Local impedance guides catheter ablation in patients with ventricular tachycardia

Abstract

Aims: Catheter contact and local tissue characteristics are relevant information for successful radiofrequency current (RFC)-ablation. Local impedance (LI) has been shown to reflect tissue characteristics and lesion formation during RFC-ablation.Using a novel ablation catheter incorporating three mini-electrodes, we investigated LI in relation to generator impedance (GI) in patients with ventricular tachycardia (VT) and its applicability as an indicator of effective RFC-ablation. Methods and Results: Baseline impedance, Δimpedance during ablation and drop rate (Δimpedance/time) were analyzed for 625 RFC-applications in 28 patients with recurrent VT undergoing RFC-ablation. LI was lower in scarred (87.0 Ω [79.0-95.0]) compared to healthy myocardium (97.5 Ω ([82.75-111.50]; P = .03) while GI did not differ between scarred and healthy myocardium. ΔLI was higher (18 Ω [9.4-26.0]) for VT-terminating as compared to non-terminating RFC-ablation (ΔLI 13 Ω [8.85-18.0]; P = .03), but did not differ for ΔGI between terminating vs nonterminating RFCablation. Correspondingly, LI drop rate was higher for RFC-ablation terminating the VT compared with RFC-ablation not terminating the VT (0.63 Ω/s [0.52-0.76] vs 0.32 Ω [0.20-0.58]; P = .008) while there was no difference for GI drop rate. ΔLI was higher in patients with nonischemic cardiomyopathy vs patients with ischemic cardiomyopathy (16 Ω [11.0-20.0] vs 11.0 Ω [7.85-17.00]; P = .003).Conclusion: Our findings suggest that LI is a sensitive parameter to guide RFCablation in patients with VT. LI indicates differences in tissue characteristics and generally is higher in patients with nonischemic cardiomyopathy. Hence, the etiology of the underlying cardiomyopathy needs to be considered when adopting LI for monitoring catheter ablation of VT. K E Y W O R D Scatheter ablation, electrical impedance, high-density mapping, radiofrequency, ventricular tachycardia ---

A novel local impedance algorithm to guide effective pulmonary vein isolation in atrial fibrillation patients: Preliminary experience across different ablation sites from the CHARISMA pilot study

“…In our present study, a 15 Ω drop during RF correlated with effective lesions in left atrial tissue ablations, irrespective of the baseline voltage of the area. In two studies, 11,15 LI was reported to be a sensitive parameter for guiding RF ablation in patients with ventricular tachycardia (VT) when VT termination or loss of capture in the left ventricle was considered as ablation endpoint.…”

Optimal local impedance drops for an effective radiofrequency ablation during cavo‐tricuspid isthmus ablation

“…10,11,19 Munkler et al demonstrated that the absolute LI drops were significantly greater at the effective ablation sites than ineffective sites during the VT ablation. 9 Martin et al demonstrated that the absolute and percentage LI drops were significantly greater at the successful lesions than unsuccessful lesions during ablation in the left atrium (LA) and ventricle. 11 The results of our study with a CTI ablation were consistent with that of those previous studies.…”

“…Recent studies demonstrated that the LI provides valuable information on the catheter-tissue coupling and lesion formation during RF catheter ablation (RFCA), and a change in the LI during ongoing ablation is more sensitive than that in the generator impedance. [9][10][11] So far there have been limited studies evaluating the usefulness of LI monitoring during CTI linear ablation. Thus, the purpose of this study was to determine the optimal values of the LI drops for an effective RF ablation during an LI-guided CTI linear ablation.…”

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

“…When the ablation catheter (IntellaNav Mifi OI) was positioned at the corresponding location, the fragmented signals due to gap conduction into the veins were barely visible on ablation traces and were completely different from the Orion TM signals previously recorded at the same location (Figure 1, left panel), suggesting either that the catheter tip was not exactly on the gap, or that a large cancellation effect had occurred because of the wider field of view of the ablation electrodes than that of the Orion TM catheter one. [8] LI values at the same location showed an impedance value greater than 120 ohms (Figure 1, right panel), which was more compatible with the presence of surviving myocardial fibers in a gap region than with nearly unexcitable tissue, as suggested by signals on the ablation traces J o u r n a l P r e -p r o o f (LI values were around 88 ohms in the blood and around 95 ohms at lines of block in this patient). We applied RF energy and the veins became isolated when the LI drop reached 20 ohm (supplemental video 2).…”