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Halaby RN, Bruce CG, Kolandaivelu A, Bhatia NK, Rogers T, Khan JM, Yildirim DK, Jaimes AE, O'Brien K, Babaliaros VC, Greenbaum AB, Lederman RJ. Ventricular Intramyocardial Navigation for Tachycardia Ablation Guided by Electrograms (VINTAGE): Deep Ablation in Inaccessible Targets. JACC Clin Electrophysiol 2024; 10:814-825. [PMID: 38811066 DOI: 10.1016/j.jacep.2024.04.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2024] [Revised: 03/27/2024] [Accepted: 04/03/2024] [Indexed: 05/31/2024]
Abstract
BACKGROUND Deep intramural ventricular tachycardia substrate targets are difficult to access, map, and ablate from endocardial and epicardial surfaces, resulting in high recurrence rates. OBJECTIVES In this study, the authors introduce a novel approach called ventricular intramyocardial navigation for tachycardia ablation guided by electrograms (VINTAGE) to access and ablate anatomically challenging ventricular tachycardia from within the myocardium. METHODS Guidewire/microcatheter combinations were navigated deep throughout the extravascular myocardium, accessed directly from the right ventricle cavity, in Yorkshire swine (6 naive, 1 infarcted). Devices were steered to various intramyocardial targets including the left ventricle summit, guided by fluoroscopy, unipolar electrograms, and/or electroanatomic mapping. Radiofrequency ablations were performed to characterize ablation parameters and reproducibility. Intramyocardial saline irrigation began 1 minute before ablation and continued throughout. Lesions were analyzed on cardiac magnetic resonance and necropsy. RESULTS VINTAGE was feasible in all animals within naive and infarcted myocardium. Forty-three lesions were created, using various guidewires and power settings. Forty-one (95%) lesions were detected on cardiac magnetic resonance and 38 (88%) on necropsy; all undetected lesions resulted from intentionally subtherapeutic ablation energy (10 W). Larger-diameter guidewires yielded larger size lesions. Lesion volumes on necropsy were significantly larger at 20 W than 10 W (178 mm3 [Q1-Q3: 104-382 mm3] vs 49 mm3 [Q1-Q3: 35-93 mm3]; P = 0.02). Higher power (30 W) did not create larger lesions. Median impedance dropped with preablation irrigation by 12 Ω (Q1-Q3: 8-17 Ω), followed by a further 15-Ω (Q1-Q3: 11-19 Ω) drop during ablation. Intramyocardial navigation, ablation, and irrigation were not associated with any complications. CONCLUSIONS VINTAGE was safe and effective at creating intramural ablation lesions in targets traditionally considered inaccessible from the endocardium and epicardium, both naive and infarcted. Intramyocardial guidewire irrigation and ablation at 20 W creates reproducibly large intramural lesions.
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Affiliation(s)
- Rim N Halaby
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Christopher G Bruce
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA; Emory University Hospital, Atlanta, Georgia, USA
| | - Aravindan Kolandaivelu
- Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | | | - Toby Rogers
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA; MedStar Washington Hospital Center, Washington, DC, USA
| | - Jaffar M Khan
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA; St Francis Hospital, Roslyn, New York, USA
| | - D Korel Yildirim
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Andi E Jaimes
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Kendall O'Brien
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | | | | | - Robert J Lederman
- Cardiovascular Branch, Division of Intramural Research, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA.
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Iwakawa H, Takigawa M, Yamaguchi J, Martin CA, Goya M, Yamamoto T, Amemiya M, Ikenouchi T, Negishi M, Kawamura I, Goto K, Shigeta T, Nishimura T, Takamiya T, Tao S, Miyazaki S, Watanabe H, Sasano T. Superiority of the Combination of Input and Output Parameters to the Single Parameter for Lesion Size Estimation. Circ J 2023; 87:1757-1764. [PMID: 37899173 DOI: 10.1253/circj.cj-23-0574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/31/2023]
Abstract
BACKGROUND For lesion size prediction, each input parameter, including ablation energy (AE), and output parameter, such as impedance, is individually used. We hypothesize that using both parameters simultaneously may be more optimal.Methods and Results: Radiofrequency applications at a range of power (30-50 W), contact force (10 g and 20 g), duration (10-60 s), and catheter orientation with normal saline (NS)- or half-normal saline (HNS)-irrigation were performed in excised porcine hearts. The correlations, with lesion size of AE, absolute impedance drop (∆Imp-drop), relative impedance drop (%Imp-drop), and AE*%Imp-drop were examined. Lesion size was analyzed in 283 of 288 lesions (NS-irrigation, n=142; HNS-irrigation, n=141) without steam pops. AE*%Imp-drop consistently showed the strongest correlations with lesion maximum depth (NS-irrigation, ρ=0.91; HNS-irrigation, ρ=0.94), surface area (NS-irrigation, ρ=0.87; HNS-irrigation, ρ=0.86), and volume (NS-irrigation, ρ=0.94; HNS-irrigation, ρ=0.94) compared with the other parameters. Moreover, compared with AE alone, AE*%Imp-drop significantly improved the strength of correlation with lesion maximum depth (AE vs. AE*%Imp-drop, ρ=0.83 vs. 0.91, P<0.01), surface area (ρ=0.73 vs. 0.87, P<0.01), and volume (ρ=0.84 vs. 0.94, P<0.01) with NS-irrigation. This tendency was also observed with HNS-irrigation. Parallel catheter orientation showed a better correlation with lesion depth and volume using ∆Imp-drop, %Imp-drop, and AE*%Imp-drop than perpendicular orientation. CONCLUSIONS The combination of input and output parameters is more optimal than each single parameter for lesion prediction.
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Affiliation(s)
- Hidehiro Iwakawa
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
- Department of Cardiovascular Medicine, Akita University Graduate School of Medicine
| | - Masateru Takigawa
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Junji Yamaguchi
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | | | - Masahiko Goya
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Tasuku Yamamoto
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Miki Amemiya
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Takashi Ikenouchi
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Miho Negishi
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Iwanari Kawamura
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Kentaro Goto
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Takatoshi Shigeta
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Takuro Nishimura
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Tomomasa Takamiya
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Susumu Tao
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Shinsuke Miyazaki
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
| | - Hiroyuki Watanabe
- Department of Cardiovascular Medicine, Akita University Graduate School of Medicine
| | - Tetsuo Sasano
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University
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Lepillier A, Maggio R, De Sanctis V, Malacrida M, Stabile G, Zakine C, Champ-Rigot L, Anselmino M, Segreti L, Dell’Era G, Garnier F, Mascia G, Pandozi C, Dello Russo A, Scaglione M, Cosaro G, Ferraro A, Paziaud O, Maglia G, Solimene F. Insight into contact force local impedance technology for predicting effective pulmonary vein isolation. Front Cardiovasc Med 2023; 10:1169037. [PMID: 37476572 PMCID: PMC10354239 DOI: 10.3389/fcvm.2023.1169037] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Accepted: 06/19/2023] [Indexed: 07/22/2023] Open
Abstract
Background Highly localized impedance (LI) measurements during atrial fibrillation (AF) ablation have the potential to act as a reliable predictor of the durability of the lesions created. Objective We aimed to collect data on the procedural parameters affecting LI-guided ablation in a large multicenter registry. Methods A total of 212 consecutive patients enrolled in the CHARISMA registry and undergoing their first pulmonary vein (PV) isolation for paroxysmal and persistent AF were included. Results In all, 13,891 radiofrequency (RF) applications of ≥3 s duration were assessed. The first-pass PV isolation rate was 93.3%. A total of 80 PV gaps were detected. At successful ablation spots, baseline LI and absolute LI drop were larger than at PV gap spots (161.4 ± 19 Ω vs. 153.0 ± 13 Ω, p < 0.0001 for baseline LI; 22.1 ± 9 Ω vs. 14.4 ± 5 Ω, p < 0.0001 for LI drop). On the basis of Receiver operating characteristic curve analysis, the ideal LI drop, which predicted successful ablation, was >21 Ω at anterior sites and >18 Ω at posterior sites. There was a non-linear association between the magnitude of LI drop and contact-force (CF) (r = 0.14, 95% CI: 0.13-0.16, p < 0.0001) whereas both CF and LI drop were inversely related with delivery time (DT) (-0.22, -0.23 to -0.20, p < 0.0001 for CF; -0.27, -0.29 to -0.26, p < 0.0001 for LI drop). Conclusion An LI drop >21 Ω at anterior sites and >18 Ω at posterior sites predicts successful ablation. A higher CF was associated with an increased likelihood of ideal LI drop. The combination of good CF and adequate LI drop allows a significant reduction in RF DT. Clinical trial registration http://clinicaltrials.gov/, identifier: NCT03793998.
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Affiliation(s)
| | | | | | | | | | | | | | - Matteo Anselmino
- Division of Cardiology, “Città della Salute e della Scienza di Torino” Hospital, Department of Medical Sciences, University of Turin, Turin, Italy
| | - Luca Segreti
- Second Division of Cardiology, Cardiac-Thoracic-Vascular Department, New Santa Chiara Hospital, Azienda Ospedaliero Universitaria Pisana, Pisa, Italy
| | - Gabriele Dell’Era
- Azienda Ospedaliera Universitaria “Maggiore della Carità”, Novara, Italy
| | | | | | | | - Antonio Dello Russo
- Cardiology and Arrhythmology Clinic, Marche Polytechnic University, Ancona, Italy
| | | | | | | | | | | | - Francesco Solimene
- Department of Cardiac Electrophysiology and Arrhythmology, Clinica Montevergine, Mercogliano, Italy
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Fukaya H, Mori H, Oikawa J, Kawano D, Nakamura H, Ishizue N, Kishihara J, Hojo R, Tsutsui K, Ikeda Y, Kato R, Fukamizu S. Optimal local impedance parameters for successful pulmonary vein isolation in patients with atrial fibrillation. J Cardiovasc Electrophysiol 2023; 34:71-81. [PMID: 36378816 DOI: 10.1111/jce.15748] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/24/2022] [Accepted: 11/07/2022] [Indexed: 11/16/2022]
Abstract
INTRODUCTION Local impedance (LI) parameters of IntellaNav STABLEPOINT for successful pulmonary vein isolation (PVI) of atrial fibrillation (AF) remain unclear. The purpose of this study was to seek LI data achieving successful PVI. METHODS Consecutive AF patients who underwent catheter ablation with STABLEPOINT were prospectively enrolled in two centers. PVI was performed under a constant 35-or 40-watt power, 20-s duration, and >5-g contact force. The operators were blinded to the LI data. The characteristics of all ablation points with/without conduction gaps (Unsuccess or Success tags) after the first-attempt PVI were evaluated for the right/left PVs and anterior/posterior wall (RPV/LPV and AW/PW, respectively), and cutoff values of LI data were calculated for successful lesion formation. RESULTS A total of 5257 ablation points in 102 patients (65 [58-72] years old, 65.7% male) were evaluated. The LI drop values were higher in the Success tags than Unsuccess tags on the LPV-AW and RPV-AW/PW (p < .001), except for the LPV-PW (p = .105). The %LI drop values (LI drop/initial LI) were higher for the Success tags in all areas (15.8 [12.2%-19.6%] vs. 11.6 [9.7%-15.6%] in LPV-AW: p < .001, 15.0 [11.5%-19.3%] vs. 11.4 [8.7%-17.3%] in LPV-PW: p = .035, 15.3 [11.5%-19.4%] vs. 9.9 [8.1%-13.7%] in RPV-AW: p < .001, and 13.3 [10.1%-17.4%] vs. 8.1 [6.3%-9.5%] in RPV-PW, p < .001). The LI drop and %LI drop cutoff values were 20.0 ohms and 11.6%, respectively. CONCLUSIONS An insufficient LI drop with STABLEPOINT was associated with a gap formation during PVI, and the best cutoff values for the LI drop and %LI drop were 20.0 ohms and 11.6%, respectively.
