Evaluation of a digital stethoscope for electrocardiographic recording in donkeys: Preliminary results.

The digital stethoscope (DS) is a cost-effective single-lead digital stethoscope that allows simultaneous electrocardiographic (ECG) and phonocardiographic recordings on a smartphone. Despite its application in small animals and horses, there are currently no studies on its use in donkeys. The aim of this study was to evaluate the use of a new smartphone-based DS device in recording ECG tracings in donkeys. Standard base-apex lead ECG (sECG) and single-lead DS ECG (dECG) were simultaneously recorded for at least 30 s. Both sECG and dECG tracings were analysed by the same operator, recording heart rate, ECG waves and intervals, and the presence and duration of artefacts. Thirty-seven donkeys were included. The dECG tracings were interpretable in all the animals (100 %). The results showed perfect agreement between the sECG and dECG data for the classification of heart rhythm and P-wave polarity. Strong agreement was found in the evaluation of heart rate calculated manually and automatically by the smartphone app, QRS complex polarity, T wave polarity, and duration of the PR interval. However, no agreement was found in the evaluation of P wave duration, QRS complex duration and amplitude, and T wave duration and amplitude. In conclusion, although this is only a preliminary study, the DS was a valid, practical, and easy to use electrocardiographic tool for recording good-quality ECG tracings to assess the ECGs of donkeys in the field.

Occurrence of cardiovascular events in 168 cats with acute urinary tract obstruction.

Background: Cardiovascular dysfunction associated with acute kidney injury has been recently described in veterinary medicine, but limited information is available for cats with urinary tract obstruction (UTO). Objective: This retrospective study aimed to describe the type, frequency, timeline, and risk factors for cardiovascular events (CVEs) in cats treated for acute UTO. Animals and procedures: Medical records of cats admitted to the intensive care unit for either upper (ureteral: UUTO) or lower (urethral: LUTO) UTO from 2016 to 2021 were reviewed. Cardiovascular events were defined as development of arrhythmia, heart murmur or gallop sound, clinical signs consistent with fluid overload (CRFO), or decreased tissue perfusion (DTP). Results: One hundred and sixty-eight cats with UTO were recruited (56 with UUTO and 112 with LUTO). Cardiovascular events were reported in 61.9% of cases, including arrhythmia (33.6%), gallop rhythm (28.1%), heart murmur (15.3%), CRFO (14.4%), and DTP (8.6%). Potassium concentration, preexisting chronic kidney disease, and renal pelvic dilation at abdominal ultrasonography were associated with CVE occurrence in multivariate analysis. Conclusions: This study highlighted frequent CVEs in cats treated for UTO, with a potential strong impact on outcome. Therefore, cardiovascular parameters of cats with preexisting chronic kidney disease or those admitted with hyperkalemia or renal pelvic dilation should be closely monitored.

Survenue d'anomalies cardio-vasculaires chez 168 chats présentés pour obstruction du tractus urinaire. Contexte: Si des anomalies cardiovasculaires secondaires à une insuffisance rénale aigue ont été décrites récemment en médecine vétérinaire, ces données restent limitées concernant les obstructions du tractus urinaire (OTU) chez le chat. Objectif: Décrire le type, la fréquence, le délai d'apparition et les facteurs de risques d'anomalies cardio-vasculaires (ACV) chez des chats hospitalisés pour OTU aigue. Animaux et protocoles: Les dossiers médicaux des chats admis en unité de soins intensifs pour obstruction du tractus urinaire haut ( urétérales-OTUH) et bas (urétrales-OTUB) entre 2016 et 2021 ont été consultés. Les ACV retenus étaient des arythmies cardiaques, le développement de souffles cardiaques et de bruits de galop, les signes relatifs à une surcharge en fluide (SRSF) et de diminution de la perfusion tissulaire (SDPT). Résultats: Cent soixante-huit chats avec des OTU ont été recrutés (56 OTUH, 112 OTUB). Des ACV ont été observés dans 61,9 % des cas, incluant des arythmies (33,6 %), l'apparition de bruits de galop (28,1 %) et de souffles cardiaques (15,3 %), des SRSF (14,4 %) et des SDPT (8,6 %). La concentration plasmatique en potassium, la présence d'une MRC sous-jacente et d'une dilatation pyélique à l'échographie abdominale ont été associées à la présence d'ACV par l'analyse multivariée. Conclusions: Cette étude montre que les ACV surviennent fréquemment chez les chats présentés pour OTU, et suggère un impact sur la survie de ces animaux. Les animaux avec un historique de MRC, ceux présentés avec une hyperkaliémie et/ou avec une dilatation pyélique à l'échographie abdominale devraient être surveillés avec plus de précautions que les autres.(Traduit per les auteurs).

