Cryoablation catheter shaft structure

Abstract

Embodiments of the present disclosure relate to a cryoablation probe comprising a precooler fluid circuit, a working fluid circuit, a vacuum circuit, and a shaft. The shaft includes a feed tube and a return tube surrounding the feed tube. The return tube includes a first polymer layer configured to contain fluid from the working fluid circuit, a reinforcing layer, and a second polymer layer. Other embodiments are also included in the present disclosure.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to a cryoablation system, and more particularly to a flexible cryoablation system. This application claims priority to U.S. Provisional Patent Application No. 63 / 468,962, filed May 25, 2023, and U.S. Patent Application No. 18 / 671,489, filed May 22, 2024, the contents of which are hereby incorporated by reference in their entirety.

Background Art

[0002] During cryosurgery, a surgeon may place one or more cryoprobes to freeze and thaw tissue to excise a target area of a patient's anatomical structure. In one example, the cryoprobe uses the Joule-Thomson effect to effect cooling or heating at the tip of the probe. In such a case, the cryogenic fluid within the cryoablation probe expands from high pressure to low pressure, causing the device tip to cool to a temperature corresponding to or lower than the cryoablation of the tissue in the vicinity of the tip. Heat transfer between the expanded cryogenic fluid and the outer wall of the cryoprobe forms an ice ball in the tissue around the tip, followed by cryoablation of the tissue.

Summary of the Invention

[0003] A first aspect may include a cryoablation probe having a pre-cooler fluid circuit, a working fluid circuit, a vacuum circuit, and a shaft. The shaft may include a supply tube and a return tube surrounding the supply tube. The return tube may include a first polymer layer configured to contain fluid from the working fluid circuit, a reinforcing layer, and a second polymer layer. The shaft may further include a heat insulation region where the vacuum circuit may be defined within the heat insulation region between the return tube and the heat insulation shaft, and an expansion chamber extending distally of the heat insulation region, where fluid from the working fluid circuit moves through the supply tube and expands within the expansion chamber.

[0004] In a second embodiment, in addition to or instead of one or more of the embodiments described above, the shaft may form a curve having a minimum radius of curvature of 30 mm or less. In a third embodiment, the first polymer layer may include PTFE in addition to or instead of one or more of the embodiments described above or below. The second polymer layer may include polyether block amide.

[0005] In a fourth embodiment, in addition to or instead of one or more of the embodiments described above, the vacuum circuit terminates at the distal end of the adiabatic region. The distal end of the adiabatic region may be the proximal end of the expansion chamber.

[0006] In the fifth embodiment, in addition to or instead of one or more of the embodiments described above or below, the second polymer layer may have a substantially constant durometer hardness along its length.

[0007] In the sixth embodiment, in addition to or instead of one or more of the embodiments described above or below, the second polymer layer may be a thermoplastic material and may include multiple regions with different durometer hardnesses along its length.

[0008] In the seventh embodiment, in addition to or instead of one or more of the embodiments described above, the second polymer layer is characterized by a decrease in hardness at at least one point from the proximal end of the shaft toward the distal end of the shaft.

[0009] In the eighth aspect, in addition to or instead of one or more of the preceding or succeeding aspects, the second polymer layer may include at least a first region having the first durometer hardness and a second region located proximal to the first region and having the second durometer hardness. The first durometer hardness may be greater than the second durometer hardness.

[0010] In the ninth embodiment, in addition to or instead of one or more of the embodiments described above or below, the first durometer hardness may be about 70 Shore A, and the second durometer hardness may be about 55 Shore A.

[0011] In the tenth embodiment, in addition to or instead of one or more of the embodiments described above or below, the first region and the second region may each consist of separate polymer tube portions.

[0012] In the eleventh embodiment, in addition to or instead of one or more of the embodiments described above or below, the first region may be joined to the second region using a reflow process. In the twelfth embodiment, in addition to or in place of one or more of the embodiments described above or below, the first polymer layer, the reinforcing layer, and the second polymer layer extend from the first proximal end of the shaft to the second distal end of the shaft.

[0013] In a thirteenth embodiment, in addition to or instead of one or more of the embodiments described above or below, the second polymer layer of the return tube may be sealed to the insulating shaft using the reflow process.

[0014] In a fourteenth embodiment, in addition to or instead of one or more of the embodiments described above, the second polymer layer of the return tube may be sealed to the tip of the cryoablation probe by reflow.

[0015] In a 15th embodiment, in addition to or in place of one or more of the embodiments described above or below, the second polymer layer of the return tube may be sealed to the insulating shaft by an adjustable sealing mechanism such that the return tube is movable axially relative to the insulating shaft while maintaining a seal between the return tube and the insulating shaft.

[0016] In the sixteenth embodiment, in addition to or instead of one or more of the embodiments described above or below, the reinforcing layer may include a braided material and be configured to increase the radial strength of the return pipe.

[0017] In a 17th embodiment, the cryoablation probe may include a precooler fluid circuit, a working fluid circuit, a vacuum circuit, and a shaft. The shaft may include an adiabatic region, the vacuum circuit extending within the adiabatic region, and an expansion chamber extending distal to the adiabatic region. The expansion chamber may include a supply pipe having a distal outlet within the expansion chamber, through which a fluid from the working fluid circuit moves and expands within the expansion chamber. The expansion chamber may further include a first polymer layer configured to contain the fluid from the working fluid circuit, a reinforcing layer configured to increase the radial strength of the shaft, and a second polymer layer as the outermost layer of the expansion chamber, the second polymer layer configured to contain the fluid from the working fluid circuit.

[0018] In the 18th embodiment, in addition to or instead of one or more of the embodiments described above or below, the first polymer layer may include a plurality of separate layers that are thermally bonded to each other, and the reinforcing layer includes a braided material.

[0019] In the 19th embodiment, the second polymer layer may include a polyether block amide in addition to or instead of one or more of the embodiments described above or below. In the 20th embodiment, in addition to or instead of one or more of the embodiments described above or below, the second polymer layer may have a substantially constant durometer hardness along its length.

[0020] This summary is a brief overview of some of the teachings of this application and is not intended to be an exclusive or comprehensive treatment of the subject matter. Further details are found in the detailed description and the appended claims. Each aspect can be more fully understood when associated with the figures. Other aspects may become apparent to those skilled in the art by reading the following detailed description and viewing the drawings that form a part thereof, but each aspect should not be construed in a limiting sense. The scope of the present disclosure is defined by the appended claims and their legal equivalents.

Brief Description of the Drawings

[0021] [Figure 1] Figure 1 is a schematic diagram of a cryoablation system according to various embodiments of the present disclosure. [Figure 2] Figure 2 is a schematic diagram of a part of a cryoablation system according to various embodiments of the present disclosure. [Figure 3] Figure 3 is a schematic diagram of a part of a cryoablation shaft shown according to various embodiments of the present disclosure. [Figure 4] Figure 4 is a cross-sectional view of the shaft of Figure 3 taken along section 4-4 according to various embodiments of the present disclosure. [Figure 5] Figure 5 is a cross-sectional view of the shaft of Figure 3 taken along section 5-5 according to various embodiments of the present disclosure. [Figure 6] Figure 6 is a schematic diagram of a biliary system according to various embodiments of the present disclosure. [Figure 7] Figure 7 is a schematic diagram of the growth of an ice ball generated by a cryoablation system according to various embodiments of the present disclosure. [Figure 8-15] Figures 8-15 are schematic diagrams of a part of a cryoablation shaft according to various embodiments of the present disclosure.

Modes for Carrying Out the Invention

[0022] Each embodiment may take various modifications and alternative forms, but details of each embodiment are shown by example in the drawings and described in detail below. The scope of this disclosure is not limited to the specific embodiments described. Rather, it is intended to encompass the modifications, equivalents, and alternative forms that fall within the spirit and scope of this disclosure.

[0023] Some cryoablation systems may be useful for ablating lesions in the biliary system or other hard-to-reach parts of human anatomical structures. In such cases, the cryoprobe may need to navigate a winding passage. Cryoprobes with rigid shafts may not be suitable for such applications.

[0024] This disclosure relates to a cryoablation system equipped with a flexible shaft. The shaft may be flexible enough to access specific parts of human anatomical structures, such as the biliary system, while simultaneously maintaining adequate rupture strength and thermal insulation to ensure patient safety.

[0025] The concepts described herein may be applied in connection with the cryoablation systems described in U.S. Patent Application Publication No. 2021 / 00045793, entitled "Dual Stage Cryocooler," and U.S. Patent Application Publication No. 2021 / 00045794, entitled "Flexible Cryoprobe," both filed on August 14, 2020, both of which are incorporated herein by reference in their entirety.

[0026] Referring to Figure 1, schematic diagrams of cryoablation systems according to various embodiments of the present disclosure are shown. In various embodiments, the cryoablation system may include a handle 102 and a shaft 104. In various embodiments, the shaft 104 is insertable into the handle 102 and can be securely attached to the handle using a shaft-to-handle connector 103. In various embodiments, the shaft 104 and the shaft-to-handle connector 103 of the cryoablation system 100 may form a catheter assembly. In some embodiments, the catheter assembly includes components of the cryoablation system that are replaced each time a cryoablation procedure is performed. In some aspects, the cryoablation system 100 may include a working fluid source 110, a pre-cooler fluid source 112, and a vacuum source 114, each connectable to the cryoablation system 100.

[0027] These three sources correspond to three independent circuits within the refrigeration ablation system 100: namely, the precooler, the working fluid, and the active vacuum. In some embodiments, the working fluid source 110 and the precooler fluid source 112 are connected to the base of the handle 102 of the refrigeration ablation system 100, and the vacuum source 114 is connected near the distal end of the handle, adjacent to the shaft-to-handle connector 103. The refrigeration ablation system may further include a precooler gas exhaust port 116 and a working gas exhaust port 118 connected to the handle 102. In various embodiments, the shaft-to-handle connector 103 functions as a manifold, maintaining each fluid circuit isolated from one another.

[0028] In some embodiments, the cryoablation system 100 includes a console 117. The console may be used to control the system. The console may be electrically connected to the handle and the cryoablation assembly, and may also be in fluid communication. In some embodiments, the working fluid source 110, the precooler fluid source 112, and the vacuum source 114 may all be connectable to the console 117 of the cryoablation system 100 using conduits. In one embodiment, the precooler gas exhaust port 116, the working gas exhaust port 118, or both may be connectable to conduits that return the exhaust to the console 117 or another location in the treatment room, so that the exhaust is released into the ambient environment at an appropriate location. Various supply and exhaust ports may be positioned along the handle 102 in predetermined locations and in any appropriate configuration. Thus, the arrangement in Figure 1 is only one example of an appropriate configuration.

