SD, Winther MLK, Poulsen SK, Hopster-Iversen C, Jespersen T, Sanders P, Carstensen H, Hesselkilde EM. Implantable loop recorders can detect paroxysmal atrial fibrillation in Standardbred racehorses with intermittent poor performance. Equine Vet J 2020; 53:955-963. [PMID: 33113157 PMCID: PMC8451893 DOI: 10.1111/evj.13372] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Accepted: 10/22/2020] [Indexed: 11/27/2022]
Abstract
Background Limited information is available on paroxysmal atrial fibrillation (PAF) in the horse. Indeed, undiagnosed PAF could result in poor performance. Due to the intermittent occurrence, PAF is difficult to diagnose. However, implanting a small ECG device (implantable loop recorder, ILR) subcutaneously, allows the continuous and automatic detection of PAF. Objectives The aim was to investigate the potential of ILRs as a tool for diagnosing PAF in horses with poor performance. Study design Prospective field study. Methods Twelve racing Standardbred trotters with intermittent reduced performance (mean age: six years) were enrolled prospectively. The ILR was implanted subcutaneously at the fifth or sixth left intercostal space and data from the ILR was collected during the study period in which the horses were followed for a median duration of 7.5 month (range 6‐28). Results The ILR was able to detect PAF in four out of twelve racehorses. The ILR also detected sustained atrial fibrillation (AF) in one horse during the study. The ILRs rely on RR detection and R waves were correctly identified in 96%. One hundred episodes were categorised as AF by the ILRs and subsequently visual ECG inspection categorised 12 as sinus rhythm (SR), 28 as sinus arrhythmia (SA), 14 as other arrhythmias and 46 as AF episodes. The Root Mean Square of the Successive Differences (RMSSD) values were significantly increased for AF compared to SR and SA. Main limitations Few horses included and duration of study period varied among the horses. Further it was not possible to assess the sensitivity of the device in the current study and the ILRs proved to have a high rate of false positive misclassifications. Conclusions This study indicates that ILRs can be used for detection of PAF episodes and could be a useful ECG tool for horses presenting with poor performance. This methodology provides a platform to facilitate the long‐term assessment of AF development and quantification of AF burden in horses. Further studies including both healthy and poor performing horses are needed in order to learn more about PAF prevalence in racehorses.
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Affiliation(s)
- Rikke Buhl
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Sarah D Nissen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Marie L K Winther
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Sofie K Poulsen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Charlotte Hopster-Iversen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Thomas Jespersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Prashanthan Sanders
- Centre for Heart Rhythm Disorders, Royal Adelaide Hospital and University of Adelaide, Adelaide, Australia
| | - Helena Carstensen
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Eva M Hesselkilde
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
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20
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Catheter-based electrical interventions to study, diagnose and treat arrhythmias in horses: From refractory period to electro-anatomical mapping. Vet J 2020; 263:105519. [PMID: 32928488 DOI: 10.1016/j.tvjl.2020.105519] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 06/03/2020] [Accepted: 07/14/2020] [Indexed: 11/23/2022]
Abstract
Minimally-invasive catheter-based interventional cardiology is a mainstay for the diagnosis and treatment of arrhythmias in human medicine. Very accurate imaging using fluoroscopy, CT and MRI is essential during interventional cardiology procedures. Because these imaging techniques are either not possible or provide too little anatomical detail in horses, echocardiography is currently the best technique to visualize catheters in horses. Over the past decades, catheter-based techniques have been applied to induce arrhythmias using pacing and to perform arrhythmia research using electrophysiological studies. In bradycardic animals with clinical signs, permanent pacing can be achieved by pacemaker implantation via the cephalic vein. Transvenous electrical cardioversion, based on one cardioversion catheter in the pulmonary artery and one in the right atrium, has become the treatment of choice for atrial fibrillation in horses, even for longstanding or drug-resistant atrial fibrillation. Recently, the highly advanced technique of three dimensional electroanatomical mapping has been described in horses. This technique has not only revealed essential electrophysiological data in horses, but has also facilitated the successful ablation of atrial tachycardia in horses.
