PRIVILEGED & CONFIDENTIAL — ATTORNEY WORK PRODUCT
CALDERWOOD & HARKNESS LLP 600 Lexington Avenue, 22nd Floor New York, NY 10022 Tel: (212) 554-7800
MEMORANDUM
TO: Alan Ngo, Responsible Partner (Reg. No. 58,412) Marcus Delgado, Billing Partner (Reg. No. 51,987)
FROM: Peter Vassiliev, Lead Associate (Reg. No. 72,340) Wendy Schultz, Working Associate (Reg. No. 78,115)
REVIEWED BY: Dr. Claire Nakamura, Patent Agent / Technical Specialist (Reg. No. 66,203)
DATE: November \\\_, 2024
RE: Prior-Art Analysis — Non-Final Office Action in U.S. Application No. 17/851,216 (SBD-001-CON2), "Cryoablation Catheter with Integrated Impedance Mapping Electrodes"
CLIENT: Solstice Biomedical Devices Ltd. (Matter No. SBD-IP-2021-003)
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I. Executive Summary
The purpose of this memorandum is to provide a comprehensive analysis of the Non-Final Office Action mailed on September 15, 2024, by Primary Examiner James R. Dougherty (Art Unit 3794, Supervisory Patent Examiner Linda M. Kowalski) in the second continuation application (CON-2), U.S. Application No. 17/851,216, filed on behalf of Solstice Biomedical Devices Ltd. ("SBD" or the "Client"). This memorandum sets forth the rejections and objections raised in the Office Action, evaluates the cited prior art, assesses the merits of each rejection, and recommends a prosecution strategy for responding to the Office Action within the applicable statutory and extended deadlines.
Application Overview. CON-2 (U.S. Application No. 17/851,216) is titled "Cryoablation Catheter with Integrated Impedance Mapping Electrodes." It was filed on June 27, 2022, and claims priority to the parent application, U.S. Application No. 16/914,337, which issued as U.S. Patent No. 11,284,561 on March 22, 2022, with twenty-four (24) allowed claims directed to a "Cryoablation Catheter System with Variable-Zone Cooling." CON-2 presently contains twenty (20) pending claims (Claims 1–20), directed to the catheter apparatus, methods of calibrating the impedance mapping electrodes, and a cryoablation system incorporating a feedback algorithm.
Named Inventors and Assignee. The named inventors are Dr. Aisling Connolly and Dr. Tomás Brennan, both employees of Solstice Biomedical Devices Ltd. The applicant and assignee of record is Solstice Biomedical Devices Ltd., an Irish private limited company (Companies Registration Office No. 647832), with prosecution activities coordinated through its U.S. subsidiary, Solstice Biomedical Inc., a Delaware corporation (DE File No. 7291456). Small-entity status has been confirmed under 37 C.F.R. § 1.27, as SBD has 312 employees globally as of December 31, 2023, and there is no outstanding licensing obligation to a large entity that would affect fee status.
Summary of Rejections and Objections. The Office Action raises the following rejections and objections:
1. Claims 1–8 — Rejected under 35 U.S.C. § 103 as being unpatentable over a combination of three prior-art references: U.S. Patent No. 10,537,418 ("Vantage '418"), U.S. Patent No. 9,861,432 ("Vantage '432"), and U.S. Published Application No. 2019/0183567 ("Helios '567").
2. Claims 9–14 — Rejected under 35 U.S.C. § 112(a) for alleged lack of written description support for the impedance mapping calibration algorithm and related method steps.
3. Claims 15–20 — Objected to as dependent on a rejected base claim (Claim 1) but identified by the Examiner as containing allowable subject matter.
Response Deadline. The three-month statutory response period expires on January 15, 2025. Under 37 C.F.R. § 1.136(a), the deadline may be extended by up to three additional months through successive one-month extension requests, pushing the maximum extended deadline to April 15, 2025. The cumulative small-entity extension fees total $1,380 ($230 for the first month, $460 for the second month, and $690 for the third month).
Overall Assessment. Based on our analysis, we believe the rejections are traversable and that a well-crafted response can place the application in condition for allowance or, at minimum, significantly advance prosecution. For Claims 1–8, we recommend amending independent Claim 1 to more explicitly recite the distinguishing structural and functional limitations of SBD's invention — particularly the independently controllable cryogenic zones with separate cryogen supply lumens and the spatial integration of impedance mapping electrodes on the catheter body configured for real-time impedance measurement during cryogenic delivery — and presenting detailed arguments distinguishing each of the three cited prior-art references. For Claims 9–14, we recommend not amending the claims but instead supplementing the record with detailed specification citations and a Rule 132 declaration from co-inventor Dr. Aisling Connolly, demonstrating that the specification fully supports the recited calibration algorithm. For Claims 15–20, we recommend rewriting Claim 15 in independent form to capture the allowable subject matter identified by the Examiner and to position those claims for allowance regardless of the outcome of the amended Claims 1–8.
Docket Status. We note that this docket has been dormant since July 3, 2023, when the last recorded activity in CON-2 was the filing of a two-month extension of time by Peter Vassiliev. The dormancy coincided with the shelving of SBD's CryoNova program following the FROST-AF trial results. Prosecution activity was reactivated following Ronan Gallagher's (SBD General Counsel) October 28, 2024 request for a comprehensive portfolio review in connection with SBD's board-level assessment of the patent portfolio's independent licensing value.
II. Procedural Background
A. Patent Family Overview
The CON-2 application at issue forms part of a family of four related U.S. patent applications filed by Solstice Biomedical Devices Ltd., together with corresponding foreign filings. The family tree is summarized below for reference, with additional detail provided in Appendix E.
Parent Application (SBD-001). U.S. Application No. 16/914,337 was filed on June 28, 2021, and is titled "Cryoablation Catheter System with Variable-Zone Cooling." The parent application was prosecuted to allowance and issued as U.S. Patent No. 11,284,561 on March 22, 2022, with twenty-four (24) claims. The issued parent patent covers the foundational cryoablation catheter system with the variable-zone cooling architecture that forms the platform technology for SBD's CryoNova product and related intellectual property. The parent patent's claims are directed broadly to the catheter structure, the variable-zone cooling element, and the cryogenic delivery system. The parent patent remains in force, with maintenance fees currently in compliance.
