Prevalence of cardiac arrhythmias and R-R interval variation in healthy Thoroughbred horses during official Chuckwagon races and recovery.

The prevalence and severity of cardiac arrhythmias in healthy racehorses undergoing competition is not well defined. The aim was to characterize arrhythmias in Thoroughbreds participating in official Chuckwagon races and to determine normal beat-to-beat (R-R) variability during supramaximal exercise. Electrocardiograph (ECG) recordings were obtained during pre-race, race, and active-recovery from 82 clinically healthy Thoroughbreds. ECG recordings were analyzed for arrhythmias and mean percent R-R deviation. Plasma lactate and high-sensitivity troponin (hs-cTnT) were also measured. Fifty-two ECGs were included in the analysis. Arrhythmias were seen in 48/52 horses (92%) and were predominantly isolated events. No complex rhythms were observed. During the race, 92% of horses had arrhythmias (81% supraventricular premature complex [SVPC]; 33% ventricular premature complex [VPC]). Eleven percent of racing arrhythmias were VPCs (all singlets except for two couplets). During active-recovery, 58% of horses had arrhythmias (56% SVPC; 15% VPCs): Three horses had VPC couplets and one horse had a VPC triplet. All plasma hs-cTnT were within normal limits. The measured lactate was 28.5 ± 4.5 mmol/L, confirming supramaximal exercise. R-R variation ranged between -9.5 to +18.8% during pre-race (mean heart rate [HR], 155 ± 22 beats per min [bpm]), -27.8 to +45.3% during racing (mean HR, 200 ± 9 bpm) and -16.4 to +40.1% during active-recovery (mean HR, 165 ± 14 bpm). Maximal and 1st percentile R-R shortening and lengthening were significantly greater at race than pre-race and active-recovery (P < 0.0001). Racing and active-recovery maximal R-R lengthening were significantly greater than pre-race (P = 0.0003). Supraventricular premature complexes and VPCs are prevalent in healthy horses undergoing Chuckwagon racing. R-R variation is greater during racing than has previously been described.

Transthoracic echocardiography and cardiac biomarkers in healthy captive male and female squirrel monkeys (Saimiri spp.).

BACKGROUND: Echocardiography is the most frequently used non -invasive diagnostic tool to evaluate cardiac anatomy and function in domestic species but increasingly also in non -domestic species, especially since cardiac disease is being recognized as an important cause of death in captive primates. The purpose of this cross -sectional study was to investigate the feasibility of transthoracic echocardiography in healthy squirrel monkeys as well as to provide species specific normal values for standard echocardiographic measurements. A secondary aim was to determine plasma and serum levels of the cardiac biomarkers, N -terminal pro -brain natriuretic peptide (NT -proBNP) and cardiac troponin T (cTnT). Furthermore, a commercial, non -invasive, smartphone -based ECG (AliveCor Vet TM) monitoring device was used to evaluate the heart rate and rhythm and to diagnose possible arrhythmias. RESULTS: In this study, transthoracic echocardiography of 14 squirrel monkeys was performed in right and left lateral recumbency. Similar standard right parasternal and left apical images were obtained as in dogs and cats and normal values for routine two -dimensional, time motion mode and Doppler mode measurements were generated. Thirteen animals were considered healthy and one squirrel monkey was identified with significant aortic dilation and regurgitation and consequently values obtained from this animal were not used when species specific normal values were calculated. NT -ProBNP and cTnT concentrations were available for 7 of the 13 healthy monkeys with NT -proBNP concentrations below detection limit in all animals and a mean cTnT concentration of 0.049 ng/mL. Electrocardiography was performed in all squirrel monkeys. The mean heart rate was 172 bpm. Frequent supraventricular premature beats were diagnosed in the squirrel monkey suffering from significant aortic dilation and regurgitation. CONCLUSION: This study presents echocardiographic normal values and additional cardiovascular data in anaesthetised Saimiri monkeys, fundamental from both the perspective of zoo animal health care as well as scientific research, since the squirrel monkey is often used as an animal model for human disease.

The prevalence of atrial premature complexes in healthy Doberman Pinschers and their role in the diagnosis of occult dilated cardiomyopathy.

