Topic:Cardiac Arrhythmias
Cardiac arrhythmias in horses refer to irregularities in the heart's rhythm, which can affect the efficiency of blood circulation. These arrhythmias can result from various factors, including electrolyte imbalances, structural heart changes, or systemic diseases. Common types of arrhythmias in horses include atrial fibrillation, ventricular tachycardia, and premature ventricular contractions. The presence and type of arrhythmia can influence a horse's performance and overall health. Diagnostic tools such as electrocardiography (ECG) are used to identify and assess these irregular heart rhythms. This page compiles peer-reviewed research studies and scholarly articles that explore the mechanisms, diagnosis, and management of cardiac arrhythmias in equine medicine.
Detection of exercising ectopic atrial and ventricular beats using non-linear analysis of clinically normal racehorse electrocardiograms at rest or low-intensity exercise. Cardiac arrhythmias are common in healthy athletic horses and may lead to poor athletic performance or exercise-associated sudden death. Early detection of high-risk horses is an important goal of cardiovascular diagnostics. We hypothesised that non-linear analysis of electrocardiogram disorderliness can be used to identify horses exhibiting intermittent ectopic atrial and ventricular heart rhythm abnormalities at exercise using brief, artifact-free recordings of normal sinus rhythm electrocardiograms collected at submaximal heart rates. In a convenience prospective cross-sectional study, ambu...
Cardiac morphologic changes induced by a 10-week water treadmill training for show jumping horses: A preliminary evaluation. This study aimed to investigate cardiac adaptations and energy expenditure of jumping horses after water treadmill (WT) training. Six trained horses were evaluated before (PRETR) and after (TR) a WT training (20 min, twice/week, water at carpus height) for 10 weeks. Transthoracic echocardiography was performed at PRETR and TR with phased array transducer (1.9-4 MHz) to obtain interventricular septal thickness (IVS), LV internal diameter (LVID), and posterior wall thickness (LVPW) at end-diastole (d) and systole (s) and heart rate (HR). Left ventricule end diastolic volume (Vd) and end syst...
QT interval and cardiac restitution dynamics in racehorses: Observations during maximal effort. Sudden cardiac death is a leading cause of athletic death in both humans and horses, making racehorses a potentially valuable model for investigating sudden cardiac death. Cardiac restitution ratio (QT/TQ interval) is used to assess arrhythmia risk in humans, but investigations in athletes are scarce. The objective was to characterize QT interval and cardiac restitution ratio in Thoroughbred racehorses during maximal effort. Automated restitution analysis was performed using 2709 pairs of cardiac cycles from 30 Thoroughbred horses during races. Cardiac cycles were obtained during: pre-race; ac...
Vectorcardiography at rest and during exercise in horses using the Delta (Δ) 12-lead configuration. Twelve-lead electrocardiography (ECG) is essential in human cardiology but remains poorly investigated in equine medicine due to a lack of standardization and inconsistent findings. Objective: Describe the normal vectorcardiogram (VCG) variation in horses at rest and during exercise using Delta 12-lead ECG, including repeatability and intra- and interobserver variations. Methods: One hundred two healthy Warmblood horses, aged 3-20 years, were examined at rest, of which 30 also during exercise. Methods: Prospective, observational study. Electrocardiograms were recorded using a Δ 12-lead confi...
Utility of dynamic preload indices of hypovolemia in isoflurane-anesthetized horses. To evaluate the utility of the dynamic indices, systolic pressure variation (SPV%), pulse pressure variation (PPV%) and plethysmographic variability index (PVI%) during induced hypovolemia, and to determine their correlation with cardiac output (CO) in anesthetized horses. Methods: Prospective experimental study. Methods: A group of eight healthy adult research horses. Methods: After sedation with intravenous (IV) xylazine, anesthesia was induced with IV ketamine and diazepam and maintained with constant-dose isoflurane delivered in 100% oxygen. Horses were positioned in dorsal recumbency, par...