First Continuation (CON-1, SBD-001-CON1). U.S. Application No. 17/702,489 was filed on March 23, 2022, and is titled "Methods of Cryoablation Using Variable-Zone Cooling Catheter." CON-1 was prosecuted to a Notice of Allowance, which was mailed on April 10, 2023. However, the issue fee of $540 (small entity) was not paid by the July 10, 2023 deadline, and the application was deemed abandoned as of July 11, 2023. This abandonment occurred during the period of docket dormancy following the shelving of the CryoNova program. A petition to revive under 37 C.F.R. § 1.137(a) (unintentional delay) is available and is being addressed in a separate memorandum currently under preparation. The CON-1 claims are directed to methods of performing cryoablation using SBD's variable-zone cooling catheter and would complement the apparatus and system claims in the parent patent and in CON-2 and CON-3.
Second Continuation (CON-2, SBD-001-CON2). U.S. Application No. 17/851,216, filed June 27, 2022, is the subject of this memorandum. CON-2 is titled "Cryoablation Catheter with Integrated Impedance Mapping Electrodes" and contains twenty (20) pending claims directed to the catheter apparatus with integrated impedance mapping electrodes (Claims 1–8), methods of calibrating those electrodes (Claims 9–14), and a cryoablation system incorporating a feedback algorithm that adjusts cryogenic delivery based on impedance data (Claims 15–20). CON-2 is the application most directly relevant to SBD's differentiating technology — the integration of impedance mapping with variable-zone cryoablation — and thus holds particular importance for licensing discussions.
Third Continuation (CON-3, SBD-001-CON3). U.S. Application No. 18/109,744 was filed on February 14, 2023, and is titled "Control Unit and Algorithm for Multi-Zone Cryoablation Delivery." CON-3 is currently pending and awaiting a first Office Action. Its claims are directed to the electronic control unit and software algorithm for managing multi-zone cryogenic delivery, and it represents a further extension of the patent family's coverage into the control-system and software aspects of SBD's technology.
Foreign Filings. The patent family includes corresponding foreign applications filed via the Patent Cooperation Treaty: European Patent Application No. 21 741 632.8 (derived from PCT/EP2021/067891), currently pending before the European Patent Office, and Japanese Patent Application No. 2023-500714, currently pending before the Japan Patent Office. The European filing is handled by Dunmore & Firth Patent Attorneys in Dublin, and the Japanese filing is handled by Takeda & Morioka Patent Office in Tokyo. While these foreign applications are outside the scope of Calderwood & Harkness's engagement, we note their existence here because claim-scope coordination across jurisdictions may be relevant in the context of any licensing discussions or freedom-to-operate assessments.
B. CryoNova Program Status
This subsection provides context on the commercial program underlying SBD's patent family, which is relevant to the strategic assessment of prosecution priorities and the allocation of resources to this response.
SBD's CryoNova product is a second-generation cryoablation catheter designed for pulmonary-vein isolation ("PVI") in the treatment of atrial fibrillation. The CryoNova catheter's key technical differentiator — and the core subject matter of the CON-2 claims — is its integration of variable-zone cooling with impedance mapping electrodes on a single catheter body. This integrated design was conceived as a significant advance over existing market-leading devices, most notably Vantage Cryosurgical Systems, Inc.'s single-zone balloon cryoablation catheter (the "CryoVantage" system), which requires a separate diagnostic mapping catheter to assess tissue impedance before and after ablation but does not provide real-time impedance feedback during the ablation procedure itself.
SBD initiated the FROST-AF pivotal investigational device exemption ("IDE") clinical trial (IDE No. G210047) to support U.S. Food and Drug Administration premarket approval of the CryoNova catheter. The FROST-AF trial enrolled 220 patients (n=220) at twenty clinical sites. However, the trial failed to meet its primary efficacy endpoint: freedom from atrial arrhythmia at twelve months was observed in 58.2% of patients, falling short of the pre-specified performance target of 65% (p = 0.14). The failure of the primary endpoint was publicly announced on May 17, 2023.
In response to the clinical trial results, the SBD Board of Directors resolved on June 8, 2023, to shelve the CryoNova program. The decision resulted in a reduction in force within SBD's R&D and clinical operations divisions and a general wind-down of prosecution activity on the associated patent docket. As noted above, the prosecution docket has been dormant since July 3, 2023.
Despite the clinical failure of the CryoNova product, the underlying patented technology — particularly the impedance-mapping integration on a variable-zone cryoablation platform — retains potential licensing value independent of the CryoNova product. This assessment has been confirmed by Pinnacle Health Ventures, LLC, which holds approximately 34% of SBD's equity and has been conducting its own analysis of the patent portfolio's monetization potential. Pinnacle Health Ventures has identified two entities as potential licensees for SBD's impedance-mapping integration technology: Helios Surgical Technologies, Inc., an IP holding and licensing company with interests in interventional cardiology technologies, and Vantage Cryosurgical Systems, Inc., SBD's primary competitor in the cryoablation space, which may be interested in licensing or cross-licensing the impedance-mapping integration technology for incorporation into its own product line.
The reactivation of the CON-2 prosecution docket, prompted by Ronan Gallagher's October 28, 2024 request, is driven by this licensing rationale. Securing allowed claims in CON-2 that cover the integrated impedance-mapping and variable-zone cryoablation combination would materially strengthen SBD's position in any licensing negotiation.
C. Office Action Procedural Details
The Non-Final Office Action in CON-2 was mailed on September 15, 2024, by Primary Examiner James R. Dougherty of Art Unit 3794. The Supervisory Patent Examiner for Art Unit 3794 is Linda M. Kowalski. The Office Action is the first substantive examination on the merits for this application.
The three-month statutory response period under 37 C.F.R. § 1.134 expires on January 15, 2025. Under 37 C.F.R. § 1.136(a), the response deadline may be extended by up to three additional months through the filing of successive one-month extension-of-time requests accompanied by the applicable fees. At small-entity rates, the fees for each successive extension are:
The maximum extended response deadline is therefore April 15, 2025.
