Oesophageal electrocardiography in healthy horses.
Authors: Verheyen T, Decloedt A, De Clercq D, Sys S, Van Loon G
Journal: Equine veterinary journal
Summary
# Oesophageal Electrocardiography in Healthy Horses Oesophageal ECG, a diagnostic technique already established in human cardiology for enhancing P wave visibility, has been adapted and validated for equine use by Verheyen and colleagues. The team assessed the feasibility of recording oesophageal ECG from six different electrode configurations at varying depths in the oesophagus and compared P wave amplification relative to conventional base-apex and unipolar surface recordings. Recording at a depth equal to withers height plus 10 cm using bipolar oesophageal electrodes spaced 10 cm apart consistently produced the largest P waves and the most favourable P/QRS magnitude ratios—significantly outperforming standard base-apex recordings, which showed the poorest P wave detection of all methods tested. This improved P wave visualisation has substantial clinical relevance for diagnosing supraventricular dysrhythmias, which can be notoriously difficult to characterise on surface ECG alone, and opens potential applications in equine electrophysiological research and cardiac pacing procedures. For practitioners encountering suspected atrial arrhythmias where surface tracings prove inconclusive, oesophageal ECG represents a minimally invasive technique worthy of consideration in referral settings.
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Practical Takeaways
- •Oesophageal ECG is a practical, feasible technique for equine practitioners to better visualize P waves and diagnose supraventricular arrhythmias that may be missed on standard surface ECG
- •When performing oesophageal ECG, position the electrode at withers height plus 10 cm with 10 cm spacing between electrodes for optimal P wave visualization
- •Consider this technique for horses with suspected arrhythmias where surface ECG recordings show unclear or small P waves, and for potential future cardiac pacing or electrophysiological interventions
Key Findings
- •Oesophageal ECG recording is feasible in all horses tested and produces significantly larger P waves compared to surface recordings
- •Optimal P wave amplification occurred at oesophageal depth equal to height of withers plus 10 cm (HW+10) with 10 cm interelectrode spacing
- •P/QRS magnitude ratio was significantly larger for oesophageal recordings than base-apex surface recordings
- •Oesophageal ECG is promising for diagnosis of supraventricular tachydysrhythmias and electrophysiological studies