Evaluation of Pulse Pressure as a Hemodynamic Marker of Cardiac Disease in Dogs and Horses Undergoing Pre-Anesthetic Assessment. Pulse pressure (PP) reflects ventricular stroke volume and arterial compliance, but its utility as a marker of cardiac disease in animals is not well established. This study evaluated the association between PP and echocardiographically confirmed cardiac abnormalities in dogs and horses and assessed its potential in pre-anesthetic evaluation. Clinical and echocardiography examination of 20 dogs and 20 horses was sufficient for inter-group comparisons and assignments to a Cardiac group (echocardiographically confirmed cardiac disease) or a Control group (healthy animals). Non-invasive oscillome...
Case Report: Inhaled salbutamol in the successful treatment of life-threatening acute hyperkalaemia in an anaesthetised horse. Hyperkalaemia is an uncommon complication of general anaesthesia in healthy horses. This case report describes the occurrence of life-threatening acute hyperkalaemia in a 13-year-old, female French Trotter anaesthetised for experimental right and left atrial 3D electro-anatomical mapping. Intra-operative development of hyperkalaemia (7.55 mmol/L) (Ref. 3.00-4.00 mmol/L) with atrial standstill on ECG necessitated transvenous ventricular pacing while initial treatment with insulin and glucose was initiated. Plasma potassium levels continued to increase (8.00 mmol/L) prompting adjunctive tr...
Endurance exercise induces distinct skeletal and cardiac mitochondrial adaptations in racehorses. Mitochondrial respiration sustains the high energy demands of endurance exercise, yet the extent to which atrial, ventricular, and skeletal muscle mitochondria adapt remains uncertain. At the same time, endurance athletes face an increased risk of atrial fibrillation (AF), but the role of cardiac metabolism in arrhythmia susceptibility is poorly understood. Here, we compared mitochondrial respiration in skeletal muscle and across all four cardiac chambers between trained and untrained racehorses ( = 34) to investigate adaptations associated with long-term endurance exercise. We further examine...
Effect of a Constant Rate Infusion of Ketamine on a Variable Rate Infusion of Xylazine in Standing Horses Undergoing Ventriculocordectomy and Laryngoplasty. Standing sedation in horses provides immobilization and analgesia for surgery while avoiding the high risks of general anesthesia. Ketamine at subanesthetic doses may enhance sedation and reduce xylazine requirements, but evidence in clinical settings is limited. In a randomized blinded trial, we evaluated whether adding a low-dose ketamine infusion could reduce the xylazine dose required for effective sedation during standing ventriculocordectomy and laryngoplasty. Fifty-one horses were randomly assigned to sedation with xylazine alone (SX group) or xylazine plus ketamine (KX group) in a cont...
Mono-dimensional, two-dimensional and Doppler echocardiographic measurements in healthy Standardbred neonatal foals in the first 5 days of life. Bodyweight, age and breed influence the echocardiographic assessment of foals. There are no echocardiographic studies in Standardbred neonatal foals. Objective: To describe echocardiographic values for selected variables, evaluate intra- and inter-observer variability and assess cardiac changes in the first 5 days of life in healthy Standardbred neonatal foals. Methods: Prospective observational study. Methods: Fifty-six healthy Standardbred neonatal foals were examined by transthoracic echocardiography using standard right parasternal and subcostal views at three time points: in the first 4...
Transcriptomic Remodeling of Pulmonary Vein Sleeves Suggests a Role in Atrial Arrhythmogenesis in Thoroughbred Horses. The initiation and maintenance of atrial fibrillation have been associated with physiological alterations in myocardial sleeves of the pulmonary veins (PVs). Gene expression profiles of the myocardial sleeves of the PVs in healthy (n = 3) and paroxysmal atrial fibrillation (PAF) (n = 6) thoroughbred horses (Equus caballus) were studied. Tissue collected from the left superior PV, adjacent to the left atrium, was analyzed by RNA sequencing. Gene Set Enrichment Analysis demonstrated positive enrichment of gene ontology biological processes related to muscle and endothelial cell development, cell...