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21
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Decloedt A, Van Steenkiste G, Vera L, Buhl R, van Loon G. Atrial fibrillation in horses part 1: Pathophysiology. Vet J 2020; 263:105521. [PMID: 32928494 DOI: 10.1016/j.tvjl.2020.105521] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Revised: 07/05/2020] [Accepted: 07/21/2020] [Indexed: 01/30/2023]
Abstract
Atrial fibrillation (AF) is the most common clinically relevant arrhythmia in horses, with a reported prevalence up to 2.5%. The pathophysiology has mainly been investigated in experimental animal models and human medicine, with limited studies in horses. Atrial fibrillation results from the interplay between electrical triggers and a susceptible substrate. Triggers consist of atrial premature depolarizations due to altered automaticity or triggered activity, or local (micro)reentry. The arrhythmia is promoted by atrial myocardial ion channel alterations, Ca2+ handling alterations, structural abnormalities, and autonomic nervous system imbalance. Predisposing factors include structural heart disease such as valvular regurgitation resulting in chronic atrial stretch, although many horses show so-called 'lone AF' or idiopathic AF in which no underlying cardiac abnormalities can be detected using routine diagnostic techniques. These horses may have underlying ion channel dysfunction or undiagnosed myocardial (micro)structural alterations. Atrial fibrillation itself results in electrical, contractile and structural remodelling, fostering AF maintenance. Electrical remodelling leads to shortening of the atrial effective refractory period, promoting reentry. Contractile remodelling consists of decreased myocardial contractility, while structural remodelling includes the development of interstitial fibrosis and atrial enlargement. Reverse remodelling occurs after cardioversion to sinus rhythm, but full recovery may take weeks to months depending on duration of AF. The clinical signs of AF depend on the aerobic demands during exercise, ventricular rhythm response and presence of underlying cardiac disease. In horses with so-called 'lone AF', clinical signs are usually absent at rest but during exercise poor performance, exercise-induced pulmonary hemorrhage, respiratory distress, weakness or rarely collapse may develop.
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Affiliation(s)
- Annelies Decloedt
- Equine Cardioteam Gent University, Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Belgium.
| | - Glenn Van Steenkiste
- Equine Cardioteam Gent University, Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Belgium
| | - Lisse Vera
- Equine Cardioteam Gent University, Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Belgium
| | - Rikke Buhl
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Gunther van Loon
- Equine Cardioteam Gent University, Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Belgium
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22
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The complexity of clinically-normal sinus-rhythm ECGs is decreased in equine athletes with a diagnosis of paroxysmal atrial fibrillation. Sci Rep 2020; 10:6822. [PMID: 32321950 PMCID: PMC7176685 DOI: 10.1038/s41598-020-63343-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 03/09/2020] [Indexed: 11/09/2022] Open
Abstract
Equine athletes have a pattern of exercise which is analogous to human athletes and the cardiovascular risks in both species are similar. Both species have a propensity for atrial fibrillation (AF), which is challenging to detect by ECG analysis when in paroxysmal form. We hypothesised that the proarrhythmic background present between fibrillation episodes in paroxysmal AF (PAF) might be detectable by complexity analysis of apparently normal sinus-rhythm ECGs. In this retrospective study ECG recordings were obtained during routine clinical work from 82 healthy horses and from 10 horses with a diagnosis of PAF. Artefact-free 60-second strips of normal sinus-rhythm ECGs were converted to binary strings using threshold crossing, beat detection and a novel feature detection parsing algorithm. Complexity of the resulting binary strings was calculated using Lempel-Ziv (‘76 & ‘78) and Titchener complexity estimators. Dependence of Lempel-Ziv ‘76 and Titchener T-complexity on the heart rate in ECG strips obtained at low heart rates (25–60 bpm) and processed by the feature detection method was found to be significantly different in control animals and those diagnosed with PAF. This allows identification of horses with PAF from sinus-rhythm ECGs with high accuracy.
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23
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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. J Cardiovasc Electrophysiol 2020; 31:1211-1212. [PMID: 32108401 DOI: 10.1111/jce.14422] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Revised: 02/16/2020] [Accepted: 02/19/2020] [Indexed: 01/02/2023]
Abstract
Atrial fibrillation is triggered by the pulmonary veins in humans. Although atrial fibrillation is known to occur in other species, the mechanisms of disease in these are not known. Here we present evidence for pulmonary vein triggers in the horse, where 3D HD Grid mapping was undertaken in the conscious state in the absence of fluoroscopy.