Clinical outcome of idiopathic juvenile ventricular arrhythmias in 25 dogs.

INTRODUCTION/OBJECTIVES: Juvenile ventricular arrhythmias in the absence of structural heart disease have been characterized in a small number of canine breeds with limited long-term follow up. The objective of this study was to describe the clinical outcome of dogs with JVA presenting to a university teaching hospital. ANIMALS, MATERIALS, METHODS: Twenty five dogs, less than two years old with idiopathic ventricular arrhythmias were retrospectively identified via a medical record search. Young dogs with ventricular arrhythmias were excluded if they had structural heart disease, systemic illness, or an abnormal troponin (if performed). Electrocardiographic and Holter monitor data was evaluated for arrhythmia frequency and complexity at the time of diagnosis and over time. Long-term follow up was achieved through client and primary veterinarian contact. RESULTS: Breeds included German Shepherd (eight), Boxer (four), Great Dane (three), mixed breed (two) and one each of the following: Anatolian Shepherd, French Bulldog, golden retriever, Great Pyrenees, Labrador retriever, Shiloh Shepherd, miniature Poodle and Siberian Husky. The average age at diagnosis was 7.9 months (range, 2-22 months). The overall median survival was 10.96 years (range, 1.75-15.66 years). There was an average reduction in the number of ventricular beats by 86.7 % per year (P value -0.0257) based on Holter data. CONCLUSION: In most cases, idiopathic juvenile ventricular arrhythmias had a favorable long-term prognosis with reduced ectopy over time in this case series. Juvenile ventricular arrhythmias remains a diagnosis of exclusion but can be considered in a broader range of dog breeds than previously described.

Perioperative ventricular arrhythmias are increased with hemoperitoneum and are associated with increased mortality in dogs undergoing splenectomy for splenic masses.

OBJECTIVE: To identify risk factors for intra- and postoperative ventricular arrhythmias (VAs) and in-hospital mortality in dogs undergoing splenectomy for splenic masses. ANIMALS: 308 dogs. METHODS: Records from 2010 through 2018 were reviewed for dogs undergoing splenectomy for a splenic mass. Clinical and laboratory findings on admission, diagnostic imaging, anesthesia, surgery and pathology reports, treatment records, and in-hospital mortality were evaluated with logistic regression. RESULTS: VAs occurred in 138 (44.8%) dogs (126/308 [40.9%] postoperative, 51/308 [16.6%] intraoperative, 26/308 [8.4%] preoperative), with 50/308 (16.2%) dogs having more than one type of VA. Increasing heart rate and body weight, decreasing PCV and platelet count, hemoperitoneum, receipt of a transfusion, and diagnosis of hemangiosarcoma were associated with the presence of intra- and postoperative VAs on univariable analysis (all P < .001). On multivariable analysis, hemoperitoneum (P < .001 , < .001), increasing body weight (P = .026, < .001), and increasing heart rate (P = .028, < .001) were significant for intra- and postoperative VAs, respectively. Twenty dogs died (20/308 [6.5%]; 14/138 [10.1%] with VAs, 6/170 [3.5%] without VAs). Intra- and postoperative VAs were associated with in-hospital mortality (P = .009, .025, respectively). CLINICAL RELEVANCE: Perioperative VAs were common and odds of VAs were increased with hemoperitoneum, increasing heart rate, and increasing body weight. Presence of VAs increased the odds of in-hospital mortality. Despite this, the overall in-hospital mortality rate was low (6.5%), indicating a good prognosis for survival of surgery in dogs with splenic masses, regardless of the presence of VAs or hemoperitoneum.

Characterization of the electrocardiogram of microminipig in comparison with that of Clawn miniature swine: impacts of miniaturization of body size on electrocardiographic indices.