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Affiliation(s)
- Hidehira Fukaya
- Department of Cardiovascular Medicine, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Hitoshi Mori
- Department of Cardiovascular Medicine, Saitama Medical University International Medical Center, Hidaka, Japan
| | - Jun Oikawa
- Department of Cardiovascular Medicine, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Daisuke Kawano
- Department of Cardiovascular Medicine, Saitama Medical University International Medical Center, Hidaka, Japan
| | - Hironori Nakamura
- Department of Cardiovascular Medicine, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Naruya Ishizue
- Department of Cardiovascular Medicine, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Jun Kishihara
- Department of Cardiovascular Medicine, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
| | - Rintaro Hojo
- Department of Cardiology, Tokyo Metropolitan Hiroo Hospital, Tokyo, Japan
| | - Kenta Tsutsui
- Department of Cardiovascular Medicine, Saitama Medical University International Medical Center, Hidaka, Japan
| | - Yoshifumi Ikeda
- Department of Cardiovascular Medicine, Saitama Medical University International Medical Center, Hidaka, Japan
| | - Ritsushi Kato
- Department of Cardiovascular Medicine, Saitama Medical University International Medical Center, Hidaka, Japan
| | - Seiji Fukamizu
- Department of Cardiology, Tokyo Metropolitan Hiroo Hospital, Tokyo, Japan
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A computational comparison of radiofrequency and pulsed field ablation in terms of lesion morphology in the cardiac chamber. Sci Rep 2022; 12:16144. [PMID: 36167959 PMCID: PMC9515184 DOI: 10.1038/s41598-022-20212-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 09/09/2022] [Indexed: 11/15/2022] Open
Abstract
Pulsed Field Ablation (PFA) has been developed over the last years as a novel electrical ablation technique for treating cardiac arrhythmias. It is based on irreversible electroporation which is a non-thermal phenomenon innocuous to the extracellular matrix and, because of that, PFA is considered to be safer than the reference technique, Radiofrequency Ablation (RFA). However, possible differences in lesion morphology between both techniques have been poorly studied. Simulations including electric, thermal and fluid physics were performed in a simplified model of the cardiac chamber which, in essence, consisted of a slab of myocardium with blood in motion on the top. Monopolar and bipolar catheter configurations were studied. Different blood velocities and catheter orientations were assayed. RFA was simulated assuming a conventional temperature-controlled approach. The PFA treatment was assumed to consist in a sequence of 20 biphasic bursts (100 µs duration). Simulations indicate that, for equivalent lesion depths, PFA lesions are wider, larger and more symmetrical than RFA lesions for both catheter configurations. RFA lesions display a great dependence on blood velocity while PFA lesions dependence is negligible on it. For the monopolar configuration, catheter angle with respect to the cardiac surface impacted both ablation techniques but in opposite sense. The orientation of the catheter with respect to blood flow direction only affected RFA lesions. In this study, substantial morphological differences between RFA and PFA lesions were predicted numerically. Negligible dependence of PFA on blood flow velocity and direction is a potential important advantage of this technique over RFA.
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Orbán G, Salló Z, Perge P, Ábrahám P, Piros K, Nagy KV, Osztheimer I, Merkely B, Gellér L, Szegedi N. Characteristics of Very High-Power, Short-Duration Radiofrequency Applications. Front Cardiovasc Med 2022; 9:941434. [PMID: 35911564 PMCID: PMC9326019 DOI: 10.3389/fcvm.2022.941434] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 06/13/2022] [Indexed: 11/13/2022] Open
Abstract
Introduction Pulmonary vein isolation is the cornerstone of rhythm-control therapy for atrial fibrillation (AF). The very high-power, short-duration (vHPSD) radiofrequency (RF) ablation is a novel technology that favors resistive heating while decreasing the role of conductive heating. Our study aimed to evaluate the correlations between contact force (CF), power, impedance drop (ID), and temperature; and to assess their role in lesion formation with the vHPSD technique. Methods Consecutive patients who underwent initial point-by-point RF catheter ablation for AF were enrolled in the study. The vHPSD ablation was performed applying 90 W for 4 s with an 8 ml/min irrigation rate. Results Data from 85 patients [median age 65 (59–71) years, 34% female] were collected. The median procedure time, left atrial dwelling time, and fluoroscopy time were 70 (60–90) min, 49 (42–58) min, and 7 (5–11) min, respectively. The median RF time was 312 (237-365) sec. No steam pop nor major complications occurred. A total of 6,551 vHPSD RF points were analyzed. The median of CF, maximum temperature, and ID were 14 (10–21) g, 47.6 (45.1–50.4) °C, and 8 (6–10) Ohms, respectively. CF correlated significantly with the maximum temperature (p < 0.0001). A CF of 5 g and above was associated with a significantly higher temperature compared to those lesions with a CF below 5 grams (p < 0.0001). Bilateral first-pass isolation rate was 84%. The 6-month AF-recurrence rate was 7%. Conclusion The maximum temperature and CF significantly correlate with each other during vHPSD applications. A CF ≥ 5 g leads to better tissue heating and thus might be more likely to result in good lesion formation, although this clinical study was unable to assess actual lesion sizes.
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Comparison of two catheters measuring local impedance: local impedance variation vs lesion characteristics and steam pops. J Interv Card Electrophysiol 2022; 65:419-428. [PMID: 35438394 DOI: 10.1007/s10840-022-01214-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 03/31/2022] [Indexed: 10/18/2022]
Abstract
PURPOSE The size of the distal electrode and the method of measuring local impedance (LI) are different between the IntellaNav MiFi-OI™ (MiFi-OI) and IntellaNav STABLE POINT™ (SP) catheters. We investigated the impact of these differences on LI, efficacy, and safety of radiofrequency (RF) applications. METHODS RF applications at a range of powers (30 W, 40 W, and 50 W), contact forces (10 g and 20 g), and durations (10-120 s) were performed in excised porcine hearts (N = 48). LI variation was defined by δLI-drop (= initial LI - post-RF LI) and %LI-drop (= δLI-drop/initial LI) × 100, and the relationship between lesion characteristics and LI variation was compared. RESULTS A total of 576 lesions were examined. Although absolute δLI-drop during RF applications was significantly larger for the SP than MiFi-OI catheter (47[31-65]ohm for SP vs 37[24-51]ohm for MiFi-OI, p < 0.0001), %LI-drop was similar (23.3 [15.5-30.6]% in SP vs 24.9[17.3-32.5]% in MiFi-OI, p = 0.10). Although lesions produced by both catheters were similarly correlated with LI variation, the SP catheter produced generally larger lesions (depth; 5.0 [3.7-6.1]mm vs 4.7 [3.3-6.0]mm, p = 0.06; surface areas, 46.9 [36.8-58.8]mm2 vs 44.7 [34.3-55.5]mm2, p = 0.02; volume, 321 [165-533]mm3 vs 265[141-471]mm3, p = 0.02). Steam pops were similarly observed with both catheters. In both catheters, %LI-drop was superior to δLI-drop in correlation to lesion size (p < 0.0001) and in predicting steam pops (p < 0.01). CONCLUSIONS Although no difference in safety profile is observed between MiFi-OI and SP catheters, the SP catheter produces larger lesions. %LI-drop is superior to δLI-drop in correlation to lesion size and in predicting steam pops as well as in normalizing the difference between catheters.
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Schillaci V, Strisciuglio T, Stabile G, Salito A, Arestia A, Agresta A, Shopova G, De Simone A, Solimene F. Cavotricuspid isthmus ablation by means of very high power, short-duration, temperature-controlled lesions. J Interv Card Electrophysiol 2022; 65:97-102. [PMID: 35378611 DOI: 10.1007/s10840-022-01197-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 03/22/2022] [Indexed: 12/18/2022]
Abstract
BACKGROUND A very high-power short-duration (vHPSD) strategy of radiofrequency (RF) ablation aims to minimize conductive heating and increase resistive heating. We evaluated the feasibility, efficacy and safety of the vHPSD ablation of the cavotricuspid isthmus (CTI) in patients presenting with typical atrial flutter (AFL). METHODS This prospective non-randomized study enrolled 28 consecutive patients (FAST Group) with typical AFL undergoing CTI ablation. The vHPSD ablation was performed applying 90 W, for 4 s, with an irrigation of 8 ml/min. Thirty consecutive patients who, previously, underwent CTI ablation by means of a contact force surrounding flow catheter guided by ablation index (500) served as control group (AI Group). RESULTS In the FAST Group, the mean CTI length was 29 ± 6 mm, and the mean number of RF tags was 20 ± 9. The CTI bidirectional "first pass" block was reached in 25 (89%) patients. There were no major procedural complications. After a mean follow-up of 6 ± 2 months, one (3.5%) patient had arrhythmia recurrence. The vHPSD ablation was as effective as AI-guided ablation in achieving acute CTI block (rate of first pass 89% vs 93%, p = 0.59), with a shorter RF time (88 ± 40 s vs 492 ± 269 s, p < 0.001) and similar procedure (30 ± 4 min vs 34 ± 10 min, p = 0.5) and fluoroscopy time (103 ± 29 vs 108 ± 52 s, p = 0.7). At 8 months, the freedom from AFL recurrence was 96% in the FAST group and 97% in the AI group. CONCLUSIONS Our preliminary data show that the vHPSD ablation represents an effective and safe ablation strategy to achieve bidirectional block for the treatment of typical AFL.
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Affiliation(s)
- Vincenzo Schillaci
- Clinica Montevergine, via Mario Malzoni, 5, 83013, Mercogliano, AV, Italy
| | - Teresa Strisciuglio
- Department of Advanced Biomedical Sciences, University of Naples Federico II, Naples, Italy
| | - Giuseppe Stabile
- Clinica Montevergine, via Mario Malzoni, 5, 83013, Mercogliano, AV, Italy.
- Anthea Hospital, Bari, Italy.
- Casa di Cura San Michele, Maddaloni, CE, Italy.
| | - Armando Salito
- Clinica Montevergine, via Mario Malzoni, 5, 83013, Mercogliano, AV, Italy
| | - Alberto Arestia
- Clinica Montevergine, via Mario Malzoni, 5, 83013, Mercogliano, AV, Italy
| | - Alessia Agresta
- Clinica Montevergine, via Mario Malzoni, 5, 83013, Mercogliano, AV, Italy
| | - Gergana Shopova
- Clinica Montevergine, via Mario Malzoni, 5, 83013, Mercogliano, AV, Italy
| | | | - Francesco Solimene
- Clinica Montevergine, via Mario Malzoni, 5, 83013, Mercogliano, AV, Italy
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Mulder MJ, Kemme MJB, Allaart CP. Radiofrequency ablation to achieve durable pulmonary vein isolation. Europace 2021; 24:874-886. [PMID: 34964469 DOI: 10.1093/europace/euab279] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Indexed: 11/13/2022] Open
Abstract
Pulmonary vein isolation (PVI) by radiofrequency (RF) ablation is an important alternative to antiarrhythmic drugs in the treatment of symptomatic atrial fibrillation. However, the inability to consistently achieve durable isolation of the pulmonary veins hampers the long-term efficacy of PVI procedures. The large number of factors involved in RF lesion formation and the complex interplay of these factors complicate reliable creation of durable and transmural ablation lesions. Various surrogate markers of ablation lesion formation have been proposed that may provide information on RF lesion completeness. Real-time assessment of these surrogates may aid in the creation of transmural ablation lesions, and therefore, holds potential to decrease the risk of PV reconnection and consequent post-PVI arrhythmia recurrence. Moreover, titration of energy delivery until lesions is transmural may prevent unnecessary ablation and subsequent adverse events. Whereas several surrogate markers of ablation lesion formation have been described over the past decades, a 'gold standard' is currently lacking. This review provides a state-of-the-art overview of ablation strategies that aim to enhance durability of RF-PVI, with special focus on real-time available surrogates of RF lesion formation in light of the biophysical basis of RF ablation.
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Affiliation(s)
- Mark J Mulder
- Department of Cardiology, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam Cardiovascular Sciences, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands
| | - Michiel J B Kemme
- Department of Cardiology, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam Cardiovascular Sciences, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands
| | - Cornelis P Allaart
- Department of Cardiology, Amsterdam UMC, Vrije Universiteit Amsterdam, Amsterdam Cardiovascular Sciences, De Boelelaan 1117, 1081 HV Amsterdam, The Netherlands
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Stabile G, Schillaci V, Strisciuglio T, Arestia A, Agresta A, Shopova G, De Simone A, Solimene F. In vivo biophysical characterization of very high power, short duration, temperature-controlled lesions. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2021; 44:1717-1723. [PMID: 34498748 DOI: 10.1111/pace.14358] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 07/30/2021] [Accepted: 09/05/2021] [Indexed: 11/27/2022]
Abstract
INTRODUCTION A very high-power short-duration (vHPSD) strategy of radiofrequency (RF) ablation aims to minimize conductive heating and increase resistive heating. This study aimed to clarify the contribution of contact force (CF) and temperature and their interrelationship in making an adequate lesion with the vHPSD catheter. METHODS We enrolled 46 consecutive patients undergoing first catheter ablation for atrial fibrillation (AF). The vHPSD ablation was performed applying 90 W, for 4 s, with an irrigation of 8 ml/min. During an application, an impedance drop (ID) ≥10 Ω was regarded as an adequate lesion formation. RESULTS The mean procedural time was 95 ± 15 min. First-pass isolation was reached in 89% of patients and at the end of the procedure all pulmonary veins were isolated. No steam pop nor procedural complication occurred. A total of 3829 qualified RF points were analyzed and the median values of ID, CF and maximum temperature were respectively 10.6 (IQR 8.6-13.1) Ohm, 9 (5.8-13.8) g, 46.8 (44.1-49.8) °C. The mean ID significantly increased in parallel with the increasing CF as well as with the increasing maximum temperature. In the multivariable analysis only the CF and the maximum temperature were independent predictors of ID. From receiver operating characteristic curve analysis, a CF of 8 g and a maximum temperature of 47°C are the optimal cutoff discriminatory value for adequate lesion formation. CONCLUSIONS The vHPSD ablation is highly effective and safe. The CF and the maximum temperature are independent predictors of adequate lesion formation assessed by means of ID.