[0029] Examples of the specifications and functions of each of these circuits are provided in the following paragraphs. However, the specific fluid and pressure values ​​are for illustrative purposes only, and other configurations are possible. In one embodiment, the pre-cooler circuit may include pressurized argon at 24.1 megapascals (MPa). The pre-cooler circuit can cool the incoming working fluid and operate within the handle. In one embodiment, the working fluid circuit may include pressurized argon at 12.4 MPa and / or pressurized helium at 12.4 MPa. The working fluid circuit generates and / or thaws an ice ball. The working fluid circuit can operate within the handle, within the insulated portion or region of the shaft, and within the expansion chamber of the shaft. In one embodiment, the active vacuum can maintain a vacuum of 6.67 pascals (Pa) or less. The active vacuum can insulate the shaft. The active vacuum can operate within the handle and within the insulated region of the shaft.

[0030] In various embodiments, the working fluid circuit extends inside both the handle 102 and the shaft 104 of the cryoablation system 100 and carries the fluid that generates and thaws the ice ball. The term “fluid circuit” as used throughout this application may be replaced in various embodiments with a gas circuit, a liquid circuit, a fluid chamber, a gas chamber, or a liquid chamber. Also, the term “fluid” as used throughout this application may be replaced in various embodiments with a gas or a liquid. During ablation (freezing cycle), argon at 12.4 MPa is circulated through the probe to generate an ice ball inside the patient’s body surrounding the expansion chamber 106. The working fluid can be any suitable cooling fluid (e.g., nitrogen, air, argon, krypton, xenon, N2O, CO2, CF4). In some embodiments, the pressure of the high-pressure flow of the working fluid may be 6.9 MPa, 8.3 MPa, 9.7 MPa, 11.0 MPa, 12.4 MPa, 17.2 MPa, 27.6 MPa, or 41.4 MPa or higher. In some embodiments, the pressure of the working fluid high-pressure flow may be 55.2 MPa, 34.5 MPa, 20.7 MPa, 18.6 MPa, 16.5 MPa, 14.5 MPa, or 12.4 MPa or less. In some embodiments, the pressure of the working fluid high-pressure flow may be in the range of 6.9 MPa to 41.4 MPa, 8.3 MPa to 27.6 MPa, 9.7 MPa to 16.5 MPa, 11.0 MPa to 14.5 MPa, or about 12.4 MPa. Therefore, in embodiments where the working fluid is a cooling fluid, the temperature of the working fluid in the expansion chamber 106 may be about 190 Kelvin. In some embodiments, the temperature of the working fluid may be 250 Kelvin, 200 Kelvin, 150 Kelvin, or 100 Kelvin or less, or within a range of any of these.

[0031] In various embodiments, the pre-cooler circuit is completely housed within the handle 102. In various embodiments, the pre-cooler circuit is located within the system console 117. In various embodiments, the pre-cooler circuit is located within a portion of the catheter located immediately proximal to the handle. In various embodiments, the pre-cooler circuit is located within a portion of the catheter located immediately distal to the handle. In various embodiments, the pre-cooler circuit operates using argon or any other suitable cooling fluid. In some embodiments, the high-pressure flow of the pre-cooler fluid may be at a higher pressure than the high-pressure flow of the working fluid. The pre-cooler fluid may be supplied at a pressure higher than, for example, about 13.8 MPa. In some embodiments, the pressure of the pre-cooler fluid may be 10.3 MPa, 13.8 MPa, 17.2 MPa, 20.7 MPa, or 24.1 MPa or higher. In some embodiments, the pressure of the pre-cooler fluid may be 31.0 MPa, 29.3 MPa, 25.9 MPa, or 24.1 MPa or lower. In some embodiments, the pressure of the precooler fluid may be in the range of 10.3 MPa to 31.0 MPa, 13.8 MPa to 29.3 MPa, 17.2 MPa to 27.6 MPa, 20.7 MPa to 25.9 MPa, or about 24.1 MPa.

[0032] In some embodiments, the outer surface of the shaft 104 can be insulated from the inner surface of the shaft. In various embodiments, a vacuum circuit or vacuum chamber extends both within the handle 102 and within the insulated region 105 of the shaft 104. Throughout the cryoablation procedure, a vacuum is actively drawn along the insulated region 105 of the shaft 104, providing a protective barrier between the outer surface of the shaft 104 and the patient. In alternative embodiments, shaft insulation can be achieved by circulating a fluid, gas, or heating fluid throughout the shaft, or by electrically heating a portion of the shaft. In alternative embodiments, shaft insulation can be achieved by housing a non-circulating fluid or gas within the insulated shaft.

[0033] The shaft 104 may be any appropriate length that allows it to reach the target anatomical structure of the subject. In some embodiments, the shaft length may be 20 cm, 38 cm, 55 cm, 72 cm, or 90 cm or more. In some embodiments, the shaft length may be 150 cm, 135 cm, 120 cm, 105 cm, or 90 cm or less. In some embodiments, the shaft length may be in the range of 20 cm to 150 cm, 38 cm to 135 cm, 55 cm to 120 cm, 72 cm to 105 cm, or about 90 cm.

[0034] In various embodiments, specific portions of the shaft 104 may be flexible. In one embodiment, the entire length of the shaft may be flexible. For example, the shaft may be bendable about its longitudinal axis. In some such embodiments, the shaft may have a shaft diameter configured such that the shaft is flexible enough to form a curve with a desired radius of curvature. For example, the shaft may be flexible enough to form a curve with a minimum radius of curvature of 30 mm, 20 mm, 10 mm, or 5 mm or less.

[0035] In various embodiments, the shaft 104 may include an insulated region 105 and an expansion chamber 106. The insulated region 105 defines the portion of the shaft 104 that is insulated by the vacuum chamber. The expansion chamber 106 is the portion of the shaft 104 that is not insulated by the vacuum and defines the portion where the ice ball is generated. In various embodiments, the shaft delivers a high-pressure working fluid from the handle 102 to the expansion chamber 106, where it undergoes Joule-Thomson expansion and the corresponding temperature change. The working fluid either flows down the shaft, through the handle, and is discharged into the atmosphere from the console, or enters the handle and is discharged from the handle.

[0036] The distal end of the shaft may terminate with a distal working tip 108. During use, the distal working tip 108 is positioned in the patient's body, surrounded by tissue, and possibly to ablate the tissue at cryogenic temperatures. The distal working tip 108 may, advantageously, be configured to puncture tissue in some examples. For example, the distal working tip 108 may include a sharp tip, such as a trocar tip. Alternatively, the distal working tip 108 may not have a sharp tip. In some embodiments, the distal working tip 108 may be a non-traumatic tip designed to cause minimal tissue damage. In some embodiments, the distal working tip 108 may include a working port configured for aspiration, delivery of therapeutic drugs, and delivery of other devices, including but not limited to guidewires, imaging catheters, sensing devices, biopsy devices, balloons, and stents.

[0037] [Handle equipped with a pre-cooling circuit (Figure 2)] Referring to Figure 2, schematic diagrams of some of the refrigeration ablation systems according to various embodiments of the present disclosure are shown. In some embodiments, the refrigeration ablation system 100 may include a working fluid source 110 connected to a working fluid circuit and a pre-cooler fluid source 112 connected to a pre-cooler fluid circuit. The working fluid circuit may include a working fluid supply conduit 210 for transporting a high-pressure flow of working fluid from the working fluid source 110 to the distal end of the shaft 104 (not shown in this figure). The working fluid circuit may also include a working fluid return conduit (not shown in this figure) for returning a low-pressure flow of working fluid from the distal end of the shaft to the base of the handle 102.

[0038] The precooler fluid circuit may include a precooler supply circuit 212 that terminates at a precooler Joule-Thomson orifice 223 and delivers a high-pressure flow of precooler fluid from a precooler fluid source 112 to the precooler fluid expansion region 222 within the handle 102. The precooler fluid circuit may also include a precooler return conduit (indicated by arrow 213). The precooler return conduit may be configured to deliver precooler fluid away from the precooler fluid expansion region 222 back to the base of the handle 102. The precooler return conduit may be housed together with the precooler supply circuit 212 and extend back to the control console and gas manifold.

[0039] In various embodiments, a pre-cooler fluid circuit can facilitate heat exchange between the working fluid and the pre-cooler fluid. For example, in embodiments where the working fluid cools during expansion to cryogenically ablate the tissue around the distal working tip 108, a pre-cooler fluid circuit can be used to pre-cool the high-pressure flow of the working fluid. In various embodiments, the working fluid supply conduit 210 may include a first heat exchanger 216. The first heat exchanger 216 can facilitate heat exchange between the high-pressure flow of the working fluid in the working fluid supply conduit 210 and the low-pressure flow of the pre-cooler fluid in the pre-cooler return conduit.

[0040] In various embodiments, the precooler supply conduit 212 may include a second heat exchanger 218 that enables heat exchange (e.g., regenerative heat exchange) between a high-pressure flow of precooler fluid and a low-pressure flow of precooler fluid. In some embodiments, the precooler fluid may be a cooling fluid. In such embodiments, heat can be removed from the high-pressure flow of precooler fluid by regenerative heat exchange between the high-pressure flow of precooler fluid and the low-pressure flow of precooler fluid. Thus, the second heat exchanger 218 can facilitate the precooling of the high-pressure flow of precooler fluid.

[0041] In various embodiments, the high-pressure precooler fluid flowing out of the second heat exchanger 218 continues to flow through the precooler supply conduit 212 into the precooler fluid expansion region 222. In the precooler fluid expansion region, which is entirely contained within the handle 102, the precooler supply conduit 212 terminates at a Joule-Thomson orifice. The high-pressure precooler fluid flow may expand at or downstream of the Joule-Thomson orifice within the precooler fluid expansion region 222. This rapid decrease in pressure causes a corresponding decrease in temperature. The precooler fluid expansion region 222 may be in fluid communication with a precooler return conduit to transport the expanded low-pressure precooler fluid flow (for example, to discharge into the atmosphere if the precooler fluid circuit is open, or to return to the precooler fluid source if the precooler fluid circuit is closed). After expanding in the Joule-Thomson orifice, the cooled precooler fluid returns through the handle 102 in the annular space between the core tube 215 and the outer surface of the handle 102. As the precooler fluid passes through the precooler return conduit, it cools the working fluid in the first heat exchanger 216.

