[Investigation of impedance drop during lesions created by robot-assisted radiofrequency ablation]

Introduction: The efficiency and safety of radiofrequency catheter ablation can be further improved using robotics. We can employ the objective data provided by the related sensors during the intervention. Objective: The aim of our research was to develop and implement a custom robotic measurement platform to investigate sensor-controlled ablation processes during in vitro experiments, ensuring stable catheter positioning. We then observed the impedance drop during lesion formation under varying temperature settings and ablation durations while maintaining a constant contact force. Method: Our experiments were carried out with a custom-developed equipment. The sizes of the lesions formed under different temperatures (60, 65, 70 °C) and ablation times (10, 20, 30 seconds) were investigated. Porcine heart tissue samples were ablated, creating a total of 186 lesions. After treatment, impedance drop were measured. A multivariate linear regression model was used to examine the effect of temperature and ablation duration on lesion impedance drop. Results: A robot-assisted radiofrequency ablation assisting in vitro device was set up using a proprietary designed and manufactured contact force measurement device. Our experiments have successfully generated accurate and repeatable ablation patterns, producing consistent and reliable results. The results of the multivariable regression analysis demonstrated that a temperature of 65 °C, compared to 60 °C, independently resulted in a 3.6 Ω reduction in impedance (95% confidence interval: –5.9 to –1.3; p = 0.026). Additionally, prolongation of the ablation duration had a significant impact on the decrease in impedance; for instance, at 20 seconds, the impedance value decreased by 4.1 Ω (95% confidence interval: –6.5 to –1.8; p = 0.0006). Conclusion: Robot-assisted ablation can significantly improve the precision and reproducibility of procedures, especially in in vitro experiments on porcine tissues. By setting optimal temperature and duration parameters, unwanted tissue damage can be minimised. Our observations indicate that higher temperatures result in a significantly greater reduction in impedance, and increasing the duration of ablation also significantly enhances the extent of impedance decrease. Orv Hetil. 2025; 166(6): 219–227.