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Affiliation(s)
- Giuseppe Stabile
- Clinica Montevergine, Mercogliano, Avellino, Italy.,Clinica San Michele, Maddaloni, Caserta, Italy.,Anthea Hospital, Bari, Italy
| | | | - Teresa Strisciuglio
- Clinica Montevergine, Mercogliano, Avellino, Italy.,Department of Advanced Biomedical Sciences, University of Naples Federico II, Naples, Italy
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11
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Bhaskaran A, Niri A, Azam MA, Nayyar S, Porta-Sánchez A, Massé S, Liang T, Veluppillai A, Du B, Lai PFH, Ha A, Nanthakumar K. Safety, efficacy, and monitoring of bipolar radiofrequency ablation in beating myopathic human and healthy swine hearts. Heart Rhythm 2021; 18:1772-1779. [PMID: 34182170 DOI: 10.1016/j.hrthm.2021.06.1189] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 06/17/2021] [Accepted: 06/21/2021] [Indexed: 10/21/2022]
Abstract
BACKGROUND The safety and efficacy parameters for bipolar radiofrequency (RF) ablation are not well defined. OBJECTIVE The purpose of this study was to investigate the safe range of power, utility of transmyocardial bipolar electrogram (EGM) amplitude, and circuit impedance in ablation monitoring. METHODS Sixteen beating ex vivo human and swine hearts were studied in a Langendorff setup. Ninety-two bipolar ablations using two 4-mm irrigated catheters were performed at settings of 20-50 W, 60 seconds, and 30 mL/min irrigation in the left ventricle. RESULTS For low-power ablations (20 and 30 W), transmurality was observed in 29 of 38 (76%) and 10 of 28 (36%) ablations for tissue thickness ≤17 mm and >17 mm, respectively. For high-power ablations (40 and 50 W), transmurality was observed in 5 of 7 (71%) and 7 of 19 (37%) ablations for tissue thickness ≤17 mm and >17 mm, respectively. Steam pop occurrence for low- and high-power ablations was 11 of 66 (16%) and 16 of 26 (62%), respectively (P = .0001), respectively. Lesion depth (limited by transmurality) was 12.0 ± 5.7 mm and 12.3 ± 5.8 mm, respectively (P = 1). Transmyocardial EGM amplitude decrement >60% strongly predicted transmurality (area under the curve [AUC] 0.8), and circuit impedance decrement >26% predicted steam pops (AUC 0.75). Half-normal saline did not affect transmurality or incidence of steam pops compared to normal saline irrigation. CONCLUSION Bipolar RF ablation at power of 20-30 W provided an ideal balance of safety and efficacy, whereas power ≥40 W should be used with caution due to the high incidence of steam pops. Lesion transmurality monitoring and steam pop avoidance were best achieved using transmyocardial bipolar EGM voltage and circuit impedance, respectively.
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Affiliation(s)
- Abhishek Bhaskaran
- The Hull Family Cardiac Fibrillation Management Laboratory, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network Toronto, Ontario, Canada
| | - Ahmed Niri
- The Hull Family Cardiac Fibrillation Management Laboratory, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network Toronto, Ontario, Canada
| | - Mohammed Ali Azam
- The Hull Family Cardiac Fibrillation Management Laboratory, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network Toronto, Ontario, Canada
| | - Sachin Nayyar
- The Hull Family Cardiac Fibrillation Management Laboratory, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network Toronto, Ontario, Canada
| | - Andreu Porta-Sánchez
- Arrhythmia Unit, Hospital Universitario Quirónsalud Madrid, Fundación Centro Nacional de Investigaciones Cardiovasculares Carlos III (CNIC)
| | - Stéphane Massé
- The Hull Family Cardiac Fibrillation Management Laboratory, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network Toronto, Ontario, Canada
| | - Timothy Liang
- The Hull Family Cardiac Fibrillation Management Laboratory, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network Toronto, Ontario, Canada
| | - Arulalan Veluppillai
- The Hull Family Cardiac Fibrillation Management Laboratory, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network Toronto, Ontario, Canada
| | - Beibei Du
- The Hull Family Cardiac Fibrillation Management Laboratory, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network Toronto, Ontario, Canada
| | - Patrick F H Lai
- The Hull Family Cardiac Fibrillation Management Laboratory, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network Toronto, Ontario, Canada
| | - Andrew Ha
- The Hull Family Cardiac Fibrillation Management Laboratory, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network Toronto, Ontario, Canada
| | - Kumaraswamy Nanthakumar
- The Hull Family Cardiac Fibrillation Management Laboratory, Peter Munk Cardiac Centre, Toronto General Hospital, University Health Network Toronto, Ontario, Canada.
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12
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Takigawa M, Goya M, Iwakawa H, Martin CA, Anzai T, Takahashi K, Kamata T, Matsumura Y, Amemiya M, Yamamoto T, Hirao T, Sekigawa M, Shirai Y, Tao S, Takahashi Y, Sasano T. Impact of a formula combining local impedance and conventional parameters on lesion size prediction. J Interv Card Electrophysiol 2021; 63:389-398. [PMID: 34156611 DOI: 10.1007/s10840-021-01013-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 05/23/2021] [Indexed: 11/28/2022]
Abstract
BACKGROUND Although ablation energy (AE) and force-time integral (FTI) are well-known active predictors of lesion characteristics, these parameters do not reflect passive tissue reactions during ablation, which may instead be represented by drops in local impedance (LI). This study aimed to investigate if additional LI data improves predicting lesion characteristics and steam pops. METHODS RF applications at a range of powers (30 W, 40 W, and 50 W), contact forces (8 g, 15 g, 25 g, and 35 g), and durations (10-180 s) using perpendicular/parallel catheter orientations were performed in excised porcine hearts (N = 30). The correlation between AE, FTI, and lesion characteristics was examined, and the impact of LI (%LI drop (%LID) defined by the ΔLI divided by the initial LI) was additionally assessed. RESULTS Three hundred seventy-five lesions without steam pops were examined. Ablation energy (W × s) and FTI (g × s) showed a positive correlation with lesion depth (ρ = 0.824:P < 0.0001 and ρ = 0.708:P < 0.0001), surface area (ρ = 0.507:P < 0.0001 and ρ = 0.562:P < 0.0001), and volume (ρ = 0.807:P < 0.0001 and ρ = 0.685:P < 0.0001). %LID also showed a positive correlation individually with lesion depth (ρ = 0.643:P < 0.0001), surface area (ρ = 0.547:P < 0.0001), and volume (ρ = 0.733:P < 0.0001). However, the combined indices of AE × %LID (AE multiplied by %LID) and FTI × %LID (FTI multiplied by %LID) provided significantly stronger correlation with lesion depth (ρ = 0.834:P < 0.0001 and ρ = 0.809:P < 0.0001), surface area (ρ = 0.529:P < 0.0001 and ρ = 0.656:P < 0.0001), and volume (ρ = 0.864:P < 0.0001 and ρ = 0.838:P < 0.0001). This tendency was observed regardless of the catheter placement (parallel/perpendicular). AE (P = 0.02) and %LID (P = 0.002) independently remained as significant predictors to predict steam pops (N = 27). However, the AE × %LID did not increase the predictive power of steam pops compared to the AE alone. CONCLUSION LI, when combined with conventional parameters (AE and FTI), may provide stronger correlation with lesion characteristics.
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Affiliation(s)
- Masateru Takigawa
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan.
- Department of Advanced Arrhythmia Research, Tokyo Medical and Dental University, Tokyo, Japan.
| | - Masahiko Goya
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan
| | - Hidehiro Iwakawa
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan
- Department of Cardiovascular Medicine, Graduate School of Medicine, Akita University, Akita, Japan
| | | | - Tatsuhiko Anzai
- Department of Biostatistics M&D Data Science Center, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kunihiko Takahashi
- Department of Biostatistics M&D Data Science Center, Tokyo Medical and Dental University, Tokyo, Japan
| | - Tatsuaki Kamata
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan
| | - Yu Matsumura
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan
| | - Miki Amemiya
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan
| | - Tasuku Yamamoto
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan
| | - Tatsuhiko Hirao
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan
| | - Masahiro Sekigawa
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan
| | - Yasuhiro Shirai
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan
| | - Susumu Tao
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan
| | - Yoshihide Takahashi
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan
- Department of Advanced Arrhythmia Research, Tokyo Medical and Dental University, Tokyo, Japan
| | - Tetsuo Sasano
- Department of Cardiovascular Medicine, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, Japan
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13
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Shi LB, Wang YC, Chu SY, De Bortoli A, Schuster P, Solheim E, Chen J. The impacts of contact force, power and application time on ablation effect indicated by serial measurements of impedance drop in both conventional and high-power short-duration ablation settings of atrial fibrillation. J Interv Card Electrophysiol 2021; 64:333-339. [PMID: 33891228 PMCID: PMC9399015 DOI: 10.1007/s10840-021-00990-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Accepted: 04/05/2021] [Indexed: 11/08/2022]
Abstract
Background This study aimed to clarify the interrelationship and additive effects of contact force (CF), power and application time in both conventional and high-power short-duration (HPSD) settings. Methods Among 38 patients with paroxysmal atrial fibrillation who underwent first-time pulmonary vein isolation, 787 ablation points were collected at the beginning of the procedure at separate sites. Energy was applied for 60 s under power outputs of 25, 30 or 35 W (conventional group), or 10 s when using 50 W (HPSD group). An impedance drop (ID) of 10 Ω was regarded as a marker of adequate lesion formation. Results ID ≥ 10 Ω could not be achieved with CF < 5 g under any power setting. With CF ≥ 5 g, ID could be enhanced by increasing power output or prolonging ablation time. ID for 30 and 35 W was greater than for 25 W (p < 0.05). Ablation with 35 W resulted in greater ID than with 30 W only when CF of 10–20 g was applied for 20–40 s (p < 0.05). Under the same power output, ID increased with CF level at different time points. The higher the CF, the shorter the time needed to reach ID of 10 Ω and maximal ID. ID correlated well with ablation index under each power, except for lower ID values at 25 W. ID with 50 W for 10 s was equivalent to that with 25 W for 40 s, but lower than that with 30 W for 40 s or 35 W for 30 s. Conclusions CF of at least 5 g is required for adequate ablation effect. With CF ≥ 5g, CF, power output, and ablation time can compensate for each other. Time to reach maximal ablation effect can be shortened by increasing CF or power. The effect of HPSD ablation with 50 W for 10 s is equivalent to conventional ablation with 25 W for 40 s and 30–35 W for 20–30 s in terms of ID.
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Affiliation(s)
- Li-Bin Shi
- Department of Clinical Science, University of Bergen, Bergen, Norway.,Department of Heart Disease, Haukeland University Hospital, N-5021, Bergen, Norway
| | - Yu-Chuan Wang
- Department of Heart Disease, Haukeland University Hospital, N-5021, Bergen, Norway.,Peking University First Hospital, Beijing, China
| | - Song-Yun Chu
- Department of Heart Disease, Haukeland University Hospital, N-5021, Bergen, Norway.,Peking University First Hospital, Beijing, China
| | | | - Peter Schuster
- Department of Clinical Science, University of Bergen, Bergen, Norway.,Department of Heart Disease, Haukeland University Hospital, N-5021, Bergen, Norway
| | - Eivind Solheim
- Department of Heart Disease, Haukeland University Hospital, N-5021, Bergen, Norway
| | - Jian Chen
- Department of Clinical Science, University of Bergen, Bergen, Norway. .,Department of Heart Disease, Haukeland University Hospital, N-5021, Bergen, Norway.
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14
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Qian PC, Nguyen DM, Barry MA, Tran V, Lu J, Thiagalingam A, Thomas SP, McEwan A. Optimizing Impedance Change Measurement During Radiofrequency Ablation Enables More Accurate Characterization of Lesion Formation. JACC Clin Electrophysiol 2020; 7:471-481. [PMID: 33888268 DOI: 10.1016/j.jacep.2020.09.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 09/08/2020] [Accepted: 09/09/2020] [Indexed: 11/26/2022]
Abstract
OBJECTIVES This study sought to determine whether a novel impedance thermal imaging system (ITIS) provides an impedance measurement that is better correlated with lesion dimensions than circuit impedance during radiofrequency (RF) ablation. BACKGROUND A 5- to 10-Ω impedance drop is clinically used to corroborate an effective RF ablation lesion. However, the contribution of local tissue heating to circuit impedance change is small and dependent on the local environment of the catheter and placement of the grounding patch. METHODS ITIS uses ablation catheter and skin electrodes to perform 4-terminal impedance measurements with separate voltage sensing and current injection electrode pairs. Seven sheep underwent endocardial ventricular irrigated RF ablation at 40 W for 60 s. ITIS impedance and circuit impedance were both measured throughout ablation. When the sheep were sacrificed, ablation lesions were cut along their long axis; the depth, width, and surface area of the cut surface were measured. RESULTS A total of 68 RF ablations were performed, with a median depth of 3.5 mm (interquartile range [IQR]: 2.1 to 4.9 mm), width of 8.3 mm (IQR: 5.7 to 10.8 mm), and surface area of 23.8 mm2 (IQR: 9.3 to 43.0 mm2). ITIS impedance change had good correlation with lesion depth, width, and surface area (R = 0.76, R = 0.87, and R = 0.87, respectively); and superior to circuit impedance for lesion depth, width, and surface area (p = 0.0018, p = 0.0004, and p = 0.0001, respectively). CONCLUSIONS By optimizing the current path and using 4-terminal impedance measurement during RF ablation, the contribution of tissue temperature changes to measured impedance is better standardized to provide a more reliable measure than conventional ablation circuit impedance.
