Doctor-Assistant Ghent University Merelbeke, Oost-Vlaanderen, Belgium
Abstract:
Background: The most efficient treatment option for atrial fibrillation (AF) in horses is transvenous electrical cardioversion (TVEC) but the position of the electrodes during TVEC has been empirically determined.
Objective: To rationalize electrode positioning in horses during TVEC procedures by using finite element models (FEMs) to compare electric fields using different electrode configurations. Animals: Scaled 3D heart model based on a CT scan of a healthy pony
Methods: The FEMs were created by segmenting a CT scan into tissue compartments, followed by meshing and assigning tissue conductivities. The FEMs were modified during segmentation by adding 9Fr 10cm long TVEC catheter electrodes in different configurations during the segmentation stage. The electrical fields of different configurations with the positive and negative electrodes were calculated at different energy levels typically used by truncated biphasic exponential waveform defibrillators, as described in table 1. The relative efficacy and safety were calculated by determining the amount of atrial myocardium above the defibrillation threshold (5V/cm) and at risk for potential tissue damage (>30V/cm).
Results: Increasing the energy above 200J only yields marginal improvements in defibrillation efficacy. Defibrillation between the middle of the right atrium and the coronary sinus resulted in the highest efficacy. Detailed results are given in table 1. Conclusions and clinical importance: Using an in-silico model improves our understanding of atrial fibrillation cardioversion in horses and may contribute to the development of alternative cardioversion techniques. It may be more beneficial to change the position of the catheters rather than increase the energy.