Metformin Protects Against Persistent Atrial Fibrillation in an Equine Model. Horses are one of the few animals that spontaneously develop atrial fibrillation (AF), making them a powerful model for studying AF mechanisms and treatment effects. Despite the initial effectiveness of treatment in horses and humans, AF-induced atrial remodeling compromises its long-term success. Observational studies have suggested that metformin may reduce the risk of AF, but its effects on progressive AF-induced atrial remodeling have yet to be evaluated in a high-fidelity large animal model. Unassigned: Here, we used a longitudinal horse model of tachypacing-induced self-sustained AF to c...
Equine coronary sinus and great cardiac vein anatomy relevant to cardiac electrophysiology. The coronary sinus (CS) and great cardiac vein (GCV) are crucial in cardiac electrophysiology and can be arrhythmogenic in humans. In horses, CS/GCV catheterisation is increasingly performed for arrhythmia diagnosis and treatment. Improved anatomical understanding of these structures is needed to clarify relationships to surrounding structures. Methods: Postmortem examinations of 64 adult warmblood equine hearts were carried out. Middle cardiac vein and vein of Marshall ostia locations were described. Right atrial myocardial sleeve (MS) length was measured from the CS ostium. In 23 horses, CS/...
Validation of a smart textile device for long-duration heart rate variability and detection of physiological arrhythmias in resting horses. A smart textile device has been developed for the recording of electrocardiograms (ECGs) in horses; however, the utility of this device for long-duration heart rate variability (HRV) monitoring and detection of physiological arrhythmias is unknown. Therefore, the objective of this study was to validate a smart textile device for HRV over long durations (6 h) in resting horses. ECGs were recorded simultaneously via the Myant Skiin Equine textile device and a reference device (Televet 100) in 12 horses. ECGs were evaluated by a blinded observer for arrhythmias, and HRV metrics were calculated. ...
The horse cardiac transcriptome: Moving towards a molecular understanding of atrial fibrillation. High recurrence rates after atrial fibrillation (AF) treatment may be driven by myocardial changes induced by the arrhythmia itself. Understanding the molecular mechanisms behind these changes is crucial for developing targeted therapies and improving outcomes. Objective: To characterise the cardiac transcriptome of healthy horses and explore transcriptional changes associated with persistent AF (naturally occurring and tachypacing-induced). Methods: Case-control study. Methods: RNA-sequencing was performed on atrial and ventricular tissue samples collected from six horses with naturally occur...
Cardiac-Metabolic Coupling Revealed by Lipid and Energy Metabolomics Determines 80 km Endurance Performance in Yili Horses. This study aimed to investigate the regulatory mechanisms underlying the relationship between cardiac structure and function and plasma metabolic characteristics in Yili horses participating in an 80-km endurance, by integrating echocardiography, lipidomics, and energy metabolomics analyses. Twenty four competing Yili horses were selected and divided based on competition outcomes: Pre-Completion Group: PCG ( = 6); Post-Completion Group: PoCG ( = 6); Overtime Completion Group: OCG ( = 6); and Non-Completion Group: NCG ( = 6). Cardiac structural and functional parameters were assessed via echoca...
Multi-Omics Deciphers Divergent Mechanisms in Differentially Cardiac-Remodeled Yili Horses Under Conditions of Equivalent Power Output. Exercise performance is a critical trait for evaluating the economic and breeding value of working and athletic horses, with cardiac structure and function serving as essential physiological determinants of athletic capacity. This study aimed to investigate the multi-omics response mechanisms associated with varying degrees of cardiac remodeling under identical exercise intensity. Twenty 2-year-old Yili horses were selected and categorized based on echocardiographic parameters into a high cardiac remodeling group (BH; EDV > 500 mL, SV > 350 mL, EF > 66%) and a low cardiac remodeling group (BL;...
Seasonal Trends in Cardiac Troponin I Concentration and Creatine Kinase and Aspartate Aminotransferase Enzyme Activity in Relation to Myocardial Velocity Rates in Eventing Horses. This study examines seasonal changes in muscle and heart parameters in eventing horses over the course of a competition season. Blood levels of the enzymes creatine kinase (CK) and aspartate aminotransferase (AST) as well as the heart muscle-specific concentration of cardiac troponin I (cTnI) were measured before (pre), 30 min (p30) and 24 h (p24) after competitions. Creatine kinase (CK: median pre-competition = 175 U/L, 30 min post = 221 U/L, 24 h post = 140 U/L), aspartate aminotransferase (AST: pre = 319 U/L, p30 = 335 U/L, p24 = 333 U/L), and cardiac troponin I concentration (cTnI: pre = 0...