Effects of body size reduction on electrocardiographic indices were examined using microminipigs in comparison with Clawn miniature swine (Clawn). Electrocardiogram was recorded using Holter electrocardiograph in conscious state for 24 hr for microminipigs (male: 11.6 ± 0.1 kg, 12-17 months, n=5; and female: 9.9 ± 0.4 kg, 6 months, n=5) and Clawn (female: 20.3 ± 0.4 kg, 8-9 months, n=8). Microminipig had shorter PR interval and QRS width than Clawn, whereas no significant difference was detected in JTcF/QTcF between them. Ratios of PR interval, QRS width, and body weight cubic root for microminipigs to Clawn ranged between 0.713 and 0.830. These findings indicate that PR interval and QRS width will depend on distance for excitatory current propagation, whereas JTcF/QTcF may be governed by local electrical activities.

Presumed primary cardiac mast cell tumor, pericardial effusion, and arrhythmia in a dog.

A 13-year-old female spayed border collie cross presented for pericardial effusion, arrhythmia, and a suspected cardiac mass. Echocardiogram revealed severe thickening and hypokinesis of the interventricular septum with a heterogenous, cavitated myocardium, concerning for neoplasia. Electrocardiogram revealed predominantly accelerated idioventricular rhythm with frequent periods of nonsustained ventricular tachycardia. Occasional prolonged PR intervals terminating in an aberrantly conducted QRS complex were present. These beats were postulated to represent either first-degree atrioventricular block with aberrant QRS conduction or atrioventricular dissociation. Cytology of the pericardial effusion revealed atypical, suspected neoplastic, mast cells. The patient was euthanized, and postmortem examination confirmed full-thickness infiltration of the interventricular septum by a mast cell tumor, with metastasis to the tracheobronchial lymph node and spleen. Given the anatomic location of the mass, the observed atrioventricular nodal conduction delay may represent neoplastic infiltration of the atrioventricular node. Neoplastic infiltration of the ventricle was suspected to cause the accelerated idioventricular rhythm and ventricular tachycardia. To the authors' knowledge, this is the first reported case of a primary cardiac mast cell tumor causing arrhythmia and pericardial effusion in a dog.

Evaluating the accuracy of a six-lead smartphone-based electrocardiographic device compared with standard electrocardiography in brachymorphic dogs.

BACKGROUND: No previous study has evaluated the accuracy of a six-lead smartphone-based electrocardiographic (s-ECG) device in dogs. METHODS: This was a prospective multicentre study. Patients referred for cardiologic consultation were selected. In each patient, a 30-second electrocardiogram was simultaneously acquired with a novel six-lead s-ECG and a standard six-lead ECG machine (st-ECG). A board-certified cardiologist evaluated each recording. Nineteen ECG variables, including heart rate and rhythm, as well as quantitative and qualitative features of waves, segments and intervals, were analysed. Agreement between s-ECG and st-ECG was evaluated using Cohen's kappa coefficient and the Bland-Altman test. RESULTS: Seventy-five dogs were enrolled, and 140 ECG tracings were analysed. There was perfect agreement between the two methodologies for heart rate and rhythm classification, both in dogs with sinus rhythm and those with pathological rhythms. Although some disagreement was found when comparing measurements of quantitative variables obtained with the s-ECG and the st-ECG, none of the differences was of clinical relevance. LIMITATIONS: The sample size was limited, and the interobserver variability was not analysed. CONCLUSION: The six-lead s-ECG studied herein is comparable to the st-ECG for heart rate and rhythm assessment, and seems clinically acceptable for the interpretation of waves, segments and intervals in dogs.

Medical causes of poor performance and their associations with fitness in Standardbred racehorses.

