A Novel Impedance-guided Contact Mapping Technique for the Circular Multielectrode Pulsed-Field Ablation Catheter

A Novel Impedance-guided Contact Mapping Technique for the Circular Multielectrode Pulsed-Field Ablation Catheter | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Method Article A Novel Impedance-guided Contact Mapping Technique for the Circular Multielectrode Pulsed-Field Ablation Catheter Kennosuke Yamashita, Yohei Kikuchi, Keita Yoshiyama, Daiki Kumazawa, and 3 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6998414/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Pulsed field ablation (PFA) has emerged as a promising technology for atrial fibrillation (AF) treatment. However, real-time catheter-tissue contact assessment remains a critical limitation, particularly for ring-type catheters lacking force sensing. We report a novel impedance-guided mapping method—i-Pulse—adapted for the PulseSelect™ catheter using the EnSite™ X Contact Index, originally designed for the Farapulse™ system. This workflow enables real-time contact assessment by reassigning catheter electrodes and visualizing impedance changes ≥ 5Ω as contact tags. In a series of four patients undergoing zero-fluoroscopy PFA, i-Pulse facilitated accurate lesion delivery without procedural complications. The technique integrates ICE guidance and 3D mapping to overcome fluoroscopy dependence and enhances procedural reproducibility. i-Pulse may offer a valuable contact evaluation strategy for current PFA practice, especially for non-magnetic catheters. Cardiac & Cardiovascular Systems Pulsed field ablation PulseSelect catheter Contact Index zero fluoroscopy impedance mapping Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction Pulmonary vein isolation utilizing pulsed field ablation (PFA) has gained widespread adoption as a treatment modality for atrial fibrillation due to its favorable safety profile and clinical efficacy, as demonstrated in trials such as the Pulsed AF trial[ 1 – 3 ]. However, conventional PFA workflows rely heavily on fluoroscopy[ 4 , 5 ], thereby exposing patients and operators to ionizing radiation and increasing the risk of radiation-related injuries and malignancies. Despite the nonthermal nature of PFA, effective lesion formation remains dependent on adequate electrode-tissue proximity[ 6 ]. However, PFA catheters typically lack contact force sensors, necessitating auxiliary methods such as fluoroscopy to confirm catheter-tissue contact—consequently increasing radiation usage. Technological advancements, including three-dimensional electroanatomical mapping systems and intracardiac echocardiography (ICE), have substantially reduced reliance on fluoroscopy by providing integrated electrical and anatomical visualization[ 7 – 9 ]. While ICE is effective in assessing the catheter proximity to cardiac tissue, it is often insufficient to confirm contact at all electrode sites during ablation, especially without advancing ICE into the left atrium due to the associated risk of an iatrogenic atrial septal defect. The VARIPULSE™ catheter (Biosense Webster, Irvine, CA) integrates with the CARTO™ mapping system and utilizes a Tissue Proximity Indicator based on impedance changes to determine electrode-tissue contact. Recently, the EnSite™ X EP System (Abbott, Abbott Park, IL) introduced a similar impedance-based "Contact Index" designed for the Farapulse ™ catheter (Boston Scientific, Marlborough, MA); however, this system is not compatible with the PulseSelect™ catheter (Medtronic, Minneapolis, MN). To address this limitation, we proposed a novel approach—i-Pulse (Impedance-guided PulseSelect™ Contact Mapping)—which adapts the EnSite™ X Contact Index concept for use with the PulseSelect™ catheter, offering a real-time visual assessment of tissue contact based on impedance dynamics without fluoroscopy. Methods To minimize procedural disruptions caused by patient movement or reflexive coughing during PFA, general anesthesia was administered using propofol and rocuronium, targeting a BIS score below 60. Two venous access points were obtained under echocardiographic guidance: an 8.5Fr SL0 sheath (Abbott) for the transseptal puncture and a 10Fr, 30 cm sheath for ICE using the ViewFlex™ Xtra catheter (Abbott). A radiofrequency needle (Sepnee; Kaneka Medix, Japan) was inserted into the SL0 sheath and guided to the fossa ovalis, with successful puncture confirmed by ICE imaging. The SL0 sheath was then exchanged for a FlexCath Advance sheath (Medtronic). The left atrial geometry and impedance field were acquired using the Advisor™ HD Grid X catheter (Abbott) on the EnSite™ X system in the Voxel mode. To visualize the guidewire, the proximal end of the wire was electrically clipped. Although the PulseSelect™ catheter contains nine electrodes, the EnSite™ X Version 3.1.1 Contact Index supports only five electrodes for an impedance-based contact assessment, originally designed for the Farapulse ™ system. It is technically feasible to map electrodes 1, 3, 5, 7, and 9 of the PulseSelect™ catheter onto electrodes 1 through 5 of the Farapulse ™ configuration for display on the EnSite™ X system. However, due to the anterior tilt of electrode 5, which plays a critical role in tissue contact, we aligned electrodes 3 to 7 of the PulseSelect™ catheter with electrodes 1 to 5 of the Farapulse ™ configuration (Fig. 1 ). Electrodes 1, 2, 8, and 9 were also visualized as a separate catheter to provide a comprehensive catheter position. The PulseSelect™ catheter was advanced into the left atrium over the guidewire (Video 1), and ring deployment was confirmed using ICE. The procedure was performed while continuously visualizing the wire and catheter positions on the 3D mapping system. Manual tags (5 mm in diameter) were placed at sites where the impedance increased by > 5%, indicating electrode-tissue contact. Minimum required applications were delivered at each site to ensure adequate lesion coverage. Additional applications were placed to ensure complete circumferential coverage around the pulmonary veins based on the tags. After full lesion delivery, post-ablation voltage mapping using the HD Grid X catheter and omnipolar technology confirmed the absence of residual pulmonary vein potentials and the presence of entrance and exit block. Results Video 2 presents the first procedure (Case 1). Lesions were created based on a Computed Tomography-fused geometry that had been reconstructed using the HD Grid X catheter. Prior to ablation, the anatomical