Integrating miRNA, mRNA, and Targeted Metabolomics Analyses to Explore the Regulatory Mechanism of Cardiac Remodeling in Yili Horses. Training not only enhances the athletic performance of horses but also improves cardiac structure and function, strengthens cardiovascular adaptability, and reduces the risk of cardiovascular diseases. However, the consequences of training on equine cardiac structure and function remain unclear. This study investigated the morphological, functional, genetic, and metabolic changes in the hearts of Yili horses divided into three groups: high athletic performance (agility group, AG), low athletic performance (ordinary group, OG), and untrained (untrained group, UN). The results showed remodeling ...
Ventricular arrhythmias induced by snake bite in a horse: A case report. A Mangalarga Marchador mare was referred to treatment with a history of poisoning with evident tachyarrhythmia detected on cardiac auscultation. The electrocardiogram was performed and detected occurrences of paroxysmal monomorphic ventricular bigeminy (pMVB), pMVB with pairs of premature ventricular contractions (PVC) (pMVBPC), and paroxysmal monomorphic ventricular tachycardia (pMVT). In all cases, incomplete atrioventricular dissociation and coupling variation are observed. These characteristics, associated with non-reduction of successive subsequent coupling intervals and the absence of ty...
Effect of N-Butylscopolammonium Bromide and Metamizol Sodium on Heart Rate, Blood Pressure, and Echocardiographic Measurements in Warmblood Horses With Aortic and Mitral Valve Regurgitation. Administration of N-butylscopolammonium bromide (NBB) with metamizol sodium (NBBM) causes tachycardia and hypertension, and has been associated with accentuated cardiac murmurs. Objective: To evaluate the effect of a pharmacological challenge using NBBM on valvular regurgitation and cardiac murmurs in horses with aortic (AR) and mitral valve regurgitation (MR). Methods: Twenty Warmblood horses with AR and 20 with MR. Methods: Cardiac auscultation and two-dimensional (2D), M-mode, color flow, pulsed wave Doppler flow, and tissue Doppler echocardiography were performed with simultaneous ECG reco...
Use of Artificial Intelligence to Detect Cardiac Rhythm Disturbances in Athletes: A Scoping Review. Artificial intelligence (AI) is increasingly used to enhance electrocardiogram (ECG) interpretation in human medicine. In equine athletes, exercise-associated arrhythmias are common and linked to sudden cardiac death at rates higher than in humans. However, ECG interpretation in horses remains time-consuming and subjective, with the clinical relevance of mild rhythm disturbances often unclear. Objective: Evaluate the application of AI to ECG interpretation for arrhythmia detection, with emphasis on current and potential use in athletic species, particularly horses. Methods: About 17 studies we...
Multiple Catheter Recording in Horses to Investigate Atrial Depolarization Pattern During Sinus Rhythm and Induced Premature Atrial Complexes. Detailed characterization of arrhythmias can be performed by multiple catheter mapping; but this has not yet been explored in horses. Objective: Perform ultrasound-guided multiple catheter mapping of the right heart during sinus rhythm and right and left atrial pacing to identify activation patterns characteristic of the origin of ectopy. Obtain His signals and effective refractory periods (ERP). Methods: Eight healthy adult horses. Methods: Experimental study. Recording catheters were placed at the terminal crest, intervenous tubercle, caudal vena cava, and coronary sinus. Right atrial pacing...