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Affiliation(s)
- Pierre C Qian
- Westmead Hospital, Sydney, Australia; Faculty of Medicine, University of Sydney, Sydney, Australia; Westmead Applied Research Centre, Sydney, Australia.
| | - Duc Minh Nguyen
- Faculty of Engineering and Information Technology, University of Sydney, Sydney, Australia; Department of Biomedical Engineering, Hanoi University of Science and Technology, Hanoi, Vietnam
| | - Michael Anthony Barry
- Westmead Hospital, Sydney, Australia; Westmead Applied Research Centre, Sydney, Australia; Faculty of Engineering and Information Technology, University of Sydney, Sydney, Australia
| | - Vu Tran
- Westmead Hospital, Sydney, Australia; Westmead Applied Research Centre, Sydney, Australia
| | - Juntang Lu
- Westmead Hospital, Sydney, Australia; Westmead Applied Research Centre, Sydney, Australia
| | - Aravinda Thiagalingam
- Westmead Hospital, Sydney, Australia; Faculty of Medicine, University of Sydney, Sydney, Australia; Westmead Applied Research Centre, Sydney, Australia
| | - Stuart P Thomas
- Westmead Hospital, Sydney, Australia; Faculty of Medicine, University of Sydney, Sydney, Australia; Westmead Applied Research Centre, Sydney, Australia
| | - Alistair McEwan
- Faculty of Engineering and Information Technology, University of Sydney, Sydney, Australia
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15
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Gunawardene M, Münkler P, Eickholt C, Akbulak RÖ, Jularic M, Klatt N, Hartmann J, Dinshaw L, Jungen C, Moser JM, Merbold L, Willems S, Meyer C. A novel assessment of local impedance during catheter ablation: initial experience in humans comparing local and generator measurements. Europace 2020; 21:i34-i42. [PMID: 30801126 DOI: 10.1093/europace/euy273] [Citation(s) in RCA: 46] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 11/10/2018] [Indexed: 11/14/2022] Open
Abstract
AIMS A novel measure of local impedance (LI) has been found to predict lesion formation during radiofrequency current (RFC) catheter ablation. The aim of this study was to investigate the utility of this novel approach, while comparing LI to the well-established generator impedance (GI). METHODS AND RESULTS In 25 consecutive patients with a history of atrial fibrillation, catheter ablation was guided by a 3D-mapping system measuring LI in addition to GI via an ablation catheter tip with three incorporated mini-electrodes. Local impedance and GI before and during RFC applications were studied. In total, 381 RFC applications were analysed. The baseline LI was higher in high-voltage areas (>0.5 mV; LI: 110.5 ± 13.7 Ω) when compared with intermediate-voltage sites (0.1-0.5 mV; 90.9 ± 10.1 Ω, P < 0.001), low-voltage areas (<0.1 mV; 91.9 ± 16.4 Ω, P < 0.001), and blood pool LI (91.9 ± 9.9 Ω, P < 0.001). During ablation, mean LI drop (△LI; 13.1 ± 9.1 Ω) was 2.15 times higher as mean GI drop (△GI) (6.1 ± 4.2 Ω, P < 0.001). Baseline LI correlated with △LI: a mean LI of 99.9 Ω predicted a △LI of 12.9 Ω [95% confidence interval (12.1-13.6), R2 0.41; P < 0.001]. This relationship was weak for baseline GI predicting △GI (R2 0.06, P < 0.001). Catheter movements were represented by rapid LI changes. The duration of an RFC application was not predictive for catheter-tissue coupling with no further change of △LI (P = 0.247) nor △GI (P = 0.376) during prolonged ablation. CONCLUSION Local impedance can be monitored during ablation. Compared with the sole use of GI, baseline LI is a better predictor of impedance drops during ablation and may provide useful insights regarding lesion formation. However, further studies are needed to investigate if this novel approach is useful to guide catheter ablation.
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Affiliation(s)
- Melanie Gunawardene
- Department of Cardiac Electrophysiology, University Heart Center, University Hospital Hamburg Eppendorf, Martinistrasse 52, Hamburg, Germany
| | - Paula Münkler
- Department of Cardiac Electrophysiology, University Heart Center, University Hospital Hamburg Eppendorf, Martinistrasse 52, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Luebeck, Berlin, Germany
| | - Christian Eickholt
- Department of Cardiac Electrophysiology, University Heart Center, University Hospital Hamburg Eppendorf, Martinistrasse 52, Hamburg, Germany
| | - Ruken Ö Akbulak
- Department of Cardiac Electrophysiology, University Heart Center, University Hospital Hamburg Eppendorf, Martinistrasse 52, Hamburg, Germany
| | - Mario Jularic
- Department of Cardiac Electrophysiology, University Heart Center, University Hospital Hamburg Eppendorf, Martinistrasse 52, Hamburg, Germany
| | - Niklas Klatt
- Department of Cardiac Electrophysiology, University Heart Center, University Hospital Hamburg Eppendorf, Martinistrasse 52, Hamburg, Germany
| | - Jens Hartmann
- Department of Cardiac Electrophysiology, University Heart Center, University Hospital Hamburg Eppendorf, Martinistrasse 52, Hamburg, Germany
| | - Leon Dinshaw
- Department of Cardiac Electrophysiology, University Heart Center, University Hospital Hamburg Eppendorf, Martinistrasse 52, Hamburg, Germany
| | - Christiane Jungen
- Department of Cardiac Electrophysiology, University Heart Center, University Hospital Hamburg Eppendorf, Martinistrasse 52, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Luebeck, Berlin, Germany
| | - Julia M Moser
- Department of Cardiac Electrophysiology, University Heart Center, University Hospital Hamburg Eppendorf, Martinistrasse 52, Hamburg, Germany
| | | | - Stephan Willems
- Department of Cardiac Electrophysiology, University Heart Center, University Hospital Hamburg Eppendorf, Martinistrasse 52, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Luebeck, Berlin, Germany
| | - Christian Meyer
- Department of Cardiac Electrophysiology, University Heart Center, University Hospital Hamburg Eppendorf, Martinistrasse 52, Hamburg, Germany.,DZHK (German Center for Cardiovascular Research), Partner Site Hamburg/Kiel/Luebeck, Berlin, Germany
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16
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Masuda M, Kanda T, Kurata N, Asai M, Iida O, Okamoto S, Ishihara T, Nanto K, Tsujimura T, Matsuda Y, Hata Y, Uematsu H, Mano T. Clinical utility of local impedance monitoring during pulmonary vein isolation. J Cardiovasc Electrophysiol 2020; 31:2584-2591. [PMID: 32671932 DOI: 10.1111/jce.14678] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2020] [Revised: 07/08/2020] [Accepted: 07/13/2020] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Local impedance (LI) at the tip of ablation catheter can be measured using a recently available technology. We aimed to explore target LI measurements at each radiofrequency application (RFA) for creating sufficient ablation lesions during pulmonary vein (PV) isolation. METHODS This prospective study included 15 consecutive patients scheduled to undergo an initial ablation of paroxysmal atrial fibrillation (AF). Circumferential ablation around both ipsilateral PVs was performed using a 4-mm irrigated ablation catheter with an LI sensor. Point-by-point ablation was used with a 4-mm inter-ablation-point distance. Operators were blinded to LI measurements during the procedure. Creation of sufficient ablation lesions was assessed by the absence of a conduction gap. RESULTS After first-pass encircling PV antrum ablation, left atrium to PV conduction remained in 12 of 30 (40%) ipsilateral PVs. Mapping using the minibasket catheter identified 48 ablation points through which the propagation wave entered the PV. At ablation points with a gap, the LI drop during RFA was half that at points without a gap (12 ± 7 vs. 23 ± 12 Ω; p < .001). The generator impedance drop did not differ between ablation points with and without a gap (12 ± 7 vs. 14 ± 10 Ω; p = .10). An LI drop of 13.4 Ω predicted sufficient lesion formation without a gap with a sensitivity of 0.78, specificity of 0.75, and predictive accuracy of 0.75. CONCLUSION An LI drop of 13.4 Ω at each RFA under the conditions of a 4-mm inter-ablation-point distance and RFA duration ≥20 s may facilitate creation of sufficient lesions during PV isolation.
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Affiliation(s)
- Masaharu Masuda
- Department of Arrhythmia, Kansai Rosai Hospital Cardiovascular Center, Amagasaki, Japan
| | - Takashi Kanda
- Department of Arrhythmia, Kansai Rosai Hospital Cardiovascular Center, Amagasaki, Japan
| | - Naoya Kurata
- Department of Arrhythmia, Kansai Rosai Hospital Cardiovascular Center, Amagasaki, Japan
| | - Mitsutoshi Asai
- Department of Arrhythmia, Kansai Rosai Hospital Cardiovascular Center, Amagasaki, Japan
| | - Osamu Iida
- Department of Arrhythmia, Kansai Rosai Hospital Cardiovascular Center, Amagasaki, Japan
| | - Shin Okamoto
- Department of Arrhythmia, Kansai Rosai Hospital Cardiovascular Center, Amagasaki, Japan
| | - Takayuki Ishihara
- Department of Arrhythmia, Kansai Rosai Hospital Cardiovascular Center, Amagasaki, Japan
| | - Kiyonori Nanto
- Department of Arrhythmia, Kansai Rosai Hospital Cardiovascular Center, Amagasaki, Japan
| | - Takuya Tsujimura
- Department of Arrhythmia, Kansai Rosai Hospital Cardiovascular Center, Amagasaki, Japan
| | - Yasuhiro Matsuda
- Department of Arrhythmia, Kansai Rosai Hospital Cardiovascular Center, Amagasaki, Japan
| | - Yosuke Hata
- Department of Arrhythmia, Kansai Rosai Hospital Cardiovascular Center, Amagasaki, Japan
| | - Hiroyuki Uematsu
- Department of Arrhythmia, Kansai Rosai Hospital Cardiovascular Center, Amagasaki, Japan
| | - Toshiaki Mano
- Department of Arrhythmia, Kansai Rosai Hospital Cardiovascular Center, Amagasaki, Japan
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17
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Nguyen DM, Qian P, Barry T, McEwan A. The region-of-interest based measurement selection process for electrical impedance tomography in radiofrequency cardiac ablation with known anatomical information. Biomed Signal Process Control 2020. [DOI: 10.1016/j.bspc.2019.101706] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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18
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Münkler P, Gunawardene MA, Jungen C, Klatt N, Schwarzl JM, Akbulak RÖ, Dinshaw L, Hartmann J, Jularic M, Kahle AK, Riedel R, Merbold L, Eickholt C, Willems S, Meyer C. Local impedance guides catheter ablation in patients with ventricular tachycardia. J Cardiovasc Electrophysiol 2019; 31:61-69. [PMID: 31701589 DOI: 10.1111/jce.14269] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Revised: 10/16/2019] [Accepted: 11/04/2019] [Indexed: 12/27/2022]
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 RFC-ablation. 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 RFC-ablation 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.
