A theoretical study of radio frequency ablation of the myocardium.

Theoretical modeling of the lesion formation process during radio-frequency ablation of the myocardium is presented. The model is axisymmetric and consists of a catheter electrode coming in contact at right angle with the heart tissue. The electric power dissipated in the tissue is calculated and from it the temperature distribution and the resulting lesion are evaluated as a function of time. The cooling effect of the blood flow and the temperature dependence of the electrical conductivity are included in the model, making it non-linear. The finite-element method is used to discretize the spatial domain and a finite-difference algorithm resolves the time dependence. The numerical simulator is validated with a series of experiments performed on a tissue-equivalent material. Both the measured temperature distribution in the tissue sample and the electrode resistance as a function of time agree well with the theoretical predictions. The model is used to study the effect of the electrode geometry and the electrical excitation on the resulting lesion. Theoretical predictions for the time evolution of the lesion size and the electrode resistance are presented for the first time. Recommendations for the improvement of the RF ablation procedure are formulated