landmarks were marked: the pulmonary vein (PV) ostia with white lines and the PV antra with yellow lines, and ablation was guided accordingly. The isolation was initiated from the right inferior pulmonary vein (RIPV). After confirming the insertion of the over-the-wire tip and the catheter into the RIPV, lesions were delivered based on the Contact Index (Δimpedance ≥ 5 Ω), with corresponding tags placed on the 3D geometry (Fig. 2 ). It should be noted that the Contact Index is displayed for the inner paddle of the ring, while actual lesion delivery is performed by the red ring electrodes; therefore, tags must be placed with this in mind. As this was our first case, the time required for the right PV isolation was 16 minutes, and for the left PV isolation, 13 minutes (Fig. 3 ). However, the procedure was completed entirely without fluoroscopy (zero-fluoroscopy ablation), with a total fluoroscopy time of 0.0 minutes. A summary of all four procedures is shown in the Table. The numbers are presented as median values with interquartile ranges (IQR). The time required for isolation of the left and right PVs was 11.0 (IQR 10.5–11.5) minutes and 13.0 (IQR 12.5–13.8) minutes, respectively. The premapping and postmapping times were 8.0 (IQR 7.6–9.4) minutes and 7.2 (IQR 6.6–9.2) minutes, with a left atrial dwell time of 42.5 (IQR 41.3–44.3) minutes. All procedures were performed without fluoroscopy, with a fluoroscopy time of 0.0 minutes. These results were comparable to those reported by Hirata et al.⁹ In one case (Case 3), the patient had a left common PV. However, the procedure itself did not differ substantially; ablation was performed on both the superior and inferior branches of the common PV, followed by an antral ablation to complete the isolation. Despite the anatomical variation, the left atrial dwell time was relatively short at 39 minutes. PV isolation was achieved in all cases, and no additional ablation was required after post-mapping. No procedural complications such as pericardial effusions, esophageal injury, phrenic nerve palsy, or anesthesia-related issues were observed. All patients were discharged the following day without adverse events. Discussion Our findings build upon previous reports, such as that by Palmeri et al.[ 7 ], which demonstrated the feasibility of zero-fluoroscopy PFA using the Farapulse ™ catheter with the EnSite NavX system and ICE. In their workflow, ablation tags were projected onto a pre-acquired geometry using impedance-based mapping. However, application of this method to the PulseSelect™ catheter is more challenging due to its thinner shaft, smaller electrodes, and more limited visualization capability with ICE alone. Additionally, the PulseSelect™ catheter requires multiple rotations (e.g., 12, 3, 6, and 9 o’clock) to achieve a full 360° PV isolation, which can be technically demanding and time-consuming under ICE-only guidance. Another limitation of relying solely on the EnSite NavX mode is the potential for geometry shifts during the procedure due to respiratory motion, PFA application effects, and impedance variability. To mitigate this, we advocate the use of the Voxel mode, which offers magnetic field-based navigation with higher spatial accuracy and reliability. Although the PulseSelect™ catheter lacks magnetic sensors and therefore requires manual tagging of lesions, real-time ICE visualization and impedance-guided mapping compensate for these constraints. The i-Pulse workflow avoids pitfalls associated with bipolar potential-based contact assessments, such as bipolar blindness[ 10 ]—where wavefront propagation perpendicular to the electrode pair can yield false negatives. Nishiuchi et al.[ 11 ] proposed the pre-PFA application peak frequency (PPAP) map method, which evaluates the frequency of bipolar electrograms prior to ablation to estimate catheter-tissue contact. While this approach provides useful insights, it has notable limitations: (1) it remains susceptible to far-field signal contamination and distortion from fibrotic tissue; (2) following a single application, local electrograms may disappear, making it difficult to verify stable contact; and (3) the reliability of the bipolar frequency near ablation lesions remains uncertain. Importantly, the PPAP map relies solely on the bipolar frequency analysis, whereas unipolar frequency data—which may offer more direct information on the electrode-tissue interface—is not currently supported. In contrast, the i-Pulse method utilizes a generator-based impedance signal between each electrode and the skin patch, enabling an objective and reproducible contact assessment that is independent of the activation direction and voltage drop. We analyzed a total of 256 points across all cases to examine the correlation between the Δimpedance (Ω) and peak frequency (Hz) at each location. However, no significant correlation was observed (R² = 0.03; Fig. 4 A). Furthermore, although a statistically significant difference in peak frequency values was found between sites with a ΔImpedance ≥ 5 Ω and those with < 5 Ω, no clear cutoff value could be determined (Fig. 4 B). These findings suggest that an impedance-based contact assessment may still be feasible even in regions where only low peak frequency values are observed. We acknowledge that our use of the Contact Index software, originally developed for the Farapulse ™ catheter, introduces certain limitations when applied to the PulseSelect ™ system. The software can monitor only five electrodes at a time, requiring the operator to select either a 1-3-5-7-9 or 3-4-5-6-7 configuration. Although both options are viable, we selected the latter to center the assessment on electrode 5, which is uniquely designed to angle 20° anteriorly and serves as the primary point of contact in the PulseSelect ™ catheter. This catheter structure is specifically designed to optimize tissue contact at electrode 5, and thus, evaluating contact using the 3-4-5-6-7 configuration allows for a more comprehensive assessment around this central electrode. For instance, in anatomically challenging regions such as the ridge between the left superior pulmonary vein (LSPV) and the left atrial appendage (LAA), assessing contact with the intermediate electrodes (4 and 6) becomes particularly important (Fig. 5 ). In contrast, using the 1-3-5-7-9 configuration may overlook potential gaps between these central electrodes, even if contact appears sufficient at 3, 5, and 7. However, care must be taken to ensure that the peripheral electrodes, such