The importance of atrial premature complexes (APCs) as a possible marker of occult dilated cardiomyopathy (DCM) in Doberman Pinschers (DP) is unknown. The aim of this study was to identify APC in healthy DP and to investigate their role as early markers of occult DCM. Holter-ECG results from 561 examinations of 153 DP at different time points were retrospectively evaluated, with special emphasis on APCs. Holter results from 110 healthy control DPs were compared to the last normal Holter and echocardiographic examinations in 43 DP that subsequently developed DCM within 15 months (DCM group), and to the first examination in the DCM group that contained ventricular premature complexes (VPC). There were no significant differences in the number of APCs or the coupling interval between the control group and the last normal examination in the DCM group (P > 0.05). The number of APCs increased slightly at the first abnormal examination in the DCM group. Healthy male DP had more APCs than females (P = 0.009) and older dogs had APCs more frequently than younger dogs (P < 0.001). About 85% of healthy DP with at least one APC/24 h had <20 APCs/24 h. Extracardiac diseases, especially gastrointestinal diseases influenced the occurrence of APCs (P = 0.037 and P = 0.006, respectively). APCs were present without obvious cardiac disease and were not a marker for the development of DCM, as they were not identified until after VPCs were present.

Twenty-four hour Holter monitoring in finishing cattle housed outdoors.

INTRODUCTION: Atrial premature complexes have been reported to be the most common arrhythmia in cattle and is suspected to be secondary to systemic disease, especially gastrointestinal disease. In order to properly identify pathologic arrhythmia in cattle, the normal rhythm and arrhythmia prevalence should be defined. The objective of this study was to determine the normal heart rate, rhythm, number of ventricular premature complexes (VPCs), and atrial premature complexes (APCs) in unrestrained Angus steers. ANIMALS: Twenty-seven client owned steers with unremarkable physical examinations and serum biochemical analyses were used. MATERIALS AND METHODS: Twenty-four hour Holter monitors, attached by a custom-made harness, were retrospectively evaluated. Three lead electrocardiographic registrations of good quality and normal sinus rhythm were obtained from all steers in the study. RESULTS: The mean heart rate was 66.8 bpm ± 16.4 bpm. Ventricular premature complexes were rare (noted in 14.8% of steers), and APCs were common (noted in 85% of the steers). Simple second degree AV block was observed in 18.5% of the steers. CONCLUSION: In summary, healthy steers have rare single VPCs, although it is possible for an individual animal to have apparent more frequent VPCs. Mean heart rate varies with a diurnal pattern similar to other species. Atrial premature complexes are the most prevalent abnormality observed in feedlot steers.

Changes in heart rate, arrhythmia frequency, and cardiac biomarker values in horses during recovery after a long-distance endurance ride.

OBJECTIVE To evaluate heart rate, heart rate variability, and arrhythmia frequency as well as changes in cardiac biomarker values and their association with heart rate in horses before and after an endurance ride. DESIGN Cross-sectional study. ANIMALS 28 Arabian horses competing in a 120- or 160-km endurance ride. PROCEDURES ECG recordings were obtained from each horse before (preride) and after (recovery) an endurance ride to evaluate changes in heart rate and the SD of normal R-R intervals (SDNN) during the initial 12 hours of recovery. Frequencies of supraventricular and ventricular premature complexes before and after the ride were evaluated. Blood samples were obtained before the ride and twice during recovery. Hematologic analyses included measurement of serum cardiac troponin I concentration and creatine kinase isoenzyme MB activity. RESULTS Heart rate was significantly increased and SDNN was decreased during the recovery versus preride period. Frequency of ventricular premature complexes increased during recovery, albeit not significantly, whereas frequency of supraventricular premature complexes was not significantly different between preride and recovery periods. Serum cardiac troponin I concentration and creatine kinase isoenzyme MB activity were significantly increased in the recovery versus preride period. No associations were identified between cardiac biomarkers and velocity, distance, or mean heart rate. CONCLUSIONS AND CLINICAL RELEVANCE Heart rate increased and SDNN decreased in horses after completion of an endurance ride. These and other cardiac changes suggested that prolonged exercise such as endurance riding might have cardiac effects in horses. Additional studies are needed to clarify the clinical relevance of the findings.

