Measurement variability of right atrial and ventricular monophasic action potential and refractory period measurements in the standing non-sedated horse.
Authors: De Clercq Dominique, Broux Barbara, Vera Lisse, Decloedt Annelies, van Loon Gunther
Journal: BMC veterinary research
Summary
# Editorial Summary Monophasic action potential (MAP) analysis offers valuable insight into local cardiac electrophysiological properties and can help identify dysrhythmias and drug effects on the myocardium, yet its applicability in standing non-sedated horses remained unexplored. De Clercq and colleagues developed and tested a protocol using an 8F quadripolar contact catheter placed via jugular access under ultrasound guidance to record MAP from the right atrium and right ventricular apex in six healthy Warmbloods, measuring action potential duration at 90% repolarization (APD90) and effective refractory periods (ERP) across multiple conditions on two separate days. The team evaluated measurements at resting sinus rhythm (30–42 bpm) and at two pacing cycle lengths (1000 and 600 ms) to assess reproducibility and feasibility in conscious horses. This represents the first systematic evaluation of measurement variability for this electrophysiological technique in standing equine patients, establishing whether the methodology is sufficiently reliable for clinical investigation of arrhythmias and pharmacological interventions. The findings provide practitioners and researchers with evidence regarding the feasibility and reproducibility of MAP recording in awake horses, potentially opening new avenues for investigating cardiac conduction abnormalities and therapeutic responses without sedation-related confounds.
Read the full abstract on PubMed
Practical Takeaways
- •This technique enables detailed cardiac electrophysiological assessment in standing horses without sedation, potentially improving safety and reducing stress during diagnostic procedures
- •The method can assess how the heart's electrical properties change with heart rate, providing valuable diagnostic information for dysrhythmia evaluation and drug effects on myocardium
- •Ultrasound-guided catheter placement allows precise positioning at critical cardiac sites (RA free wall, RV apex) for accurate electrophysiological measurements
Key Findings
- •Monophasic action potential (MAP) analysis is feasible in standing non-sedated horses using contact electrode catheter technique
- •MAP duration (APD90) was successfully measured at right atrial and right ventricular sites at resting heart rates of 30-42 bpm and pacing cycle lengths of 1000 and 600 ms
- •Effective refractory period (ERP) determination was performed at multiple pacing cycle lengths in healthy Warmblood horses