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Affiliation(s)
- Paula Münkler
- Department of Cardiology, University Heart and Vascular Center, Hamburg, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Berlin, Germany
| | - Melanie A Gunawardene
- Department of Cardiology, University Heart and Vascular Center, Hamburg, Germany.,Department of Cardiology, Asklepios Hospital St. Georg, Hamburg, Germany
| | - Christiane Jungen
- Department of Cardiology, University Heart and Vascular Center, Hamburg, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Berlin, Germany
| | - Niklas Klatt
- Department of Cardiology, University Heart and Vascular Center, Hamburg, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Berlin, Germany
| | - Jana M Schwarzl
- Department of Cardiology, University Heart and Vascular Center, Hamburg, Germany
| | - Ruken Ö Akbulak
- Department of Cardiology, University Heart and Vascular Center, Hamburg, Germany
| | - Leon Dinshaw
- Department of Cardiology, University Heart and Vascular Center, Hamburg, Germany
| | - Jens Hartmann
- Department of Cardiology, University Heart and Vascular Center, Hamburg, Germany.,Department of Cardiology, Asklepios Hospital St. Georg, Hamburg, Germany
| | - Mario Jularic
- Department of Cardiology, University Heart and Vascular Center, Hamburg, Germany.,Department of Cardiology, Asklepios Hospital St. Georg, Hamburg, Germany
| | - Ann-Kathrin Kahle
- Department of Cardiology, University Heart and Vascular Center, Hamburg, Germany
| | - René Riedel
- Max Planck Institute for Evolutionary Biology, Plön, Germany
| | | | - Christian Eickholt
- Department of Cardiology, University Heart and Vascular Center, Hamburg, Germany.,Department of Cardiology, Asklepios Hospital St. Georg, Hamburg, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Berlin, Germany
| | - Stephan Willems
- Department of Cardiology, University Heart and Vascular Center, Hamburg, Germany.,Department of Cardiology, Asklepios Hospital St. Georg, Hamburg, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Berlin, Germany
| | - Christian Meyer
- Department of Cardiology, University Heart and Vascular Center, Hamburg, Germany.,German Center for Cardiovascular Research (DZHK), Partner Site Hamburg/Kiel/Lübeck, Berlin, Germany
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John RM, Stevenson WG. A new impedance-based method to guide RF ablation: Still scratching the surface? J Cardiovasc Electrophysiol 2018; 29:1207-1209. [PMID: 29949216 DOI: 10.1111/jce.13687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 06/25/2018] [Indexed: 11/30/2022]
Affiliation(s)
- Roy M John
- Cardiovascular Division, Department of Medicine, Vanderbilt University Medical Center Nashville, Nashville, Tennessee
| | - William G Stevenson
- Cardiovascular Division, Department of Medicine, Vanderbilt University Medical Center Nashville, Nashville, Tennessee
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20
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Grossi S, Grassi F, Galleani L, Bianchi F, Conte MR. A comparison of contact force and remote magnetic navigation on lesion formation for the ablation of atrial fibrillation. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2018; 41:450-458. [DOI: 10.1111/pace.13295] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Revised: 11/01/2017] [Accepted: 11/28/2017] [Indexed: 11/29/2022]
Affiliation(s)
| | - Francesco Grassi
- Department of Electronics and Telecommunications; Politecnico di Torino; Turin Italy
| | - Lorenzo Galleani
- Department of Electronics and Telecommunications; Politecnico di Torino; Turin Italy
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21
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Rebling J, Oyaga Landa FJ, Deán-Ben XL, Douplik A, Razansky D. Integrated catheter for simultaneous radio frequency ablation and optoacoustic monitoring of lesion progression. OPTICS LETTERS 2018; 43:1886-1889. [PMID: 29652390 DOI: 10.1364/ol.43.001886] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 03/03/2018] [Indexed: 06/08/2023]
Abstract
Radio frequency (RF) catheter ablation is commonly used to eliminate dysfunctional cardiac tissue by heating via an alternating current. Clinical outcomes are highly dependent on careful anatomical guidance, electrophysiological mapping, and careful RF power titration during the procedure. Yet, current treatments rely mainly on the expertise of the surgeon to assess lesion formation, causing large variabilities in the success rate. We present an integrated catheter design suitable for simultaneous RF ablation and real-time optoacoustic monitoring of the forming lesion. The catheter design utilizes copper-coated multimode light guides capable of delivering both ablation current and near-infrared pulsed-laser illumination to the target tissue. The generated optoacoustic responses were used to visualize the ablation lesion formation in an ex-vivo bovine heart specimen in 3D. The presented catheter design enables the monitoring of ablation lesions with high spatiotemporal resolution while the overall therapy-monitoring approach remains compatible with commercially available catheter designs.
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22
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Hussein A, Das M, Chaturvedi V, Asfour IK, Daryanani N, Morgan M, Ronayne C, Shaw M, Snowdon R, Gupta D. Prospective use of Ablation Index targets improves clinical outcomes following ablation for atrial fibrillation. J Cardiovasc Electrophysiol 2017. [PMID: 28639728 DOI: 10.1111/jce.13281] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
AIMS Late recovery of ablated tissue leading to reconnection of pulmonary veins remains common following radiofrequency catheter ablation for AF. Ablation Index (AI), a novel ablation quality marker, incorporates contact force (CF), time, and power in a weighted formula. We hypothesized that prospective use of our previously published derived AI targets would result in better outcomes when compared to CF-guided ablation. METHODS Eighty-nine consecutive drug-refractory AF patients (49% paroxysmal) underwent AI-guided ablation (AI-group). AI targets were 550 for anterior/roof and 400 for posterior/inferior left atrial segments. Procedural and clinical outcomes of these patients were compared to 89 propensity-matched controls who underwent CF-guided ablation (CF-group). All 178 procedures were otherwise similar, and both groups were followed-up for 12 months. The last 25 patients from each group underwent analysis of all VisiTags™ for ablation duration, CF, Force-Time Integral, and impedance drop. RESULTS First-pass pulmonary vein isolation (PVI) was more frequent in AI-group than in CF-group (173 [97%] vs. 149 [84%] circles, P < 0.001), and acute PV reconnection was lower (11 [6%] vs. 24 [13%] circles, P = 0.02). Mean PVI ablation time was similar (AI-group: 42 ± 9 vs. CF-group: 45 ± 14 minutes, P = 0.14). Median impedance drop for AI-group was significantly higher than in CF-group (13.7 [9-19] Ω vs. 8.8 [5.2-13] Ω, P < 0.001). Two major complications occurred in CF-group and none in AI-group. Atrial tachyarrhythmia recurrence was significantly lower in AI-group (15 of 89 [17%]) than in CF-group (33 of 89 [37%], P = 0.002). CONCLUSION AI-guided ablation is associated with significant improvements in the incidence of acute PV reconnection and atrial tachyarrhythmia recurrence rate compared to CF-guided ablation, potentially due to creation of better quality lesions as suggested by greater impedance drop.
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Affiliation(s)
- Ahmed Hussein
- Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Liverpool, UK
| | - Moloy Das
- Department of Cardiology, Freeman Hospital, Newcastle upon Tyne, UK
| | - Vivek Chaturvedi
- Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Liverpool, UK
| | - Issa Khalil Asfour
- Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Liverpool, UK
| | - Niji Daryanani
- Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Liverpool, UK
| | - Maureen Morgan
- Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Liverpool, UK
| | - Christina Ronayne
- Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Liverpool, UK
| | - Matthew Shaw
- Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Liverpool, UK
| | - Richard Snowdon
- Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Liverpool, UK
| | - Dhiraj Gupta
- Institute of Cardiovascular Medicine and Science, Department of Cardiology, Liverpool Heart and Chest Hospital, Liverpool, UK
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23
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Gaeta S, Bahnson TD. Impedance Guided Radiofrequency Ablation for Atrial Fibrillation: Something Old Is New Again. J Cardiovasc Electrophysiol 2016; 27:1399-1402. [PMID: 27696590 DOI: 10.1111/jce.13105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Stephen Gaeta
- Duke Center for Atrial Fibrillation and the Clinical Cardiac Electrophysiology Section, Duke University, Durham, North Carolina, USA
| | - Tristram D Bahnson
- Duke Center for Atrial Fibrillation and the Clinical Cardiac Electrophysiology Section, Duke University, Durham, North Carolina, USA
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CHINITZ JASONS, KAPUR SUNIL, BARBHAIYA CHIRAG, KUMAR SAURABH, JOHN ROY, EPSTEIN LAURENCEM, TEDROW USHA, STEVENSON WILLIAMG, MICHAUD GREGORYF. Sites With Small Impedance Decrease During Catheter Ablation for Atrial Fibrillation Are Associated With Recovery of Pulmonary Vein Conduction. J Cardiovasc Electrophysiol 2016; 27:1390-1398. [DOI: 10.1111/jce.13095] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 08/13/2016] [Accepted: 08/25/2016] [Indexed: 11/29/2022]
Affiliation(s)
- JASON S. CHINITZ
- Department of Cardiology; Southside Hospital, Northwell Health Physician Partners; Hofstra Northshore-LIJ School of Medicine; Bayshore New York USA
- Cardiac Arrhythmia Service, Division of Cardiology, Department of Medicine; Brigham and Women's Hospital, Harvard Medical School; Boston Massachusetts USA
| | - SUNIL KAPUR
- Cardiac Arrhythmia Service, Division of Cardiology, Department of Medicine; Brigham and Women's Hospital, Harvard Medical School; Boston Massachusetts USA
| | - CHIRAG BARBHAIYA
- Cardiac Arrhythmia Service, Division of Cardiology, Department of Medicine; Brigham and Women's Hospital, Harvard Medical School; Boston Massachusetts USA
| | - SAURABH KUMAR
- Cardiac Arrhythmia Service, Division of Cardiology, Department of Medicine; Brigham and Women's Hospital, Harvard Medical School; Boston Massachusetts USA
| | - ROY JOHN
- Cardiac Arrhythmia Service, Division of Cardiology, Department of Medicine; Brigham and Women's Hospital, Harvard Medical School; Boston Massachusetts USA
| | - LAURENCE M. EPSTEIN
- Cardiac Arrhythmia Service, Division of Cardiology, Department of Medicine; Brigham and Women's Hospital, Harvard Medical School; Boston Massachusetts USA
| | - USHA TEDROW
- Cardiac Arrhythmia Service, Division of Cardiology, Department of Medicine; Brigham and Women's Hospital, Harvard Medical School; Boston Massachusetts USA
| | - WILLIAM G. STEVENSON
- Cardiac Arrhythmia Service, Division of Cardiology, Department of Medicine; Brigham and Women's Hospital, Harvard Medical School; Boston Massachusetts USA
| | - GREGORY F. MICHAUD
- Cardiac Arrhythmia Service, Division of Cardiology, Department of Medicine; Brigham and Women's Hospital, Harvard Medical School; Boston Massachusetts USA
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25
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BHASKARAN ABHISHEK, BARRY M, POULIOPOULOS JIM, NALLIAH CHRISHAN, QIAN PIERRE, CHIK WILLIAM, THAVAPALACHANDRAN SUJITHA, DAVIS LLOYD, MCEWAN ALISTAIR, THOMAS STUART, KOVOOR PRAMESH, THIAGALINGAM ARAVINDA. Circuit Impedance Could Be a Crucial Factor Influencing Radiofrequency Ablation Efficacy and Safety: A Myocardial Phantom Study of the Problem and Its Correction. J Cardiovasc Electrophysiol 2016; 27:351-7. [DOI: 10.1111/jce.12893] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2015] [Revised: 11/20/2015] [Accepted: 11/25/2015] [Indexed: 01/24/2023]
Affiliation(s)
- ABHISHEK BHASKARAN
- Cardiology Department; Westmead Hospital; Sydney Australia
- Sydney Medical School; University of Sydney; Australia
| | - M.A. BARRY
- Cardiology Department; Westmead Hospital; Sydney Australia
- Sydney Medical School; University of Sydney; Australia
- School of Electrical and Information Engineering; University of Sydney; Australia
| | - JIM POULIOPOULOS
- Cardiology Department; Westmead Hospital; Sydney Australia
- Sydney Medical School; University of Sydney; Australia
| | | | - PIERRE QIAN
- Cardiology Department; Westmead Hospital; Sydney Australia
| | - WILLIAM CHIK
- Cardiology Department; Westmead Hospital; Sydney Australia
- Sydney Medical School; University of Sydney; Australia
| | - SUJITHA THAVAPALACHANDRAN
- Cardiology Department; Westmead Hospital; Sydney Australia
- Sydney Medical School; University of Sydney; Australia
| | - LLOYD DAVIS
- Cardiology Department; Westmead Hospital; Sydney Australia
- Sydney Medical School; University of Sydney; Australia
| | - ALISTAIR MCEWAN
- School of Electrical and Information Engineering; University of Sydney; Australia
| | - STUART THOMAS
- Cardiology Department; Westmead Hospital; Sydney Australia
- Sydney Medical School; University of Sydney; Australia
| | - PRAMESH KOVOOR
- Cardiology Department; Westmead Hospital; Sydney Australia
- Sydney Medical School; University of Sydney; Australia
| | - ARAVINDA THIAGALINGAM
- Cardiology Department; Westmead Hospital; Sydney Australia
- Sydney Medical School; University of Sydney; Australia
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26
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BHASKARAN ABHISHEK, CHIK WILLIAM, NALLIAH CHRISHAN, POULIOPOULOS JIM, BARRY TONY, NGUYEN DOANTRANG, MIDEKIN CHRISTINE, SAMANTA RAHUL, FARRAHA MELAD, THOMAS STUART, KOVOOR PRAMESH, THIAGALINGAM ARAVINDA. Observations on Attenuation of Local Electrogram Amplitude and Circuit Impedance During Atrial Radiofrequency Ablation: An In vivo
Investigation Using a Novel Direct Endocardial Visualization Catheter. J Cardiovasc Electrophysiol 2015; 26:1250-1256. [DOI: 10.1111/jce.12774] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2014] [Revised: 07/15/2015] [Accepted: 07/20/2015] [Indexed: 01/01/2023]
Affiliation(s)
- ABHISHEK BHASKARAN
- Cardiology Department; Westmead Hospital; Australia
- Sydney Medical School; Australia
| | - WILLIAM CHIK
- Cardiology Department; Westmead Hospital; Australia
- Sydney Medical School; Australia
| | | | - JIM POULIOPOULOS
- Cardiology Department; Westmead Hospital; Australia
- Sydney Medical School; Australia
| | - TONY BARRY
- Cardiology Department; Westmead Hospital; Australia
- Sydney Medical School; Australia
- School of Electrical and Information Engineering; University of Sydney; Australia
| | - DOAN TRANG NGUYEN
- Sydney Medical School; Australia
- School of Electrical and Information Engineering; University of Sydney; Australia
| | | | | | - MELAD FARRAHA
- Cardiology Department; Westmead Hospital; Australia
- Sydney Medical School; Australia
| | - STUART THOMAS
- Cardiology Department; Westmead Hospital; Australia
- Sydney Medical School; Australia
| | - PRAMESH KOVOOR
- Cardiology Department; Westmead Hospital; Australia
- Sydney Medical School; Australia
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27
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Reichlin T, Knecht S, Lane C, Kühne M, Nof E, Chopra N, Tadros TM, Reddy VY, Schaer B, John RM, Osswald S, Stevenson WG, Sticherling C, Michaud GF. Initial impedance decrease as an indicator of good catheter contact: insights from radiofrequency ablation with force sensing catheters. Heart Rhythm 2013; 11:194-201. [PMID: 24177370 DOI: 10.1016/j.hrthm.2013.10.048] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Indexed: 12/22/2022]
Abstract
BACKGROUND Good catheter-tissue contact force (CF) is critical for transmural and durable lesion formation during radiofrequency (RF) ablation but is difficult to assess in clinical practice. Tissue heating during RF application results in an impedance decrease at the catheter tip. OBJECTIVE The purpose of this study was to correlate achieved CF and initial impedance decreases during atrial fibrillation (AF) ablation. METHODS We correlated achieved CF and initial impedance decreases in patients undergoing ablation for AF with two novel open-irrigated CF-sensing RF catheters (Biosense Webster SmartTouch, n = 647 RF applications; and Endosense TactiCath, n = 637 RF applications). We then compared those impedance decreases to 691 RF applications with a standard open-irrigated RF catheter (Biosense Webster ThermoCool). RESULTS When RF applications with the CF-sensing catheters were analyzed according to an achieved average CF <5 g, 5-10 g, 10-20 g, and >20 g, the initial impedance decreases during ablation were larger with greater CF. Corresponding median values at 20 seconds were 5 Ω (interquartile range [IQR] 2-7), 8 Ω (4-11), 10 Ω (7-16), and 14 Ω (10-19) with the SmartTouch and n/a, 4 Ω (0-10), 8 Ω (5-12), and 13 Ω (8-18) with the TactiCath (P <.001 between categories for both catheters). When RF applications with the SmartTouch (CF-sensing catheter, median achieved CF 12 g) and ThermoCool (standard catheter) were compared, the initial impedance decrease was significantly greater in the CF-sensing group with median decreases of 10 Ω (6-14 Ω) vs 5 Ω (2-10 Ω) at 20 seconds (P <.001 between catheters). CONCLUSION The initial impedance decrease during RF applications in AF ablations is larger when greater catheter contact is achieved. Monitoring of the initial impedance decrease is a widely available indicator of catheter contact and may help to improve formation of durable ablation lesions.
