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Endocardial electro-anatomic mapping in healthy horses: Normal sinus impulse propagation in the left and right atrium
G Van Steenkiste1, Vera L1, A Decloedt1
1Equine Cardioteam, Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium.
Insights
This study maps equine heart electrical activity using 3D electro-anatomical mapping, revealing normal sinus rhythm patterns. Findings correlate endocardial depolarization with the surface electrocardiogram (ECG) for horses.
Area of Science:
- Veterinary Cardiology
- Cardiac Electrophysiology
Background:
- Understanding equine heart electrical activity is crucial for diagnosing arrhythmias.
- Previous studies lacked detailed mapping of normal depolarization patterns.
Purpose of the Study:
- To map normal atrial and ventricular endocardial depolarization in horses.
- To correlate these patterns with the surface electrocardiogram (ECG).
Main Methods:
- Used a 3D electro-anatomical mapping system in seven healthy horses under general anesthesia.
- Analyzed bipolar activation maps of the endocardium during sinus rhythm.
Main Results:
- Identified the origin of atrial activation at the terminal crest with one interatrial pathway.
- Described ventricular activation initiating from the septum and apex, progressing in an explosive pattern.
- Confirmed all ventricular depolarization contributes to the surface ECG QRS complex.
Conclusions:
- Established a reference for normal equine endocardial impulse propagation and conduction velocities.
- Provided insights into the relationship between endocardial activation and surface ECG.
- A foundation for future research into equine cardiac arrhythmias.
Abstract:
Understanding the depolarisation pattern of the equine heart under normal physiologic conditions, and its relationship to the surface electrocardiogram (ECG), is of uppermost importance before any further research can be done about the pathophysiology of complex arrhythmias. In the present study, a 3D electro-anatomical mapping system was used to evaluate the qualitative and quantitative depolarisation patterns and correlation to the surface ECG of both the atrial and ventricular endocardium in seven healthy horses in sinus rhythm under general anaesthesia. Bipolar activation maps of the endocardium were analysed. The first atrial activation was located at the height of the terminal crest. Only one interatrial conduction pathway was recognised. The first and second P wave deflections represent the right and left atrial depolarisation, respectively. Bundle of His electrograms could be recorded in 5/7 horses. Left ventricular activation started at the mid septum and right ventricular activation started apically from the supraventricular crest. This was followed by separate depolarisations at the height of the mid free wall. Further ventricular depolarisation occurred in an explosive pattern. Electrically active tissue could be found in all pulmonary veins. In contrast to findings of previous studies, all parts of the ventricular depolarisation contributed to the surface ECG QRS complex. This study provides a reference for the normal sinus impulse endocardial propagation pattern and for conduction velocities in equine atria and ventricles.
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