Multiple Catheter Recording in Horses to Investigate Atrial Depolarization Pattern During Sinus Rhythm and Induced Premature Atrial Complexes.
Authors: Buschmann Eva, Van Steenkiste Glenn, Vernemmen Ingrid, Demeyere Marie, Schauvliege Stijn, Decloedt Annelies, van Loon Gunther
Journal: Journal of veterinary internal medicine
Summary
# Editorial Summary Atrial arrhythmias in horses remain diagnostically challenging, and until now, electrophysiological mapping techniques routinely used in human and small animal cardiology have not been systematically evaluated in equine patients. Belgian researchers performed intracardiac catheter mapping in eight healthy horses, positioning recording electrodes at multiple right atrial sites and the coronary sinus whilst pacing from various atrial locations—both right atrial sites in standing, sedated animals and left atrial sites during general anaesthesia—to establish characteristic activation patterns and determine refractory periods. The group successfully identified distinctive electrical signatures: late activation in the coronary sinus strongly suggested ectopy originating from the right atrium or the right pulmonary vein ostium, whilst the direction of coronary sinus activation helped differentiate left atrial ectopic foci, and atrial refractory periods ranged considerably (170–420 ms) with substantial variation both between and within individual horses. This proof-of-concept work demonstrates that detailed electrophysiological mapping is technically feasible in equine patients and provides a foundation for future investigation of naturally occurring atrial arrhythmias—potentially enabling clinicians to localise ectopic sites with greater precision, inform targeted ablation strategies, or better understand the mechanisms underlying conditions like atrial fibrillation in performance horses.
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Practical Takeaways
- •Electrophysiological mapping can now be used in horses to precisely locate the origin of atrial ectopy, improving diagnostic accuracy for recurrent arrhythmias
- •Characteristic activation patterns during pacing may help clinicians differentiate between right and left atrial ectopy sources before considering interventional treatment
- •His bundle recordings and refractory period measurements establish baseline reference values for equine cardiac electrophysiology, enabling better interpretation of abnormal conduction
Key Findings
- •Multiple catheter mapping of the right heart is feasible in horses under standing sedation and general anesthesia
- •Late coronary sinus activation indicates ectopy originating from the right atrium or ostium III
- •His bundle signals were successfully recorded in 5 of 8 horses
- •Atrial effective refractory periods varied between 170-420 ms with significant inter-horse and intra-horse variation