BACKGROUND: Poor performance is a multifactorial syndrome of racehorses, commonly associated with subclinical disorders, which can be diagnosed by exercise testing. OBJECTIVES: Describe the prevalence of medical causes of poor performance in Standardbreds unassociated with lameness, and evaluate their relationships with fitness variables measured by exercise treadmill test. ANIMALS: Hospital population of 259 nonlame Standardbred trotters referred for poor performance. METHODS: The horses' medical records were retrospectively reviewed. Horses underwent a diagnostic protocol including resting examination, plasma lactate concentration, treadmill test with continuous ECG and assessment of fitness variables, creatine kinase activity, treadmill endoscopy, postexercise tracheobronchoscopy, bronchoalveolar lavage (BAL), and gastroscopy. The prevalence of different disorders was evaluated, including cardiac arrhythmias, exertional myopathies, dynamic upper airway obstructions (DUAOs), exercise-induced pulmonary hemorrhage (EIPH), moderate equine asthma (MEA), and gastric ulcers (EGUS). The associations of these disorders with fitness variables were investigated individually and using multivariable models. RESULTS: Moderate equine asthma and EGUS were the most common disorders, followed by EIPH, DUAOs, cardiac arrhythmias, and exertional myopathies. Hemosiderin score was positively correlated with BAL neutrophils, eosinophils, and mast cells; increased creatine kinase activity was associated with BAL neutrophilia, DUAOs, premature complexes, and squamous gastric disease. Treadmill velocity at a plasma lactate concentration of 4 mmol/L and at heart rate of 200 beats per minute was negatively affected by BAL neutrophilia, multiple DUAOs, exertional myopathies, and squamous gastric disease. CONCLUSIONS: The multifactorial nature of poor performance was confirmed, with MEA, DUAOs, myopathies and EGUS representing the main diseases involved in fitness impairment.

Overall good agreement of smartphone-based and standard base-apex electrocardiography in healthy sheep.

OBJECTIVE: To assess and compare the quality of smartphone ECG tracings to standard (base-apex) ECG tracings and assess agreement of ECG parameters between smartphone-based ECG and standard ECG. ANIMALS: 25 rams. PROCEDURES: The rams were consecutively examined with standard ECG and smartphone-based ECG (KardiaMobile; AliveCor Inc) after physical examination. ECGs were compared for quality score, heart rate, and ECG waves, complexes, and intervals. Quality scores were based on the presence or absence of baseline undulation and tremor artifacts using a 3-point scoring system (lowest possible = 0; highest possible = 3). A lower score was indicative of a better-quality ECG. RESULTS: Smartphone-based ECGs were interpretable in 65% of cases, while 100% of standard ECGs were interpretable. Standard ECG quality was superior to smartphone-based ECG quality, with no agreement in the quality between devices (κ coefficient, -0.0062). There was good agreement for heart rate with mean difference 2.86 beats/min (CI, -3.44 to 9.16) between the standard and smartphone ECGs. Good agreement was observed for P wave amplitude with mean difference 0.02 mV (CI, -0.01 to 0.05), QRS duration with mean difference -10.5 ms (CI, -20.96 to -0.04), QT interval with mean difference -27.14 ms (CI, -59.36 to 5.08), T wave duration with mean difference -30.00 ms (CI, -66.727 to 6.727), and T wave amplitude with mean difference -0.07 mV (CI, -0.22 to 0.08) between the 2 devices. CLINICAL RELEVANCE: Our findings indicate good agreement between standard and smartphone ECG for most parameters, although 35% of smartphone ECGs were uninterpretable.

Evaluation of automated external defibrillator designed for people in dogs.

OBJECTIVE: To determine if human automated external defibrillators (AEDs) could successfully record cardiac electrical activity in dogs, make appropriate recommendations regarding shock delivery, and characterize skin preparation required for a readable ECG based on dog haircoat characteristics. DESIGN: Prospective study of AED use in dogs conducted between January and March 2021. SETTING: University teaching hospital. ANIMALS: Three groups of client-owned dogs were evaluated. Group 1 consisted of 23 healthy dogs with sinus rhythms, group 2 consisted of 9 dogs with documented cardiac arrhythmias, and group 3 consisted of 9 dogs receiving CPR following naturally occurring cardiopulmonary arrest. MATERIALS AND METHODS: Haircoat characteristics and clipping or ECG paste required to obtain a readable ECG were recorded. The time interval from a readable ECG by the investigator until AED shock advisement was measured. Correctness of shock advice was recorded. Analyses were performed using commercial statistical software. P-values <0.05 were considered significant. RESULTS: The attending veterinarian judged the ECG on the AED to be readable in all dogs. Time to shock advisement in all dogs was median 18 (range: 7-180) seconds. Dogs with heavy, long, or double haircoats required clipping in 24 of 27 (89%) cases to obtain a readable ECG. ECG paste on the AED pad was required in 36 of 40 dogs (90%) in order to obtain a readable ECG. The AED advice for delivery of shock was appropriate in 51 of 52 (98%) queries of the machine across all groups. CONCLUSIONS: Human AEDs can successfully record cardiac electrical activity in dogs. AEDs appropriately recommend delivery of a shock most times, contingent on skin preparation. Dogs with double, long, or heavy haircoats should be clipped prior to pad application. ECG paste will aid AED reading in all haircoat types. Further investigation is warranted into AED use in dogs, particularly in general practices.