as 1–2 or 8–9, do not unintentionally touch surrounding tissue. If they do, energy may be delivered to unintended areas, potentially resulting in unwanted lesions. Therefore, it is important for the operator to check the full catheter position carefully and not rely only on the central five-electrode contact view. Our workflow integrates EnSite X mapping and ICE imaging to facilitate near-zero fluoroscopy procedures using the PulseSelect™ catheter[ 8 , 12 ]. It addresses key limitations in catheter visualization and contact confirmation inherent to impedance-only systems. By combining impedance-based 3D mapping with ICE, we ensured an accurate catheter localization and safe energy delivery. Although impedance mapping offers lower positional precision (± 3 mm) compared to magnetic systems (± 1 mm), this is effectively mitigated by ICE guidance. Finally, general anesthesia was employed to eliminate respiratory artifact and patient movement, ensuring a stable anatomical environment throughout the procedure. Although the PulseSelect™ catheter's design can make contact verification challenging—especially during transitions from linear to circular configurations—ICE remains invaluable for confirming ring deployment and detecting entanglement or mechanical complications[ 13 ]. Conclusion The i-Pulse workflow represents a practical, reproducible, and fluoroscopy-sparing method for PFA using the PulseSelect™ catheter. Further prospective studies with larger sample sizes and long-term follow-up are warranted to validate the durability and generalizability of this workflow. Abbreviations AF atrial fibrillation ICE intracardiac echocardiography PV pulmonary vein PFA pulsed field ablation LA left atrium LAA left atrial appendage LSPV left superior pulmonary vein RIPV right inferior pulmonary vein IQR interquartile range Δimpedance change in impedance 3D three-dimensional Declarations Author contributions KY and YK drafted the manuscript. SI, DK, YM, KO, and TN critically revised the manuscript for its important intellectual content. All the authors approved the final version of the manuscript. Ethics Approval: The ethical committee of Sendai Kousei Hospital waived the requirement for obtaining ethical approval because this research was neither a clinical study nor an animal experiment. Data availability: Raw data were generated at Sendai Kousei Hospital. Derived data supporting the findings of this study are available from the corresponding author, Kennosuke Yamashita, upon request. Funding: This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Conflict of Interest: KY received speaker honoraria and lecture fees from Abbott Medical Japan, Biosense Webster, Daiichi Sankyo, and Medtronic. The other authors have no conflict of interest. Informed consent: Written informed consent was obtained from the patient for publication of this case report and accompanying images. Clinical trial registration: N/A Acknowledgments We are grateful to John Martin for his linguistic assistance and Hiroaki Sakata and Ryo Ichii for their assistance with the electrophysiological assessment. References Verma A, Boersma L, Haines DE, Natale A, Marchlinski FE, Sanders P et al (2022) First-in-human experience and acute procedural outcomes using a novel Pulsed Field Ablation system: The PULSED AF pilot trial. Circ Arrhythm Electrophysiol [Internet]. ;15(1):e010168. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8772438/pdf/hae-15-e010168.pdf Duytschaever M, De Potter T, Grimaldi M, Anic A, Vijgen J, Neuzil P et al (2023) Paroxysmal Atrial Fibrillation Ablation Using a Novel Variable-Loop Biphasic Pulsed Field Ablation Catheter Integrated With a 3-Dimensional Mapping System: 1-Year Outcomes of the Multicenter inspIRE Study. Circ Arrhythm Electrophysiol [Internet]. ;16(3):e011780. Available from: http://dx.doi.org/10.1161/CIRCEP.122.011780 Reddy VY, Gerstenfeld EP, Natale A, Whang W, Cuoco FA, Patel C et al (2023) Pulsed field or conventional thermal ablation for paroxysmal atrial fibrillation. N Engl J Med [Internet]. ;389(18):1660–71. Available from: https://www.nejm.org/doi/full/ 10.1056/NEJMoa2307291 Kariki O, Mililis P, Saplaouras A, Efremidis T, Chatziantoniou A, Panagiotopoulos I et al Investigating the role of electroanatomical mapping in single-shot pulsed field catheter ablation. J Arrhythm [Internet]. 2024 Dec 10 [cited 2025 Jan 13];40(6):1374–8. Available from: https://pubmed.ncbi.nlm.nih.gov/39669915/ de Campos MCAV, Moraes VRY, Daher RF, Micheleto JPC, de Campos LAV, Barros GFA et al Pulsed-field ablation versus thermal ablation for atrial fibrillation: A meta-analysis. Heart Rhythm O2 [Internet]. 2024 Jun 30 [cited 2025 Jun 18];5(6):385–95. Available from: http://dx.doi.org/10.1016/j.hroo.2024.04.012 Howard B, Verma A, Tzou WS, Mattison L, Kos B, Miklavčič D et al Effects of electrode-tissue proximity on cardiac lesion formation using pulsed field ablation. Circ Arrhythm Electrophysiol [Internet]. 2022 Oct [cited 2025 Jun 16];15(10):e011110. Available from: http://dx.doi.org/10.1161/CIRCEP.122.011110 Palmeri NO, Alyesh D, Keith M, Greenhaw E, Erickson C, Choe W et al Pulsed-field ablation for atrial fibrillation without the use of fluoroscopy. J Interv Card Electrophysiol [Internet]. 2024 Aug 23 [cited 2024 Oct 15]; Available from: https://pubmed.ncbi.nlm.nih.gov/39179911/ Rauber M, Manninger M, Eberl AS, Scherr D (2024) Zero-fluoroscopy ablation with multielectrode pulse field ablation system: Case series. Pacing Clin Electrophysiol [Internet]. ;47(1):117–20. Available from: https://onlinelibrary.wiley.com/doi/epdf/ 10.1111/pace.14860 Hirata S, Nagashima K, Watanabe R, Wakamatsu Y, Hirata M, Kurokawa S et al (2024) Workflow of the zero-fluoro pulsed field ablation. J Arrhythm [Internet]. ;40(6):1529–32. Available from: https://onlinelibrary.wiley.com/doi/epdf /10.1002/joa3.13174 Josephson ME, Anter E Substrate mapping for ventricular tachycardia: Assumptions and misconceptions. JACC Clin Electrophysiol [Internet]. 2015 Oct [cited 2025 Jun 18];1(5):341–52. Available from: http://dx.doi.org/10.1016/j.jacep.2015.09.001 Nishiuchi S, Nakamura K, Sasaki T, Kodama A, Masuyama T, Matsuo Y et al Peak frequency value of catheter electrodes before pulsed field applications stratifies the lesion formation. J Interv Card Electrophysiol [Internet]. 2024 Dec 12 [cited 2025 Jun 18]; Available from: http://dx.doi.org/10.1007/s10840-024-01967-9 Dello Russo A, Tondo C, Schillaci V, Casella M, Iacopino S, Bianchi S et al Intracardiac echocardiography-guided pulsed-field ablation for successful ablation of atrial fibrillation: a propensity-matched analysis from a large nationwide multicenter experience. J Interv Card Electrophysiol [Internet]. 