Recommendation. We recommend filing an extension-of-time request promptly to preserve the April 15, 2025 deadline while the response strategy is finalized and client authorization is obtained. Given the dormancy of this docket and the need to coordinate with Dr. Connolly on a Rule 132 declaration, as well as to obtain Board-level authorization for the prosecution expenditure, we anticipate that the full extended deadline will be necessary. The extension-of-time request can be filed concurrently with or in advance of the substantive response; however, to avoid any risk of inadvertent abandonment during the strategy-development period, we recommend filing the first extension promptly and the remaining extensions as needed.
III. Summary of Pending Claims
CON-2 contains twenty (20) pending claims, organized into three groups: apparatus claims directed to the cryoablation catheter (Claims 1–8), method claims directed to calibrating the impedance mapping electrodes (Claims 9–14), and system claims directed to a cryoablation system with a feedback algorithm (Claims 15–20). The full text of all twenty claims is reproduced in Appendix B. Below, we summarize the independent claims and the scope of the dependent claims.
A. Independent Claims
Claim 1 (Apparatus — Cryoablation Catheter). Independent Claim 1 is directed to a cryoablation catheter comprising: (a) a catheter body having a proximal end and a distal end; (b) a variable-zone cooling element disposed at the distal end, the variable-zone cooling element including at least two independently controllable cryogenic zones configured to deliver cryogenic cooling to target tissue; and (c) a plurality of impedance mapping electrodes integrated on the catheter body and configured to measure tissue impedance in real time during ablation. Claim 1 is the broadest apparatus claim and serves as the base claim for dependent Claims 2–8 and, indirectly, as the foundation for system Claim 15. Claim 1 is the subject of the § 103 obviousness rejection.
Claim 9 (Method — Calibration of Impedance Mapping Electrodes). Independent Claim 9 is directed to a method of calibrating impedance mapping electrodes on a cryoablation catheter, the method comprising the steps of: (a) measuring a baseline impedance value for each electrode in the plurality of impedance mapping electrodes; (b) detecting tissue contact via an impedance threshold comparison; (c) initiating a calibration algorithm that adjusts electrode sensitivity based on tissue contact and cooling-zone temperature; and (d) continuously updating calibration parameters in real time during the ablation procedure. Claim 9 introduces the algorithmic and procedural aspects of the electrode calibration process, which is a core aspect of SBD's inventive contribution. Claim 9 is the subject of the § 112(a) written-description rejection.
Claim 15 (System — Cryoablation System with Feedback Algorithm). Independent Claim 15 is directed to a cryoablation system comprising: (a) the cryoablation catheter of Claim 1; (b) a console operatively coupled to the catheter, the console including a processor; and (c) a feedback algorithm executed by the processor, the feedback algorithm configured to receive impedance data from the integrated impedance mapping electrodes and to adjust cryogenic delivery parameters based on the impedance data in real time during the ablation procedure. Claim 15 presently depends from Claim 1 and adds the system-level feedback-loop functionality. Claims 15–20 are the subject of the Examiner's objection (containing allowable subject matter but dependent on a rejected base claim).
B. Dependent Claims
Claims 2–8 (Depend from Claim 1). These dependent claims further specify various structural, functional, and performance aspects of the cryoablation catheter. Specifically, these claims recite additional limitations including: specific electrode configurations (e.g., ring electrodes, electrode spacing, electrode count); cryogenic zone geometries (e.g., annular zones, asymmetric zone sizing); cryogen delivery rates and temperature ranges; balloon compliance characteristics (e.g., compliant vs. semi-compliant balloon material); and mapping resolution parameters (e.g., minimum impedance measurement resolution, electrode density per unit area). Claims 2–8 are rejected along with Claim 1 under § 103.
Claims 10–14 (Depend from Claim 9). These dependent claims further specify the calibration method. Specifically, these claims recite additional limitations including: specific calibration sub-steps (Claims 10–11, directed to temperature-compensation algorithms and thermistor-based feedback); electrode contact-force thresholds for triggering calibration (Claims 12–13); and real-time display requirements for presenting calibrated impedance data to the operator (Claim 14). Claims 10–14 are rejected along with Claim 9 under § 112(a).
Claims 16–20 (Depend from Claim 15). These dependent claims further specify the cryoablation system. Specifically, these claims recite additional limitations including: feedback loop timing parameters (e.g., update frequency, latency thresholds); safety-shutoff thresholds (e.g., impedance values indicating over-ablation or tissue charring risk); multi-zone delivery sequencing (e.g., sequential vs. simultaneous zone activation, zone-specific dosimetry); and data-logging features for procedural recording and post-procedure analysis. Claims 16–20 are objected to along with Claim 15 as dependent on a rejected base claim, but the Examiner has indicated they contain allowable subject matter.
IV. Analysis of § 103 Obviousness Rejection — Claims 1–8
A. Cited Prior-Art References
The Examiner has rejected Claims 1–8 under 35 U.S.C. § 103 as being unpatentable over a combination of three prior-art references. We analyze each reference below, identifying both the teachings relied upon by the Examiner and the critical limitations that each reference fails to teach or suggest.
1. U.S. Patent No. 10,537,418 (Primary Reference — "Vantage '418")
U.S. Patent No. 10,537,418 ("Vantage '418") is assigned to Vantage Cryosurgical Systems, Inc., located at 1420 Gateway Boulevard, South San Francisco, California 94080. The Vantage '418 patent is directed to a cryoablation catheter employing a single-zone balloon design for pulmonary-vein isolation in the treatment of atrial fibrillation. The Examiner relies on Vantage '418 as the primary reference and maps it to the following elements of Claim 1: the catheter body having a proximal end and a distal end, the cryogenic delivery mechanism employing an expandable balloon element, and tissue-contact sensing functionality.
Vantage '418 describes a cryoablation catheter comprising an elongated catheter shaft with a single expandable cryoballoon at the distal end. The cryoballoon is inflated with a cryogenic fluid (nitrous oxide or a similar refrigerant) to achieve circumferential tissue ablation at the ostium of a pulmonary vein. The patent further describes a tissue-contact sensing mechanism that uses pressure feedback to determine whether the balloon has achieved adequate occlusion of the pulmonary vein.
Key Limitations of Vantage '418. Despite the Examiner's reliance on this reference, Vantage '418 has several critical limitations with respect to the claims of CON-2:
• No variable-zone cooling. Vantage '418 discloses only a single-zone cryoballoon design. The entire balloon surface delivers uniform cryogenic cooling. There is no teaching of, suggestion of, or motivation to develop independently controllable cryogenic zones. The concept of tailoring ablation depth across different segments of the target tissue — which is central to SBD's invention — is entirely absent from this reference.
