Computer modeling of radiofrequency cardiac ablation including heartbeat-induced electrode displacement

Abstract

Background: The state of the art in computer modeling of radiofrequency catheter ablation (RFCA) only considers a static situation, i.e. it ignores ablation electrode displacements induced by tissue movement due to heartbeats. This feature is theoretically required, since heartbeat-induced changes in contact force can be detected during this clinical procedure.

Methods: We built a 2D RFCA model coupling electrical, thermal and mechanical problems and simulated a standard energy setting (25 W-30 s). The mechanical interaction between the ablation electrode and tissue was dynamically modeled to reproduce heartbeat-induced changes in the electrode insertion depth from 0.86 to 2.05 mm, which corresponded with contact forces between 10 and 30 g when cardiac tissue was modeled by a hyperelastic Neo-Hookean model with a Young's modulus of 75 kPa and Poisson's ratio of 0.49.

Results: The lesion size computed in the dynamic case was 6.04 mm deep, 9.48 mm maximum width and 6.98 mm surface width, which is within the range of previous experimental results based on a beating heart for a similar energy setting and contact force. The lesion size was practically identical (less than 0.04 mm difference) in the static case with the electrode inserted to an average depth of 1.46 mm (equivalent to 20 g contact force).

Conclusions: The RFCA model including heartbeat-induced electrode displacement predicts lesion depth reasonably well compared to previous experimental results based on a beating heart model.

Keywords: Computer model; Contact force; Mechanical deformation; Radiofrequency ablation.