[0042] The working fluid circuit 210 may further include a third heat exchanger 220 in the shaft 104 of the refrigeration ablation system configured to perform heat exchange (e.g., regenerative heat exchange) between the high-pressure flow of working fluid in the working fluid supply circuit 210 and the low-pressure flow of working fluid (not shown in this figure) returning through the shaft 104.

[0043] [Details of the distal tip and inflation chamber (Figure 3)] Referring to Figure 3, schematic diagrams of some of the cryoablation shafts according to various embodiments of the present disclosure are shown. In various embodiments, the shaft includes an insulated region 105 and an expansion chamber 106. In various embodiments, the insulated region 105 of the shaft 104 includes a supply pipe 324 located within a return pipe 326 located within an insulated shaft 328. A concentric shaft structure is designed to isolate the working fluid circuit 210 and the vacuum chamber 336 from each other.

[0044] In various embodiments, the high-pressure flow of working fluid travels down the supply pipe 324 after exiting the handle 102. When the working fluid reaches the working fluid expansion chamber 106, the supply pipe 324 terminates at a Joule-Thomson orifice 332 or distal outlet 332. The high-pressure flow of working fluid may undergo expansion in the Joule-Thomson orifice 332 within the expansion chamber 106, or downstream thereof. This rapid decrease in pressure causes a corresponding decrease in temperature. Heat transfer between the expanded working fluid and the outer wall of the expansion chamber 106 causes ice balls to form in the tissue around the tip 108, resulting in cryoablation of the tissue.

[0045] The expansion chamber 106 may be in fluid communication with a working fluid return conduit (defined by the annular space between the supply pipe 324 and the inner surface of the return pipe 326 of the expansion chamber) to transport the expanded low-pressure flow of working fluid (for example, to discharge it into the atmosphere if the working fluid circuit is open, or to return it to the working fluid source if the working fluid circuit is closed). As the working fluid passes through the working fluid return conduit, it cools the working fluid input flow in the third heat exchanger 220 (Figure 2).

[0046] In various embodiments, the working fluid is a cooling fluid and / or cooling gas (e.g., nitrogen, air, argon, krypton, xenon, N2O, CO2, CF4). In this case, the working fluid in the high-pressure flow may be at a pressure at which expansion through the Joule-Thomson orifice 332 cools the working fluid to a temperature at which cryogenic ablation occurs in the tissue surrounding the expansion chamber 106. In certain embodiments, the pressure of the working fluid in the high-pressure flow upstream of the Joule-Thomson orifice 332 may be about 6.9 MPa to about 13.8 MPa (e.g., about 12.4 MPa). Therefore, in embodiments where the working fluid is a cooling fluid, the temperature of the working fluid after expansion exiting the Joule-Thomson orifice 332 may be 150 Kelvin, 160 Kelvin, 170 Kelvin, 180 Kelvin, 190 Kelvin, or 200 Kelvin or higher, or within a range of any of these values.

[0047] The cryoablation system 100 may be designed so that the outermost surface of the shaft does not cause thermal damage to non-target structures. In various embodiments, ice ball formation is limited to the expansion chamber 106 of the shaft 104, which may also be referred to as the operating region of the apparatus. Selective ice ball formation is achieved by vacuuming through the insulated region 105 of the shaft 104. In various embodiments, the cryoablation system 100 may be configured to establish a vacuum communication between the shaft 104 and the vacuum source 114.

[0048] Referring to Figure 1, the cryoablation system 100 may be configured to connect to a vacuum source 114 at a handle 102. In various embodiments, the vacuum source 114 is configured to evacuate along the length of the insulated region 105 of the shaft 104. In one embodiment, the entire insulated region 105 of the shaft 104 is evacuated between the outer diameter of the return pipe 326 and the inner diameter of the insulated shaft 328.

[0049] In various embodiments, the vacuum source 114 is configured to evacuate within at least a portion of the handle 102. Such a configuration can insulate the handle 102 and protect the operator of the refrigeration ablation system from cryogenic exhaust gases. In some embodiments, the vacuum source 114 is connected to the handle 102, and the space between the supply pipe 324 and the return pipe 326 can be evacuated by evacuating the inside of the handle 102, by fluid communication between the shaft 104 and the handle 102. In other embodiments, the vacuum source 114 is connected directly to the shaft 104, for example, using a T-fitting along the length of the shaft 104.

[0050] To provide thermal insulation along the insulated region 105 of the shaft 104, the shaft wall is a double wall (return tube surrounded by the insulated shaft) with a small gap between the return tube 326 and the insulated shaft 328. By preventing convective heat transfer by vacuuming the space between the return tube and the insulated shaft, the working fluid temperature does not cause ablation of healthy, non-target patient tissue along the insulated region of the shaft or induce uncontrolled apoptosis / necrosis. Sufficient insulation is achieved by actively evacuating the air in the gap and maintaining a vacuum of about 0.05 Torr. However, depending on the configuration of the cryoablation system, other vacuum pressures may be appropriate. In some embodiments, a support filament 330 is wound along the outer diameter of the return tube 326. One choice of filament material is a polymer such as polyetheretherketone (PEEK). The filament can prevent direct contact between the outer surface of the return tube and the inner surface of the insulated shaft. The filament 330 minimizes heat conduction between the inner shaft and the insulated shaft. Instead of filament 330, other alternatives may be used, such as an extruded tube / co-extruded shape or other features positioned on a shaft.

[0051] In some embodiments, the shaft may not include a filament. In such embodiments, the return tube 326 and the insulated shaft 328 are selected to have material properties sufficient to minimize heat conduction between the inner shaft and the insulated shaft.

[0052] The joint 334 is located at the junction of the insulating region 105 and the expansion chamber 106. This joint can seal the vacuum layer. [Cross section, dimensions, and material of a flexible shaft (Figure 4)] Referring to Figure 4, a cross-sectional view of the shaft of Figure 3 obtained along section 4-4 according to various embodiments of the present disclosure is shown. In various embodiments, the insulated region 105 of the shaft 104 includes a supply pipe 324 concentrically located within a return pipe 326 concentrically located within an insulated shaft 328. The insulated region 105 may include the shaft portion of the vacuum chamber 336 and the insulated portion of the working gas circuit 210. In various embodiments, the vacuum chamber 336 surrounds and isolates the insulated portion of the working gas circuit 210 from the insulated portion.

[0053] In various embodiments, after exiting the handle 102, the high-pressure working fluid flows distally through the adiabatic region of the shaft via the supply pipe 324. After cooling and expanding in the expansion chamber 106, the working fluid returns proximal through the adiabatic region 105 of the shaft 104 in the annular space between the supply pipe 324 and the return pipe 326.

[0054] In various embodiments, the material and dimensions of each layer of the shaft 104 may be selected to have a degree of flexibility sufficient to allow the shaft to bend about its longitudinal axis at the operating temperature of the apparatus.

[0055] In various embodiments, the supply tube 324, which may also be referred to herein as a capillary tube, is made of any suitable material such as a flexible metal, polymer, or composite material. In one embodiment, the supply tube 324 is made of nitinol (NiTi), stainless steel, or the like.

[0056] In some embodiments, the inner diameter of the supply pipe 324 may be 0.30 mm, 0.35 mm, 0.40 mm, or 0.45 mm or more. In some embodiments, the inner diameter of the supply pipe 324 may be 0.60 mm, 0.55 mm, 0.50 mm, or 0.45 mm or less. In some embodiments, the diameter of the supply pipe 324 may be in the range of 0.30 mm to 0.60 mm, in the range of 0.35 mm to 0.55 mm, in the range of 0.40 mm to 0.50 mm, or about 0.45 mm.

[0057] In some embodiments, the outer diameter of the supply pipe 324 may be 0.38 mm, 0.43 mm, 0.48 mm, 0.53 mm, or 0.58 mm or more. In some embodiments, this outer diameter may be 0.78 mm, 0.73 mm, 0.68 mm, 0.63 mm, or 0.58 mm or less. In some embodiments, this outer diameter may be in the range of 0.38 mm to 0.78 mm, in the range of 0.43 mm to 0.73 mm, in the range of 0.48 mm to 0.68 mm, in the range of 0.53 mm to 0.63 mm, or about 0.58 mm.

[0058] In some embodiments, the thickness of the supply pipe 324 may be 0.10 mm, 0.11 mm, 0.12 mm, 0.14 mm, or 0.15 mm or more. In some embodiments, the thickness of the supply pipe 324 may be 0.20 mm, 0.19 mm, 0.18 mm, 0.16 mm, or 0.15 mm or less. In some embodiments, the thickness of the supply pipe 324 may be in the range of 0.10 mm to 0.20 mm, in the range of 0.11 mm to 0.19 mm, in the range of 0.12 mm to 0.18 mm, in the range of 0.14 mm to 0.16 mm, or about 0.15 mm.

[0059] In various embodiments, the return tube 326 is composed of any suitable material or combination of materials, such as flexible metal or polymer. In various embodiments, the return tube 326 may be made of polyimide, fluorinated ethylene propylene (FEP), Teflon®, etc. In one embodiment, the return tube 326 is formed from a polyimide material to have high gas impermeability over a wide temperature range, thereby allowing a vacuum to be maintained on the outside while accommodating the working fluid inside. In certain examples, the return tube 326 is made of braided-reinforced polyimide tubing to enhance gas impermeability, burst strength, and flexibility. In some embodiments, the return tube 326 is formed from a single layer of material. In some embodiments, the return tube 326 may be formed from two or more material layers selected to optimize the performance of the shaft 104. These material layers may be joined to each other using any suitable one or more techniques, such as adhesives or reflow processes.

[0060] In some embodiments, the outer diameter of the return pipe 326 may be 1 mm, 1.1 mm, 1.2 mm, 1.3 mm, or 1.4 mm or more. In some embodiments, the outer diameter of the return pipe 326 may be 1.8 mm, 1.7 mm, 1.6 mm, 1.5 mm, or 1.4 mm or less. In some embodiments, the outer diameter of the return pipe 326 may be in the range of 1.0 mm to 1.8 mm, 1.1 mm to 1.7 mm, 1.2 mm to 1.6 mm, 1.3 mm to 1.5 mm, or about 1.4 mm.