QT interval instability and variability in dogs with naturally-occurring hypercortisolism.

Hypercortisolism is one of the most common endocrine diseases in dogs. In humans, it is clearly associated with a higher risk of cardiovascular events, but studies in dogs are scarce. To investigate the arrhythmogenic risk of dogs with naturally-occurring hypercortisolism (NOHC), indices of variability and instability of the QT interval were retrospectively studied in 38 dogs with NOHC and prospectively studied in 12 healthy dogs: variance (QTv), total instability (TI), short-term (STI) and long-term (LTI), and mean (QTm). Except for QTm, all parameters studied were higher in the NOHC group than in the control group. In addition, STI and QTv showed moderate positive correlation with left ventricle wall thickness. The NOHC group was subdivided according to cortisol suppression pattern in the low-dose dexamethasone suppression test. All electrocardiographic indices of partial and absent suppression patterns were numerically higher than healthy dogs. QTv and TI were lower in the control group than in both NOHC subgroups. LTI and STI were lower in the CG than in the group with the partial suppression pattern. There was no statistical difference between sex groups in any of the electrocardiographic parameters studied. This result might indicate that the etiology of NOHC, and its consequent influence on hypothalamus-pituitary-adrenal axis could interfere on the heterogeneity of ventricular repolarization parameters in different ways, especially in the short-term and the long-term stability; however further studies are necessary to understand the role of cortisol on electrical instability in dogs.

Frequency of cardiac arrhythmias in horses during straight and untethered swimming.

BACKGROUND: Cardiac arrhythmias have not been previously reported in horses while swimming. OBJECTIVES: To describe the type and frequency of encountered arrhythmias during repetitive swimming cycles. STUDY DESIGN: Descriptive observational study. METHODS: Sixteen horses swam five pool lengths (75 m), each separated by an active recovery walk. Continuous electrocardiograms (ECGs) were recorded (n = 80) and analysed during the pre-swim, swim and active-recovery periods. Arrhythmias were categorised as sinus arrhythmia (SA), sinus block, sinus pause (compensatory and non-compensatory), second degree atrioventricular block (2AVB) for physiological arrhythmias, supraventricular premature depolarisation (SVPD) and ventricular premature depolarisation (VPD) for non-physiological arrhythmias. A linear mixed-effects model was used to examine the effects of repetitive swim lengths on arrhythmias and swimming parameters. Data were reported as median [interquartile range]. RESULTS: Fifteen horses (94%) experienced at least one arrhythmia; however, the frequency remained low and 2AVB were only observed during the pre-swim period. The swimming heart rate (HR) was 162 bpm [141;173]. Sinus blocks, sinus pauses, SA, SVPD and VPD were all recorded at least once during swimming. Except for one VPD couplet, all premature depolarisations were isolated. During active-recovery, the HR was 105 bpm [103;106], with SA observed in 13 horses (81%), isolated SVPD in six horses (38%), sinus pause in one horse (6%) but no VPD present. MAIN LIMITATIONS: Limited number of horses precluding population prevalence assessment. CONCLUSION AND CLINICAL IMPORTANCE: High-quality underwater ECGs were acquired in swimming horses for the first time. The frequency of arrhythmias remained low and rare pathological arrhythmias were observed during repetitive swimming and active-recovery cycles. Swimming with active-recovery periods is not a high-risk cardio-arrhythmic exercise.