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Affiliation(s)
- Tobias Reichlin
- Cardiovascular Division, Brigham and Women's Hospital, Boston, Massachusetts; University Hospital, Basel, Switzerland.
| | | | - Christopher Lane
- Cardiovascular Division, Brigham and Women's Hospital, Boston, Massachusetts
| | | | - Eyal Nof
- Cardiovascular Division, Brigham and Women's Hospital, Boston, Massachusetts; Leviev Heart Center, Sheba Medical Center, Tel Hashomer, Israel
| | - Nagesh Chopra
- Cardiovascular Division, Brigham and Women's Hospital, Boston, Massachusetts
| | - Thomas M Tadros
- Cardiovascular Division, Brigham and Women's Hospital, Boston, Massachusetts
| | - Vivek Y Reddy
- Helmsley Electrophysiology Center, The Cardiovascular Institute, Mount Sinai School of Medicine, New York, New York
| | | | - Roy M John
- Cardiovascular Division, Brigham and Women's Hospital, Boston, Massachusetts
| | | | - William G Stevenson
- Cardiovascular Division, Brigham and Women's Hospital, Boston, Massachusetts
| | | | - Gregory F Michaud
- Cardiovascular Division, Brigham and Women's Hospital, Boston, Massachusetts
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KUMAR SAURABH, CHAN MARTIN, LEE JUSTIN, WONG MICHAELC, YUDI MATIAS, MORTON JOSEPHB, SPENCE STEVENJ, HALLORAN KAREN, KISTLER PETERM, KALMAN JONATHANM. Catheter-Tissue Contact Force Determines Atrial Electrogram Characteristics Before and Lesion Efficacy After Antral Pulmonary Vein Isolation in Humans. J Cardiovasc Electrophysiol 2013; 25:122-9. [DOI: 10.1111/jce.12293] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 08/25/2013] [Accepted: 08/29/2013] [Indexed: 11/30/2022]
Affiliation(s)
- SAURABH KUMAR
- Department of Cardiology; Parkville Victoria Australia
- Department of Medicine, The Royal Melbourne Hospital; University of Melbourne; Parkville Victoria Australia
| | - MARTIN CHAN
- Department of Cardiology; Parkville Victoria Australia
| | - JUSTIN LEE
- Department of Cardiology; Parkville Victoria Australia
| | - MICHAEL C.G. WONG
- Department of Cardiology; Parkville Victoria Australia
- Department of Medicine, The Royal Melbourne Hospital; University of Melbourne; Parkville Victoria Australia
| | - MATIAS YUDI
- Department of Cardiology; Parkville Victoria Australia
| | - JOSEPH B. MORTON
- Department of Cardiology; Parkville Victoria Australia
- Department of Medicine, The Royal Melbourne Hospital; University of Melbourne; Parkville Victoria Australia
| | | | | | - PETER M. KISTLER
- Department of Medicine, The Royal Melbourne Hospital; University of Melbourne; Parkville Victoria Australia
- Department of Cardiology; Alfred Hospital and Baker IDI; Melbourne Australia
| | - JONATHAN M. KALMAN
- Department of Cardiology; Parkville Victoria Australia
- Department of Medicine, The Royal Melbourne Hospital; University of Melbourne; Parkville Victoria Australia
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DE BORTOLI ALESSANDRO, SUN LIZHI, SOLHEIM EIVIND, HOFF PERIVAR, SCHUSTER PETER, OHM OLEJ, CHEN JIAN. Ablation Effect Indicated by Impedance Fall is Correlated with Contact Force Level During Ablation for Atrial Fibrillation. J Cardiovasc Electrophysiol 2013; 24:1210-5. [DOI: 10.1111/jce.12215] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Revised: 05/23/2013] [Accepted: 06/07/2013] [Indexed: 11/30/2022]
Affiliation(s)
- ALESSANDRO DE BORTOLI
- Department of Heart Disease; Haukeland University Hospital and Department of Clinical Science; University of Bergen; Bergen Norway
| | - LI-ZHI SUN
- Department of Heart Disease; Haukeland University Hospital and Department of Clinical Science; University of Bergen; Bergen Norway
| | - EIVIND SOLHEIM
- Department of Heart Disease; Haukeland University Hospital and Department of Clinical Science; University of Bergen; Bergen Norway
| | - PER IVAR HOFF
- Department of Heart Disease; Haukeland University Hospital and Department of Clinical Science; University of Bergen; Bergen Norway
| | - PETER SCHUSTER
- Department of Heart Disease; Haukeland University Hospital and Department of Clinical Science; University of Bergen; Bergen Norway
| | - OLE-JøRGEN OHM
- Department of Heart Disease; Haukeland University Hospital and Department of Clinical Science; University of Bergen; Bergen Norway
| | - JIAN CHEN
- Department of Heart Disease; Haukeland University Hospital and Department of Clinical Science; University of Bergen; Bergen Norway
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30
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Kumar S, Haqqani H, Chan M, Lee J, Yudi M, Wong MC, Morton JB, Ling LH, Robinson T, Heck PM, Kelland NF, Halloran K, Spence SJ, Kistler PM, Kalman JM. Predictive value of impedance changes for real-time contact force measurements during catheter ablation of atrial arrhythmias in humans. Heart Rhythm 2013; 10:962-9. [DOI: 10.1016/j.hrthm.2013.03.022] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2013] [Indexed: 11/16/2022]
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31
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Yeo WT, Sporton SCE, Dhinoja M, Schilling RJ, Earley MJ. Utility of mapping signals to improve precision of atrioventricular node ablation. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2013; 36:1357-63. [PMID: 23763518 DOI: 10.1111/pace.12199] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Revised: 04/04/2013] [Accepted: 05/04/2013] [Indexed: 12/01/2022]
Abstract
BACKGROUND Atrioventricular node (AVN) ablation is effective for rate control in atrial fibrillation. This may require multiple radiofrequency applications to achieve complete atrioventricular block (CAB). In this retrospective study, we tested the hypothesis that mapping the AVN utilizing electrograms (EGMs) on both proximal and distal bipoles of the mapping catheter may improve the likelihood of CAB. METHODS Lesion characteristics and EGM components on the proximal and distal bipoles of the ablation catheter in first-time AVN ablation procedures were analyzed. Outcomes of each lesion, including presence of CAB, acute recurrence of AVN conduction, new-onset right bundle branch block (RBBB), and junctional escape rhythm, were analyzed. Multivariate binary logistic regression analysis was performed to identify EGM characteristics that independently predicted the outcomes of interest. Lesions with these EGM characteristics were then identified and their outcomes compared with the whole cohort. RESULTS A total of 441 ablation lesions were analyzed. EGM characteristics that independently predicted outcomes were the presence of His and atrial EGMs on the distal bipole and the absence of ventricular EGM on the proximal bipole. Among the 25 lesions with all these characteristics, 18 (72%) resulted in CAB compared to the overall cohort rate of 38% (P = 0.001). There was no new-onset RBBB. The likelihood of acute recurrent AVN conduction and junctional escape rhythm were similar. CONCLUSION Combining proximal and distal bipole EGM characteristics of the ablation catheter can improve the accuracy of AVN localization during AVN ablation and avoid right bundle branch injury.
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Affiliation(s)
- Wee Tiong Yeo
- Department of Cardiology, St Bartholomew's Hospital, London, UK; Department of Cardiology, National University Heart Centre, Singapore
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PIORKOWSKI CHRISTOPHER, SIH HARIS, SOMMER PHILIPP, MILLER STEPHANP, GASPAR THOMAS, TEPLITSKY LIANE, HINDRICKS GERHARD. First in Human Validation of Impedance-Based Catheter Tip-to-Tissue Contact Assessment in the Left Atrium. J Cardiovasc Electrophysiol 2009; 20:1366-73. [DOI: 10.1111/j.1540-8167.2009.01552.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Kuck KH, Ernst S, Dorwarth U, Hoffmann E, Pitschner H, Tebbenjohanns J, Kottkamp H. [Guidelines for catheter ablation]. Clin Res Cardiol 2008; 96:833-49. [PMID: 17955158 DOI: 10.1007/s00392-007-0590-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Karl-Heinz Kuck
- AK St. Georg, II. Med. Abteilung (Kardiologie), Lohmühlenstr. 5, 20099, Hamburg, Germany.
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Thiagalingam A, D'Avila A, McPherson C, Malchano Z, Ruskin J, Reddy VY. Impedance and temperature monitoring improve the safety of closed-loop irrigated-tip radiofrequency ablation. J Cardiovasc Electrophysiol 2007; 18:318-25. [PMID: 17313656 DOI: 10.1111/j.1540-8167.2006.00745.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
INTRODUCTION Irrigated-tip catheter ablation allows larger ablation lesions to be created, but also decreases catheter temperature monitoring accuracy. It is unclear which parameters should be monitored to optimize efficacy and safety during irrigated-tip ablation. METHODS AND RESULTS Freshly excised hearts from eight male pigs were perfused and superfused using oxygenated swine blood in an ex vivo model. Ablations were performed for 1 minute using one of five different ablation protocols: (1) Temperature Control (42 degrees C 40 W), (2) Fixed Power 20 W, (3) Fixed Power 30 W, (4) Impedance Control (target 10 ohm impedance drop), and (5) Impedance Control (target 20 ohm drop). All ablations were performed with a perpendicular orientation of the catheter to the endocardial surface. Ablation lesions depth was significantly lower in the temperature control group (5.0 +/- 1.7 mm) compared with the fixed power ablation groups (6.5 +/- 1.0 mm for Power 20 W, 6.6 +/- 1.2 mm for Power 30 W). Impedance-controlled ablation created lesions intermediate in depth between fixed power and temperature controlled (6.0 +/- 1.6 for Impedance 10 ohms and 6.2 +/- 1.4 mm for Impedance 20 ohms groups). There was a significantly greater incidence of pops and thrombus formation in the Power 20 W (9/14), Power 30 W (10/14), and Impedance 20 ohms (10/16) groups than the Temperature Control (1/16) and Impedance control 10 ohms (2/16) groups. CONCLUSION Temperature control improved the safety profile during irrigated-tip ablation in comparison with fixed-power ablations, but resulted in significantly smaller lesions. Impedance-controlled ablation lesions (target 10 ohm drop) created lesions of comparable size to fixed-power ablations with a significantly better safety profile.