[0061] In some embodiments, the inner diameter of the return pipe 326 may be 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, or 1.3 mm or more. In some embodiments, the inner diameter of the return pipe 326 may be 1.7 mm, 1.6 mm, 1.5 mm, 1.4 mm, or 1.3 mm or less. In some embodiments, the inner diameter of the return pipe 326 may be in the range of 0.9 mm to 1.7 mm, in the range of 1.0 mm to 1.6 mm, in the range of 1.1 mm to 1.5 mm, in the range of 1.2 mm to 1.4 mm, or about 1.3 mm.

[0062] In some embodiments, the thickness of the return tube 326 may be 0.10 mm, 0.11 mm, 0.12 mm, 0.14 mm, or 0.15 mm or more. In some embodiments, the thickness of the return tube 326 may be 0.20 mm, 0.19 mm, 0.18 mm, 0.16 mm, or 0.15 mm or less. In some embodiments, the thickness of the return tube 326 may be in the range of 0.10 mm to 0.20 mm, in the range of 0.11 mm to 0.19 mm, in the range of 0.12 mm to 0.18 mm, in the range of 0.14 mm to 0.16 mm, or about 0.15 mm.

[0063] In various embodiments, the insulated shaft 328 is made of any suitable material such as a flexible metal or polymer. In various embodiments, the insulated shaft 328 is made of polyimide, fluorinated ethylene propylene (FEP), Teflon®, etc. In certain embodiments, the insulated shaft 328 may include polytetrafluoroethylene (PTFE) and / or one or more polyether block amides (trade name Pebax®, hereinafter known as "Pebax").

[0064] In some embodiments, the insulated shaft 328 is formed from a single layer of material. In some embodiments, the insulated shaft 328 may be formed from two or more layers of material selected to optimize the performance of the shaft 104. These layers of material may be joined to each other using one or more suitable techniques, such as adhesives or reflow processes.

[0065] In one embodiment, the insulated shaft may be formed using a braided-reinforced polyimide tube coated with an outer layer of Pebax. Such a three-layer structure allows a high vacuum to be maintained between the return tube and the insulated shaft without the insulated shaft 328 collapsing on the return tube 326.

[0066] In some embodiments, the outer diameter of the insulating shaft 328 may be 1.2 mm, 1.4 mm, 1.5 mm, 1.6 mm, or 1.8 mm or more. In some embodiments, the outer diameter of the insulating shaft may be 2.2 mm, 2.1 mm, 2.0 mm, 1.9 mm, or 1.8 mm or less. In some embodiments, the outer diameter of the insulating shaft may be in the range of 1.3 mm to 2.3 mm, 1.4 mm to 2.1 mm, 1.5 mm to 2.0 mm, 1.6 mm to 1.9 mm, or about 1.8 mm.

[0067] In some embodiments, the inner diameter of the insulating shaft 328 may be 1.0 mm, 1.2 mm, 1.3 mm, 1.4 mm, or 1.6 mm or more. In some embodiments, the inner diameter of the insulating shaft 328 may be 2.2 mm, 2.0 mm, 1.9 mm, 1.8 mm, or 1.6 mm or less. In some embodiments, the inner diameter of the insulating shaft 328 may be in the range of 1.0 mm to 2.2 mm, 1.2 mm to 2.0 mm, 1.3 mm to 1.9 mm, 1.4 mm to 1.8 mm, or about 1.6 mm.

[0068] In some embodiments, the thickness of the insulating shaft 328 may be 0.10 mm, 0.11 mm, 0.12 mm, 0.14 mm, or 0.15 mm or more. In some embodiments, the thickness of the insulating shaft 328 may be 0.20 mm, 0.19 mm, 0.18 mm, 0.16 mm, or 0.15 mm or less. In some embodiments, the thickness of the insulating shaft 328 may be in the range of 0.10 mm to 0.20 mm, in the range of 0.11 mm to 0.19 mm, in the range of 0.12 mm to 0.18 mm, in the range of 0.14 mm to 0.16 mm, or about 0.15 mm.

[0069] In some embodiments, PEEK filaments 330 are wound around the return tube 326. The PEEK filaments 330 may have a pitch of 0.5 mm, 1.0 mm, 1.5 mm, or 2.0 mm or more, or a pitch within a range of any of these values. Alternatively, the filaments may be multiple separate parts mounted along the return tube 326. The PEEK filaments 330 maintain their coaxial arrangement by preventing direct contact between the return tube 326 and the insulated shaft 328. In some embodiments, an adhesive (e.g., LOCTITE®) is applied to the filaments at the ends of the return tube 326 and the insulated shaft 328 to attach the PEEK filaments 330. In various embodiments, the winding of the PEEK filaments is configured to minimize or prevent conductive heat transfer from the return tube to the insulated shaft. In alternative embodiments, other insulating polymers such as stretched PTFE (ePTFE) and nylon may be used as substitutes for the PEEK filaments.

[0070] In some embodiments, the diameter of the PEEK filament 330 may be 0.002 mm, 0.004 mm, or 0.005 mm or more. In some embodiments, the diameter of the PEEK filament 330 may be 0.007 mm, 0.006 mm, or 0.005 mm or less. In some embodiments, the diameter of the PEEK filament 330 may be in the range of 0.002 mm to 0.007 mm, in the range of 0.004 mm to 0.006 mm, or about 0.005 mm.

[0071] [Shaft inside the expansion chamber (Figure 5)] Referring to Figure 5, a cross-sectional view of the shaft of Figure 3 obtained along cross-section 5-5 according to various embodiments of the present disclosure is shown. The cross-sectional view of Figure 5 shows the expansion chamber 106 of the shaft 104. In various embodiments, the expansion chamber 106 is located distal to the adiabatic region 105 along the shaft 104. The expansion chamber 106 may include the expansion portion of the working fluid circuit 210.

[0072] In various embodiments, the high-pressure working fluid flows down the supply pipe 324 after exiting the handle 102. After cooling and expanding in the expansion chamber 106, the working fluid returns downward through the expansion chamber 106 in the annular space between the supply pipe 324 and the outer wall of the expansion chamber. In various embodiments, the expansion chamber 106 is configured to maximize heat transfer between the working gas and the patient's tissue through the optimization of parameters such as wall thickness and material.

[0073] In various embodiments, the expansion chamber 106 is made of any suitable material or combination of materials, such as a flexible metal or polymer. In various embodiments, the expansion chamber 106 is made of polyimide, fluorinated ethylene propylene (FEP), Teflon®, etc. In some embodiments, the expansion chamber 106 includes an extension of the return tube 326 in the insulated region 105 of the shaft 104. Alternatively, the expansion chamber is a separate component from the return tube 326 and can be joined to the shaft 104 using any suitable joining and / or fitting, such as reflow soldering, adhesive bonding, soldering, or any other suitable mechanical joining process capable of withstanding cryogenic pressure and temperature.

[0074] In some embodiments, the expansion chamber 106 is formed from a single material layer. In some embodiments, the expansion chamber 106 is formed from two or more material layers. These material layers can be joined to each other using any suitable one or more techniques, such as adhesives or reflow processes.

[0075] In some embodiments, the outer diameter of the expansion chamber 106 may be 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, or 1.7 mm or more. In some embodiments, the outer diameter of the expansion chamber 106 may be 2.1 mm, 2.0 mm, 1.9 mm, 1.8 mm, or 1.7 mm or less. In some embodiments, the outer diameter of the expansion chamber 106 may be in the range of 1.3 mm to 2.1 mm, 1.4 mm to 2.0 mm, 1.5 mm to 1.9 mm, 1.6 mm to 1.8 mm, or about 1.7 mm.

[0076] In some embodiments, the inner diameter of the expansion chamber 106 may be 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, or 1.4 mm or more. In some embodiments, the inner diameter of the expansion chamber 106 may be 1.8 mm, 1.7 mm, 1.6 mm, 1.5 mm, or 1.4 mm or less. In some embodiments, the inner diameter of the expansion chamber 106 may be in the range of 1.0 mm to 1.8 mm, 1.1 mm to 1.7 mm, 1.2 mm to 1.6 mm, 1.3 mm to 1.5 mm, or about 1.4 mm.

[0077] In some embodiments, the wall thickness of the expansion chamber 106 may be 0.20 mm, 0.22 mm, 0.25 mm, 0.28 mm, or 0.30 mm or more. In some embodiments, the wall thickness of the expansion chamber 106 may be 0.40 mm, 0.38 mm, 0.35 mm, 0.32 mm, or 0.30 mm or less. In some embodiments, the wall thickness of the expansion chamber 106 may be in the range of 0.20 mm to 0.40 mm, in the range of 0.22 mm to 0.38 mm, in the range of 0.25 mm to 0.35 mm, in the range of 0.28 mm to 0.32 mm, or about 0.30 mm.

[0078] [Examples of treatment areas (Figure 6)] The cryoablation systems and structures described herein are flexible and are highly suitable for cryoablation of areas along lumens, blood vessels, or passages of the body. The cryoablation system 100 is configured to be sufficiently flexible to access and ablate many different such structures. The inflation chamber may have a shape and size that produces a geometrically shaped ice ball or ice column suitable for ablating structures along the length of a body lumen. Furthermore, the materials and structures of the probes described herein are selected to protect patient tissue and withstand high operating pressures and low temperatures.

[0079] Referring to Figure 6, schematic diagrams of the biliary system according to various embodiments of the present disclosure are shown. The biliary system includes organs and tubules that produce, store, and release bile (a fluid produced by the liver that helps digest fats) into the small intestine. The biliary system includes the gallbladder, as well as the bile ducts inside and outside the liver.

[0080] Cholangiocarcinoma, or cholangiocarcinoma, is a rare disease in which cancer cells form in the bile ducts. The treatment outcomes for cholangiocarcinoma are generally poor. Current treatment options (e.g., Whipple surgery or biliary drainage) are high-risk and often ineffective.

[0081] Cryoablation is a promising treatment for cholangiocarcinoma. This cryoablation system 100 is configured to be flexible enough to access and ablate the patient's bile duct. The expansion chamber may have a shape and size that produces an ice ball with a suitable geometric shape for resecting tumors within the bile duct.