HISTORIAL: Arritmias cardiacas no han sido previamente descritas en caballos nadando. OBJETIVOS: Describir el tipo y frecuencia de arritmias encontradas durante ciclos de natación repetitivos. DISEÑO DEL ESTUDIO: Estudio descriptivo observacional. MÉTODOS: Diez y seis caballos nadaron cinco largos de piscina (75 m), cada uno separado por una caminata de recuperación. Electrocardiogramas continuos (ECGs) fueron grabados (n = 80) y analizados durante el pre-natación, natación y periodos de recuperación activa. Las arritmias fueron categorizadas en arritmia sinusal (SA), bloqueo sinusal, pausa sinusal (compensatoria y no compensatoria), bloqueo atrio ventricular de segundo grado (2AVB) para las arritmias fisiológicas, y en despolarización supraventricular prematura (SVPD) y despolarización ventricular prematura (VPD) para las arritmias no fisiológicas. Se utilizo un modelo linear de efecto mixto para examinar los efectos de nadar largos de piscina en forma repetitiva sobre las arritmias y parámetros de natación. Los datos fueron reportados como mediana [rango intercuartil]. RESULTADOS: Quince caballos (94%) sufrieron de al menos una arritmia, sin embargo la frecuencia permaneció baja. 2AVB fueron observados solo durante el periodo de pre-natación. La frecuencia cardiaca durante la natación (HR) fue de 162 bpm [141;173]. Bloqueos sinusales, pausas sinusales, SA, SVPD y VPD fueron todos registrados por lo menos una vez durante la natación. Excepto por un par de VPD, todas las despolarizaciones fueron aisladas. Durante la recuperación activa, la HR fue de 105 bpm [103;106], con SA observado en 13 caballos (81%), SVPD aislados en 6 caballos (38%), pausa sinusal en 1 caballos (6%) pero ningún VPD presente. LIMITACIONES PRINCIPALES: Número limitado de caballos lo que imposibilita hacer un asesoramiento de la prevalencia en la población. CONCLUSIÓN E IMPORTANCIA CLÍNICA: Por primera vez, se adquirieron ECGs debajo del agua de alta calidad en caballos nadando. La frecuencia de las arritmias permaneció baja y se observaron arritmias patológicas raramente durante la natación repetitiva y los ciclos de recuperación activa. Nadar con periodos de recuperación activa no es un ejercicio de alto riesgo cardio-arrítmico.

Heart rate variability during high-speed treadmill exercise and recovery in Thoroughbred racehorses presented for poor performance.

BACKGROUND: Heart rate variability (HRV) analysis measures the inter-beat interval variation of successive cardiac cycles. Measurement of these indices has been used to assess cardiac autonomic modulation and for arrhythmia identification in exercising horses. OBJECTIVES: To report HRV indices during submaximal exercise, strenuous exercise and recovery, and explore relationships with clinical conditions (arrhythmias, lameness, equine gastric ulcer syndrome [EGUS], lower airway inflammation and upper respiratory tract obstructions [URTOs]) in Thoroughbred racehorses. STUDY DESIGN: Retrospective, observational cross-sectional study. METHODS: One hundred and eighty Thoroughbred horses underwent a treadmill exercise test with simultaneous electrocardiographic recording. Time-domain HRV indices (standard deviation of the R-R interval [SDRR]; root mean square of successive differences [RMSSD]) were derived for submaximal and strenuous exercise and recovery segments. Clinical conditions (arrhythmia [during each phase of exercise], lameness, EGUS, lower airway inflammation and URTO) were assigned to binary categories for statistical analysis. Relationships between selected HRV indices and the clinical conditions were explored using linear regression models. RESULTS: During submaximal exercise, lameness was associated with decreased logRMSSD (B = -0.19 95% confidence interval [CI] -0.31 to -0.06, p = 0.006) and arrhythmia was associated with increased logRMSSD (B = 0.31 95% CI 0.01-0.608, p = 0.04). During strenuous exercise, arrhythmia was associated with increased HRV indices (logSDRR B = 0.51 95% CI 0.40-0.62, p < 0.001; RMSSD B = 0.60 95% CI 0.49-0.72, p < 0.001). During recovery, arrhythmia was associated with increased HRV indices (logSDRR B = 0.51 95% CI 0.40-0.62, p < 0.001, logRMSSD B = 0.60 95% CI 0.49-0.72, p < 0.001). MAIN LIMITATIONS: The main limitations of this retrospective study were that not every horse had the full range of clinical testing, therefore some horses may have had undetected abnormalities. CONCLUSIONS: The presence of arrhythmia increased HRV in both phases of exercise and recovery. Lameness decreased HRV during submaximal exercise.

Feasibility and safety of three-dimensional electroanatomical cardiac mapping, mapping-guided biopsy and transseptal puncture in dogs.