QT Interval and Cardiac Restitution Ratio Complexity in Standardbred Racehorses From Rest to Maximal Effort: Insights Into Arrhythmia Risk. Sudden cardiac death is common in racehorses. Factors associated with the QT interval that could predispose to fatal cardiac arrhythmias are unknown. Cardiac restitution, expressed as a ratio of QT/TQ, has been used in humans to assess arrhythmia risk but has not been described in horses during maximal intensity exercise. Objective: Describe factors associated with the QT interval and cardiac restitution ratio (CRR) in clinically normal Standardbred racehorses under race-day conditions. Methods: Archival electrocardiograms from 42 Standardbred horses during live racing in Ontario. Methods: Obs...
Three-dimensional electro-anatomical mapping of premature atrial complexes originating from the right atrial free wall and treatment by radiofrequency ablation in three horses. Frequent premature atrial complexes (PACs) can increase the risk of atrial fibrillation or atrial tachycardia, and pharmacological therapy can be challenging. Objective: To report the use of three-dimensional electro-anatomical mapping of PAC originating from the right atrial free wall and treatment by radiofrequency ablation in three horses. Methods: Retrospective case report. Methods: Frequent premature atrial complexes (PACs) were diagnosed in three horses. Twelve-lead ECG and vectorcardiography suggested an origin in the right lateral free wall in two horses and the caudal right atrium in ...
Horse model of spontaneous atrial fibrillation share proteomic changes with humans. Horses and humans are among the few mammals susceptible to spontaneous atrial fibrillation (AF), both suffering from high recurrence rates after treatment. Treatment resistance is often attributed to progressive atrial remodeling, but current treatment options fail to effectively address this aspect. Here, we introduce a novel horse model of spontaneous AF to investigate the biological pathway changes in early stages of the disease. Through data-independent acquisition mass spectrometry on biopsies from the right and left atrium and left ventricular chamber of horses with early-stage persisten...
Differential Metabolomics and Cardiac Function in Trained vs. Untrained Yili Performance Horses. This study aimed to investigate the effects of training on cardiac structure and function, as well as plasma metabolite profiles in horses, in order to uncover the molecular regulatory mechanisms and cardiac remodeling under long-term exercise. We hypothesize that long-term standardized training induces physiological cardiac remodeling and differential metabolomic changes in Yili horses, which correlate with improved athletic performance. The study focuses on physiological exercise-induced cardiac remodeling, characterized by increased left ventricular wall thickness and chamber size. A total ...
Traumatic Ventricular Septal Defect Caused by a Horse Kick Injury: 2 Rare Pediatric Cases. We present 2 cases of traumatic ventricular septal defects (VSDs), both caused by horse kick injuries. Given this rare but critical condition, we decided to share our experiences and the lessons learned managing these cases. Methods: The first patient, a 12-year-old girl, was trampled by a horse, sustained a traumatic apical ventricular septal defect with pseudoaneurysm, was stabilized first, and underwent surgical closure 19 days after the injury. The second patient, a 9-year-old girl, was kicked by a horse in the chest; developed profound cardiogenic shock; and was found to have multiple lar...
Cardiac arrhythmia prevalence and risk factors in 24-h electrocardiograms of sedentary horses. Cardiac arrhythmias are common in horses, but their clinical relevance remains controversial. Objective: To describe prevalence and identify risk factors for arrhythmias that may warrant additional screening in a sedentary mixed-breed population of horses. Methods: Prospective cross-sectional. Methods: Ninety-four clinically healthy, university-owned, sedentary horses underwent 24-h ambulatory electrocardiograms and echocardiograms. Potential risk factors were recorded for all horses. Affected individuals were defined as those with >1 supraventricular premature complex/h or with any ventric...
Orthodromic Atrioventricular Reentry Bradycardia and Tachycardia Caused by an Accessory Pathway in Horses. Accessory pathways (APs) are muscular bundles directly connecting the atria and ventricles, bypassing the atrioventricular (AV) node-His-Purkinje system. Anterograde conduction along the AP results in ventricular preexcitation. A retrograde conducting AP allows ventriculo-atrial (VA) conduction, creating a reentry circuit that mediates orthodromic atrioventricular reentry tachycardia (OAVRT). This condition is well described in humans and small animals, but has not been reported previously in horses. Objective: Describe clinical and electrocardiographic findings of horses with retrograde AP co...