[0082] In addition to treating cholangiocarcinoma, the cryoablation system 100 can be used to treat several conditions, including other cancerous tumors (e.g., skin, liver, kidney, bone, lung, prostate, and breast), pain, skin conditions (e.g., atypical moles, warts, skin tags, or actinic keratosis), and arrhythmias. The cryoablation system 100 can also ablate benign tumors, soft tissue, and healthy tissue.

[0083] [Ice ball formation (Figure 7)] Referring to Figure 7, schematic diagrams of the growth of ice balls produced by cryoablation systems according to various embodiments of this disclosure are shown. Cryoablation is defined as cell destruction at low temperatures. Ice balls are formed in the expansion chamber of the cryoablation system, freezing intracellular and extracellular material to temperatures below 173 Kelvin. The application of these extremely low temperatures induces cell death. Ablation temperatures low enough to induce complete cell death are achieved. Lethal temperatures for various tissues have been reported to be between 253 Kelvin and 233 Kelvin.

[0084] Figure 7 shows the growth of the ice ball over the course of the cryoablation procedure. The times in this example are 60 seconds, 120 seconds, 180 seconds, and 240 seconds. Isotherms of 273 Kelvin, 253 Kelvin, and 233 Kelvin are shown for each time period. As the cryoablation procedure progresses over time, the overall ice ball size increases. More importantly, the isotherms of cell death (253 Kelvin and 233 Kelvin isotherms) grow along both the long and short axes of the ice ball.

[0085] The times and temperatures given in Figure 7 are intended for illustrative purposes only. Ice ball formation may be modified based on the cryoablation system and the structure of the patient's tissue. Ice ball growth may also stabilize after reaching a specific ablation time. For example, in some embodiments, the ice ball may reach its maximum diameter after ablation of the tissue for about 10 minutes. In some embodiments, the operator of the cryoablation system may terminate the cryoablation procedure when the ice ball reaches its maximum size. In some embodiments, since keeping the tissue at a cryogenic temperature for a longer period of time may have therapeutic benefits, the operator of the cryoablation system may continue the cryoablation procedure even after the ice ball has reached its maximum size over a predetermined period of time.

[0086] In some embodiments, an ice ball is formed, and then, upon thawing, it is formed again. In some embodiments, an active thawing method is used, while in other embodiments, a passive thawing method is used.

[0087] In the example in Figure 7, the ice ball is elliptical (for example, the ice ball is longer along the first axis than along the second axis). The first axis of the ice ball corresponds to the longitudinal axis of the expansion chamber. The ratio of height to diameter of the expansion chamber can correlate with the shape of the ice ball. In particular, an expansion chamber that is much longer than its width results in a more oval ice ball. Such ice balls are more compatible with the anatomical structure of the bile duct and are therefore generally more suitable for the treatment of cholangiocarcinoma. However, other cryoablation applications may require a more spherical ice ball. In such cases, the expansion chamber can be modified to have a smaller length-to-diameter ratio.

[0088] In some embodiments, the major axis length of the ice ball may be 0.5 mm, 2 mm, 4 mm, 6 mm, 8 mm, or 10 mm or more, or within a range of any of these. In some embodiments, the minor axis length of the ice ball may be 0.5 mm, 2 mm, 4 mm, 6 mm, 8 mm, or 10 mm or more, or within a range of any of these.

[0089] [Cryoablation shaft including slotted tube section, polymer layer, and reinforcing layer (Figure 8)] Referring to Figure 8, schematic diagrams of the tip portions of cryoablation shafts according to various embodiments of the present disclosure are shown. In various embodiments, the shaft includes an insulated region 105 and an expansion chamber 106. In various embodiments, the insulated region 105 of the shaft 104 includes a supply pipe 324 concentrically located within a return pipe 326 concentrically located within an insulated shaft 328. The concentric shaft structure is designed to isolate the working gas circuit and the active vacuum circuit from each other.

[0090] In various embodiments, the high-pressure working fluid flows down the supply pipe 324 after exiting the handle 102. The high-pressure working fluid undergoes expansion in or downstream of the Joule-Thomson orifice 332 and can return through the shaft in the annular space between the supply pipe 324 and the return pipe 326.

[0091] In various embodiments, the expansion chamber 106 of the shaft 104 includes a supply pipe 324 concentrically located within a return pipe 326. In various embodiments, the return pipe 326 includes multiple layers.

[0092] In various embodiments, the innermost layer of the return tube is a slotted tube 830, which includes slots 840 along at least a portion of the length of the shaft 104. The slots 840 are formed in the tube material by any suitable means, such as laser cutting. The slots 840 may be laser-cut in the shaft using any suitable pattern to optimize the strength and flexibility of the return tube 326. The material of the slotted tube 830 may be a metal, such as stainless steel, Nitinol, or other durable material. Many different configurations and patterns of the slotted tube 830 are also available, and one may be selected to have the desired flexibility for its application. In various embodiments, the slotted tube forms the core of the return tube 326.

[0093] In one embodiment, the slotted tube 830 contains slots only within the expansion chamber 106. In this embodiment, the portion of the slotted tube 830 extending into the insulated region 105 has a solid wall. Figure 8 shows a schematic side view of the slotted tube 830 including slots 840 within the expansion chamber 106, with the supply tube 324 within the slotted tube 830 indicated by a dashed line. In an alternative embodiment, the slotted tube 830 has slots along its entire length.

[0094] The slotted tube may be configured to have sufficient flexibility to form a curve with a desired radius of curvature. For example, the slotted tube may have sufficient flexibility so that the shaft can form a curve with a minimum radius of curvature of 30 mm, 20 mm, 10 mm, 5 mm, or 3 mm or less. The slotted tube 830 may have different levels of flexibility in the expansion chamber and the insulated region 105.

[0095] In various embodiments, the first polymer layer 842 surrounds a portion of the slotted tube 830, which includes slots, for accommodating the working fluid within the shaft 104. In various embodiments, a reinforcing layer 844 surrounds the first polymer layer 842 and is configured to reduce the possibility of leakage or rupture in the first polymer layer by reinforcing the first polymer layer 842 with additional strength.

[0096] In various embodiments, the first polymer layer 842 may be formed from any suitable polymer such as polyethylene terephthalate (PET), PTFE, ePTFE, PEEK, polyetherimide (PEI), or polyimide (PI). In various embodiments, the reinforcing layer 844 may be a second polymer layer formed from any suitable polymer such as PET, PTFE, PEEK, polyetherimide (PEI), or polyimide (PI). In various embodiments, the reinforcing layer is gas impermeable. In various embodiments, the reinforcing layer 844 is not impermeable and may contain braided polymer material, and / or coiled polymer or metallic material, and / or coating and sealing material.

[0097] In various embodiments, the number of polymer layers in the return tube may vary, such as two, three, four, or more.

[0098] In the embodiment shown in Figure 8, where the slotted portion of the slotted tube 830 is located within the expansion chamber, the first polymer layer 842 and the reinforcing layer 844 extend from within the heat insulating region 105 to the distal end. In various embodiments, the first polymer layer 842 is joined to the slotted tube 830 at a first joint 846 near the proximal end of the expansion chamber 106 and a second joint 848 near the tip 108 of the shaft 104.

[0099] In various embodiments, the reinforcing layer 844 is joined to the slotted tube 830 at a first joint 847 near the proximal end of the expansion chamber 106 and / or a second joint 849 near the tip 108 of the shaft 104.

[0100] Additional joints may be positioned along any other suitable location on the shaft. The joints can be formed from any suitable material such as Vectran, UHMWPE, PEEK, polyimide, or metal wire. Vectran is a synthetic fiber spun from a liquid crystal polymer that exhibits high tensile strength at low temperatures and is advantageous for use in cryoablation systems. In alternative embodiments, joints 846, 847, 848, and 849 can be formed by alternative methods such as crimping or scribing rings, polymer reflow bonding, adhesive bonding, or soldering.

[0101] In various embodiments, the coating material for joints 846, 847, 848, 849 may be applied along the entire length of the expansion chamber around a polymer layer, a reinforcing layer, or both. The coating layer may have a higher coating pitch at the joint location and extend along the rest of the expansion chamber at a lower pitch level. The coating layer may extend from the proximal end to the distal end, then reverse direction and extend back towards the proximal end. The number of coating layers may be one, two, three, four, or more.

[0102] In various embodiments, the joints 846, 847, 848, and 849 are configured to increase the burst strength of the layers of the return pipe 326. In some embodiments, the burst strength of the first polymer layer 842 and the reinforcing layer 844 may be 12.4 MPa, 13.1 MPa, 13.8 MPa, 14.5 MPa, 15.2 MPa, or 41.4 MPa or higher. In some embodiments, the burst strength of the first polymer layer 842 and the reinforcing layer may be 41.4 MPa, 20.7 MPa, 19.3 MPa, 17.9 MPa, 16.5 MPa, or 15.2 MPa or lower. In some embodiments, this burst strength may be in the range of 12.4 MPa to 41.4 MPa, 13.1 MPa to 27.6 MPa, 13.8 MPa to 17.9 MPa, 14.5 MPa to 16.5 MPa, or about 15.2 MPa.

[0103] In some embodiments, the burst strength of the bonded first polymer layer 842 and reinforcing layer 844 may be 12.4 MPa, 13.1 MPa, 13.8 MPa, 14.5 MPa, 15.2 MPa, 27.6 MPa, or 41.4 MPa or higher. In some embodiments, the burst strength of the bonded first polymer layer 842 and reinforcing layer 844 may be 41.4 MPa, 20.7 MPa, 19.3 MPa, 17.9 MPa, 16.5 MPa, or 15.2 MPa or lower. In some embodiments, the burst strength of the bonded first polymer layer 842 and reinforcing layer 844 may be in the range of 12.4 MPa to 41.4 MPa, in the range of 13.1 MPa to 27.6 MPa, in the range of 13.8 MPa to 17.9 MPa, in the range of 14.5 MPa to 16.5 MPa, or about 15.2 MPa.

[0104] In some embodiments, the burst strength of each joint 846, 847, 848, and 849 may be 1.4 MPa, 4.8 MPa, 8.3 MPa, 11.7 MPa, 15.2 MPa, 27.6 MPa, or 41.4 MPa or higher. In some embodiments, the burst strength of each joint may be 41.4 MPa, 34.8 MPa, 28.3 MPa, 21.7 MPa, or 15.2 MPa or lower. In some embodiments, the burst strength of each joint may be in the range of 1.4 MPa to 41.4 MPa, in the range of 4.8 MPa to 34.8 MPa, in the range of 8.3 MPa to 28.3 MPa, in the range of 11.7 MPa to 21.7 MPa, or about 15.2 MPa.

