Normal electrocardiographic QT interval in race-fit Standardbred horses at rest and its rate dependence during exercise.
Abstract: Cardiac repolarization, measured as QT and Tpeak to Tend (TpTe) intervals on the ECG, is important, as irregularities caused by diseases, ventricular hypertrophy, drugs and genetic defects can trigger arrhythmias which predispose human patients to syncope and sudden cardiac death. In horses, repolarization is not well described and therefore QT analysis cannot yet be used diagnostically. Therefore, we sought to describe reference values for the normal QT and TpTe intervals in Standardbreds and to determine the best method for heart rate (HR) correction. Methods: 30 Standardbreds. Methods: QT and TpTe intervals were measured during rest and exercise and plotted against HR converted to Rpeak to Rpeak interval (RR). Data were fitted with relevant regression models. Intra- and inter-observer agreement was assessed using Bland-Altman analyses. Results: Data were best described by a piecewise linear model (r(2) > 0.97). Average prediction error of this model was smaller than for both Bazett and Fridericia corrections. Coefficient of repeatability of intra- and inter-observer variability was 8.76 ms and 5.64 ms respectively and coefficient of variation was 1.77% and 2.76% respectively. TpTe increased with RR in stallions. Conclusions: The QT interval in Standardbred horses shortens with decreasing RR interval (increasing HR) as in humans, but in a markedly different order as it clearly follows a piecewise linear model. The equine QT interval can be measured easily and there is small intra- and inter-observer variability. This model of the equine QT interval provides clinicians with a method that could support a diagnosis of repolarization disturbances in horses.
Copyright © 2013 Elsevier B.V. All rights reserved.
Publication Date: 2013-02-22 PubMed ID: 23434174DOI: 10.1016/j.jvc.2012.08.002Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Cardiac Arrhythmias
- Cardiovascular Health
- Clinical Findings
- Clinical Study
- Diagnosis
- Diagnostic Technique
- Disease Diagnosis
- Disease Treatment
- Electrocardiography
- Equine Diseases
- Equine Health
- Exercise
- Exercise Physiology
- Heart
- Heart Rate
- Horses
- Physiology
- Regression Analysis
- Standardbred Horses
- Veterinary Medicine
- Veterinary Research
Summary
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The study focuses on understanding cardiac repolarization in Standardbred horses by defining normal values of the QT and TpTe intervals, and figuring out how to best adjust these values for varying heart rates. It further aims to develop a diagnostic tool for detecting disruptions in heart rhythm in these animals.
Background
- The research emphasizes the importance of cardiac repolarization, which is monitored via QT and TpTe intervals in an ECG. Any inconsistencies in this process can lead to arrhythmias, leading to potential situations of syncope and sudden cardiac death in humans.
- However, in horses, especially Standardbreds, the process of repolarization is less defined, hence eliminating the possibility of using changes in QT intervals as a form of diagnosis.
Methodology
- The study was conducted on 30 Standardbred horses. Their QT and TpTe intervals, two crucial parts of cardiac repolarization, were measured while they were in a state of rest and also during physical exertion. These values were compared against the horse’s heart rate, converted into Rpeak to Rpeak interval (or RR).
- In order to align the data, various regression models were fitted until an appropriate one was found. The reliability of measurements taken by multiple observers was tested using Bland-Altman analyses.
Results
- The researchers found that a piecewise linear model described the data best, with a high r square value (r(2) > 0.97), which indicates a close fit to the data. This model outperformed other correction methods such as the Bazett and Fridericia corrections.
- The model was found to be consistent both within and between observers, thus indicating high reliability.
- It was found that the TpTe interval expanded with the RR in stallions. The QT interval contracted with a lowering RR interval, that is, an increased heart rate, but it clearly followed a piecewise linear model, which was different from patterns seen in humans.
Conclusions
- This research, therefore, provides a reliable model to measure the QT interval in horses, and has low variability between different observers.
- The study’s findings could be used to develop a diagnostic tool for detecting anomalies in horses’ repolarization processes, paving the way for potential treatment protocols for cardiovascular disorders in horses.
Cite This Article
APA
Pedersen PJ, Kanters JK, Buhl R, Klaerke DA.
(2013).
Normal electrocardiographic QT interval in race-fit Standardbred horses at rest and its rate dependence during exercise.
J Vet Cardiol, 15(1), 23-31.
https://doi.org/10.1016/j.jvc.2012.08.002 Publication
Researcher Affiliations
- Department of Veterinary Clinical and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark. philip@sund.ku.dk
MeSH Terms
- Animals
- Cardiac Electrophysiology / methods
- Electrocardiography / veterinary
- Female
- Heart Rate
- Horses / physiology
- Male
- Physical Conditioning, Animal / physiology
- Sports
Citations
This article has been cited 11 times.- 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 Apr 4;.
- Cicogna M, Boni P, Frigo T, Caivano D. Base-apex electrocardiographic examination in healthy cows of Chianina breed.. Open Vet J 2022 Nov-Dec;12(6):951-955.
- 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 May;36(3):1119-1130.
- Cosgun A, Oren H. Variation of the T-wave peak-end interval and heart rate variability values in healthy males and females at various hours of the same day, and relationship of them.. J Arrhythm 2020 Feb;36(1):118-126.
- Schumacher SA, Toribio RE, Lakritz J, Bertone AL. Radio-Telemetric Assessment of Cardiac Variables and Locomotion With Experimentally Induced Hypermagnesemia in Horses Using Chronically Implanted Catheters.. Front Vet Sci 2019;6:414.
- Hesselkilde EZ, Carstensen H, Flethøj M, Fenner M, Kruse DD, Sattler SM, Tfelt-Hansen J, Pehrson S, Braunstein TH, Carlson J, Platonov PG, Jespersen T, Buhl R. Longitudinal study of electrical, functional and structural remodelling in an equine model of atrial fibrillation.. BMC Cardiovasc Disord 2019 Oct 21;19(1):228.
- Carstensen H, Hesselkilde EZ, Fenner M, Loft-Andersen AV, Flethøj M, Kanters JK, Sattler SM, Tfelt-Hansen J, Pehrson S, Jespersen T, Buhl R. Time-dependent antiarrhythmic effects of flecainide on induced atrial fibrillation in horses.. J Vet Intern Med 2018 Sep;32(5):1708-1717.
- 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.
- Gunther-Harrington CT, Arthur R, Estell K, Martinez Lopez B, Sinnott A, Ontiveros E, Varga A, Stern JA. Prospective pre- and post-race evaluation of biochemical, electrophysiologic, and echocardiographic indices in 30 racing thoroughbred horses that received furosemide.. BMC Vet Res 2018 Jan 18;14(1):18.
- Carstensen H, Kjær L, Haugaard MM, Flethøj M, Hesselkilde EZ, Kanters JK, Pehrson S, Buhl R, Jespersen T. Antiarrhythmic Effects of Combining Dofetilide and Ranolazine in a Model of Acutely Induced Atrial Fibrillation in Horses.. J Cardiovasc Pharmacol 2018 Jan;71(1):26-35.
- Pedersen PJ, Thomsen KB, Olander ER, Hauser F, Tejada Mde L, Poulsen KL, Grubb S, Buhl R, Calloe K, Klaerke DA. Molecular Cloning and Functional Expression of the Equine K+ Channel KV11.1 (Ether à Go-Go-Related/KCNH2 Gene) and the Regulatory Subunit KCNE2 from Equine Myocardium.. PLoS One 2015;10(9):e0138320.
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