Heart rate variability and arrhythmias evaluated with Holter in dogs with degenerative mitral valve disease / Variabilidade da frequência cardíaca e arritmias detectadas pelo exame Holter em cães com degeneração valvar mitral

Cardiac diseases promote alterations in the autonomic control of the heart, leading to an increase in heart rate and, as a result, a decrease in heart rate variability (HRV).The aim of this study was to evaluate if the development of heart failure secondary to degenerative mitral valve disease (DMVD) concurs with changes in autonomic modulation of heart rhythm which are assessed by long electrocardiography examination (Holter). Dogs were evaluated by clinical examination and echocardiography in order to be categorized into the following groups: Control (healthy; n=6), DMVD (disease without heart failure; n=8), and DMVD heart failure (disease with heart failure; n=13). Arrhythmias and frequency domain HRV were determined by Holter. Diseased animals, when compared to healthy, had significantly lower total power, which indicates overall HRV. DMVD heart failure dogs also showed other disturbances such as high incidence of supraventricular arrhythmias, high heart rate, little amount of pauses (2.0s long between consecutive heartbeats), longer time in tachycardia, shorter time in bradycardia, low high frequency (parasympathetic control), and high low frequency (sympathetic and parasympathetic control) when compared to control (p<0.05). In DMVD dogs, Holter-derived variables changed with the development of heart failure...

As cardiopatias cursam com alterações do controle autonômico do coração, resultando em taquicardia e consequente diminuição na variabilidade da frequência cardíaca (VFC). O objetivo deste estudo foi avaliar se o desenvolvimento de insuficiência cardíaca secundária à degeneração valvar mitral (DVM) leva a alterações no controle autonômico do coração, as quais podem ser determinadas pela eletrocardiografia contínua (Holter). Cães foram distribuídos em grupos experimentais após avaliação clínica e ecocardiográfica da seguinte maneira: controle (saudáveis; n=6), DVM sem insuficiência cardíaca (n=8) e DVM com insuficiência cardíaca (n=13). Arritmias e VFC foram determinadas pelo Holter. Animais portadores de DVM, quando comparados ao controle, apresentaram diminuição significativa da potência total, a qual é representativa de toda a VFC. Somente cães doentes e com insuficiência cardíaca apresentaram incidência elevada de arritmias supraventriculares, frequência cardíaca aumentada, pequena quantidade de pausas superiores a 2,0s entre batimentos consecutivos, permanência por mais tempo em taquicardia do que em bradicardia, diminuído índice de alta frequência (indicativo de controle parassimpático) e elevado índice de baixa frequência (indicativo de controle simpático e parassimpático), quando comparados ao controle (p<0,05). Assim, conclui-se que, em cães portadores de DVM, as variáveis obtidas com o Holter apresentam-se alteradas devido ao desenvolvimento de insuficiência cardíaca...

Prevalence of exercise-associated arrhythmias in normal performing dressage horses.

REASONS FOR PERFORMING STUDY: Exercise-associated arrhythmias are important differentials when evaluating poor performance sport horses. However, most studies of arrhythmias have been conducted in racehorses and therefore there is a paucity of knowledge concerning the prevalence and significance of exercise-associated arrhythmias in riding horses. OBJECTIVES: The objective of this study was to examine the prevalence of arrhythmias, particularly supraventricular premature complex (SVPCs) and ventricular premature complex (VPCs), associated with exercise in normal performing dressage horses. METHODS: In total, 21 normal performing dressage horses, aged 5-16 years (mean 9 years), were examined clinically and echocardiographically to detect the prevalence of valvular regurgitation. Electrocardiographic (ECG) examinations were performed during rest and during a standardised dressage exercise programme, as well as during recovery period 1 h after exercise. All ECG recordings were analysed for presence and frequency of arrhythmias and arrhythmias were correlated with HR. Mean HR for walk, trot, canter and for specific dressage movements, as well as maximum HR was calculated. Fisher's exact test was used to test for associations between arrhythmias, valvular regurgitation, age and gender. RESULTS: SVPCs occurred rarely during rest, but occurred during exercise in 6 (28.6%), and in 13 (61.9%) horses during recovery period. Most horses had ≤ 3 SVPCs. Ventricular premature complex were seen in one horse, which developed twice during exercise. Mild valvular regurgitation was seen in 11 (52%) of the horses. No significant associations between arrhythmia and age, gender or valvular regurgitation were observed. CONCLUSIONS: Reference values for normal performing dressage horses are presented for the first time, demonstrating that arrhythmias occur infrequently during exercise and recovery. Maximum HR in dressage horses is low compared to both showjumping and racehorses. Studies of dressage horses with moderate to severe valvular regurgitation at rest or poor performance are needed to further elucidate the significance of cardiac arrhythmias.

Correlation of heart rate to body weight in apparently normal dogs.