• No integrated impedance mapping electrodes. Vantage '418 does not disclose impedance mapping electrodes integrated on the catheter body. The tissue-contact sensing in Vantage '418 is limited to pressure-based feedback for confirming balloon occlusion and does not involve impedance measurement of any kind.
• No real-time impedance measurement during cryoablation. Because Vantage '418 does not include impedance mapping electrodes, it necessarily does not teach real-time impedance measurement during the cryoablation procedure. In fact, Vantage '418 describes a workflow in which ablation verification is performed post-procedure using a separate diagnostic catheter.
2. U.S. Patent No. 9,861,432 (Secondary Reference — "Vantage '432")
U.S. Patent No. 9,861,432 ("Vantage '432") is also assigned to Vantage Cryosurgical Systems, Inc. The Vantage '432 patent is directed to a multi-electrode mapping catheter used as a standalone diagnostic tool for cardiac tissue assessment. The Examiner relies on Vantage '432 as a secondary reference for the impedance mapping electrode teachings, mapping it to the "plurality of impedance mapping electrodes" limitation in Claim 1.
Vantage '432 describes a diagnostic mapping catheter comprising a flexible catheter body with an array of impedance-sensing electrodes distributed along a spline or basket configuration at the distal end. The electrodes are configured to measure tissue impedance in the cardiac chambers for purposes such as identifying scar tissue, mapping conduction pathways, and assessing tissue thickness. The catheter is designed to be introduced into the cardiac chambers as a separate diagnostic instrument, typically before or after an ablation procedure.
Key Limitations of Vantage '432. This reference, while teaching impedance mapping electrodes, is critically deficient in several respects:
• Standalone diagnostic device — not integrated with an ablation catheter. Vantage '432 describes a mapping catheter that is a separate instrument from the ablation catheter. The electrodes in Vantage '432 are not disposed on an ablation catheter body and are not configured to operate in the presence of cryogenic cooling. The Vantage '432 catheter is introduced into the heart as a separate device during a separate procedural step.
• Electrodes not integrated onto a cryoablation catheter body. There is no teaching in Vantage '432 of placing impedance mapping electrodes on a catheter body that also houses cryogenic delivery elements. The mechanical and spatial constraints of integrating electrodes onto a cryoablation catheter — where the catheter body must accommodate a cryogen supply lumen, an exhaust lumen, a balloon inflation mechanism, and other structural components — are not addressed or even contemplated in Vantage '432.
• Does not address cryogenic-environment challenges. The Vantage '432 mapping catheter operates at or near body temperature. The reference does not discuss the engineering challenges associated with impedance measurement in a cryogenic environment, including electrode material brittleness at extreme low temperatures, thermal drift in impedance readings caused by cryogenic cooling, frost formation on electrode surfaces, and the need for temperature-compensated calibration algorithms.
3. U.S. Published Application No. 2019/0183567 (Tertiary Reference — "Helios '567")
U.S. Published Application No. 2019/0183567 ("Helios '567") is assigned to Helios Surgical Technologies, Inc., located at 750 Bering Drive, Suite 400, Houston, Texas 77057. The Helios '567 publication is directed to the general concept of combining ablation and tissue-property sensing functionalities in a single catheter device. The Examiner relies on Helios '567 as a tertiary reference for the concept of integrating sensing elements with ablation elements on a catheter body.
Helios '567 describes a catheter system in which radiofrequency (RF) ablation electrodes are co-located with tissue-property sensing elements (including, generically, impedance sensors, temperature sensors, and force sensors) on a single catheter body. The publication teaches that integrating these functionalities into a single catheter eliminates the need for catheter exchanges during the procedure and enables continuous tissue monitoring during RF ablation delivery.
Key Limitations of Helios '567. Despite the Examiner's reliance on this reference for the integration concept, Helios '567 is critically distinguishable:
• Directed to RF ablation — not cryoablation. Helios '567 is exclusively concerned with radiofrequency ablation. The thermal and mechanical environment of RF ablation is fundamentally different from that of cryoablation. RF ablation involves heating tissue to temperatures typically in the range of 50°C–70°C, whereas cryoablation involves cooling tissue to temperatures as low as –80°C. The physical challenges of integrating impedance-sensing electrodes in these two environments are entirely different.
• Does not address cryogenic-environment challenges. Because Helios '567 operates in the RF ablation context, it does not address the distinct thermal and mechanical challenges of integrating impedance electrodes with cryogenic cooling elements. Specifically, Helios '567 does not address: (a) the risk of electrode material embrittlement at cryogenic temperatures; (b) thermal drift in impedance measurements caused by the extreme temperature differential between cryogenic zones and adjacent tissue; (c) frost and ice formation on electrode surfaces that can degrade or block impedance readings; or (d) the need for temperature-compensated calibration algorithms unique to the cryogenic environment.
• No variable-zone cooling concept. The concept of variable-zone cooling is entirely absent from Helios '567. The RF ablation catheter described in Helios '567 delivers energy from a single ablation electrode or from a linear array of electrodes along the catheter tip; there is no analog to independently controllable cryogenic zones.
• No disclosure of impedance mapping calibration in cryogenic environment. Helios '567 provides no guidance on how impedance measurements should be calibrated or compensated in the context of cryogenic cooling, because the reference does not contemplate cryogenic cooling at all.
B. Examiner's Rationale for Combination
Examiner Dougherty's rejection is premised on the assertion that it would have been obvious to a person having ordinary skill in the art ("PHOSITA") at the time of the effective filing date to modify the Vantage '418 single-zone cryoablation catheter by incorporating the impedance mapping electrodes taught by Vantage '432, using the combined ablation-and-sensing integration approach described in Helios '567. The Examiner's stated rationale for combining the three references includes the following points:
First, the Examiner asserts that the motivation to combine arises from a general desire to "improve ablation efficacy by providing real-time tissue assessment during cryoablation." The Examiner characterizes this motivation as flowing naturally from the known benefits of tissue monitoring during ablation procedures, as exemplified in the Helios '567 publication.