[0105] In some embodiments, joints 846, 847, 848, and 849 may have the same burst strength. Alternatively, some of these joints may have a higher burst strength than others. For example, the proximal joints 846 and 847 may have a lower burst strength than the distal joints 848 and 849.

[0106] In various embodiments, the return tube 326 may be configured to be flexible enough to form a curve having a desired radius of curvature. For example, the return tube may be flexible enough so that the shaft can form a curve having a minimum radius of curvature of 30 mm, 20 mm, 10 mm, 5 mm, or 3 mm or less.

[0107] [A slotted tube section that can extend along the entire length of the return tube] Figure 8 shows that the slotted tube 830 contains slots only within the expansion chamber 106, but in an alternative embodiment, the slotted tube 830 has slots along its entire length. In this alternative embodiment, the first polymer layer 842 and the reinforcing layer 844 extend along the entire length of the return tube 326. A reinforcing coating layer, such as a Vectran material coating, may also extend along the entire length of the return tube. It may be desirable to have slots along the entire length of the return tube in order to achieve a desired level of flexibility along the return tube.

[0108] [Refrigerated ablation shaft including slotted pipe section and gradient braid (Figure 9)] Referring to Figure 9, schematic diagrams of some of the cryoablation shafts according to various embodiments of the present disclosure are shown. In various embodiments, the shaft includes an insulated region 105 and an expansion chamber 106. In various embodiments, the insulated region 105 of the shaft 104 includes a supply pipe 324 located within a return pipe 326. The return pipe 326 in Figure 9 includes multiple layers.

[0109] The innermost layer of the return pipe 326 is a slotted pipe 830, which may be constructed using any optional configuration and detailed configuration described herein. The slotted pipe 830 is surrounded by a polymer layer 956, which is concentrically surrounded by a reinforcing gradient braided layer 940.

[0110] In various embodiments, the gradient braided layer 940 includes regions of different braiding densities, with the density increasing toward the distal end of the apparatus. The first braided region 958 is located within the insulating region and has the lowest density. The second braided region 960 overlaps the insulating region 105 and the expansion chamber 106 and is denser than the first braided region 958. The third braided region 962 has the highest density and is located within the expansion region. The return pipe may include one, two, three, or more braided layers.

[0111] In various embodiments, the polymer layer 956 is configured to contain the working fluid in the return tube while preventing the working fluid from escaping radially through the slots in the slotted tube. The polymer layer may consist of the options and materials described herein with respect to the first polymer layer. In some embodiments, the expansion chamber 106 may include an additional braided layer between the slotted tube 830 and the polymer layer 956 (not shown in this figure). The additional braided layer is configured to prevent friction between the polymer layer 956 and the slotted tube 830.

[0112] [Examples of braided materials, braided element diameters, braided density regions, coils, and burst strengths] Braided tubing is used in a variety of medical applications. Braided reinforcement can improve the functional properties of medical devices, such as strength, rigidity, rupture pressure resistance, torque transmission, and torsional resistance. These features can allow the cryoablation shaft to move through tortuous sections of the patient's anatomical structures, such as the bile duct. Design considerations such as braid pattern, pick count (ppi), material, wire dimensions, wire size / shape, and resin durometer can significantly affect the device's performance.

[0113] The braided portion of the shaft can be formed from any suitable material such as metal (e.g., Nitinol, stainless steel, tungsten, MP35N, or other such materials), polymer (e.g., PET, Kevlar, carbon fiber, Vectran, or other such materials). The braided material is formed by weaving metal or fiber filaments in a braided pattern. In various embodiments, the cross-section of the filaments is circular, but other cross-sectional shapes (e.g., flat, star-shaped, triangular) are also possible. In some embodiments, the diameter of the filaments may be 0.01 mm, 0.1 mm, 0.2 mm, 0.3 mm, or 0.5 mm or more. In some embodiments, the diameter of the filaments may be 2 mm, 1.6 mm, 1.2 mm, 0.8 mm, or 0.5 mm or less. In some embodiments, the diameter of the filaments may be in the range of 0.01 mm to 2.00 mm, 0.1 mm to 1.6 mm, 0.2 mm to 1.2 mm, 0.3 mm to 0.8 mm, or about 0.5 mm.

[0114] In various embodiments, the density of the braided portion can be varied so that high-density braids increase radial strength and rigidity, while low-density braids provide flexibility. The shaft may include multiple braids having various material properties. In various embodiments, the shaft may include a lightweight braid (for example, having a relatively low braid density) between the return tube 326 and the polymer layer 956. As described above, the lightweight braid can prevent excessive friction between the slotted return tube 326 and the polymer layer 956, although structural support is limited.

[0115] In various embodiments, the density of the braided material can increase from the base of the shaft 104 to the tip 108 of the shaft. Such a configuration increases the likelihood that the shaft will fail closer to the base if the device malfunctions. This type of failure is generally preferable from the viewpoint of patient safety compared to failure closer to the tip 108 of the shaft.

[0116] In various embodiments, the first gradient braided region 958 extends into the thermal insulation region 105 of the shaft 104 (i.e., starting where the shaft connects to the handle 102 and ending in front of the expansion chamber 106). In various embodiments, the gradient braided portion 958 may have a first burst strength. The first burst strength may be constant along the thermal insulation region of the shaft. Alternatively, the first burst strength of the gradient braided portion 958 may increase from the base of the shaft to the expansion chamber. In various embodiments, the gradient braided portion 958 may have a first braid density. The first braid density may be constant along the thermal insulation region of the shaft. Alternatively, the first braid density of the gradient braided portion 958 may increase from the base of the shaft to the expansion chamber.

[0117] In some embodiments, the minimum burst strength of the braided section 958 may be 20.7 MPa, 13.8 MPa, 6.9 MPa, 5.5 MPa, 4.1 MPa, 2.8 MPa, 1.4 MPa, or 0.7 MPa or less, or within a range of any of these values. In some embodiments, the maximum burst strength of the braided section 958 may be 0.7 MPa, 2.0 MPa, 3.4 MPa, 4.8 MPa, 6.2 MPa, 6.9 MPa, 13.8 MPa, or 20.7 MPa or more, or within a range of any of these values.

[0118] In various embodiments, the second braided portion 960 extends into the expansion chamber 106 of the shaft 104. In some embodiments, the second braided portion 960 may begin at the starting end of the expansion chamber and terminate at or near the tip 108 of the shaft. Alternatively, the second braided portion 960 may begin toward the distal end of the insulating region 105 of the shaft (as shown in Figure 9) and terminate at or near the tip 108 of the shaft. In some embodiments, the second braided portion 960 is continuous with the first braided portion 958. Alternatively, the second braided portion 960 may be formed from elements physically separate from the elements of the first braided region 958.

[0119] In various embodiments, the second braided portion 960 may have a second burst strength. The second burst strength may be constant along the length of the first braided layer. Alternatively, the second burst strength of the second braided portion 960 may increase along the length of the first braided layer (from the end of the insulating region 105 to the tip 108). In various embodiments, the second braided portion 960 may have a second braid density. The second braid density may be constant along the length of the second braided portion. Alternatively, the second braid density of the second braided portion 960 may increase along the length of the second braided portion.

[0120] In some embodiments, the burst strength of the second braided portion 960 may be 10.3 MPa, 12.9 MPa, 15.5 MPa, 18.1 MPa, 20.7 MPa, or 41.4 MPa or more. In some embodiments, the burst strength of the second braided portion 960 may be 34.5 MPa, 31.0 MPa, 27.6 MPa, 24.1 MPa, or 20.7 MPa or less. In some embodiments, the burst strength of the second braided portion 960 may be in the range of 10.3 MPa to 34.5 MPa, in the range of 12.4 MPa to 31.0 MPa, in the range of 15.5 MPa to 27.6 MPa, in the range of 17.9 MPa to 34.5 MPa, or about 20.7 MPa.

[0121] In various embodiments, the third braided region 962 extends to the expansion chamber 106 of the shaft 104. In some embodiments, the third braided region 962 may start from the beginning of the expansion chamber and end at or near the tip 108 of the shaft.

[0122] In various embodiments, the third braided region 962 may have a third bursting strength. The third bursting strength may be constant along the length of the third braided region. Alternatively, the bursting strength of the third braided region 962 may increase along the length of the third braided region. In various embodiments, the third braided region 962 may have a third braid density. The third braid density may be constant along the length of the third braided region. Alternatively, the braid density of the third braided region 962 may increase along the length of the first braided layer.

[0123] In some embodiments, the burst strength of the third braided region 962 may be 10.3 MPa, 12.9 MPa, 15.5 MPa, 18.1 MPa, or 20.7 MPa or higher. In some embodiments, the burst strength of the third braided region 962 may be 34.5 MPa, 31.0 MPa, 27.6 MPa, 24.1 MPa, or 20.7 MPa or lower. In some embodiments, the burst strength of the third braided region 962 may be in the range of 10.3 MPa to 34.5 MPa, in the range of 12.4 MPa to 31.0 MPa, in the range of 15.5 MPa to 27.6 MPa, in the range of 17.9 MPa to 24.1 MPa, or about 20.7 MPa.

[0124] In alternative embodiments, any or all of the gradient braided regions 958, 960, 962 may be formed from a coil. A coil as defined herein is a filament material wound around a shaft. Similar to the braided materials described above, the filament may be selected to have one or more suitable materials and to have a cross-sectional shape such as circular, rectangular, or other shapes. Each region may contain a coil having different densities, radial strengths, stiffness, and flexibility. The coil may be single-layer or multi-layer. In some embodiments, multi-layer coils may have alternating winding directions (e.g., the first layer is wound clockwise and the second layer counterclockwise). In various embodiments, the coil pitch may be modified to optimize the shaft's properties such as flexibility and burst strength. For example, a denser coil pitch may increase the burst strength of the shaft, while a looser coil pitch may increase the shaft's flexibility. In various embodiments, the pitch of the coil material may increase from the base of the shaft 104 to the tip 108 of the shaft.

[0125] [Transitions between braided regions] In some embodiments, the transitions between the first, second, and third braided sections are density transitions of the same physical braided elements, such that one braided region is continuous with an adjacent braided region. Alternatively, one braided section may be made from elements that are physically separated from the elements of the adjacent braided region.