2024 Aug [cited 2025 Feb 8];67(5):1257–66. Available from: https://pubmed.ncbi.nlm.nih.gov/37985538/ Mountantonakis S, Beccarino N, Abrams M, Sharma N, Skipitaris N, Bernstein N et al (2024) Methods and techniques to optimize energy delivery using the circular array pulsed field ablation catheter. Heart Rhythm [Internet]. ;0(0). Available from: https://www.heartrhythmjournal.com/action/showPdf?pii=S1547-5271%2824%2903506-9 Additional Declarations The authors declare potential competing interests as follows: Kennosuke Yamashiat received speaker honoraria and lecture fees from Abbott Medical Japan, Biosense Webster, Daiichi Sankyo, and Medtronic. The other authors have no conflict of interest. Supplementary Files Video1PS.mp4 Video 1 Video2.mp4 Video 2 Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6998414","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Method Article","associatedPublications":[],"authors":[{"id":477760700,"identity":"87d6b779-ca70-435e-adb9-7d590f6f4de3","order_by":0,"name":"Kennosuke Yamashita","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABCUlEQVRIiWNgGAWjYBACCShtAKVr5EDkgQdEamFsYGA4ZgzWkkCCFubEBhAXnxbJ9t5jDz78OWzMz8D8/NHNHLb0+WGHHwJtsZPTbcCuRZrnXLrhzLbDZpINbIbNudtkcjfeTjMAakk2NjuAXYucRI6ZNG/DYRuDAwwgLWy5G2cngLQcSNyGS4v8GzNpnj+HbewPsH8EamFON5yd/gGvFmkJHqAWtsNmBgw8IFuYE+Slc/DbItmTYyY5sy3dWOIwT+Hs3G3HDDdI5xQcSDDA7ReJ42fMJD78sTbsb2/f8Dl3W428/Oz0zR8+VNjJ4dKCAMxQ2gCs0gC3Qkwg30CK6lEwCkbBKBgJAADvUV5sPnauyAAAAABJRU5ErkJggg==","orcid":"https://orcid.org/0000-0002-5630-1975","institution":"Sendai Kosei Hospital","correspondingAuthor":true,"prefix":"","firstName":"Kennosuke","middleName":"","lastName":"Yamashita","suffix":""},{"id":477760701,"identity":"f4b53522-50c1-408d-a742-bd80da8546dd","order_by":1,"name":"Yohei Kikuchi","email":"","orcid":"","institution":"Sendai Kosei Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yohei","middleName":"","lastName":"Kikuchi","suffix":""},{"id":477760702,"identity":"4953b7b6-2e04-47c2-910c-aac735556628","order_by":2,"name":"Keita Yoshiyama","email":"","orcid":"","institution":"Sendai Kosei Hospital","correspondingAuthor":false,"prefix":"","firstName":"Keita","middleName":"","lastName":"Yoshiyama","suffix":""},{"id":477760703,"identity":"d513acfd-a313-491d-8406-45345192ed4d","order_by":3,"name":"Daiki Kumazawa","email":"","orcid":"","institution":"Sendai Kosei Hospital","correspondingAuthor":false,"prefix":"","firstName":"Daiki","middleName":"","lastName":"Kumazawa","suffix":""},{"id":477760704,"identity":"ae0a8ae8-68d8-45ea-a341-69b5e96629c3","order_by":4,"name":"Yosuke Mizuno","email":"","orcid":"","institution":"Sendai Kosei Hospital","correspondingAuthor":false,"prefix":"","firstName":"Yosuke","middleName":"","lastName":"Mizuno","suffix":""},{"id":477760705,"identity":"d427b738-b170-471c-a79e-bc5bd30fe20a","order_by":5,"name":"Kosuke Onodera","email":"","orcid":"","institution":"Sendai Kosei Hospital","correspondingAuthor":false,"prefix":"","firstName":"Kosuke","middleName":"","lastName":"Onodera","suffix":""},{"id":477760706,"identity":"6f16cfbc-d90b-462f-9475-ffcafdeeead0","order_by":6,"name":"Takehiro Nomura","email":"","orcid":"","institution":"Sendai Kosei Hospital","correspondingAuthor":false,"prefix":"","firstName":"Takehiro","middleName":"","lastName":"Nomura","suffix":""}],"badges":[],"createdAt":"2025-06-28 14:27:29","currentVersionCode":1,"declarations":{"humanSubjects":true,"vertebrateSubjects":false,"conflictsOfInterestStatement":true,"humanSubjectEthicalGuidelines":true,"humanSubjectConsent":true,"humanSubjectClinicalTrial":false,"humanSubjectCaseReport":true,"vertebrateSubjectEthicalGuidelines":false},"doi":"10.21203/rs.3.rs-6998414/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6998414/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":85925153,"identity":"5b298a7d-13b5-4b68-af48-49bddc18350a","added_by":"auto","created_at":"2025-07-03 08:35:28","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":359090,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eA:\u003c/strong\u003e Image displaying PulseSelect\u003csup\u003eTM\u003c/sup\u003e electrodes 1, 3, 5, 7, and 9, aligned with Farapulse\u003csup\u003eTM\u003c/sup\u003e electrodes 1 through 5 for visualization purposes. All displayed electrodes show impedance values ≥5 Ω and are highlighted in blue. However, the contact status of the in-between electrodes (2, 4, 6, and 8) cannot be assessed from this view.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eB:\u003c/strong\u003e Image of the same site showing PulseSelect\u003csup\u003eTM\u003c/sup\u003e electrodes 3, 4, 5, 6, and 7, aligned with Farapulse\u003csup\u003eTM\u003c/sup\u003e electrodes 1 through 5. Again, all displayed electrodes show impedance values ≥5 Ω and are highlighted in blue. Although electrodes 1, 2, 8, and 9 are visible, their contact status is unknown due to the limitations of the display.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eC:\u003c/strong\u003e Connection of the jumper cable to electrodes 3 through 7 on the PulseSelect\u003csup\u003eTM\u003c/sup\u003e catheter (for Contact Index module).\u003c/p\u003e\n\u003cp\u003eJumper cable connection to electrodes 31–39 (for PulseSelect\u003csup\u003eTM\u003c/sup\u003e ring visualization).\u003c/p\u003e","description":"","filename":"image1.png","url":"https://assets-eu.researchsquare.com/files/rs-6998414/v1/ca02fd97b7ea047700320018.png"},{"id":85924577,"identity":"6f0faa3c-3d96-4b62-9b15-211770fccdf0","added_by":"auto","created_at":"2025-07-03 08:27:28","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":539099,"visible":true,"origin":"","legend":"\u003cp\u003eRepresentative images corresponding to the Case 1 video.\u003cbr\u003e\n \u003cstrong\u003eA:\u003c/strong\u003e Snapshot during RSPV isolation in Case 1. A gap without ablation tags is noted along the roof segment. At the current catheter position, electrode 4 shows a Δimpedance of 6%, indicating adequate tissue contact, although no local electrogram is observed due to prior ablation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eB:\u003c/strong\u003e After rotating the catheter 90° clockwise in the same case, an increased Δimpedance is observed on electrodes 3 (3%), 4 (9%), and 5 (14%), with the reappearance of local electrograms. Additional energy delivery at this location resulted in the formation of a continuous circumferential lesion.