Second, the Examiner asserts that a person of ordinary skill in the art would have had a "reasonable expectation of success" in achieving the combination, based on what the Examiner characterizes as the "general maturity" of both cryoablation technology and impedance mapping technology. The Examiner appears to take the position that because both technologies are individually well-known, their combination would not present undue difficulty.
Third, the Examiner does not specifically address the variable-zone cooling limitation of Claim 1 (i.e., "at least two independently controllable cryogenic zones") in the rejection. The Examiner's mapping of the prior art to the claim limitations focuses on the catheter body structure, the cryogenic delivery mechanism, and the impedance mapping electrodes, but the rejection does not identify any reference that teaches or suggests the multi-zone cooling aspect of the claimed invention.
C. Key Distinctions and Arguments for Traversing the Rejection
Based on our analysis, there are several strong bases for traversing the § 103 rejection of Claims 1–8. We address each in turn below.
1. Variable-Zone Cooling — Not Taught or Suggested
The most fundamental deficiency in the Examiner's rejection is the failure to account for the variable-zone cooling limitation of Claim 1. Claim 1 expressly requires "a variable-zone cooling element disposed at the distal end, the variable-zone cooling element including at least two independently controllable cryogenic zones configured to deliver cryogenic cooling to target tissue." This is a specific structural and functional limitation that goes to the heart of SBD's inventive contribution.
Vantage '418, the primary reference, discloses only a single-zone cryoballoon. The balloon in Vantage '418 delivers uniform cryogenic cooling across its entire surface and does not include — nor does it suggest — the capability to control cooling independently in two or more separate zones. Vantage '432 is directed to a diagnostic mapping catheter that does not include any cryogenic cooling element, let alone a multi-zone one. Helios '567 is directed to an RF ablation catheter with no cryogenic cooling element whatsoever. In short, the concept of independently controllable cryogenic zones is entirely absent from all three cited references, individually and in combination.
This omission is not a minor gap. The variable-zone cooling architecture is the foundational structural innovation of SBD's invention. It addresses the specific clinical problem of non-uniform tissue thickness at the pulmonary vein ostia, where different anatomical regions may require different ablation depths to achieve transmural lesion formation without over-ablating thin tissue or under-ablating thick tissue. This problem is not recognized or addressed in any of the cited references. The Vantage '418 single-zone balloon, by design, delivers the same degree of cooling to all tissue in contact with the balloon — an approach that SBD's inventors recognized as a limitation and sought to overcome with the variable-zone design.
Moreover, the variable-zone cooling limitation is not merely a design choice that a PHOSITA would have found obvious to implement. The implementation of independently controllable cryogenic zones requires multiple separate cryogen supply lumens within the catheter body, individual flow-control valves or orifices for each zone, and a control architecture capable of modulating cooling independently in each zone. These structural complexities are neither taught nor suggested by the cited art.
2. Integration of Impedance Mapping Electrodes on a Cryoablation Catheter Body
Even setting aside the variable-zone cooling limitation (which alone should be dispositive), the Examiner's proposed combination improperly conflates two fundamentally different types of catheter devices and two fundamentally different technical environments.
Vantage '432 teaches impedance mapping electrodes on a standalone diagnostic catheter. The electrodes in Vantage '432 are deployed on a flexible spline or basket structure that is designed to be maneuvered within the cardiac chambers at normal body temperature. The catheter body of a diagnostic mapping catheter is fundamentally different from that of a cryoablation catheter: it does not accommodate cryogen supply or exhaust lumens, it does not include a balloon inflation mechanism, and it is not subjected to the extreme temperatures associated with cryogenic delivery.
Helios '567 teaches the concept of co-locating ablation and sensing elements on a single catheter, but exclusively in the context of RF ablation. In the RF ablation environment, temperatures are elevated (50°C–70°C) and the thermal environment is relatively stable compared to cryoablation. The materials, configurations, and calibration approaches suitable for impedance sensing in an RF environment are not directly transferable to the cryogenic environment. In particular, the following engineering challenges — which are discussed in SBD's specification at paragraphs [0045]–[0058] — are unique to impedance electrode integration on a cryoablation catheter and are not addressed in any of the cited references:
(a) Electrode material brittleness. At the cryogenic temperatures involved in cryoablation (as low as –80°C), many standard electrode materials become brittle and may crack or lose conductivity. SBD's specification describes the selection and validation of specific electrode materials (e.g., platinum-iridium alloys with enhanced low-temperature ductility) to address this challenge.
(b) Thermal drift in impedance measurements. The extreme temperature differential between the cryogenic zones and the adjacent tissue creates significant thermal drift in impedance readings. Impedance is inherently temperature-dependent, and a PHOSITA would understand that impedance measurements taken at cryogenic temperatures cannot be directly compared to baseline measurements taken at body temperature without a temperature-compensation algorithm. This challenge is not addressed or even contemplated in the cited art.
(c) Frost formation on electrode surfaces. In the cryogenic environment, condensation and frost formation on the catheter surface — including on the electrode surfaces — can degrade or completely block impedance readings. SBD's specification describes specific design features to mitigate frost interference, including electrode surface coatings and heating elements adjacent to the electrode contacts.
(d) Spatial constraints. Integrating impedance mapping electrodes onto a catheter body that already houses multiple cryogen supply lumens, an exhaust lumen, and a multi-zone balloon structure creates significant spatial and mechanical engineering challenges that are not present when designing a standalone diagnostic mapping catheter or an RF ablation catheter with integrated sensors.
The Examiner's combination essentially requires a PHOSITA to take a single-zone cryoballoon catheter (Vantage '418), add impedance mapping electrodes from a completely separate diagnostic device (Vantage '432), and rely on a general teaching about sensor integration from an RF ablation context (Helios '567) — all without any guidance on how to address the specific and substantial engineering challenges of the cryogenic environment. This is precisely the type of hindsight reconstruction that the Federal Circuit has repeatedly cautioned against. See In re Kahn, 441 F.3d 977, 988 (Fed. Cir. 2006) ("Rejections on obviousness grounds cannot be sustained by mere conclusory statements; instead, there must be some articulated reasoning with some rational underpinning to support the legal conclusion of obviousness."); KSR Int'l Co. v. Teleflex Inc., 550 U.S. 398, 421 (2007) (rejections must avoid "the distortion caused by hindsight bias" and must be supported by "some articulated reasoning").
