Computer simulation of low-power and long-duration bipolar radiofrequency ablation under various baseline impedances

Compared to traditional unipolar radiofrequency ablation (RFA), bipolar RFA offers advantages such as more precise heat transfer and higher ablation efficiency. Clinically, myocardial baseline impedance (BI) is one of the important factors affecting the effectiveness of ablation. We aim at finding suitable ablation protocols and coping strategies by analyzing the ablation effects and myocardial impedance changes of bipolar RFA under different BIs. In this research, a three-dimensional local myocardial computer model was constructed for bipolar RFA simulation, and in vitro experimental data were used to validate accuracy. Four fixed low-power levels (20 W, 25 W, 30 W, and 35 W) and six myocardial BIs (91.02 Ω, 99.83 Ω, 111.03 Ω, 119.77 Ω, 130.03 Ω, and 135.45 Ω) were set as initial conditions, with an ablation duration of 120-s. In the context of low-power and long-duration (LPLD) ablation, the maximum TID (TID_M) decreased by 21-32 Ω, depending on the BI. In cases where steam pop did not occur, TID_M increased with the increase in power. For the same power, there was no significant difference in TID_M for the range of BIs. In cases where steam pop occurred, for every 1 Ω increase in BI, TID_M increased by 0.34-0.41 Ω. The simulation results also showed that using a higher power resulted in a smaller decrease in TID_M. This study provided appropriate ablation times and impedance decrease ranges for bipolar LPLD RFA. The combination of 25 W for 120-s offered optimal performance when considering effectiveness and safety simultaneously.