\u003c/p\u003e","description":"","filename":"image2.png","url":"https://assets-eu.researchsquare.com/files/rs-6998414/v1/5daff56ad248511d943378d2.png"},{"id":85924581,"identity":"68debccd-7520-4e27-946f-ceb61e4a4244","added_by":"auto","created_at":"2025-07-03 08:27:28","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":322360,"visible":true,"origin":"","legend":"\u003cp\u003ePost-ablation voltage maps showing representative examples from two cases.\u003cbr\u003e\n \u003cstrong\u003eA (Case 1):\u003c/strong\u003e Voltage map from the same case as shown in Figure 3, demonstrating a complete PVI at locations corresponding to the green tags (Δimpedance ≥5 Ω, tag diameter: 5 mm).\u003cbr\u003e\n \u003cstrong\u003eB (Case 4):\u003c/strong\u003e Another representative case showing a similar pattern, with no acute gaps observed as all tags are contiguous, indicating a complete lesion set.\u003c/p\u003e","description":"","filename":"image3.png","url":"https://assets-eu.researchsquare.com/files/rs-6998414/v1/b4d034632b82caf02cbf5f8f.png"},{"id":85925155,"identity":"03fc0c48-87cd-4f1f-b453-cb5097a06e1b","added_by":"auto","created_at":"2025-07-03 08:35:28","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":44269,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eA:\u003c/strong\u003e Correlation between the Δimpedance and peak frequency at a total of 256 points. The regression equation is Y = 0.01x + 4.14 with an R² value of 0.03, indicating no significant correlation between the two parameters.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eB:\u003c/strong\u003e Comparison of the peak frequency between sites with a Δimpedance ≥5 Ω and \u0026lt;5 Ω. Although a statistically significant difference was observed, there was substantial overlap between the two groups, suggesting that a clear cutoff value could not be established.\u003c/p\u003e","description":"","filename":"image4.png","url":"https://assets-eu.researchsquare.com/files/rs-6998414/v1/8dceb3be90921168021be101.png"},{"id":85924582,"identity":"da7d606e-8e2a-499b-b623-bed077e4e3b0","added_by":"auto","created_at":"2025-07-03 08:27:28","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":472265,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eA: \u003c/strong\u003eImage showing catheter contact on the LSPV–LAA ridge. The Δimpedance values are as follows: electrode 1 (10%), 2 (4%), 3 (2%), 4 (3%), and 5 (9%). Using a 5% cutoff for contact detection, only electrodes 1 and 5 are considered to be in contact, and their corresponding paddles are highlighted in blue.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eB: \u003c/strong\u003eA simulation model replicating the anatomical situation shown in panel A. The PulseSelect catheter is positioned over the ridge, making contact at electrodes 1 and 5 (yellow arrow). Electrodes 2, 3, and 4 (white arrow) are located on the LAA side and are visibly lifted off the tissue, indicating lack of contact.\u003c/p\u003e\n\u003cp\u003eLA = left atrium; LAA = left atrial appendage; LSPV = left superior pulmonary vein; LIPV = left inferior pulmonary vein; RSPV = right superior pulmonary vein; RIPV = right inferior pulmonary vein; PVI = pulmonary vein isolation\u003c/p\u003e","description":"","filename":"image5.png","url":"https://assets-eu.researchsquare.com/files/rs-6998414/v1/5296d90020ec84f86389cdd0.png"},{"id":85926750,"identity":"4d27cd2e-256c-40b8-8658-8fd6b788acb9","added_by":"auto","created_at":"2025-07-03 08:43:29","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2150001,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6998414/v1/7e3a022b-89f8-4d8a-b8c8-5da00b9ee01b.pdf"},{"id":85924597,"identity":"b524df62-8cf8-4f55-972e-fb870fae4337","added_by":"auto","created_at":"2025-07-03 08:27:29","extension":"mp4","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":55542883,"visible":true,"origin":"","legend":"\u003cp\u003eVideo 1\u003c/p\u003e","description":"","filename":"Video1PS.mp4","url":"https://assets-eu.researchsquare.com/files/rs-6998414/v1/27ac441f075e203b5dc54ef9.mp4"},{"id":85925158,"identity":"8d4f8a63-86df-4fcd-8223-76eca94377e0","added_by":"auto","created_at":"2025-07-03 08:35:29","extension":"mp4","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":39825587,"visible":true,"origin":"","legend":"\u003cp\u003eVideo 2\u003c/p\u003e","description":"","filename":"Video2.mp4","url":"https://assets-eu.researchsquare.com/files/rs-6998414/v1/749363642043fcb1237ae58a.mp4"}],"financialInterests":"The authors declare potential competing interests as follows: Kennosuke Yamashiat received speaker honoraria and lecture fees from Abbott Medical Japan, Biosense Webster, Daiichi Sankyo, and Medtronic. The other authors have no conflict of interest.","formattedTitle":"\u003cp\u003eA Novel Impedance-guided Contact Mapping Technique for the Circular Multielectrode Pulsed-Field Ablation Catheter\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePulmonary vein isolation utilizing pulsed field ablation (PFA) has gained widespread adoption as a treatment modality for atrial fibrillation due to its favorable safety profile and clinical efficacy, as demonstrated in trials such as the Pulsed AF trial[\u003cspan additionalcitationids=\"CR2\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e–\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. However, conventional PFA workflows rely heavily on fluoroscopy[\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], thereby exposing patients and operators to ionizing radiation and increasing the risk of radiation-related injuries and malignancies. Despite the nonthermal nature of PFA, effective lesion formation remains dependent on adequate electrode-tissue proximity[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. However, PFA catheters typically lack contact force sensors, necessitating auxiliary methods such as fluoroscopy to confirm catheter-tissue contact—consequently increasing radiation usage.\u003c/p\u003e \u003cp\u003eTechnological advancements, including three-dimensional electroanatomical mapping systems and intracardiac echocardiography (ICE), have substantially reduced reliance on fluoroscopy by providing integrated electrical and anatomical visualization[\u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e–\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. While ICE is effective in assessing the catheter proximity to cardiac tissue, it is often insufficient to confirm contact at all electrode sites during ablation, especially without advancing ICE into the left atrium due to the associated risk of an iatrogenic atrial septal defect.