J Cardiovasc Electrophysiol. 2021 Jul 5. doi: 10.1111/jce.15135. Online ahead of print.
ABSTRACT
BACKGROUND: Local impedance (LI) drop measured with micro-fidelity electrodes embedded in the tip of an ablation catheter accurately reflects tissue heating during radiofrequency (RF) ablation. Previous studies found 15-30Ω LI drops created successful lesions, while >40Ω drops were associated with steam pops. The objective of this study was to evaluate the safety and efficacy of LI-guided ablation using standard (30W) and high-power (50W) in a pre-clinical model.
METHODS: RF lesions were created in explanted swine hearts (n=6) to assess the feasibility of LI-guided ablation by targeting 10, 20, or 30Ω (n=20/group) drops. Subsequently LI-guided ablation was evaluated in a chronic animal model (n=8 Canines, 25-29kg, 30/50W). During the index procedure point-by-point intercaval line ablation and left inferior pulmonary vein (PV) isolation were performed. RF duration was at the operators’ discretion, but discontinued early if a 15-30Ω drop was achieved. Operators attempted to avoid LI drops >40Ω⊡ At 1-month, durable conduction block was evaluated with electroanatomic mapping followed by necropsy and histopathology.
RESULTS: In explanted tissue, terminating ablation at 10, 20, or 30Ω LI drops created statistically larger lesions (p<0.05; 1.8 [1.6-2.4]mm, 3.3 [3.0-3.7]mm; 4.9 [4.3-5.5]mm). LI-guided high-power ablation in vivo significantly reduced RF duration per application compared to standard-power (p<0.05; Intercaval: 8.9±5.2 versus 18.1±11.0sec, PV: 9.6±5.4 versus 23.2±10.3sec). LI drops of 15-40Ω were more readily achievable for high-power (90.1%, 318/353) than standard-power (71.7%, 243/339). All intercaval lines and PV isolations were durable (16/16) at 1-month. Necropsy revealed no major collateral injury to the pericardium, phrenic nerve, esophagus, or lungs. There was no pericardial effusion, stroke, tamponade, or PV stenosis. Vagal nerve injury was found in two 30W animals after using 19.7±13.9 and 19.5±11.8 sec RF applications.
CONCLUSION: LI-guided ablation was found to be safe and efficacious in a chronic animal model. High-power ablation more readily achieved >15Ω drops, reduced RF duration compared to standard-power, and had no major RF collateral injury.
CONDENSED ABSTRACT: This study evaluated the safety and efficacy of Local Impedance (LI)-guided High-power ablation in a pre-clinical model. Radiofrequency(RF) lesions were created in explanted swine hearts (n=6) to assess the feasibility of LI-guided ablation. Subsequently LI-guided lesions were created at the pulmonary veins and intercaval line in a chronic animal model. The durability of conduction block was evaluated after 1-month. We found that terminating ablation at 10, 20, or 30Ω LI drops created statistically larger lesions (p<0.05) and was safe. LI-guided high-power ablation in vivo significantly reduced RF duration (p<0.05), also all lesions were durable at 1-month. This article is protected by copyright. All rights reserved.
PMID:34223691 | DOI:10.1111/jce.15135