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Affiliation(s)
- Aravinda Thiagalingam
- Department of Cardiac Electrophysiology, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
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Wittkampf FHM, Nakagawa H. RF Catheter Ablation: Lessons on Lesions. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2006; 29:1285-97. [PMID: 17100685 DOI: 10.1111/j.1540-8159.2006.00533.x] [Citation(s) in RCA: 204] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The present treatment of atrial fibrillation by radiofrequency catheter ablation requires long continuous lesions in the thin walled left atrium where side effects may lead to serious complications. Better understanding of the physical processes that take place during ablation may help to improve the quality, safety, and outcome of these procedures. These processes include the distribution of power between blood, tissue, and patient; the mechanisms of tissue heating and coagulum formation; the relation between tissue and electrode temperatures; and the effects of increased electrode size and internal and external electrode cooling. With normal electrode-tissue contact, only a fraction of all power is effectively delivered to the tissue. Due to the variability of blood flow cooling, applied power and electrode temperature rise are poor indicators of lesion formation. With a longer electrode, the efficiency of tissue heating is decreased and the greater variation in tissue contact caused by electrode orientation makes lesion formation even more unpredictable. The absence of impedance rise during ablation does not guarantee the absence of blood clot formation on the tissue contact site. Blood clots may unnoticeably be created on the lesion surface and are caused by thermal denaturization of blood proteins, independent of heparinization. Irrigated ablation with external flush may prevent blood clot formation. Irrigation minimally affects lesion size by cooling the tissue surface. Larger lesions may only be created by the application of higher power levels. Electrode cooling, however, impedes electrode temperature feed back and blinds the operator for excessive tissue heating. External cooling alone with preservation of temperature feed back is a promising concept that may lead to improved procedural safety and success.
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Reithmann C, Remp T, Hoffmann E, Matis T, Wakili R, Steinbeck G. Different Patterns of the Fall of Impedance as the Result of Heating During Ostial Pulmonary Vein Ablation: Implications for Power Titration. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2005; 28:1282-91. [PMID: 16403160 DOI: 10.1111/j.1540-8159.2005.00269.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND A variety of strategies have been proposed to avoid the risks of pulmonary vein ablation for atrial fibrillation. The fall of impedance during radiofrequency catheter ablation can be used as a real time measure of tissue heating. The aim of this study was to analyze the impedance fall during ostial pulmonary vein ablation and to evaluate whether adjusting power to the fall of impedance may contribute to a reduction of the risk of complications. METHODS Analysis of biophysical parameters of ablation and determination of ostial diameters during follow-up were performed in 70 patients undergoing impedance-guided segmental ostial pulmonary vein ablation. Repeat radiographic angiography, local electrograms, and baseline impedance were the criteria to define the position of the 4-mm electrode tip at atrial sites or inside the proximal pulmonary veins. RESULTS Energy application inside the proximal pulmonary veins led to an increased impedance fall inside the first 5-10 mm of the pulmonary veins (1.1 +/- 0.5 Omega/W) as compared to ablation at atrial sites (0.7 +/- 0.3 Omega/W) (P < 0.01). The analysis of temperature and impedance fall during ostial ablation demonstrated an increased impedance fall with heating at sites inside the proximal pulmonary veins (1.5 +/- 0.6 Omega/ degrees C) as compared to atrial sites (1.2 +/- 0.5 Omega/ degrees C) (P < 0.001). The regression lines analyzing these correlations indicated that adjusting power to a maximum impedance fall of 20 Omega would limit heating at pulmonary venous sites to lower temperatures (average maximum temperature: 48 degrees C) than at atrial sites (average maximum temperature: 63 degrees C). The ablation strategy used for segmental ostial ablation in 70 patients, which involved power limitation to a maximum impedance fall of 20 Omega, allowed isolation of 89% of targeted pulmonary veins with a low rate of impedance rises (0.3% of applications). No pulmonary vein stenoses >30% were detected by follow-up computed tomography analysis. CONCLUSIONS An increased impedance fall as the result of heating during ostial ablation was found inside the proximal pulmonary veins as compared to atrial sites. Adjusting power to the fall of impedance during segmental ostial pulmonary vein ablation contributes to the prevention of overheating inside the pulmonary veins and may lower the risk of coagulum formation and pulmonary vein stenosis.
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Daoud EG. Real-time impedance monitoring: a simple technique for a complex ablation. Heart Rhythm 2005; 2:921-2. [PMID: 16171743 DOI: 10.1016/j.hrthm.2005.07.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2005] [Indexed: 11/17/2022]
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Soejima K, Delacretaz E, Suzuki M, Brunckhorst CB, Maisel WH, Friedman PL, Stevenson WG. Saline-cooled versus standard radiofrequency catheter ablation for infarct-related ventricular tachycardias. Circulation 2001; 103:1858-62. [PMID: 11294803 DOI: 10.1161/01.cir.103.14.1858] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Saline cooling of the electrode during radiofrequency (RF) ablation increases lesion size in animal models. If cooled RF also increases lesion size in human infarcts, it should facilitate the termination of ventricular tachycardia (VT). METHODS AND RESULTS In 66 patients with VT due to prior infarction, 366 ablation sites, which were classified by entrainment and isolated potentials followed by ablation during VT with either standard RF energy (247 sites) or cooled RF (119 sites), were retrospectively reviewed to compare the efficacy for terminating VT. RF energy was applied at 259 isthmus sites, 62 bystander sites, 28 inner loop sites, and 17 outer loop sites. Compared with standard RF, cooled RF terminated VT more frequently at isthmus sites where an isolated potential was present (89% versus 54%, P=0.003), isthmus sites without an isolated potential (36% versus 21%, P=0.04), and at inner loop sites (60% versus 22%, P=0.04). Termination rates were similarly low for cooled and standard RF at bystander sites (14% versus 9%, P=0.56) and outer loop sites (13% versus 11%, P=0.93). CONCLUSIONS Greater efficacy of cooled RF for terminating VT is consistent with the production of a larger lesion in human infarctions, which should facilitate successful ablation.
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Affiliation(s)
- K Soejima
- Cardiovascular Division, Department of Internal Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Nsah E, Berger R, Rosenthal L, Hui R, Ramza B, Jumrussirikul P, Lawrence JH, Tomaselli G, Kass D, Calkins H. Relation between impedance and electrode temperature during radiofrequency catheter ablation of accessory pathways and atrioventricular nodal reentrant tachycardia. Am Heart J 1998; 136:844-51. [PMID: 9812080 DOI: 10.1016/s0002-8703(98)70130-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVES Impedance monitoring has been proposed as a method to assess the adequacy of tissue heating during catheter ablation procedures. The purpose of this study was to evaluate the relation among initial impedance, fall in impedance, and electrode temperature during catheter ablation procedures. METHODS AND RESULTS Data from 248 applications of radiofrequency energy in 45 consecutive patients (26 with accessory pathways and 19 with atrioventricular nodal reentrant tachycardia) referred for catheter ablation were analyzed. The initial impedance was higher during ablation of accessory pathways than during atrioventricular nodal reentrant tachycardia (116+/-66 versus 106+/-80 omega, P < .001). In both groups, a significant correlation was observed between the initial impedance and temperature (R = 0.98, P < .001). After accounting for differences between patients and ablation targets, an even closer correlation was observed (accessory pathways: R = 0.95, P < .0001; atrioventricular nodal reentrant tachycardia: R = 0.94, P < .0001). CONCLUSION These data suggest that monitoring of the initial impedance and the fall in impedance during ablation procedures may provide clinically valuable information to assess the efficacy of tissue heating and lesion formation.
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Affiliation(s)
- E Nsah
- Johns Hopkins Medical Institutions, Baltimore, MD, USA
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Stevenson WG, Friedman PL, Kocovic D, Sager PT, Saxon LA, Pavri B. Radiofrequency catheter ablation of ventricular tachycardia after myocardial infarction. Circulation 1998; 98:308-14. [PMID: 9711935 DOI: 10.1161/01.cir.98.4.308] [Citation(s) in RCA: 202] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Patients with ventricular tachycardia (VT) after myocardial infarction often have multiple morphologies of inducible VT, which complicates mapping and is viewed by some as a relative contraindication to ablation. Attempting to identify and target a single "clinical" VT is often limited by inability to obtain 12-lead ECGs of VTs that are terminated emergently or by defibrillators. This study assesses the feasibility of ablation in patients selected without regard to the presence of multiple VTs by targeting all VTs that allow mapping. METHODS AND RESULTS Radiofrequency catheter ablation targeting all inducible monomorphic VTs that allowed mapping was performed in 52 patients with prior myocardial infarction. Antiarrhythmic drug therapy had failed in 41 (79%) patients including amiodarone in 36 (69%) patients. An average of 3.6+/-2 morphologies of VT were induced per patient. More than 1 ablation session was required in 16 (31%) patients. Complications occurred in 5 (10%) patients, including 1 (2%) death caused by acute myocardial infarction. During follow-up 59% of patients continued to receive amiodarone; 23 (45%) had implantable defibrillators. During a mean follow-up of 18+/-15 months (range 0 to 51 months) 1 patient died suddenly, 2 died from uncontrollable VT, and 5 died from heart failure. Three-year survival rate was 70+/-10%, and rate for risk of VT recurrence was 33+/-7%. CONCLUSIONS Radiofrequency catheter ablation controls VT that is sufficiently stable to allow mapping in 67% of patients despite failure of antiarrhythmic drug therapy and multiple inducible VTs. However, ablation was largely adjunctive to amiodarone and defibrillators in this referral population.
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Affiliation(s)
- W G Stevenson
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Mass 02115, USA.
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Avitall B, Mughal K, Hare J, Helms R, Krum D. The effects of electrode-tissue contact on radiofrequency lesion generation. Pacing Clin Electrophysiol 1997; 20:2899-910. [PMID: 9455749 DOI: 10.1111/j.1540-8159.1997.tb05458.x] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
During the generation of radiofrequency (RF) lesions in the ventricular myocardium, the maintenance of adequate electrode-tissue contact is critically important. In this study, lesion dimensions and temperature and impedance changes were evaluated while controlling electrode-tissue contact levels (-5, 0, +1, and +3 mm) and power levels (10, 20, and 30 W). This data was used to assess the ability of impedance and temperature monitoring to provide useful information about the quality of electrode-tissue contact. The results show that as the electrode-tissue contact increases, so does the amount of temperature rise. With the electrode floating in blood (-5 contact), the average maximum temperature increase with 20 and 30 W was only 7 +/- 1 and 11 +/- 2 degrees C, respectively. At 20 and 30 W the temperature plateaued shortly after the initiation of power application. With good electrode-tissue contact (+1 mm or +3 mm), the temperature increase within the first 10 seconds was significantly greater than the temperature increase from baseline with poor contact (0 mm or -5 mm) and reached a maximum of 60 +/- 1 degrees C after 60 seconds of power application. As the electrode-tissue contact increased, so did the rate and level of impedance decrease. However, the rate of impedance decrease was slower compared to the rate of temperature rise. With the electrode floating in blood, the maximum impedance decreases with 20 and 30 W were 6 +/- 6 omega and 9 +/- 5 omega, respectively. The impedances plateaued after a few seconds of power application. With the electrode in good contact, the maximum impedance decreases with 20 and 30 W were 25 +/- 2 omega and 20 +/- 6 omega, respectively. In these cases the rate of the impedance decrease plateaued after 40 seconds of power application. The increase in lesion diameter and depth correlate well with decreasing impedance and increasing temperature. However, lesion depth appears to correlate better with impedance than temperature. We conclude that, since the electrode-tissue contact is not known prior to the application of power to the endocardium, in the absence of a temperature control system, the power should initially be set at a low level. The power should be increased slowly over 20-30 seconds, and then maintained at its final level for at least 90 seconds to allow for maximal lesion depth maturation. The power level should be lowered if the impedance drop exceeds 15 omega.
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Affiliation(s)
- B Avitall
- Electrophysiology Laboratory, University of Wisconsin-Milwaukee Clinical Campus, Sinai Samaritan Medical Center, USA
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Abstract
Radiofrequency catheter ablation is a highly effective, curative treatment for arrhythmias related to accessory atrioventricular connections. Compared with medical therapy, ablation is more definitive, is more cost-effective, and is associated with a lower risk of proarrhythmia. This article updates the reader on the current indications, techniques, and innovations related to ablation of accessory pathways using radiofrequency energy.