\u003c/p\u003e \u003cp\u003eThe VARIPULSE™ catheter (Biosense Webster, Irvine, CA) integrates with the CARTO™ mapping system and utilizes a Tissue Proximity Indicator based on impedance changes to determine electrode-tissue contact. Recently, the EnSite™ X EP System (Abbott, Abbott Park, IL) introduced a similar impedance-based \"Contact Index\" designed for the Farapulse\u003csup\u003e™\u003c/sup\u003e catheter (Boston Scientific, Marlborough, MA); however, this system is not compatible with the PulseSelect™ catheter (Medtronic, Minneapolis, MN). To address this limitation, we proposed a novel approach—i-Pulse (Impedance-guided PulseSelect™ Contact Mapping)—which adapts the EnSite™ X Contact Index concept for use with the PulseSelect™ catheter, offering a real-time visual assessment of tissue contact based on impedance dynamics without fluoroscopy.\u003c/p\u003e "},{"header":"Methods","content":"\u003cp\u003eTo minimize procedural disruptions caused by patient movement or reflexive coughing during PFA, general anesthesia was administered using propofol and rocuronium, targeting a BIS score below 60. Two venous access points were obtained under echocardiographic guidance: an 8.5Fr SL0 sheath (Abbott) for the transseptal puncture and a 10Fr, 30 cm sheath for ICE using the ViewFlex™ Xtra catheter (Abbott). A radiofrequency needle (Sepnee; Kaneka Medix, Japan) was inserted into the SL0 sheath and guided to the fossa ovalis, with successful puncture confirmed by ICE imaging. The SL0 sheath was then exchanged for a FlexCath Advance sheath (Medtronic).\u003c/p\u003e\u003cp\u003eThe left atrial geometry and impedance field were acquired using the Advisor™ HD Grid X catheter (Abbott) on the EnSite™ X system in the Voxel mode. To visualize the guidewire, the proximal end of the wire was electrically clipped. Although the PulseSelect™ catheter contains nine electrodes, the EnSite™ X Version 3.1.1 Contact Index supports only five electrodes for an impedance-based contact assessment, originally designed for the Farapulse\u003csup\u003e™\u003c/sup\u003e system. It is technically feasible to map electrodes 1, 3, 5, 7, and 9 of the PulseSelect™ catheter onto electrodes 1 through 5 of the Farapulse\u003csup\u003e™\u003c/sup\u003e configuration for display on the EnSite™ X system. However, due to the anterior tilt of electrode 5, which plays a critical role in tissue contact, we aligned electrodes 3 to 7 of the PulseSelect™ catheter with electrodes 1 to 5 of the Farapulse\u003csup\u003e™\u003c/sup\u003e configuration (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Electrodes 1, 2, 8, and 9 were also visualized as a separate catheter to provide a comprehensive catheter position.\u003c/p\u003e\u003cp\u003e \u003c/p\u003e\u003cp\u003eThe PulseSelect™ catheter was advanced into the left atrium over the guidewire (Video 1), and ring deployment was confirmed using ICE. The procedure was performed while continuously visualizing the wire and catheter positions on the 3D mapping system. Manual tags (5 mm in diameter) were placed at sites where the impedance increased by \u0026gt; 5%, indicating electrode-tissue contact.\u003c/p\u003e\u003cp\u003eMinimum required applications were delivered at each site to ensure adequate lesion coverage. Additional applications were placed to ensure complete circumferential coverage around the pulmonary veins based on the tags. After full lesion delivery, post-ablation voltage mapping using the HD Grid X catheter and omnipolar technology confirmed the absence of residual pulmonary vein potentials and the presence of entrance and exit block.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eVideo 2 presents the first procedure (Case 1). Lesions were created based on a Computed Tomography-fused geometry that had been reconstructed using the HD Grid X catheter. Prior to ablation, the anatomical landmarks were marked: the pulmonary vein (PV) ostia with white lines and the PV antra with yellow lines, and ablation was guided accordingly. The isolation was initiated from the right inferior pulmonary vein (RIPV). After confirming the insertion of the over-the-wire tip and the catheter into the RIPV, lesions were delivered based on the Contact Index (Δimpedance\u0026thinsp;\u0026ge;\u0026thinsp;5 Ω), with corresponding tags placed on the 3D geometry (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eIt should be noted that the Contact Index is displayed for the inner paddle of the ring, while actual lesion delivery is performed by the red ring electrodes; therefore, tags must be placed with this in mind.\u003c/p\u003e \u003cp\u003eAs this was our first case, the time required for the right PV isolation was 16 minutes, and for the left PV isolation, 13 minutes (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). However, the procedure was completed entirely without fluoroscopy (zero-fluoroscopy ablation), with a total fluoroscopy time of 0.0 minutes.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eA summary of all four procedures is shown in the Table. The numbers are presented as median values with interquartile ranges (IQR). The time required for isolation of the left and right PVs was 11.0 (IQR 10.5\u0026ndash;11.5) minutes and 13.0 (IQR 12.5\u0026ndash;13.8) minutes, respectively. The premapping and postmapping times were 8.0 (IQR 7.6\u0026ndash;9.4) minutes and 7.2 (IQR 6.6\u0026ndash;9.2) minutes, with a left atrial dwell time of 42.5 (IQR 41.3\u0026ndash;44.3) minutes. All procedures were performed without fluoroscopy, with a fluoroscopy time of 0.0 minutes. These results were comparable to those reported by Hirata et al.⁹\u003c/p\u003e \u003cp\u003eIn one case (Case 3), the patient had a left common PV. However, the procedure itself did not differ substantially; ablation was performed on both the superior and inferior branches of the common PV, followed by an antral ablation to complete the isolation. Despite the anatomical variation, the left atrial dwell time was relatively short at 39 minutes.\u003c/p\u003e \u003cp\u003ePV isolation was achieved in all cases, and no additional ablation was required after post-mapping. No procedural complications such as pericardial effusions, esophageal injury, phrenic nerve palsy, or anesthesia-related issues were observed. All patients were discharged the following day without adverse events.