3. Real-Time Impedance Measurement During Cryoablation
SBD's claims require that the impedance mapping electrodes be configured to "measure tissue impedance in real time during ablation" — that is, while the cryogenic cooling is actively being delivered to the target tissue. This simultaneous-measurement limitation is a critical distinguishing feature and is not taught or suggested by any of the cited references.
In Vantage '418, there are no impedance mapping electrodes, and therefore no impedance measurement occurs at any time, let alone during cryoablation. In Vantage '432, the mapping catheter is used as a separate diagnostic tool, typically introduced into the cardiac chambers before or after an ablation procedure; impedance mapping in Vantage '432 is performed in a non-cryogenic environment. In Helios '567, while RF ablation and sensing occur simultaneously, the reference operates in the RF domain and does not address the unique challenges of impedance measurement during cryogenic delivery, including the temperature-dependent impedance variations and frost-interference issues discussed above.
The concept of measuring impedance in real time during cryoablation is not an incremental or predictable extension of the cited art. It requires solving the technical challenges of impedance measurement in a rapidly changing cryogenic thermal environment, including the development of temperature-compensation algorithms, frost-mitigation strategies, and electrode materials suitable for simultaneous cryogenic and electrical operation. These solutions are described in SBD's specification and represent a significant inventive contribution.
4. Teaching Away / Lack of Motivation to Combine
Beyond the absence of the claimed features in the cited art, there is affirmative evidence that the art teaches away from the proposed combination. Vantage '418 specifically teaches that its single-zone balloon design achieves circumferential ablation without the need for mapping during ablation. The Vantage '418 specification describes a clinical workflow in which the cryoballoon is deployed, ablation is performed, the balloon is deflated and withdrawn, and then a separate diagnostic mapping catheter (such as the one described in Vantage '432) is introduced to verify the completeness of the ablation lesion. This sequential, two-catheter workflow is presented as a feature — not a limitation — of the Vantage system, and the reference contains no suggestion that integrating mapping electrodes onto the cryoablation catheter itself would be desirable or advantageous.
Furthermore, the Examiner's cited motivation to combine — "improve ablation efficacy by providing real-time tissue assessment during cryoablation" — is generic and conclusory. It does not account for the specific technical barriers that would confront a PHOSITA attempting to integrate impedance electrodes onto a cryoablation catheter. A motivation to combine must be accompanied by a reasonable expectation of success, and the Examiner has not explained how a PHOSITA would have had a reasonable expectation of success in overcoming the electrode-material, thermal-drift, frost-formation, and spatial-constraint challenges inherent in the proposed combination. See In re Stepan Co., 868 F.3d 1342, 1346 (Fed. Cir. 2017) (reasonable expectation of success requires more than a general desire for improvement; it requires a basis for believing the specific combination would work).
No reference in the cited art provides a motivation to combine impedance electrodes specifically with a multi-zone cryoablation catheter. Even if, arguendo, one were to accept the Examiner's generalized motivation to integrate sensing and ablation, that motivation does not extend to the specific combination of variable-zone cryoablation and integrated impedance mapping, which presents a unique set of challenges not addressed by any of the cited references.
D. Recommended Prosecution Strategy for Claims 1–8
Based on the analysis above, we recommend the following strategy for responding to the § 103 rejection of Claims 1–8:
1. Amend Independent Claim 1. We recommend amending Claim 1 to more explicitly recite the distinguishing structural and functional limitations of SBD's invention. Specifically, we recommend amending Claim 1 to recite:
(a) at least two independently controllable cryogenic zones, each zone having a separate cryogen supply lumen within the catheter body;
(b) the plurality of impedance mapping electrodes being disposed on the catheter body between or adjacent to the cryogenic zones; and
(c) the impedance mapping electrodes being configured to measure tissue impedance in real time simultaneously with cryogenic delivery from the at least two independently controllable cryogenic zones.
These amendments do not narrow the claim scope in any material respect but rather make explicit what is already implicit in the claim and fully supported by the specification. The amendments serve to draw a brighter line between SBD's invention and the cited prior art, particularly with respect to the variable-zone architecture and the simultaneous impedance measurement during cryogenic delivery.
2. Consider Conforming Amendments to Claims 2–8. Depending on the final form of the Claim 1 amendment, conforming amendments to dependent Claims 2–8 may be advisable to ensure consistency and to further recite the specific electrode-zone spatial relationship and temperature-compensated impedance measurement features. We will assess the need for dependent-claim amendments after finalizing the Claim 1 language.
3. Present Detailed Arguments Distinguishing All Three References. The response should include a comprehensive argument section that: (a) demonstrates the absence of variable-zone cooling in any of the cited references; (b) explains the unaddressed engineering challenges of impedance electrode integration in the cryogenic environment; (c) rebuts the Examiner's generic motivation to combine by showing the absence of any reference-specific motivation to integrate impedance electrodes onto a multi-zone cryoablation catheter; and (d) highlights Vantage '418's teaching away from integrated mapping by its endorsement of a two-catheter sequential workflow.
4. Support with a Rule 132 Declaration from Dr. Aisling Connolly. We recommend supporting the response with a Declaration under 37 C.F.R. § 1.132 from co-inventor Dr. Aisling Connolly (Ph.D. Biomedical Engineering, Trinity College Dublin; VP R&D at SBD). The declaration should: (a) define the level of ordinary skill in the art relevant to the invention; (b) explain the specific technical challenges of integrating impedance mapping electrodes onto a variable-zone cryoablation catheter; (c) describe the inventive process and the non-obvious nature of the combination; and (d) address any secondary considerations of non-obviousness, including any evidence of industry skepticism, long-felt need, or failure of others to achieve the integration.
5. Consider Engaging Caravel Prior Art Services LLC. We recommend reviewing the records of Caravel Prior Art Services LLC (Daniel Yoon, primary contact) for any prior landscape analysis that may have been performed in connection with the parent application or the broader SBD patent portfolio. If existing search records do not adequately support our arguments, we may recommend commissioning an updated prior-art landscape search specifically focused on the integration of impedance mapping with cryoablation technology, which could further demonstrate the novelty and non-obviousness of SBD's approach.