Three-dimensional electroanatomical mapping (3D EAM) has expanded radiofrequency catheter ablation applications in humans to almost all complex arrhythmias and has drastically reduced fluoroscopy use, yet its potential in dogs is poorly investigated. The objectives of the current study were to assess the feasibility and safety of 3D EAM of all four heart chambers, 3D EAM-guided biopsies and transseptal puncture in dogs. Eight healthy purpose-bred Beagle dogs. Electroanatomical mapping was performed under general anaesthesia during sinus rhythm using a 22-electrode mapping catheter. Left heart catheterisation was achieved by either retrograde transaortic access (n = 4) or transseptal puncture (n = 4). Successful 3D EAM of the right atrium and ventricle was achieved in all dogs at a median time of 33 (13-40) min and 17 (3-52) min, respectively. Left atrial and ventricular 3D EAM was successful in six and seven dogs, at a median time of 17 (4-27) min and 8 min (4-19 min), respectively. Complications requiring intervention occurred in one dog only and were a transient third degree atrioventricular block and pericardial effusion following transseptal puncture, which was treated by pericardiocentesis. All dogs recovered uneventfully. Fluoroscopy time was limited to a median of 7 min (0-45 min) and almost exclusively associated with transseptal puncture. Three-dimensional EAM of all cardiac chambers, including mapping-guided biopsy and transseptal puncture is feasible in small dogs. Complications are similar to those reported in human patients. This suggests a potential added value of 3D EAM to conventional electrophysiology in dogs with arrhythmias.

A pilot study of patch Holter electrocardiograph recordings in healthy cats.

Background: A patch Holter electrocardiograph (P-Holter) is cordless, making it lightweight, unlike the conventional Holter electrocardiograph (C-Holter). A P-Holter can also take continuous measurements for up to 14 days without replacing the battery or SD card. Aim: To compare the performance of the P-Holter and the C-Holter in healthy cats. Additionally, we aimed to investigate whether multiday recordings with the P-Holter decrease sympathetic nerve activity or improve the accuracy of arrhythmia detection. Methods: Five healthy domestic short-haired cats were used for this study. Both a P-Holter and C-Holter were used on the first day, but only the P-Holter was used on days 2-6. The evaluated variables were the analyzable time of both Holter types, heart rate (HR), HR variability (HRV), and the number of arrhythmia occurrences. Results: For two out of the five cats, measurement of P-Holter was interrupted. Eventually, continuous recordings using the P-Holters were able to be collected from all individuals for 6 days. The 24 hours analyzable time from the P-Holter and C-Holter was almost identical (p = 0.94). The 24 hours mean HR did not differ across Holter types (p = 0.67). In addition, the timing of the occurrences of arrhythmias was almost identical to the P-Holter and C-Holter. Results of HRV suggested that sympathetic nerve activity was likely to decrease and vagal nerve activity was likely to increase after 4-5 days of measurement, compared to the second day of measurement (p < 0.05). When only the P-Holter was installed, the number of arrhythmia occurrences was similar on days 2-6. Conclusion: In this study, the P-Holter may be as useful as the C-Holter in cats with suspected intermittent arrhythmias, although the P-Holters were placed on cats without a clinical indication. However, cats may have individual differences in their adaptation to the device. P-Holter recordings taken for more than 4-5 days may allow the cat to acclimate to the device and reduce sympathetic nerve activity. The accuracy of arrhythmia detection across multiday P-Holter recordings requires further investigation using clinical cases.

Heart inflammation and piscine orthoreovirus genotype-1 in Pacific Canada Atlantic salmon net-pen farms: 2016-2019.

Piscine orthoreovirus genotype-1 (PRV-1) is a virus commonly associated with Atlantic salmon aquaculture with global variability in prevalence and association with disease. From August 2016 to November 2019, 2,070 fish sampled at 64 Atlantic salmon net-pen farm sites during 302 sampling events from British Columbia, Canada, were screened for PRV-1 using real-time qPCR. Nearly all populations became PRV-1 positive within one year of seawater entry irrespective of location, time of stocking, or producer. Cohorts became infected between 100-300 days at sea in > 90% of repeatedly sampled sites and remained infected until harvest (typically 500-700 days at sea). Heart inflammation, which is sometimes attributed to PRV-1, was also assessed in 779 production mortalities from 47 cohorts with known PRV status. Mild heart inflammation was common in mortalities from both PRV + and PRV- populations (67% and 68% prevalence, respectively). Moderate and severe lymphoplasmacytic heart inflammation was rare (11% and 3% prevalence, respectively); however, mainly arose (66 of 77 occurrences) in populations with PRV-1. Detection of PRV-1 RNA was also accomplished in water and sediment for which methods are described. These data cumulatively identify that PRV-1 ubiquitously infects farmed Atlantic salmon in British Columbia during seawater production but only in rare instances correlates with heart inflammation.

