Impact of electrode–tissue proximity on formation of pulsed field ablation lesions: Using multi-electrode impedance measurements

Background: For pulsed field ablation (PFA), the effect of electrode-tissue contact or proximity remains unclear. Objective: In this porcine study, the effect of electrode-tissue proximity was studied after 3 weeks of follow-up, using a custom device in which the electrode-tissue distance could be varied for every electrode. Methods: An impedance-based method was used to determine electrode-tissue proximity or contact. During a bench experiment, the relation between contact value per electrode and electrode-tissue distance was studied. In addition, in 10 pigs epicardial ablation using a custom 6-polar linear ablation device was performed using bipolar, biphasic deliveries on randomized locations on the heart. After 3 weeks, macroscopic analysis was used to compare lesion width for left vs right ventricle. Based on histology, the lesion area and depth were related to electrode-tissue contact. Results: < .001) for low vs high indices respectively. Conclusion: This study shows that higher electrode-tissue proximity may result in deeper PFA lesions, and is, therefore, an important parameter in improving PFA lesions. Therefore, confirmation of tissue contact using impedance-based measurements may improve PFA ablation efficacy in a clinical setting.