Radiofrequency catheter ablation (RFCA) is an effective treatment for different types of cardiac arrhythmias. Typically, for endocardial RFCA, a catheter is inserted in the cardiac chamber and placed at the arrhythmogenic tissue. The tissue is irreversibly damaged via electrocautery and a lesion is formed at a temperature of 50°C. Radiofrequency ablation is an efficient and safe treatment for cardiac arrhythmias; however, major complications can occur, including the possibility of thrombus formation in case the blood temperature rises above 80°C, and steam pops in the occurrence of tissue overheating (at around 100°C).
We present a full 3D mathematical model for the radiofrequency ablation process that uses an open-irrigated catheter. Our model includes the blood-saline interaction through the incompressible Navier-Stokes equation. The temperature change is modeled by Penne's bioheat equation, using an electrical source term to model resistive heating. The electrical potential generated by the electrode at the tip of the catheter is considered space and temperature dependent. The Hertzian theory in contact mechanics is used to model the deformation of the tissue due to the pressure of the catheter tip at the tissue-catheter contact point.
The system is solved numerically using the finite element method with FEniCS-HPC. A post-processing step, implemented in Paraview, calculates the computational lesion dimensions by tracking the 50°C isotherm contour. We compare the lesion dimensions using an elastic tissue against a standard sharp insertion of the catheter in the tissue that other state-of-the-art RFCA computational models use.