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Affiliation(s)
- B P Knight
- Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, USA
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Berger RD, Nsah E, Calkins H. Signal-averaged intracardiac electrograms: a new method to detect kent potentials. J Cardiovasc Electrophysiol 1997; 8:155-60. [PMID: 9048246 DOI: 10.1111/j.1540-8167.1997.tb00777.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
INTRODUCTION In patients with manifest accessory pathways, Kent potentials are often difficult to identify even at sites of successful catheter ablation, due largely to signal noise and catheter instability. We hypothesized that signal averaging the intracardiac electrogram recorded from the ablation catheter over a number of beats would improve the signal-to-noise ratio of the electrogram and aid in the detection of Kent potentials at accessory pathway locations. METHODS AND RESULTS We retrospectively analyzed distal-pair electrograms recorded from 9 successful, 6 transiently successful, and 10 failed ablation sites in 10 patients with manifest accessory pathways who underwent catheter ablation. We developed custom software to finely align 20 to 30 consecutive sinus beats and compute the signal average of the electrogram (SAE) for each site. Kent potentials were classified as probable, possible, or absent in the raw ablation site electrogram and the SAE base on morphologic criteria. A measure of beat-to-beat signal instability, the variability quotient (VQ), was also computed for each site. Probable Kent potentials were found in the raw ablation site electrogram at only 2 of the 15 successful and transiently successful sites, but were found in the SAE at 10 of these sites (P = 0.008). Eight of the 9 successful sites had VQ < 0.2, suggesting stable catheter-tissue contact, while 3 of the 6 transiently successful sites had VQ > 0.2, indicating unstable contact. CONCLUSIONS Signal averaging the intracardiac ablation site electrogram enhances detection of Kent potentials at accessory pathway locations. Catheter instability can be quantified by signal variability analysis and, when high, may predict lack of successful ablation even at sites where Kent potentials are present.
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Affiliation(s)
- R D Berger
- Johns Hopkins School of Medicine, Baltimore, Maryland 21287, USA
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Wen ZC, Chen SA, Tai CT, Chiang CE, Lee SH, Chen YJ, Yu WC, Huang JL, Chang MS. Temperature monitoring in radiofrequency catheter ablation of atrial flutter using the linear ablation technique. J Cardiovasc Electrophysiol 1996; 7:1050-7. [PMID: 8930736 DOI: 10.1111/j.1540-8167.1996.tb00480.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
INTRODUCTION Information about temperature and impedance monitoring during radiofrequency catheter linear ablation of atrial flutter has not been reported. We proposed that a radiofrequency catheter ablation system using a closedloop temperature control model could decrease the incidence of coagulum formation and shorten the radiation exposure and procedure times compared with those found in a power control model. METHODS AND RESULTS Forty patients (8 women and 32 men; mean age 64 +/- 7 years) with atrial flutter were referred for radiofrequency ablation. The patients were randomized into two groups: group I patients underwent radiofrequency catheter linear ablation of atrial flutter using a power control of energy output model; and group II patients underwent the closedloop temperature control model with a target electrode temperature of 70 degrees C. As compared with group II, group I patients had a higher incidence of coagulum formation (12% vs 2%, P < 0.05), temperature shutdown (11% vs 0%, P < 0.01), and impedance shutdown (16% vs 3%, P < 0.01), more radiofrequency applications (7 +/- 3 vs 4 +/- 2, P < 0.01), and longer procedure time (100 +/- 25 vs 75 +/- 23 minutes, P < 0.05) and radiation exposure time (31 +/- 10 vs 20 +/- 7 minutes, P < 0.05) required for successful ablation. Larger deviations of temperature (9.0 degrees +/- 2.4 degrees C vs 5.0 degrees +/- 1.2 degrees C, P < 0.0001) and impedance (9.2 +/- 2.6 omega vs 5.3 +/- 1.6 omega, P < 0.0001) were also found in group I patients compared with those in group II. CONCLUSIONS This study demonstrated that a closed-loop temperature control model could facilitate the effects of radiofrequency catheter ablation of the atrial flutter circuit by decreasing coagulum formation, temperature and impedance shutdown, and procedure and radiation exposure times.
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Affiliation(s)
- Z C Wen
- Department of Medicine, National Yang-Ming University, School of Medicine, Taipei, Republic of China
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Mackey S, Thornton L, He DS, Marcus FI, Lampe LF. Simultaneous multipolar radiofrequency ablation in the monopolar mode increases lesion size. Pacing Clin Electrophysiol 1996; 19:1042-8. [PMID: 8823830 DOI: 10.1111/j.1540-8159.1996.tb03411.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Delivery of radiofrequency (RF) energy from the distal tip of electrophysiology catheters produces lesions that may be too small to ablate arrhythmogenic sites during a single application of RF energy. To produce larger lesions, we delivered RF energy via a quadripolar catheter in which all four electrodes were connected in unipolar fashion. The catheter (Webster Labs) had a 4-mm tip, 2-mm ring electrodes, and 2-mm interelectrode distance. Lesion size was compared using RF energy delivered in a multipolar configuration with that delivered only to the distal tip using fresh bovine ventricular tissue. In vivo, RF lesions were made in dogs using the distal tip as well as all four poles of the same catheter inserted percutaneously. RF energy was delivered using a constant voltage at a frequency of 400 kHz. Preliminary experiments were conducted to determine the maximum power deliverable without coagulation using each electrode configuration. The use of simultaneous multipolar RF ablation produced significantly larger lesions both in vitro and in vivo. The length of the lesion was increased by a factor of approximately 2 in both the in vitro and in vivo experiments. There was a trend toward an increasing depth of the lesion by simultaneously applying RF energy to all four electrodes. Lesion width was significantly increased in the in vivo studies. We concluded that simultaneous multipolar delivery of RF energy produces larger lesions than can be obtained with delivery of RF energy to the distal tip alone. This technique may offer a means of increasing lesion size, leading to a decrease in the number of applications of RF energy necessary for ablation of arrhythmias.
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Affiliation(s)
- S Mackey
- Department of Medicine, University of Arizona College of Medicine, Tucson, USA
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Morady F, Strickberger A, Man KC, Daoud E, Niebauer M, Goyal R, Harvey M, Bogun F. Reasons for prolonged or failed attempts at radiofrequency catheter ablation of accessory pathways. J Am Coll Cardiol 1996; 27:683-9. [PMID: 8606282 DOI: 10.1016/0735-1097(95)00493-9] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
OBJECTIVES The purpose of this study was to categorize the reasons for a prolonged or failed procedure in a series of patients undergoing catheter ablation of an accessory pathway. BACKGROUND Radiofrequency ablation of accessory pathways at times requires a lengthy procedure or a second ablation session, or both, and not prior studies have systematically investigated the reasons for this. METHODS In a consecutive series of 619 patients undergoing catheter ablation of an accessory pathway, the mean ablation time +/- SD was 68 +/- 64 min. The subjects of this study were 14 patients who had an ablation time >2 SD greater than the mean (>196 min) and 51 patients who required a second ablation session for a successful outcome. The accessory pathway in the 65 patients in this study was located in the right free wall in 19 patients (29%), septum in 14 (22%) and left free wall in 32 (49%). RESULTS The primary reasons for a lengthy or failed ablation attempt were 1) inability to position the ablation catheter at the effective target site (16 patients, 25%); 2) instability of the ablation catheter or inadequate tissue contact at the target site, or both (15 patients, 23%); 3) mapping error due to an oblique course of the accessory pathway (7 patients, 11%); 4) failure to recognize a posteroseptal accessory pathway as being left-sided instead of right-sided (4 patients, 6%); 5) other errors in accessory pathway localization (6 patients, 9%); 6) epicardial location of the accessory pathway (5 patients, 8%); 7) recurrent atrial fibrillation (2 patients, 3%); 8) occurrence of a complication (2 patients, 3%); 9) unusual right-sided accessory pathway that inserted in the anterior right ventricle, 2 cm away from the lateral tricuspid annulus (1 patient, 1.5%); and 10) unexplained factors (7 patients, 11%). The most common effective strategies employed to achieve a successful outcome in these patients were 1) substitution of a more experienced operator; 2) use of ablation catheters of varying configurations; 3) switching from a retrograde aortic to a trans-septal approach; 4) switching from an inferior to a superior vena caval approach; 5) use of a 60-cm guiding sheath; 6) detailed mapping of the atrial or ventricular insertion of the accessory pathway; and 7) searching within the coronary sinus for a presumed accessory pathway potential. CONCLUSIONS A lengthy or failed attempt at catheter ablation of an accessory pathway may be due to a variety of reasons, the most common of which are problems related to some aspect of catheter manipulation and errors in accessory pathway localization. Knowledge of the most common reasons for a lengthy or ineffective procedure may facilitate successful outcome of accessory pathway ablation.
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Affiliation(s)
- F Morady
- Division of Cardiology, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0022, USA
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47
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Affiliation(s)
- J M Miller
- Cardiology Section, Temple University School of Medicine, Philadelphia, Pennsylvania 19140, USA
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48
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Tracy CM, Moore HJ, Solomon AJ, Rodak DJ, Fletcher RD. Thermistor guided radiofrequency ablation of atrial insertion sites in patients with accessory pathways. Pacing Clin Electrophysiol 1995; 18:2001-7. [PMID: 8552513 DOI: 10.1111/j.1540-8159.1995.tb03860.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Radiofrequency ablation has gained acceptance in the treatment of patients with symptomatic Wolff-Parkinson-White syndrome. The purpose of this study was to characterize the relation between temperature and other electroconductive parameters in patients undergoing atrial insertion accessory pathway ablation utilizing a thermistor equipped catheter. The mean temperature and power at sites of atrial insertion ablation are lower than has been previously associated with creation of radiofrequency lesions in the ventricle. While high cavitary blood flow in the atrium may result in cooling, the thinner atrial tissue may require less energy to achieve adequate heating than ventricular myocardium.
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Affiliation(s)
- C M Tracy
- Georgetown University Hospital, Division of Cardiology, Washington, DC 20007, USA
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49
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Hartung WM, Burton ME, Deam AG, Walter PF, McTeague K, Langberg JJ. Estimation of temperature during radiofrequency catheter ablation using impedance measurements. Pacing Clin Electrophysiol 1995; 18:2017-21. [PMID: 8552515 DOI: 10.1111/j.1540-8159.1995.tb03862.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Temperature monitoring during radiofrequency catheter ablation is useful but requires specialized equipment that is not generally available. Previous studies have shown that impedance characteristically decreases as the result of heating at the electrode-tissue interface. The purpose of the current study was to determine if impedance changes during radiofrequency current application could be used to estimate endocardial temperature in patients undergoing catheter ablation. Data from 43 patients treated with a thermistor ablation catheter were retrospectively analyzed. The slope of the initial 2 seconds of the impedance curve and subsequent changes in impedance were incorporated into an equation for estimation of temperature in real-time. The accuracy of this equation was assessed by prospectively comparing the calculated and measured temperatures in 19 patients. Of the 88% of energy applications that were suitable for analysis, the average difference between calculated and measured temperatures was 5.2 +/- 5.6 degrees C. The average error was < 10 degrees C in 89% of applications. The results of this study suggest that impedance measurements can be used to quantify tissue temperature in real-time during radiofrequency catheter ablation. This method is sufficiently accurate to allow titration of power output to produce temperatures in the useful range (50-80 degrees C) while avoiding excessive heating (> 90 degrees C).
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Affiliation(s)
- W M Hartung
- Department of Medicine, Emory University Hospital, Atlanta, Georgia 30322, USA
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Strickberger SA, Ravi S, Daoud E, Niebauer M, Man KC, Morady F. Relation between impedance and temperature during radiofrequency ablation of accessory pathways. Am Heart J 1995; 130:1026-30. [PMID: 7484732 DOI: 10.1016/0002-8703(95)90204-x] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Temperature monitoring is a useful tool for radiofrequency ablation of accessory pathways. Impedance monitoring is also helpful, and an impedance fall of 20 ohm may predict coagulum formation. Therefore the purpose of this study was to prospectively quantitate the correlation between impedance and temperature during radiofrequency ablation. Thirty-three consecutive patients underwent radiofrequency ablation with a thermistor ablation catheter with continuous temperature and impedance monitoring during each energy application. The initial and final impedance and temperature measurements for 319 applications of radiofrequency energy were 109 +/- 17 ohm and 102 +/- 17 ohm (p < 0.0001), respectively, and 37 +/- 1 degree C and 57 degrees +/- 11 degrees C (p < 0.0001), respectively. Among the 319 applications of radiofrequency energy, 158 were associated with > or = 20 degrees C increase in tissue temperature, and 10 were associated with coagulum formation. A > or = 20 degrees C increase in tissue temperature was observed in 84 of 104 applications associated with a 5 to 10 ohm decrease in impedance (81% positive predictive value and 93% negative predictive value). The mean change in impedance for applications associated with and without coagulum formation was -19 +/- 7 ohm and -6 +/- 6 ohm (p < 0.0001), respectively, and coagulum formation never occurred with less than a 12 ohm decrease. In conclusions successful tissue heating without coagulum formation can be achieved by titrating the power to achieve a 5 to 10 ohm decrement in impedance. Impedance decrements beyond 10 ohm increase the likelihood of coagulum formation.
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Affiliation(s)
- S A Strickberger
- Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0022, USA
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