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Affiliation(s)
- Dominik Linz
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
| | - Eva Hesselkilde
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | | | - Thomas Jespersen
- Department of Biomedical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Rikke Buhl
- Department of Veterinary Clinical Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Taastrup, Denmark
| | - Prashanthan Sanders
- Centre for Heart Rhythm Disorders, University of Adelaide and Royal Adelaide Hospital, Adelaide, Australia
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Gallant L, Jacob S, Tadros E, Woodrow J, Hines M, Ewart S, Schott H. Rapid screening for cardiac arrhythmias in competition draft horses. COMPARATIVE EXERCISE PHYSIOLOGY 2019. [DOI: 10.3920/cep190029] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Cardiac arrhythmias may cause decreased performance and sudden death during exercise. Our objectives were: (1) to determine prevalence of unrecognised arrhythmias in a population of competition draft horses by performing short duration screening electrocardiograms (ECGs) at rest; and (2) to assess utility of a commercial handheld device for recording equine ECGs. Owners or trainers of 244 draft horses (age 0.5-16 years), including 82 Percherons, 69 Belgians, 69 Clydesdales, 11 Belgian mules, 8 Shires, and 5 Percheron mules, were queried to determine signalment, performance history, and known arrhythmias. All horses were auscultated for 30 s and ECGs were obtained in 204 horses using a handheld recording device (AliveCor®). ECGs were reviewed for quality and used to determine heart rate (HR) and rhythm. When ECG tracing quality permitted, PQ and QT intervals were also measured. ECGs displaying RR intervals adequate for HR determination and rhythm assessment were recorded from 161 horses (79%) while tracings with consistent P waves, QRS complexes, and T waves were recorded from only 47 horses (23%). Four arrhythmias were detected by both auscultation and ECG: atrial fibrillation (1), premature complexes (1), and second-degree atrioventricular block (2). None of these horses had a history of poor performance or previous recognition of an arrhythmia. The prevalence of unrecognised, and potentially clinically significant, arrhythmias in draft horses at rest appears to be low (2/244; 0.8%, 95% confidence interval 0.1-2.9%). Longer recordings at rest, as well as recordings during and immediately after exercise, would likely have revealed a higher prevalence of arrhythmias.
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Affiliation(s)
- L.R. Gallant
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Rd Room D202, East Lansing, MI 48824, USA
- Newcastle Equine Centre, P.O. Box 123, Broadmeadow, New South Wales 2292, Australia
| | - S.I. Jacob
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Rd Room D202, East Lansing, MI 48824, USA
| | - E.M. Tadros
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Rd Room D202, East Lansing, MI 48824, USA
| | - J.S. Woodrow
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, 2407 River Dr, Knoxville, TN 37996, USA
| | - M.T. Hines
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee, 2407 River Dr, Knoxville, TN 37996, USA
| | - S.L. Ewart
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Rd Room D202, East Lansing, MI 48824, USA
| | - H.C. Schott
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, 736 Wilson Rd Room D202, East Lansing, MI 48824, USA
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Durando MM. Cardiovascular Causes of Poor Performance and Exercise Intolerance and Assessment of Safety in the Equine Athlete. Vet Clin North Am Equine Pract 2019; 35:175-190. [PMID: 30871825 DOI: 10.1016/j.cveq.2018.12.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022] Open
Abstract
Horses have a high prevalence of resting arrhythmias, cardiac murmurs, and valvular regurgitation, and training can increase the prevalence. This makes it challenging for equine veterinarians who are asked to evaluate horses for poor performance to determine the clinical relevance of some findings. In addition, cardiac disease has the potential to cause collapse or sudden death, putting both the horse and rider at risk. Further diagnostics, such as echocardiograms and resting and exercising ECGs can help to sort out the impact of an abnormality found on resting physical examination. However uncertainty over the importance of some findings continues to exist.
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Affiliation(s)
- Mary M Durando
- Equine Sports Medicine Consultants, LLC, 40 East Main Street, Suite 232, Newark, DE 19711, USA.
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Navas de Solis C. Cardiovascular Response to Exercise and Training, Exercise Testing in Horses. Vet Clin North Am Equine Pract 2019; 35:159-173. [PMID: 30871829 DOI: 10.1016/j.cveq.2018.11.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The physiology of exercise and training is fascinating, and hundreds of interesting studies have given insight into its mechanisms. Exercise testing is a useful clinical tool that can help veterinarians assess poor performance, fitness, and performance potential and prevent injuries. The clinically applicable aspects of cardiovascular adaptions to training and exercise testing are highlighted in this review. Different exercise tests should be used to evaluate horses performing in different disciplines and levels. Exercise tests that simultaneously assess several body systems can be beneficial when assessing poor performance, because this is often a multifactorial problem with signs not detectable at rest.
