Local impedance for the optimization of radiofrequency lesion delivery: A review of bench and clinical data

Abstract

Introduction Radiofrequency catheter ablation is a cornerstone of treatment for many cardiac arrhythmias. Progression in three‐dimensional mapping and contact‐force sensing technologies have improved our capability to achieve success, but challenges still remain. Methods In this article, we discuss the importance of overall circuit impedance in radiofrequency lesion formation. This is followed by a review of the literature regarding recently developed “local impedance” technology and its current and future potential applications and limitations, in the context of established surrogate markers currently used to infer effective ablation. Results We discuss the role of local impedance in assessing myocardial substrate, as well as its role in clinical studies of ablation. We also discuss safety considerations, limitations and ongoing research. Conclusion Local impedance is a novel tool which has the potential to tailor ablation in a manner distinct from other established metrics.

In Silico Study of Local Electrical Impedance Measurements in the Atria - Towards Understanding and Quantifying Dependencies in Human

“…During invasive cardiac electrophysiological studies, generator impedance measurements have been an established method to monitor the delivery of radio frequency energy during ablation since decades [3] [4]. The transthoracic impedance of the radio frequency energy delivery pathway between an intracardiac and a cutaneous dispersive electrode assists differentiation of tissue contact during ablation.…”

“…However, the bulk impedance of the torso blurs measurements [5] [6] and impedes detailed assessment of tissue characteristics in the region of interest next to the catheter. Recently, two novel catheters have been introduced to the market that aim at a more locally focused impedance assessment in the vicinity of the catheter with all injecting and measuring electrodes being built into the intracardiac catheter itself [4]. The radio frequency ablation catheters Intel-laNav MiFi™ OI [7] and IntellaNav Stablepoint™ [8] (Boston Scientific, Malborough, MA, USA) come with a four-electrode and a threeelectrode impedance measurement circuit implemented within the catheter, respectively.…”

Tissue-Welding Device: Considerable Advantages for Spleen Surgery Based on Histological and Cardiorespiratory Investigation

“…Chu et al [ 35 ] described the importance of the absence of contact force and carbonization during cardiac surgery with radiofrequency catheters. Rebling et al [ 21 ] also asserted that radiofrequency devices did not cause carbonization during cardiac surgery.…”

Combined contact force and local impedance dynamics during repeat atrial fibrillation catheter ablation

“…Multidimensional indices incorporating parameters additional to CF were introduced aiming for real-time lesion formation estimation during ablation, while lacking information on tissue response (Hussein et al, 2018;Taghji et al, 2018). Here, LI Frontiers in Physiology frontiersin.org measurement can complement CF: According to Ohm's law, transmitted current density relies on the electrical field and local tissue resistivity (Garrott et al, 2020;Chu et al, 2022). As power output is fixed by many ablation generators, baseline LI reflects resistive heating potential (Shapira-Daniels et al, 2019) and the degree of ΔLI mirrors volumetric tissue heating during ablation (Barkagan et al, 2018;Sulkin et al, 2018;Garrott et al, 2020).…”

“…The applied electrical current inducing tissue heating is dependent on the resistive load during catheter tip-tissue contact, with measurement attempted via impedance by different technologies: classical transthoracic impedance measurement by RFC generators (between catheter tip and indifferent surface electrodes) is limited by significant inter-patient variability regarding torso impedance as well as intra-patient variability subject to the respiratory phase ( Borganelli et al, 1992 ; Barkagan et al, 2018 ; Chu et al, 2022 ). Measurement of local impedance (LI) is conducted by driving a non-stimulatory current between a distal and proximal electrode.…”