[0126] [Composite shaft (Figure 10)] Referring to Figure 10, schematic diagrams of some of the cryoablation shafts according to various embodiments of the present disclosure are shown. In various embodiments, the expansion chamber 106 of the shaft 104 includes a supply pipe 324 concentrically located within a composite return pipe 1064. In various embodiments, the return pipe may be a composite shaft. In various embodiments, the composite return pipe 1064 is formed from one or more distinct layers. One possible return pipe layer is the braided layer 1066 shown in Figure 10.

[0127] In various embodiments, the composite return tube 1064 may be formed from one or more polymer and / or braided layers, as described in detail herein. After forming the separate layers, the composite shaft may be heated to a temperature at which the separate layers bond to each other to form a single composite layer. In some embodiments, some of the separate layers may contribute to the radial strength of the expansion chamber, while others may contribute to the gas containment capacity of the expansion chamber. In such embodiments, radial strength and gas containment may be achieved from a single composite layer. Such a configuration can improve the tunability of the properties of the expansion chamber material while reducing the diameter of the expansion chamber.

[0128] In some embodiments, an additional braided layer 1066 may be placed on top of the rest of the composite return tube 1064. The additional braided layer is selected to have braided properties that increase the radial strength of the expansion chamber 106.

[0129] [Example of distal mounting (Figure 10)] In various embodiments, the working fluid can be contained in the tip 108 of the shaft using a plug 1068 and one or more joints 1070. In various embodiments, the joints 1070 and / or the plug 1068 may be formed of one or more materials suitable for coupling with the composite return tube 1064 and / or braided layer 1066 to enhance the sealing of the shaft 104. In various embodiments, the joints 1070 and / or the plug 1068 may be formed of one or more materials having sufficient strength to enhance the burst strength of the expansion chamber.

[0130] In various embodiments, the plug 1068 includes a raised portion 1072. The raised portion 1072 improves the mechanical strength of the joined joint 1070 by providing the joint with additional structural support to resist the pressure within the expansion chamber.

[0131] [Alternative configuration of composite shaft (Figure 11)] Referring to Figure 11, schematic diagrams of some of the cryoablation shafts 104 according to various embodiments of the present disclosure are shown. In various embodiments, the expansion chamber 106 of the shaft 104 includes a supply pipe 324 that is concentrically located within a composite return pipe 1064.

[0132] The composite return tube 1064 in Figure 11 may have similar layers and / or properties to the composite return tube in Figure 10. In the example in Figure 11, the outer polymer layer 1174 may be placed on top of the outermost layer of the composite return tube 1064. The outer polymer layer 1174 may be formed from any suitable polymer or polymer mixture such as Pebax, polyethylene terephthalate (PET), PTFE, ePTFE, PEEK, polyetherimide (PEI), or polyimide (PI). The outer polymer layer 1174 can enhance the functionality of the shaft 104 by improving any of the following: burst strength, biocompatibility, or resistance to cryoablation temperature and pressure.

[0133] [Continuous return pipe (Figure 12)] Referring to Figure 12, schematic diagrams of some of the cryoablation shafts according to various embodiments of the present disclosure are shown. In various embodiments, the shaft includes an insulated region 105 and an expansion chamber 106. In various embodiments, the insulated region 105 of the shaft 104 includes a supply pipe 324 located within a return pipe 326. In various embodiments, the high-pressure flow of working fluid, after exiting the handle 102, travels down the supply pipe 324. The high-pressure flow of working fluid undergoes expansion in or downstream of the Joule-Thomson orifice 332 and can return within the shaft in the annular space between the supply pipe 324 and the return pipe 326.

[0134] In various embodiments, the return tube 326 may extend continuously along the entire length of the shaft 104. For example, the return tube 326 may be a single component that extends throughout the entire thermal insulation region 105 and expansion chamber 106 of the shaft 104. In various embodiments, the return tube 326 may be a composite shaft formed from two or more layers. In the example of Figure 12, the return tube 326 may include a first polymer layer 1276, a reinforcing layer 1278, and a second polymer layer 1280.

[0135] In various embodiments, the first polymer layer 1276 forms the innermost layer of the return pipe 326. In various embodiments, the first polymer layer 1276 is configured to contain fluid from the working fluid circuit. In particular, the first polymer layer 1276 is configured to contain the working fluid returning to the handle in the annular space between the supply pipe 324 and the return pipe 326.

[0136] The first polymer layer 1276 can be formed from any suitable polymer or mixture of polymers, such as polyethylene terephthalate (PET), PTFE, ePTFE, PEEK, polyetherimide (PEI), or polyimide (PI). In various embodiments, the first polymer layer 1276 is gas impermeable.

[0137] In various embodiments, the return tube 326 may include a reinforcing layer 1278 surrounding the first polymer layer 1276. In various embodiments, the reinforcing layer 1278 is configured to increase the radial strength of the composite shaft. The reinforcing layer 1278 may also improve additional functional properties of the shaft 104, such as stiffness, burst pressure resistance, torque transmission, and torsional resistance. For example, the reinforcing layer 1278 may be configured to enhance the ability of the first polymer layer 1276 and / or the second polymer layer 1280 to pass through bends and corners without twisting or other damage.

[0138] In some embodiments, the reinforcing layer 1278 may be formed from a metallic material such as stainless steel, titanium, or tungsten. In some embodiments, the reinforcing layer 1278 may be formed from a polymer material such as Kevlar®, polyimide, or PET.

[0139] In various embodiments, the reinforcing layer 1278 may be formed from a braided material having any suitable combination of braiding pattern, pick count (measured in picks per inch, i.e., ppi), material, wire dimensions, wire size / shape, durometer, etc., as described in detail in Figure 9. In the example of Figure 12, the reinforcing layer 1278 has a uniform braiding density along the entire length of the return tube 326. The braiding density of the reinforcing layer 1278 may be selected to increase the radial strength of the shaft while maintaining the ability of the shaft to pass through bends and corners to access cryoablation sites. In one embodiment, the shaft 104 may be configured to have a radius of curvature of 30 mm or less. In an alternative embodiment, the reinforcing layer 1278 may have any suitable density profile along the length of the shaft 104. In an alternative embodiment, the reinforcing layer 1278 may be formed from one or more coils, as described in detail in Figure 9.

[0140] In various embodiments, the return tube 326 may include a second polymer layer 1280 surrounding the reinforcing layer 1278 and the first polymer layer 1276. The second polymer layer 1280 may be formed from any suitable one or more polymers, including but not limited to thermoplastic polymers, biocompatible polymers, and polyether block amides such as Pebax. In various embodiments, at least one of the first polymer layer 1276 and the second polymer layer 1278 is impermeable.

[0141] The second polymer layer 1280 can provide various functions. In various embodiments, the second polymer layer 1280 functions as a redundant gas containment layer relative to the first polymer layer 1276. In various embodiments, the second polymer layer 1280 is configured to reduce the possibility of leakage or rupture in the first polymer layer by reinforcing the first polymer layer 1276 and the reinforcing layer 1278 with additional strength.

[0142] In various embodiments, the second polymer layer 1280 is formed from a biocompatible material. A biocompatible material, as defined herein, is any material that is compatible with living tissue or organisms without causing harm or adverse reactions. In various embodiments, forming the outermost layer of the shaft 104 from a biocompatible material minimizes negative patient outcomes such as inflammation, toxicity, or rejection in the patient during cryoablation treatment.

[0143] In various embodiments, the second polymer layer 1280 is formed from a radiopaque material. In various embodiments, the radiopaque material is invisible under radiation. In one embodiment, the second polymer layer 1280 may be reinforced with a radiopaque material such as tungsten to improve the visibility of the expansion chamber under imaging processes such as fluorescence fluoroscopy.

[0144] In various embodiments, the second polymer layer 1280 is configured to exhibit stability over the entire range of cryoablation operating temperature and pressure. In various embodiments, the second polymer layer 1280 is configured to exhibit low dimensional change over the entire range of cryoablation temperature. The cryoablation operating temperature ranges from patient body temperature (approximately 310 Kelvin) to the cryoablation temperature (approximately 190 Kelvin), and the device may experience temperature transitions over this range. For example, the second polymer layer may experience little to no dimensional change from either room temperature (approximately 293 Kelvin) or patient body temperature (approximately 310 Kelvin) to the cryoablation temperature (approximately 190 Kelvin). In various embodiments, the second polymer layer 1280 is configured to exhibit small dimensional change over the entire range of cryoablation pressure. For example, the second polymer layer exhibits little to no dimensional change from a vacuum pressure (approximately 0.05 Torr) to the high pressure associated with the Joule-Thomson orifice (ranging from approximately 6.9 MPa to approximately 13.8 MPa, e.g., approximately 12.4 MPa).

[0145] In some embodiments, the outer diameter of the second polymer layer 1280 changes over the course of the cryoablation treatment by a percentage of 5%, 4%, 3%, 2%, 1%, or 0% or less from its original diameter. In some embodiments, the length of the second polymer layer 1280 changes over the course of the cryoablation treatment by a percentage of 5%, 4%, 3%, 2%, 1%, or 0% or less from its original length.

[0146] In various embodiments, the second polymer layer 1280 is configured to maintain high burst strength over the entire range of cryoablation pressure and temperature. In some embodiments, the burst strength of the second polymer layer 1280 may be 12.4 MPa, 13.1 MPa, 13.8 MPa, 14.5 MPa, 15.2 MPa, 27.6 MPa, or 41.4 MPa or higher. In some embodiments, the burst strength of the second polymer layer 1280 may be 41.4 MPa, 20.7 MPa, 19.3 MPa, 17.9 MPa, 16.5 MPa, or 15.2 MPa or lower. In some embodiments, this burst strength may be in the range of 12.4 MPa to 41.4 MPa, 13.1 MPa to 27.6 MPa, 13.8 MPa to 17.9 MPa, 14.5 MPa to 16.5 MPa, or about 15.2 MPa.

[0147] In some embodiments, the bursting strength of the second polymer layer 1280 may be 0.25 MPa, 0.62 MPa, or 1.00 MPa or higher. In some embodiments, the bursting strength of the second polymer layer 1280 may be 4.00 MPa, 2.50 MPa, or 1.00 MPa or lower. In some embodiments, the bursting strength of the second polymer layer 1280 may be in the range of 0.25 MPa to 4.00 MPa, in the range of 0.62 MPa to 2.50 MPa, or about 1.00 MPa.