Retrospective evaluation of the ST segment electrocardiographic features in 180 healthy dogs.

OBJECTIVES: Normal features of the ST segment are poorly characterised in dogs. This study aimed to describe ST segment characteristics in a population of healthy dogs. MATERIALS AND METHODS: Medical records were reviewed to identify healthy dogs that underwent an electrocardiogram. Several ST segment qualitative parameters were evaluated: presence/absence of deviation, type of deviation (depression/elevation) and morphological patterns of depression (horizontal, downsloping, upsloping and sagging) and elevation (horizontal, concave and convex). Moreover, the amplitude of ST segment depression/elevation was measured. The potential effect of sex, bodyweight, age and somatotype on the presence/absence of ST segment deviation was evaluated through binary logistic regression. RESULTS: One hundred and eighty dogs were enrolled. The deviation was evident in 43 of 180 dogs (23.9%), among which 36 showed depression and seven showed elevation. The median depression amplitude was 0.1 (range 0.05 to 0.3) mV. The mean elevation amplitude was 0.136 ±0.055 mV. Concerning depression morphology, the horizontal pattern was overrepresented, followed by the downsloping and upsloping ones. Concerning elevation morphology, all dogs showed a concave pattern. No meaningful effect of sex, bodyweight, age and somatotype on the presence/absence of ST segment deviation was documented. CLINICAL SIGNIFICANCE: Normal features of canine ST segment were described and made available for clinical use.

Subepicardial burn injuries in bullfrog heart induce electrocardiogram changes mimicking inferior wall myocardial infarction.

Using bullfrog hearts, we previously reproduced a ST segment elevation in electrocardiogram (ECG), mimicking human ischemic heart disease. In the present study, by inducing subepicardial burn injuries on the inferior part of the frog heart ventricle, we could reproduce typical ECG changes observed in human inferior wall myocardial infarction, such as the marked elevation of the ST segments in inferior limb leads (II, III, aVF) and their reciprocal depression in the opposite limb leads (I, aVL). Due to the decrease in Na+/K+-ATPase protein expression, the resting membrane potential of injured cardiomyocytes shifted toward depolarization. Such induced electrical difference between the injured and intact cardiomyocytes was thought to be responsible for the creation of "currents of injury" and the subsequent ST segment changes.

The next heartbeat: Creating dynamic and histographic Poincaré plots for the assessment of cardiac rhythms.

The rhythm of the heart is not a stationary phenomenon, and therefore, incorporation of the dynamic Poincaré plot and tachogram provides additional diagnostic information to complement and expand waveform (P-QRST) analyses from the electrocardiogram. Although pattern assessment of the Poincaré plot and tachogram can provide an appraisal for normal and abnormal rhythms and serve as a potential means for machine-learned rhythm diagnoses, time-selected windows of beat-to-beat variability permit more detailed examination. As such, expanded criteria for rhythm diagnoses, identification of arrhythmic triggers, global appreciation of rhythm changes, and recognition of patterns that provoke mechanistic questions may be gleaned from the use of the methods reviewed in this report. More specifically, these methods demonstrate that limitations exist in the reliance on traditional measures of heart rate variability in the dog due to the non-linear beat-to-beat rhythm of sinus arrhythmia in the species. Behavior of arrhythmias based on coupling intervals, repeating patterns, preceding triggers of beat-to-beat variability, and circumstantial evidence of atrioventricular nodal conduction during atrial flutter and fibrillation are a few examples of discovery founded in these techniques. The open access website, The Next Heartbeat (https://thenextheartbeat.com/), permits anyone to implement these methods in the assessment of long-term electrocardiographic examinations (Holter monitoring) so that, as yet to be revealed, features of the beating heart through time may be discovered.