How to leverage local impedance to guide effective ablation strategy: A case series

Abstract

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Optimized radiofrequency lesions through local impedance guidance for effective CTI ablation in right atrial flutter

“…In addition, ECI does not provide direct tissue feedback or real‐time localized tissue characteristics. Recently, a novel ablation catheter has been introduced into clinical use; this incorporates three equally spaced mini‐electrodes in the catheter tip and measures LI at the distal electrode of the catheter, without a reference skin electrode 9–13 . LI measurements taken with this catheter were found to well distinguish contact with healthy myocardium from contact with blood, and high‐voltage areas from low‐voltage areas; they were also able to detect significant differences in LI drop according to voltage level during ablation 9–13 .…”

“…Recently, a novel ablation catheter has been introduced into clinical use; this incorporates three equally spaced mini‐electrodes in the catheter tip and measures LI at the distal electrode of the catheter, without a reference skin electrode 9–13 . LI measurements taken with this catheter were found to well distinguish contact with healthy myocardium from contact with blood, and high‐voltage areas from low‐voltage areas; they were also able to detect significant differences in LI drop according to voltage level during ablation 9–13 . Most importantly, several studies showed that, in various types of arrhythmia, the absolute LI drops were significantly greater at effective ablation sites than ineffective sites 9,23 and the magnitude and time course of the LI drop during RF delivery was associated with effective lesion formation 10–12 …”

“…The maximal interlesion distance (ILD) between two neighboring lesions was set at ≤6 mm. Ablation was guided by the magnitude and time course of the LI drop during RF delivery 10–13 . RF applications were targeted to a minimum LI drop of 10 Ω within 30 s and were stopped when a maximum cutoff LI drop of <40 Ω was observed.…”

“…Lesion diameter and depth have been shown to correlate well with impedance decrease, displaying an even more direct relationship than with measured temperature 7,8 . The advent of novel catheters able to measure local tissue impedance (LI) has yielded important data on ablation lesion size, safety and efficacy, and their application has recently been described, especially during pulmonary vein isolation (PVI) for atrial fibrillation (AF), with the aim of reliably validating ablation endpoints 9–13 . However, it remains to be established whether LI is able to predict effective CTI ablation and what LI drop values during ablation should be used to judge a lesion as effective.…”

Early rhythm‐control ablation therapy to prevent atrial fibrillation recurrences: Insights from the CHARISMA Registry

“…Using LI seems to be a safe method of providing data on tissue contact and characterization, and yields direct data for RF titration in order to obtain acute isolation, in agreement with previous findings. [10][11]27 At present, the use of catheters with contact-force sensors remains the gold standard for the RF ablation of AF. However, a structured approach based on LI information allowed us to achieve considerable clinical success.…”