Date of Award

6-2019

Degree Name

MS in Biomedical Engineering

Department

Biomedical and General Engineering

Advisor

David Clague

Abstract

Atrial fibrillation (AF) is the disordered activation of the atrial myocardium, which is a major cause of stroke. Currently, the most effective, minimally traumatic treatment for AF is percutaneous catheter ablation to isolate arrhythmogenic areas from the rest of the atrium. The standard in vitro evaluation of ablation catheters through lesion studies is a resource intensive effort due to tissue variability and visual measurement methods, necessitating large sample sizes and multiple prototype builds. A computational test bed for ablation catheter evaluation was built in SolidWorks® using the morphology and dimensions of the left atrium adjacent structures. From this geometry, the physical model was built in COMSOL Multiphysics®, where a combination of the laminar fluid flow, electrical currents, and bioheat transfer was used to simulate radiofrequency (RF) tissue ablation. Simulations in simplified 3D geometries led to lesions sizes within the reported ranges from an in-vivo ablation study. However, though the ellipsoid lesion morphologies in the full atrial model were consistent with past lesion studies, perpendicularly oriented catheter tips were associated with decreases of -91.3% and -70.0% in lesion depth and maximum diameter. On the other hand, tangentially oriented catheter tips produced lesions that were only off by -28.4% and +7.9% for max depth and max diameter. Preliminary investigation into the causes of the discrepancy were performed for fluid velocities, contact area, and other factors. Finally, suggestions for further investigation are provided to aid in determining the root cause of the discrepancy, such that the test bed may be used for other ablation catheter evaluations.

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