Electrical Impedance Spectroscopy Facilitates Quantitative Depth Monitoring of Pulsed Field Ablation: An Impedimetric Approach with Preclinical Validation.

Background: Pulsed field ablation (PFA) is an emerging therapy for cardiac ablation, where ablation depth (D) is critical to procedural success. However, real-time intraprocedural assessment of D remains a challenging task.

Objective: Electrical impedance spectroscopy (EIS) has been proposed to predict ablation zone, but its applicability and mechanism for quantifying D is still unclear.

Methods: Monopolar and bipolar PFA were conducted via two catheter types, along with in-situ EIS measurements. The change rate of low-frequency resistance (LFR), derived from Cole-Cole modeling of EIS data, was used to evaluate D in both in vitro (205 potato samples) and in vivo canine models (n=5).

Results: LFR versus ablation depths followed a classical Gompertz growth model within 0∼15 mm (R²=0.8789). A quadratic function provided a good fit for evaluating ablation depths within 1∼9 mm (R²=0.7561). Furthermore, LFR_5min could detect a depth difference of approximately 0.8 mm in canine cardiac ablation (P=0.0003).

Conclusions: LFR_5min robustly correlated with PFA lesion depth, fitting quantitative quadratic and Gompertz models. Validated in vivo in a clinically relevant canine cardiac model, LFR_5min resolved sub-millimeter depth differences, positioning it as a promising intraoperative metric for real-time PFA guidance.