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eOur findings build upon previous reports, such as that by Palmeri et al.[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], which demonstrated the feasibility of zero-fluoroscopy PFA using the Farapulse\u003csup\u003e\u0026trade;\u003c/sup\u003e catheter with the EnSite NavX system and ICE. In their workflow, ablation tags were projected onto a pre-acquired geometry using impedance-based mapping. However, application of this method to the PulseSelect\u0026trade; catheter is more challenging due to its thinner shaft, smaller electrodes, and more limited visualization capability with ICE alone. Additionally, the PulseSelect\u0026trade; catheter requires multiple rotations (e.g., 12, 3, 6, and 9 o\u0026rsquo;clock) to achieve a full 360\u0026deg; PV isolation, which can be technically demanding and time-consuming under ICE-only guidance.\u003c/p\u003e \u003cp\u003eAnother limitation of relying solely on the EnSite NavX mode is the potential for geometry shifts during the procedure due to respiratory motion, PFA application effects, and impedance variability. To mitigate this, we advocate the use of the Voxel mode, which offers magnetic field-based navigation with higher spatial accuracy and reliability. Although the PulseSelect\u0026trade; catheter lacks magnetic sensors and therefore requires manual tagging of lesions, real-time ICE visualization and impedance-guided mapping compensate for these constraints.\u003c/p\u003e \u003cp\u003eThe i-Pulse workflow avoids pitfalls associated with bipolar potential-based contact assessments, such as bipolar blindness[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u0026mdash;where wavefront propagation perpendicular to the electrode pair can yield false negatives. Nishiuchi et al.[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] proposed the pre-PFA application peak frequency (PPAP) map method, which evaluates the frequency of bipolar electrograms prior to ablation to estimate catheter-tissue contact. While this approach provides useful insights, it has notable limitations: (1) it remains susceptible to far-field signal contamination and distortion from fibrotic tissue; (2) following a single application, local electrograms may disappear, making it difficult to verify stable contact; and (3) the reliability of the bipolar frequency near ablation lesions remains uncertain. Importantly, the PPAP map relies solely on the bipolar frequency analysis, whereas unipolar frequency data\u0026mdash;which may offer more direct information on the electrode-tissue interface\u0026mdash;is not currently supported.\u003c/p\u003e \u003cp\u003eIn contrast, the i-Pulse method utilizes a generator-based impedance signal between each electrode and the skin patch, enabling an objective and reproducible contact assessment that is independent of the activation direction and voltage drop. We analyzed a total of 256 points across all cases to examine the correlation between the Δimpedance (Ω) and peak frequency (Hz) at each location. However, no significant correlation was observed (R\u0026sup2; = 0.03; Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eA). Furthermore, although a statistically significant difference in peak frequency values was found between sites with a ΔImpedance\u0026thinsp;\u0026ge;\u0026thinsp;5 Ω and those with \u0026lt;\u0026thinsp;5 Ω, no clear cutoff value could be determined (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003eB). These findings suggest that an impedance-based contact assessment may still be feasible even in regions where only low peak frequency values are observed.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eWe acknowledge that our use of the Contact Index software, originally developed for the Farapulse\u003csup\u003e\u0026trade;\u003c/sup\u003e catheter, introduces certain limitations when applied to the PulseSelect\u003csup\u003e\u0026trade;\u003c/sup\u003e system. The software can monitor only five electrodes at a time, requiring the operator to select either a 1-3-5-7-9 or 3-4-5-6-7 configuration. Although both options are viable, we selected the latter to center the assessment on electrode 5, which is uniquely designed to angle 20\u0026deg; anteriorly and serves as the primary point of contact in the PulseSelect\u003csup\u003e\u0026trade;\u003c/sup\u003e catheter.\u003c/p\u003e \u003cp\u003eThis catheter structure is specifically designed to optimize tissue contact at electrode 5, and thus, evaluating contact using the 3-4-5-6-7 configuration allows for a more comprehensive assessment around this central electrode. For instance, in anatomically challenging regions such as the ridge between the left superior pulmonary vein (LSPV) and the left atrial appendage (LAA), assessing contact with the intermediate electrodes (4 and 6) becomes particularly important (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). In contrast, using the 1-3-5-7-9 configuration may overlook potential gaps between these central electrodes, even if contact appears sufficient at 3, 5, and 7.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eHowever, care must be taken to ensure that the peripheral electrodes, such as 1\u0026ndash;2 or 8\u0026ndash;9, do not unintentionally touch surrounding tissue. If they do, energy may be delivered to unintended areas, potentially resulting in unwanted lesions. Therefore, it is important for the operator to check the full catheter position carefully and not rely only on the central five-electrode contact view.\u003c/p\u003e \u003cp\u003eOur workflow integrates EnSite X mapping and ICE imaging to facilitate near-zero fluoroscopy procedures using the PulseSelect\u0026trade; catheter[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. It addresses key limitations in catheter visualization and contact confirmation inherent to impedance-only systems. By combining impedance-based 3D mapping with ICE, we ensured an accurate catheter localization and safe energy delivery. Although impedance mapping offers lower positional precision (\u0026plusmn;\u0026thinsp;3 mm) compared to magnetic systems (\u0026plusmn;\u0026thinsp;1 mm), this is effectively mitigated by ICE guidance.