Effect of induced chronic atrial fibrillation on exercise performance in Standardbred trotters.
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ABSTRACT:
SUBMITTER: Buhl R
PROVIDER: S-EPMC6060327 | biostudies-literature | 2018 Jul
REPOSITORIES: biostudies-literature
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Effect of induced chronic atrial fibrillation on exercise performance in Standardbred trotters.
Buhl Rikke R Carstensen Helena H Hesselkilde Eva Zander EZ Klein Bjørg Zinkernagel BZ Hougaard Karen Margrethe KM Ravn Kirsten Bomberg KB Loft-Andersen Ameli Victoria AV Fenner Merle Friederike MF Pipper Christian C Jespersen Thomas T
Journal of veterinary internal medicine 20180510 4
<h4>Background</h4>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.<h4>Objectives</h4>To quantify the effect of AF on maximum velocity (V<sub>max</sub> ), maximum heart rate (HR<sub>max</sub> ), heart rate recovery (T<sub>100</sub> ), hematologic parameters and development of abnormal QRS complexes.<h4>Animals</h4>Nine Standardbred trotters.<h4>Methods</h4>Tw ...[more]
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Project description:IntroductionWhile clinical respiratory disease is considered a main cause of poor performance in horses, the role of subclinical respiratory virus infections is less clear and needs further investigation.Aims and objectivesIn this descriptive longitudinal study the relationship of markers of subclinical respiratory viral activity to occurrence of poor performance in racing Standardbred trotters was investigated.Material and methods66 elite Standardbred trotters were followed for 13 months by nasal swabs analysed with qPCR for equine influenza virus, equine arteritis virus, equine rhinitis B virus (ERBV), equine herpesvirus type 1(EHV-1) and equine herpesvirus type 4 (EHV-4) and serology to equine rhinitis A virus (ERAV), ERBV, EHV-1 and EHV-4, as well as the acute phase protein serum amyloid A (SAA). Findings on lab analyses were subsequently assessed for possible correlations to workload performance and trainer opinion measures of poor performance.ResultsDespite occurrence of poor performance and subclinical viral activity the authors were unable to detect association neither between subclinical viral activity and poor performance, nor between SAA elevations and either viral activity or poor performance.ConclusionsConsistent with earlier study results, antibody titres to ERBV remained high for at least a year and few horses two years or older were seronegative to either ERAV or ERBV. In absence of clinical signs, serology to common respiratory viruses appears to have little diagnostic benefit in evaluation of poor performance in young athletic horses.
| S-EPMC4567161 | biostudies-literature
Project description:BackgroundLimited 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.ObjectivesThe aim was to investigate the potential of ILRs as a tool for diagnosing PAF in horses with poor performance.Study designProspective field study.MethodsTwelve 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).ResultsThe 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 limitationsFew 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.ConclusionsThis 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.
| S-EPMC8451893 | biostudies-literature
Project description: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.
| S-EPMC10615936 | biostudies-literature
Project description:Osteochondrosis (OC) is commonly diagnosed in young Standardbred racehorses but its effect on performance when surgically treated at a young age is still incompletely understood. This is especially true for Standardbred pacers, which are underrepresented in the existing literature.To characterise the short- (2-year-old) and long-term (through 5-year-old) racing performance in Standardbred pacers and trotters after early surgical intervention (<17 months of age) for tarsal OC.Retrospective clinical study.The study population consisted of related, age-matched Standardbred racehorses (n = 278; 151 pacers, 127 trotters) with (n = 133) or without (n = 145) one or more tarsal OC lesions. All OC-affected horses were treated surgically prior to being sold as yearlings. Data obtained from publicly available race records for each horse included starts, wins, finishes in the top 3 (win, place or show), earnings and fastest time. Comparisons between OC-affected and unaffected horses were made for the entire population and within gaits. A smaller related population (n = 94) had these performance measures evaluated for their 2-5-year-old racing seasons.Osteochondrosis status was associated with few performance measures. Trotters were at higher risk for lesions of the medial malleolus but lower risk for lesions of the distal intermediate ridge of the tibia than were pacers. Horses with bilateral OC lesions and lateral trochlear ridge (LTR) lesions started fewer races at 2 years of age than those with unilateral lesions or without LTR lesions.Osteochondrosis seemed to have minimal effect on racing performance in this cohort, although horses with bilateral and LTR lesions started fewer races at 2 years. There was evidence for different distribution of OC lesions among pacers and trotters, which should be explored further. Standardbreds undergoing early removal of tarsal OC lesions can be expected to perform equivalently to their unaffected counterparts.