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Affiliation(s)
- Cristobal Navas de Solis
- Department of Large Animal Clinical Sciences, Texas A&M University, 4475 TAMU, College Station, TX 77843-4475, USA.
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Assessment of the Cardiovascular System in Horses During Prepurchase and Insurance Examinations. Vet Clin North Am Equine Pract 2019; 35:191-204. [PMID: 30871830 DOI: 10.1016/j.cveq.2018.11.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Arrhythmias detected on prepurchase examination should be confirmed with an ECG. Exercising ECG determines if the arrhythmia is overdriven during exercise or is a safety concern. An echocardiogram is needed in all horses with a grade 3/6 or louder mid to late systolic, holosystolic, or pansystolic murmur or any holodiastolic decrescendo murmur to identify the cardiac abnormality and its hemodynamic impact. Most horses with arrhythmias and murmurs have a normal performance career and life expectancy and are insurable. Risks for sudden death and congestive heart failure associated with the common murmurs and arrhythmias are identified, because these horses cannot be insured.
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Abstract
Arrhythmias are common in horses. Sinus arrhythmia and first- and second-degree atrioventricular block are frequently found physiologic arrhythmias, but should immediately disappear after stress or exercise. Atrial premature depolarizations are usually not associated with poor performance, but are a potential trigger for atrial fibrillation. Atrial fibrillation results in an abnormal ventricular response during exercise and poses a risk for collapse in some horses. This arrhythmia can usually be treated by quinidine sulfate or transvenous electrical cardioversion. Ventricular premature depolarizations, especially when associated with structural heart disease, may be a risk factor for ventricular tachycardia or even ventricular fibrillation.
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Affiliation(s)
- Gunther van Loon
- Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, Merelbeke 9820, Belgium.
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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; 32:1410-1419. [PMID: 29749082 PMCID: PMC6060327 DOI: 10.1111/jvim.15137] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 03/14/2018] [Accepted: 03/27/2018] [Indexed: 11/29/2022] Open
Abstract
Background Atrial fibrillation (AF) is the most common arrhythmia affecting performance in horses. However, no previous studies have quantified the performance reduction in horses suffering from AF. Objectives To quantify the effect of AF on maximum velocity (Vmax), maximum heart rate (HRmax), heart rate recovery (T100), hematologic parameters and development of abnormal QRS complexes. Animals Nine Standardbred trotters. Methods Two‐arm controlled trial. Six horses had AF induced by means of a pacemaker and 3 served as sham‐operated controls. All horses were subjected to an exercise test to fatigue before (SET1) and after (SET2) 2 months of AF or sham. The Vmax and HRmax were assessed using a linear mixed normal model. Abnormal QRS complexes were counted manually on surface ECGs. Results Atrial fibrillation resulted in a 1.56 m/sec decrease in Vmax (P < .0001). In the AF group, HRmax ± SD increased from 226 ± 11 bpm at SET1 to 311 ± 27 bpm at SET 2. The AF group had higher HRmax at SET2 compared with controls (P < .0001), whereas no difference between the control and AF groups was observed at SET1 (P = .96). Several episodes of wide complex tachycardia were observed during exercise in 3 of the AF horses during SET2. Conclusions and Clinical Importance Atrial fibrillation resulted in a significant reduction in performance, an increase in HR and development of abnormal QRS complexes during exercise, which may be a risk factor for collapse or sudden cardiac death.
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Affiliation(s)
- Rikke Buhl
- Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Copenhagen, Denmark
| | - Helena Carstensen
- Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Copenhagen, Denmark
| | - Eva Zander Hesselkilde
- Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Copenhagen, Denmark
| | - Bjørg Zinkernagel Klein
- Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Copenhagen, Denmark
| | - Karen Margrethe Hougaard
- Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Copenhagen, Denmark
| | - Kirsten Bomberg Ravn
- Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Copenhagen, Denmark
| | | | - Merle Friederike Fenner
- Department of Veterinary Clinical Sciences, University of Copenhagen, Taastrup, Copenhagen, Denmark
| | - Christian Pipper
- Department of Public Health, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Jespersen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
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