\u003c/p\u003e \u003cp\u003eFinally, general anesthesia was employed to eliminate respiratory artifact and patient movement, ensuring a stable anatomical environment throughout the procedure. Although the PulseSelect\u0026trade; catheter's design can make contact verification challenging\u0026mdash;especially during transitions from linear to circular configurations\u0026mdash;ICE remains invaluable for confirming ring deployment and detecting entanglement or mechanical complications[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e "},{"header":"Conclusion","content":"\u003cp\u003eThe i-Pulse workflow represents a practical, reproducible, and fluoroscopy-sparing method for PFA using the PulseSelect\u0026trade; catheter. Further prospective studies with larger sample sizes and long-term follow-up are warranted to validate the durability and generalizability of this workflow.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eAF\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eatrial fibrillation\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eICE\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eintracardiac echocardiography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePV\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003epulmonary vein\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePFA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003epulsed field ablation\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eLA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eleft atrium\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eLAA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eleft atrial appendage\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eLSPV\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eleft superior pulmonary vein\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eRIPV\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eright inferior pulmonary vein\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIQR\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003einterquartile range\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eΔimpedance\u0026thinsp;\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003echange in impedance\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e3D\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ethree-dimensional\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eKY and YK drafted the manuscript. SI, DK, YM, KO, and TN critically revised the manuscript for its important intellectual content. All the authors approved the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics Approval:\u0026nbsp;\u003c/strong\u003eThe ethical committee of Sendai Kousei Hospital waived the requirement for obtaining ethical approval because this research was neither a clinical study nor an animal experiment.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability:\u003c/strong\u003e Raw data were generated at Sendai Kousei Hospital. Derived data supporting the findings of this study are available from the corresponding author, Kennosuke Yamashita, upon request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding:\u003c/strong\u003eThis research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of Interest:\u003c/strong\u003e KY received speaker honoraria and lecture fees from Abbott Medical Japan, Biosense Webster, Daiichi Sankyo, and Medtronic. The other authors have no conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eInformed consent:\u0026nbsp;\u003c/strong\u003eWritten informed consent was obtained from the patient for publication of this case report and accompanying images.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical trial registration:\u0026nbsp;\u003c/strong\u003eN/A\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe are grateful to John Martin for his linguistic assistance and Hiroaki Sakata and Ryo Ichii for their assistance with the electrophysiological assessment.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eVerma A, Boersma L, Haines DE, Natale A, Marchlinski FE, Sanders P et al (2022) First-in-human experience and acute procedural outcomes using a novel Pulsed Field Ablation system: The PULSED AF pilot trial. Circ Arrhythm Electrophysiol [Internet]. ;15(1):e010168. 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Available from: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.heartrhythmjournal.com/action/showPdf?pii=S1547-5271%2824%2903506-9\u003c/span\u003e\u003cspan address=\"https://www.heartrhythmjournal.com/action/showPdf?pii=S1547-5271%2824%2903506-9\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":true,"highlight":"","institution":"Sendai Kosei Hospital","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Pulsed field ablation, PulseSelect catheter, Contact Index, zero fluoroscopy, impedance mapping","lastPublishedDoi":"10.21203/rs.3.rs-6998414/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6998414/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePulsed field ablation (PFA) has emerged as a promising technology for atrial fibrillation (AF) treatment. However, real-time catheter-tissue contact assessment remains a critical limitation, particularly for ring-type catheters lacking force sensing. We report a novel impedance-guided mapping method\u0026mdash;i-Pulse\u0026mdash;adapted for the PulseSelect\u0026trade; catheter using the EnSite\u0026trade; X Contact Index, originally designed for the Farapulse\u0026trade; system. This workflow enables real-time contact assessment by reassigning catheter electrodes and visualizing impedance changes\u0026thinsp;\u0026ge;\u0026thinsp;5Ω as contact tags. In a series of four patients undergoing zero-fluoroscopy PFA, i-Pulse facilitated accurate lesion delivery without procedural complications. The technique integrates ICE guidance and 3D mapping to overcome fluoroscopy dependence and enhances procedural reproducibility. i-Pulse may offer a valuable contact evaluation strategy for current PFA practice, especially for non-magnetic catheters.\u003c/p\u003e","manuscriptTitle":"A Novel Impedance-guided Contact Mapping Technique for the Circular Multielectrode Pulsed-Field Ablation Catheter","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-03 08:27:23","doi":"10.21203/rs.3.rs-6998414/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"455dca8d-adaf-45aa-85bc-cad27d09bb57","owner":[],"postedDate":"July 3rd, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[{"id":50731588,"name":"Cardiac \u0026 Cardiovascular Systems"}],"tags":[],"updatedAt":"2025-07-03T08:27:24+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-03 08:27:23","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6998414","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6998414","identity":"rs-6998414","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}