| S-EPMC4229490 | biostudies-literature
Project description:BackgroundThe safety and efficacy of aerobic exercise in heart failure (HF) patients with atrial fibrillation (AF) has not been well evaluated.ObjectivesThis study examined whether outcomes with exercise training in HF vary according to AF status.MethodsHF-ACTION (Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training) randomized 2,331 ambulatory HF patients with ejection fraction ≤35% to exercise training or usual care. We examined clinical characteristics and outcomes (mortality/hospitalization) by baseline AF status (past history of AF or AF on baseline electrocardiogram vs. no AF) using adjusted Cox models and explored an interaction with exercise training. We assessed post-randomization AF events diagnosed via hospitalizations for AF and reports of serious arrhythmia caused by AF.ResultsOf 2,292 patients with baseline rhythm data, 382 (17%) had AF, 1,602 (70%) had sinus rhythm, and 308 (13%) had "other" rhythm. Patients with AF were older and had lower peak Vo2. Over a median follow-up of 2.6 years, AF was associated with a 24% per year higher rate of mortality/hospitalization (hazard ratio [HR]: 1.53; 95% confidence interval [CI]: 1.34 to 1.74; p < 0.001) in unadjusted analysis; this did not remain significant after adjustment (HR: 1.15; 95% CI: 0.98 to 1.35; p = 0.09). There was no significant difference in AF event rates by randomized treatment assignment in the overall population or by baseline AF status (all p > 0.10). There was no interaction between AF and exercise training on measures of functional status or clinical outcomes (all p > 0.10).ConclusionsAF in patients with chronic HF was associated with older age, reduced exercise capacity at baseline, and a higher overall rate of clinical events, but not a differential response to exercise training for clinical outcomes or changes in exercise capacity. (Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training [HF-ACTION]; NCT00047437).
| S-EPMC5380238 | biostudies-literature
Project description:Atrial fibrillation (AF), one of the most common arrhythmias, is associated with chronic emotional disorder. Chronic pain represents a psychological instability condition related to cardiovascular diseases, but the mechanistic linkage connecting chronic pain to AF occurrence remains unknown. Wild-type C57BL/6J male mice were randomly divided into sham and chronic pain groups. Autonomic nerve remodeling was reflected by the increased atrial parasympathetic tension and muscarinic acetylcholine receptor M2 expression. AF susceptibility was assessed through transesophageal burst stimulation in combination with electrocardiogram recording and investigating AERP in Langendorff perfused hearts. Our results demonstrated the elevated protein expression of muscarinic acetylcholine receptor M2 in the atria of mice subjected to chronic pain stress. Moreover, chronic pain induced the increase of atrial PR interval, and atrial effective refractory periods as compared to the sham group, underlying the enhanced susceptibility of AF. Thus, autonomic cholinergic nerve may mediate mice AF in the setting of chronic pain.
| S-EPMC9521049 | biostudies-literature
Project description:Admissions of Standardbred racehorses (Std) to the Ontario Veterinary College Teaching Hospital (OVCTH) for treatment of atrial fibrillation (AF) began to increase in the early 1990s. The arrhythmia has been shown to have a modest heritability (h2 ≃ 0.15), with some stallions appearing as sires or sires of mares used in breeding (broodmares) of affected horses more frequently than others. The objective of this study was to determine the marginal genetic contributions of ancestors to cohorts of Std affected with AF and their contemporary control groups, and whether these ancestors contribute significantly more to the affected cohorts than to controls. All Std admitted to OVCTH for treatment of AF that were born between 1993 and 2007 comprised the affected case group (n = 168). Five randomly selected racing contemporaries for each Std admitted, assumed to not suffer from the arrhythmia, comprised the control group (n = 840). Three-year overlapping cohorts were created for case and control horses, determined according to year of birth, for a total of 26 cohorts. Marginal genetic contributions of ancestors to each cohort were determined and differences analyzed for statistical significance using a two-tailed paired t-test, with P ≤ 0.05 considered significant. The marginal contributions of 26 ancestors were significant, with 11 contributing significantly more to affected cohorts than the corresponding controls, and 15 contributing significantly more to controls than the corresponding affected cohorts. One stallion and one broodmare were very highly significant to affected cohorts at P ≤ 0.001, and nine stallions and three broodmares were very highly significant to control cohorts at P ≤ 0.001. Therefore, a number of stallions have statistically significant contributions to the genetics of Std affected with AF, while many others have statistically significant contributions to healthy Std. The arrhythmia appears to be particularly prevalent in the descendants of one sire family.
