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Influence of electrode position on cardioversion energy requirements during transvenous electrical cardioversion in
Erin E Preiss1, Daniel G Kenney, M Kimberly J McGurrin
1BSC (Hons) Program, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada.
Insights
Optimizing electrode placement during transvenous electrical cardioversion (TVEC) in horses with atrial fibrillation significantly reduces the required cardioversion energy (CE). Proper positioning is key for effective treatment.
Area of Science:
- Veterinary cardiology
- Equine electrophysiology
Background:
- Atrial fibrillation is a common arrhythmia in horses.
- Transvenous electrical cardioversion (TVEC) is a treatment option.
Purpose of the Study:
- To determine how electrode position affects the energy needed for cardioversion in horses with atrial fibrillation.
Main Methods:
- Reviewed records of 37 horses undergoing TVEC for atrial fibrillation.
- Analyzed electrode positions using radiographs and trigonometric modeling.
- Assessed relationships between signalment, electrode position, and cardioversion energy (CE).
Main Results:
- Electrode position, specifically y-axis differences and ventral positioning relative to the right atrium, significantly predicted CE.
- Decreased distance between electrodes and pulmonary artery electrode positions correlated with increased CE.
- Model accuracy for x-axis position estimation was limited.
Conclusions:
- Optimal electrode placement can lower energy requirements for successful TVEC in horses.
- Improved positioning may enable TVEC under shorter anesthesia durations and enhance treatment success.
- Further research into electrode-catheter relationships is recommended.
Objective:
To evaluate influence of electrode position on cardioversion energy (CE; energy delivered in the shock at which cardioversion was achieved) during transvenous electrical cardioversion (TVEC) in horses with atrial fibrillation.
Animals:
37 horses with atrial fibrillation (41 cardioversion events).
Procedures:
Records were reviewed to identify horses that underwent TVEC for treatment of atrial fibrillation. Signalment and CE were recorded. Electrode positions in the right atrium and pulmonary artery were identified on intraoperative radiographs. An orthogonal coordinate space was created, and electrode y- and z-axis coordinates and shadow lengths were determined. Trigonometric modeling was used to estimate x-axis electrode positions that resulted in observed shadows. Postmortem casts of catheterized horses were used to assess electrode paths and anatomic relationships. Model assumptions were tested by use of these and a theoretical data set. Relationships between signalment, electrode position, and CE were assessed via multivariate analysis.
Results:
Sex and y-axis differences between electrode positions were significant predictors of CE. Population stratification based on examination of residuals improved model strength; populations differed in z-axis variables and in CE. Decreasing distance between electrodes and pulmonary artery electrode positions ventral to the right atrium were associated with increased CE. Agreement between estimated and actual x-axis coordinates was poor.
Conclusions And Clinical Relevance:
Optimal electrode positioning can reduce the energy requirement for successful TVEC and may eventually support application of TVEC under short-term IV anesthesia and potentially increase chances of treatment response. Further investigation into these relationships is warranted.
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