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Ventricular response during lungeing exercise in horses with lone atrial fibrillation.
Equine Vet J. 2013 May; 45(3):309-14.EV

Abstract

REASONS FOR PERFORMING THE STUDY

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.

OBJECTIVES

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.

POTENTIAL RELEVANCE

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.

Authors+Show Affiliations

Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium. tinne.verheyen@ugent.beNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

23094848

Citation

Verheyen, T, et al. "Ventricular Response During Lungeing Exercise in Horses With Lone Atrial Fibrillation." Equine Veterinary Journal, vol. 45, no. 3, 2013, pp. 309-14.
Verheyen T, Decloedt A, van der Vekens N, et al. Ventricular response during lungeing exercise in horses with lone atrial fibrillation. Equine Vet J. 2013;45(3):309-14.
Verheyen, T., Decloedt, A., van der Vekens, N., Sys, S., De Clercq, D., & van Loon, G. (2013). Ventricular response during lungeing exercise in horses with lone atrial fibrillation. Equine Veterinary Journal, 45(3), 309-14. https://doi.org/10.1111/j.2042-3306.2012.00653.x
Verheyen T, et al. Ventricular Response During Lungeing Exercise in Horses With Lone Atrial Fibrillation. Equine Vet J. 2013;45(3):309-14. PubMed PMID: 23094848.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Ventricular response during lungeing exercise in horses with lone atrial fibrillation. AU - Verheyen,T, AU - Decloedt,A, AU - van der Vekens,N, AU - Sys,S, AU - De Clercq,D, AU - van Loon,G, Y1 - 2012/10/23/ PY - 2012/06/07/received PY - 2012/08/15/accepted PY - 2012/10/26/entrez PY - 2012/10/26/pubmed PY - 2013/12/16/medline SP - 309 EP - 14 JF - Equine veterinary journal JO - Equine Vet J VL - 45 IS - 3 N2 - REASONS FOR PERFORMING THE STUDY: 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. OBJECTIVES: 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. POTENTIAL RELEVANCE: 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. SN - 2042-3306 UR - https://www.unboundmedicine.com/medline/citation/23094848/Ventricular_response_during_lungeing_exercise_in_horses_with_lone_atrial_fibrillation_ L2 - https://doi.org/10.1111/j.2042-3306.2012.00653.x DB - PRIME DP - Unbound Medicine ER -