V. Analysis of § 112(a) Written-Description Rejection — Claims 9–14
A. Examiner's Position
Examiner Dougherty rejects Claims 9–14 under 35 U.S.C. § 112(a) for alleged failure to satisfy the written-description requirement. The Examiner asserts that the impedance mapping calibration algorithm recited in independent Claim 9 and its dependent Claims 10–14 is not sufficiently described in the specification to demonstrate that the inventors had possession of the claimed invention at the time of filing.
The Examiner's rejection specifically identifies the following claim limitations as lacking adequate written-description support:
(1) Calibration algorithm steps. The Examiner contends that the steps of the calibration algorithm recited in Claim 9 — including the adjustment of electrode sensitivity based on tissue contact — are described in the specification only at a high level of generality and do not provide sufficient algorithmic detail to show possession.
(2) Temperature-compensation of impedance readings. The Examiner contends that the temperature-compensation feature recited in dependent Claims 10–11 — which involves compensating impedance readings for temperature changes during cryogenic delivery — lacks sufficient disclosure of the specific compensation methodology.
(3) Real-time calibration updating. The Examiner contends that the real-time updating of calibration parameters during the ablation procedure, as recited in Claim 9 and further specified in Claims 12–13, is not adequately described, and that the specification does not disclose the specific timing, error-correction, or computational methodology for real-time recalibration.
B. Review of Specification Disclosure
1. Parent Specification (U.S. Patent No. 11,284,561)
Because CON-2 claims the benefit of U.S. Application No. 16/914,337 (the parent application), the parent specification as filed is the relevant document for assessing written-description support. We have conducted a thorough review of the parent specification and have identified the following sections as providing relevant disclosure for each of the challenged claim limitations.
Impedance Mapping Electrode Array. Specification paragraphs [0045] through [0058] describe the impedance mapping electrode array in detail, including electrode placement on the catheter body, electrode materials (platinum-iridium alloys selected for low-temperature ductility and stable electrical conductivity), electrode spacing and count, and the electrical configuration of the electrode array (bipolar and unipolar measurement modes). These paragraphs establish the physical and electrical foundation for the calibration algorithm described in subsequent specification sections.
Calibration Procedure Overview. Specification paragraphs [0071] through [0085] describe a multi-step calibration algorithm for the impedance mapping electrodes. The disclosure includes: (a) an initial baseline impedance measurement performed with the electrodes in a known reference medium (e.g., saline at body temperature) prior to tissue contact (paragraphs [0072]–[0074]); (b) a tissue-contact detection step in which the impedance value measured by each electrode is compared to a predefined impedance threshold to determine whether the electrode is in contact with tissue (paragraphs [0075]–[0078]); (c) an electrode sensitivity adjustment step in which the gain and offset parameters for each electrode channel are adjusted based on the tissue-contact determination and the measured impedance baseline (paragraphs [0079]–[0083]); and (d) an iterative refinement step in which the calibration parameters are refined through successive impedance measurements over a defined time interval (paragraphs [0084]–[0085]). These paragraphs directly support the calibration algorithm steps recited in Claim 9.
Temperature Compensation. Specification paragraphs [0086] through [0092] describe a temperature-compensation methodology for impedance readings during cryogenic delivery. The disclosure includes: (a) the use of thermistors disposed adjacent to the impedance mapping electrodes to measure local temperature in real time (paragraph [0087]); (b) a mathematical model relating impedance to temperature for the specific electrode materials and tissue types involved (paragraphs [0088]–[0089]); (c) a correction algorithm that applies the temperature-impedance model to compensate raw impedance readings for the temperature changes induced by cryogenic cooling (paragraphs [0090]–[0091]); and (d) validation data demonstrating the accuracy of the temperature compensation across the operational temperature range (–80°C to +37°C) (paragraph [0092]). These paragraphs directly support the temperature-compensation limitations recited in Claims 10 and 11.
Real-Time Updating. Specification paragraphs [0093] through [0098] describe a continuous recalibration loop that operates during the ablation delivery. The disclosure includes: (a) the timing interval for recalibration updates (described as occurring at intervals of 100 milliseconds to 1 second, depending on the rate of temperature change in the ablation zone) (paragraph [0094]); (b) the error-correction methodology, including a Kalman-filter-based approach for filtering noise from real-time impedance readings and updating calibration parameters accordingly (paragraphs [0095]–[0096]); and (c) the real-time display of calibrated impedance values on the console display for operator monitoring (paragraphs [0096]–[0098]). These paragraphs directly support the real-time calibration updating limitations recited in Claims 9, 12, 13, and 14.
Flowchart — Figure 7. Figure 7 of the specification is a detailed flowchart illustrating the algorithmic steps of the calibration process, from initial baseline measurement through tissue-contact detection, sensitivity adjustment, temperature compensation, and real-time updating. The flowchart provides a visual representation of the algorithm that, together with the accompanying textual description, clearly demonstrates the inventors' possession of the calibration methodology.
Example Embodiment. Specification paragraphs [0112] through [0118] describe bench-test data for the calibration algorithm as applied to a prototype CryoNova catheter. The example includes specific numerical values for baseline impedance, tissue-contact thresholds, temperature-compensation correction factors, and real-time update intervals, further demonstrating that the inventors had reduced the calibration algorithm to practice at the time of filing.
2. Assessment of Written-Description Support
Based on our review, the parent specification does provide adequate written-description support for the calibration algorithm as claimed in Claims 9–14. The disclosure is detailed, specific, and encompasses each of the claim limitations identified by the Examiner as lacking support.
We believe the Examiner's rejection stems from a failure to locate and synthesize the relevant specification sections, which are distributed across multiple parts of the specification rather than consolidated in a single contiguous passage. The specification's structure separates the electrode array description (paragraphs [0045]–[0058]), the calibration algorithm description (paragraphs [0071]–[0098]), and the example embodiment (paragraphs [0112]–[0118]) into distinct sections. While this organization is conventional and appropriate for a patent specification, it may have made it difficult for the Examiner to identify the full extent of the calibration-algorithm disclosure during initial examination.
Additionally, the Examiner may have been influenced by the claims' use of functional language (e.g., "adjusting electrode sensitivity based on tissue contact and cooling-zone temperature"), which can sometimes create an impression of under-specification when the corresponding structural and algorithmic detail in the specification is not immediately apparent. However, as shown above, the specification provides ample algorithmic detail underlying the functional claim language, including specific computational methodologies (Kalman filtering, temperature-impedance modeling), timing parameters, and validation data.