OBJECTIVE: To evaluate the correlation between heart rate and body weight in the apparently healthy dog. ANIMALS: Sixty dogs weighing between 2 and 80 kg. METHODS: Heart rate was evaluated with a 24-h ambulatory electrocardiogram. Minimum, average, maximum heart rate, ventricular premature complex (VPC) number and supraventricular premature complex (SVC) number were tabulated for each dog. RESULTS: Minimum, maximum and average heart rate did not correlate to body weight. For all dogs, the median minimum heart rate was 42 bpm (beats per minute), median average heart rate was 73 bpm, and median maximum heart rate was 190. The median number of VPCs and SVC was zero. CONCLUSIONS: The present study does not support a correlation between heart rate and body weight in apparently healthy dogs.

Twenty-four hour Holter monitoring of unsedated healthy cats in the home environment.

OBJECTIVE: To determine the heart rate, rhythm, number of ventricular premature complexes (VPCs) and atrial premature complexes (APCs) in unsedated cats using Holter monitoring. ANIMALS, MATERIALS AND METHODS: Twenty-three healthy client owned cats were used. Clinical examination, blood pressure measurements, echocardiographic examination and serum biochemical analysis were performed. A lightweight Holter was used in the home environment. RESULTS: Three-lead electrocardiographic registrations of good quality were obtained from all cats. Normal sinus rhythm was present in all cats. The median heart rate was 165 beats per minute (bpm), range 70-303 bpm. Mean heart rate varied significantly with age and gender. Sinus arrhythmia occurred intermittently in 18 cats (78%). Uncommon ventricular premature complexes occurred in 18 (78%) of the cats. The median number of VPCs per cat was 3 complexes/24 h period, range 0-146. Cats 7-15 years of age had significantly more VPCs than cats 1-6 years of age (median 6 versus 1 per 24 h period, p=0.04). A single APC occurred in one cat (4%). CONCLUSIONS: Cats commonly have intermittent sinus arrhythmia. Many healthy cats have rare single VPCs per 24 h period. Old cats have significantly more VPCs than young cats. The heart rate varies significantly with age and gender.

[Long-term EKG in dogs: comparison between a computerized system and visual arrhythmia analysis]. / Das Langzeit-EKG beim Hund: Vergleich zwischen computergesteuerter und visuell ausgewerteter Arrhythmieanalyse.

Based on results of holter ecg recordings taken from 38 dogs the computerized analyses system turned out as method not exactly valuing the frequency and sensitivity of arrhythmias. Despite there was a significant correlation between the computerized and visual arrhythmia analysis for ventricular respectively supraventricular premature beats, in individual cases there was an important aberration between the particular values.

Electrocardiographic observation on spontaneously occurring arrhythmias in chickens.

In order to clarify the spontaneous occurrence of arrhythmias in chickens, electrocardiograms using standard bipolar limb leads were recorded for 461 chickens of 7 breeds, including 3 pure breeds: Rhode Island Red (RIR, n = 125), Japanese Game (JG, n = 101), and White Leghorn (WL, n = 52); and 4 crossbreeds of RIR: the first filial generation (F1) obtained by mating RIR with JG (RIR x JG, n = 44), the backcross obtained by mating the Fl of RIR x JG with the parental JG ((RIR x JG) x JG, n = 10), the F1 obtained by mating RIR with WL (RIR x WL, n = 73), and the F1 obtained by mating RIR with the commercial hybrid chicken, Dekalb Amber Link (DAL)(RIR x DAL, n = 56). Nine types of arrhythmias were observed in 107 chickens (23.2%, 107/461): 66 had sinus arrhythmia, 19 had atrial premature contraction, 9 had ventricular preexcitation syndrome, 7 had ventricular premature contraction, 2 had second-degree atrioventricular block. 1 had atrial fibrillation, I had aberrant ventricular conduction. I had intraventricular conduction disturbance, and 1 had ventricular electrical alternans. Except for sinus arrhythmia, the incidence of other arrhythmias in RIR was significantly high, compared with that in pure breeds other than RIR (p < 0.001) and that in crossbreeds of RIR (p < 0.01). Arrhythmias other than ventricular premature contraction and sinus arrhythmia will be the first to be described as spontaneously occurring arrhythmias in chicken. Although the reason for both the highest incidence of sinus arrhythmia in WL and the predominance of other arrhythmias in RIR were obscure, the present results suggest the possibility of using chickens, especially RIR which shows a high incidence of arrhythmias, as a relevant animal for studying arrhythmias.