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Project description:BackgroundStudies of separate exercise and weight loss interventions have reported improvements in quality of life (QoL) or reduction in atrial fibrillation (AF) burden. We investigated the impact of a structured exercise, nutrition, and risk-factor-modification program on QoL and AF burden.MethodsIn this trial, 81 successive patients with body mass index > 27 kg/m2 and nonpermanent AF were randomized to an intervention (n = 41) or control group (n = 40). The intervention consisted of cardiovascular risk management and a 6-month nutrition and exercise program, followed by a 6-month maintenance program. All participants received usual AF care. The primary end-point was QoL at 6 and 12 months.ResultsAt 6 months, we observed improved QoL among patients in the intervention group, relative to that among control-group patients (intervention (I) n = 34, control (C) n = 38) in the 36-item Short Form Survey Instrument scores on the subscales of vitality (I: 13.2 ± 20.4; C: 1.0 ± 14.9, P < 0.001), social functioning (I: 14.7 ± 24.1; C: 2.4 ± 21.2, P = 0.018), emotional well-being (I: 5.5 ± 14.1 ; C: -1.0 ± 13.3, P = 0.017), and general health perceptions (I: 8.1 ± 12.3; C: 2.7 ± 13.3, P = 0.009). At the 6-month follow-up, improvement in the scores on the subscales of vitality (P = 0.021) and emotional well-being (P = 0.036) remained significant. The burden of AF as measured by Holter monitor and Toronto AF symptom score was not significantly changed.ConclusionsA structured exercise and nutrition program resulted in significant sustained improvements in QoL, without reduction in AF burden. This type of program may provide an additional treatment for people with impaired QoL due to AF.
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Project description:Horseracing is under public scrutiny with increasing demands to safeguard horse welfare. It is accepted that, as a result of bit pressure and/or equipment, mouth lesions accompany many types of horse use, including racing. However, there are currently no data available on the range of bit pressures in driven trotters. Our aim was to investigate whether rein tension (RT, proxy for bit pressures) differs among gaits, between tempo within gait, between horses and drivers, and between left/right reins. Standardbreds (n = 9), driven by experienced drivers (n = 11), performed exercise tests on a racetrack (cross-over design; total 31 tests, data available from 26 tests). Horses' motion symmetry was measured before tests (trotting in hand). Rein tension, speed and heart rate were measured during exercise. A moving-window filter was applied to RT raw data. Median, maximum and interquartile range for the estimated stride median RT were determined for each rein (left/right) and segment: walk; circling in slow trot followed by transition to faster trot; fast (racing) trot; and slowing down to walk. Mixed models were used for statistical analysis. Least square means for segment median RT ranged between 17-19 N in walk, 34-40 N during circling-accelerating, 51-62 N in fast trot, and 53-71 N for slowing down. Segment maximum RT was between 60-81 N in walk, 104-106 N during circling-accelerating, 72-86 N in fast trot, and 86-129 N during slowing down. Interquartile ranges were between 7-9 N in walk, 28-31 N during circling-accelerating, 8-10 N in fast trot, and 12-18 N for slowing down. Hind limb asymmetry exceeded the recommended threshold in three horses and was associated with higher median (48 N) and maximum (106 N) RT than symmetric horses (29 N and 73 N, respectively, p < 0.01). Consistent left-right asymmetry in RT was more common among horses than among drivers. Rein tension increased with increasing heart rate (p ≤ 0.0006). Rein tensions were higher than those reported during riding or in horses worked from the ground. The findings of high RT, taken together with the high reported prevalence of oral injuries in harness trotters, call for further research into RT, motion symmetry and use of equipment.
| S-EPMC9592803 | biostudies-literature
Project description:Changes in heart rate and heart rate variabilty (HRV) were investigated in untrained (UT; starting their first racing season) and detrained (DT; with 1-3 years of race experience) racehorses before and after 14-week conventional training. HRV was measured at rest over 1 h between 9:00 and 10:00 AM on the usual rest day of the horses. The smallest worthwhile change (SWC) rate was calculated for all HRV parameters. UT horses had significantly higher heart rate compared to DT (P<0.001). There were no gender- or training-related differences in heart rate. The root-mean-square of successive differences (rMSSD) in the consecutive inter-beat-intervals obtained after the 14-week training period was lower compared to pre-training rMSSD (P<0.001). The rMSSD was not influenced by breed, age or gender. In DT horses, there was a significant decrease in the high frequency (HF) component of HRV (P≤0.05) as the result of the 14-week training. These results may reflect saturation of high-frequency oscillations of inter-beat intervals rather than the reduction in parasympathetic influence on the heart. The HF did not differ significantly between the two measurements in UT horses; however, 16.6% of the animals showed a decrease in HF below SWC (P≤0.05). This supports the likelihood of parasympathetic saturation. Although no significant decrease in heart rate was found for the post-training, 30.0% of DT and 58.3% of UT horses still showed a decrease in heart rate below the SWC. Also by individual examination, it was also visible that despite significant post-training decrease in rMSSD, 1 (4.6%) DT and 2 (6.7%) UT horses reached SWC increase in rMMSD. In the case of these horses, the possibility of maladaptation should be considered. The present results indicate that similar to as found in human athletes, cardiac ANS status of racehorses also changes during the physiological adaptation to training. To explore more precise links between HRV and training effectiveness in horses, a more frequent recording would be necessary. Detailed analysis of HRV parameters based on SWC will be able to highlight the importance of fitness evaluation at individual level.
| S-EPMC8659354 | biostudies-literature