We note that the written-description standard requires the specification to "reasonably convey to those skilled in the art that the inventor had possession of the claimed subject matter as of the filing date." Ariad Pharms., Inc. v. Crowne Albany Industries, 598 F.3d 1336, 1351 (Fed. Cir. 2010) (en banc). The standard does not require the specification to describe the claimed subject matter in haec verba or in a single consolidated passage; it requires only that a PHOSITA reading the specification as a whole would understand that the inventors possessed the invention. The SBD specification satisfies this standard.
C. Recommended Prosecution Strategy for Claims 9–14
Based on the analysis above, we recommend the following strategy for responding to the § 112(a) rejection of Claims 9–14:
1. Do NOT amend the claims. The claims as currently drafted accurately reflect the disclosed invention, and the calibration algorithm limitations are fully supported by the specification. Amending the claims to narrow the calibration-algorithm language would unnecessarily surrender claim scope without addressing the actual issue, which is the Examiner's apparent failure to identify the relevant specification disclosure. Narrowing the claims would also risk creating prosecution history estoppel that could limit the scope of the claims in enforcement or licensing contexts.
2. Provide detailed specification citations in the response. The response should include a comprehensive mapping of each challenged claim limitation to specific paragraphs and figures in the parent specification. We recommend the following cross-reference structure:
3. Support with a Declaration under 37 C.F.R. § 1.132 from Dr. Aisling Connolly. Dr. Connolly holds a Ph.D. in Biomedical Engineering from Trinity College Dublin and serves as Vice President of Research and Development at Solstice Biomedical Devices Ltd. She is a co-inventor on all four applications in the SBD patent family and was the principal architect of the calibration algorithm. A declaration from Dr. Connolly would:
(a) Define the level of ordinary skill in the art relevant to the invention, including the typical educational background and experience of practitioners in the cryoablation catheter design field;
(b) Confirm that the specification provides sufficient detail for a person of ordinary skill in the art to understand that the inventors possessed the calibration algorithm at the time of filing;
(c) Walk through the specification disclosure, pointing the Examiner to the relevant paragraphs and figures and explaining how each element of the claimed calibration algorithm is supported;
(d) Distinguish the claimed calibration algorithm from general impedance calibration approaches used in the RF ablation context, explaining the unique challenges of cryogenic-environment calibration (temperature drift, frost interference, extreme-temperature electrode behavior) and how the specification addresses those challenges; and
(e) Reference the bench-test data described in specification paragraphs [0112]–[0118] as evidence of actual reduction to practice of the calibration algorithm.
4. Consider an Examiner interview. If we assess that the written response and declaration may not be sufficient to overcome the rejection — for example, if the Examiner has a particular concern that is not evident from the Office Action itself — we recommend conducting an interview with Examiner Dougherty, or if appropriate, Supervisory Patent Examiner Kowalski, to walk through the specification support in person. An interview can be particularly effective in overcoming § 112(a) rejections where the issue is the Examiner's failure to locate disclosure rather than a genuine deficiency in the specification. The interview could be conducted before or concurrently with the filing of the written response, and could be requested via the USPTO's Automated Interview Request (AIR) system. We would propose that Dr. Claire Nakamura participate in any such interview to provide technical context.
VI. Analysis of Objection to Claims 15–20
A. Examiner's Position
Claims 15–20 are not rejected on the merits. Rather, the Examiner has objected to Claims 15–20 as being dependent on a rejected base claim (specifically, Claim 15 depends from Claim 1, which has been rejected under § 103), but has indicated that Claims 15–20 contain allowable subject matter.
Specifically, the Examiner has found that the system claims incorporating the feedback algorithm — which receives impedance data from the integrated impedance mapping electrodes and adjusts cryogenic delivery parameters based on that data in real time during the ablation procedure — distinguish over the cited prior art. The Examiner's objection follows the standard USPTO practice of noting allowable dependent claims while maintaining the objection pending resolution of the rejection of the base claim from which they depend.
B. Significance
The Examiner's indication of allowable subject matter in Claims 15–20 is a significant and positive prosecution signal. It demonstrates that the Examiner recognizes the feedback-loop/algorithm limitations — specifically, the real-time adjustment of cryogenic delivery based on impedance data — as patentably distinct over the cited prior art. This finding has several important implications:
First, it confirms that the core value proposition of SBD's technology — the closed-loop integration of impedance mapping with cryoablation delivery — is recognized by the USPTO as a novel and non-obvious contribution over the cited art. This is directly relevant to SBD's licensing strategy, as it validates the patentability of the most commercially significant aspect of the technology.
Second, the Examiner's allowance of the feedback-algorithm limitations supports our broader strategy of amending Claims 1–8 to incorporate similar distinguishing limitations. If the variable-zone/feedback concept is recognized as allowable when recited in the system context of Claims 15–20, it should logically also be allowable when incorporated into the apparatus claims of Claims 1–8 through amendment.
Third, the indication of allowable subject matter provides a fallback path to securing at least some allowed claims in CON-2 even if the amendment strategy for Claims 1–8 encounters further difficulty. By rewriting Claim 15 in independent form, we can position Claims 15–20 for immediate allowance regardless of the outcome of the § 103 rejection.
C. Recommended Strategy for Claims 15–20
Based on the Examiner's objection and indication of allowable subject matter, we recommend the following strategy:
1. Rewrite Claim 15 in independent form. We recommend rewriting Claim 15 to remove its current dependency on Claim 1 and to incorporate all necessary limitations from Claim 1 directly into the body of Claim 15. The rewritten Claim 15 should include: (a) the cryoablation catheter limitations (catheter body, variable-zone cooling element with at least two independently controllable cryogenic zones, integrated impedance mapping electrodes); (b) the console and processor limitations; and (c) the feedback algorithm limitations that the Examiner has identified as allowable. This rewriting will allow Claims 15–20 to stand independently and to be allowed without dependency on the resolution of the Claim 1 rejection.
2. Maintain parallel track. If our amendment strategy for Claim 1 succeeds and Claims 1–8 are allowed as amended, then Claims 15–20 will also be al