Influence of electrode position on cardioversion energy requirements during transvenous electrical cardioversion in horses.

This research explores how the position of electrodes impacts the energy required for successful cardioversion during trans-venous electrical cardioversion (TVEC) in horses suffering from atrial fibrillation. The study found that optimal electrode positioning could potentially reduce the energy needed for successful treatment, thereby supporting the possibility of applying TVEC under shorter intravenous anesthesia and increasing the probability of successful treatment.

Methodology

• The study involved reviewing records of 37 horses (totalling 41 cardioversion events) who underwent TVEC for treating atrial fibrillation.
• Data on each horse’s health profile and the cardioversion energy (CE; the energy used in the shock which achieves cardioversion) were recorded.
• The positions of electrodes in the right atrium and pulmonary artery were identified from intraoperative radiographs.
• A model, using orthogonal coordinate space, was created to determine electrode y- and z-axis coordinates and shadow lengths.
• X-axis electrode positions, generating the observed shadows, were estimated using trigonometric modeling.
• Postmortem casts of catheterized horses were used to assess electrode paths and anatomical relationships.
• The assumptions of the model were tested against these actual and a theoretical dataset.
• Finally, multivariate analysis was conducted to ascertain relationships between the horse’s health profile, electrode position, and CE.

Results

• Sex and y-axis differences between electrode positions were found to be significant predictors of cardioversion energy.
• Population stratification based on the examination of residuals improved the model’s strength; populations exhibited differences in z-axis variables and in CE.
• Shorter distances between electrodes and pulmonary artery electrode positions ventral to the right atrium were linked with increased cardioversion energy.
• A lack of agreement was observed between the estimated and actual coordinates on the x-axis.

Conclusion

• The findings suggest that optimal electrode positioning can help reduce the energy required for successful TVEC.
• This in turn could facilitate the use of TVEC under short-term intravenous anesthesia and may enhance chances of a positive response to the treatment.
• However, more research into these relationships is required to substantiate these conclusions.