[0148] In various embodiments, the second polymer layer 1280 is configured to maintain its elasticity over the entire range of cryoablation pressure and temperature. For example, the second polymer layer 1280 can provide sufficient flexibility to the shaft 104 so that the shaft can form a curve with a minimum radius of curvature of 30 mm, 20 mm, 10 mm, or 5 mm or less over the entire range of cryoablation pressure and temperature.

[0149] In various embodiments, the return tube 326 can be sealed and bonded to the insulated shaft 328 by any suitable one or more methods. In the example shown in Figure 12, the return tube 326 is sealed to the insulated shaft 328 using a reflow process. In particular, the second polymer layer 1280 of the composite shaft is sealed to the insulated shaft using a thermal reflow process. Thermal reflow refers to the softening and material displacement that occurs in a polymer when heated above its glass transition temperature. In such embodiments, it is desirable that the second polymer layer 1280 be formed from a material that can be repeatedly melted without affecting its material properties, such as a thermoplastic resin.

[0150] As shown in Figure 12, the return tube 326 may be slidable within the adiabatic shaft 328 to form a connection between the return tube 326 and the adiabatic shaft 328. In various embodiments, the return tube 326 may be slidable within the adiabatic shaft 328 by a predetermined amount to set the length of the expansion chamber 106. As detailed in Figure 6, the length of the expansion chamber 106 affects the size and shape of the ice ball formed by the cryoablation probe.

[0151] In some embodiments, the first tubular piece 1284 can slide between the inner and outer shafts. In various embodiments, the first tubular piece 1284 may be made of any suitable material or a combination of materials such as Pebax. In various embodiments, the first tubular piece 1284 may have a lower glass transition temperature than the other components of the shaft 104. The shaft 104 may be exposed to a temperature high enough to melt the first tubular piece 1284 during the reflow process.

[0152] In some embodiments, the second tube piece 1286 slides on the shaft 104, covering the return tube 326, the insulated shaft 328, and the first tube piece 1284. In various embodiments, the second tube piece 1286 may be any suitable material or a combination of materials such as Pebax. The shaft 104 may be exposed to a temperature high enough to melt the first tube piece 1284 and / or the second tube piece 1286 during the reflow process. In various embodiments, the shaft, by being subjected to compressive force during the reflow process, provides a leak-proof seal between the return tube 326 and the insulated shaft 328.

[0153] In an alternative embodiment, the insulated shaft 328 may be sealed to the outer layer of the return pipe 326 by any suitable means, such as an adhesive. For example, an adhesive may be applied between the inner layer of the insulated shaft 328 and the outer layer of the return pipe 326. The adhesive is selected to have material properties suitable for bonding to both the insulated shaft 328 and the return pipe 326 over the entire range of cryoablation operating temperatures and pressures.

[0154] In various embodiments, the return tube 326 can be sealed and joined to the distal working tip 108 by various methods. In the example of Figure 12, the return tube 326 is sealed to the insulated shaft 328 using a crimping process. As seen in Figure 12, a coupling element such as a crimping ring 1282 is mounted on the distal end of the return tube 326 to form a connection between the return tube 326 and the distal working tip 108. The distal working tip 108 can then be inserted into the return tube. The shaft 104 can then be inserted into a portion of a crimping device having one or more crimping dies. The crimping device applies a rotational radial force to the crimping ring 1282, reducing the diameter of the crimping ring. This reduction in diameter compresses the return tube 326 between the crimping ring 1282 and the distal working tip 108. This process forms a leak-proof seal between the return tube 326 and the distal working tip 108. In the embodiment of Figure 12, the second polymer layer 1280 is formed from a continuous material tube. The second polymer layer may have substantially uniform material properties (e.g., flexibility, burst strength, torsional rigidity, hardness, gas permeability, visibility) along the entire length of the shaft 104. In certain embodiments, the second polymer layer 1280 has a nearly constant durometer hardness along its length. In some embodiments, the hardness of the second polymer layer 1280 may be 50, 57, 63, or 70 Shore A or higher. In some embodiments, the hardness of the second polymer layer 1280 may be 100, 90, 80, or 70 Shore A or lower. In some embodiments, the hardness of the second polymer layer 1280 may be in the range of 50 to 100 Shore A, 57 to 90 Shore A, 63 to 80 Shore A, or about 70 Shore A. However, in alternative embodiments, the second polymer layer 1280 may be configured to have variable material properties along the length of the shaft 104.

[0155] [Embodiment of multiple regions of continuous return pipe (Figure 13)] Referring to Figure 13, schematic diagrams of some cryoablation shafts according to various embodiments of the present disclosure are shown. The cryoablation shaft 104 in Figure 13 is substantially similar to the cryoablation shaft 104 in Figure 12, except that the second polymer layer 1280 is configured to have variable material properties along the length of the shaft 104.

[0156] In various embodiments, the second polymer layer 1280 is formed from two or more regions, each region of which may be formed from a separate portion of the polymer tube. Each of the multiple tube portions may be formed from any suitable thermoplastic material such as Pebax. In the example in Figure 13, the second polymer layer 1280 is formed from four regions 1388, 1390, 1392, and 1394.

[0157] In various embodiments, individual regions can be formed within the second polymer layer 1280 of the return tube 326 by any suitable method. In the example of Figure 13, the second polymer layer 1280 is formed using a thermal reflow process. A desired number of individual tube sections (in this case, four individual tube sections corresponding to four regions 1388, 1390, 1392, and 1394) are placed on the shaft 104, covering the outermost layer of the return tube 326 (in this case, the reinforcing layer 1278). The individual tube sections are then fused to each other and to the outermost layer of the return tube 326 by applying heat and compressive force to the shaft in a thermal reflow process.

[0158] In the example in Figure 13, the second polymer layer 1280 includes four separate tubular sections corresponding to four regions 1388, 1390, 1392, and 1394. However, the second polymer layer 1280 may include any suitable number of regions, such as one, three, five, or more. In the example in Figure 13, each of the regions 1388, 1390, 1392, and 1394 is of approximately the same length. However, in alternative embodiments, the length of each region may be varied based on the selection of tubular sections.

[0159] In various embodiments, each region of the second polymer layer 1280 may have a set of material properties (e.g., flexibility, burst strength, hardness, torsional rigidity, gas permeability, visibility) selected to improve various performance parameters of the shaft 104. In various embodiments, each individual tube section may have the same or different material properties depending on the desired performance parameters of the shaft (e.g., strength, flexibility, biocompatibility, durability, etc.).

[0160] In one example, the distal working tip 108 inserted into the shaft 104 may reduce the flexibility of the shaft at its distal end. In this case, it may be advantageous to adjust the second polymer layer 1280 to increase flexibility (or decrease stiffness) toward the distal tip 108 of the shaft 104.

[0161] In various embodiments, the second polymer layer 1280 is a thermoplastic material having multiple regions with different durometer hardness along its length. In some embodiments, the hardness of the second polymer layer 1280 decreases at at least one point from the proximal end of the shaft toward the distal end of the shaft.

[0162] In various embodiments, the second polymer layer 1280 may include at least a first region having a first durometer hardness and a second region distal to the first region having a second durometer hardness. In some embodiments, the first durometer hardness may be 60, 63, 67, or 70 Shore A or higher. In some embodiments, the first durometer hardness may be 80, 77, 73, or 70 Shore A or lower. In some embodiments, the first durometer hardness may be in the range of 60 to 80 Shore A, 63 to 77 Shore A, 67 to 73 Shore A, or about 70 Shore A. In some embodiments, the second durometer hardness may be 35, 42, 48, or 55 Shore A or higher. In some embodiments, the second durometer hardness may be 75, 68, 62, or 55 Shore A or lower. In some embodiments, the second durometer hardness may be in the range of 35–75 Shore A, 42–68 Shore A, 48–62 Shore A, or about 55 Shore A.

[0163] In the example shown in Figure 13, the second polymer layer 1280 includes a first region 1388, a second region 1390, a third region 1392, and a fourth region 1394. Each region may have the same or different material properties as its adjacent regions. In one embodiment, the first region 1388 may have a first durometer hardness. The second region 1390 may have a second durometer hardness. The third region 1392 may have a third durometer hardness. The fourth region 1394 may have a fourth durometer hardness. In one example, the hardness of each region may decrease from the first region 1388 to the fourth region. However, the hardness profile of the second polymer layer 1280 may be modified based on the structure of the shaft 104 and its intended application.

[0164] In various embodiments, different regions of the second polymer layer 1280 may be modified to improve the performance of the shaft. For example, specific regions may be reinforced with one or more materials. In one embodiment, one or more regions of the second polymer layer 1280 may be reinforced with a radiopaque material such as tungsten to improve the visibility of the shaft 104 under fluorescence imaging.

[0165] [Expansion chamber with adjustable length (Figures 14 and 15)] Referring to Figure 14, schematic diagrams of some of the cryoablation shafts according to various embodiments of the present disclosure are shown. The cryoablation shaft 104 in Figure 14 is substantially similar to the cryoablation shaft 104 in Figure 12, except that the return pipe 326 can be sealed and joined to the insulated shaft 328 using an adjustable sealing mechanism 1496.

[0166] In various embodiments, the adjustable sealing mechanism 1496 may include one or more gaskets, O-rings, reflow bonding, etc. In the example of Figure 14, the second polymer layer 1280 of the return tube 326 is sealed to the insulated shaft 328 by the adjustable sealing mechanism 1496 so that the return tube 326 can be moved axially 1498 relative to the insulated shaft 328 while maintaining a seal between the return tube and the insulated shaft.

[0167] In various embodiments, the length of the expansion chamber 106 is changed by moving the return tube 326 axially 1498 relative to the insulated shaft 328. As detailed in Figure 6, the length of the expansion chamber 106 affects the size and shape of the ice ball formed by the cryoablation probe. Therefore, having an expansion chamber with an adjustable length can be advantageous in optimizing the size and shape of the ice ball in various cryoablation conditions. In the example in Figure 14, the expansion chamber has a first length L E1 It has.

[0168] In one embodiment, the adjustable sealing mechanism 1496 can be sealed to the shaft 104 at its ends 1497, 1499 (using adhesive, reflow, etc.). At least a portion of the adjustable sealing mechanism 1496 between ends 1497, 1499 is not sealed to the shaft. The unsealed portion of the adjustable sealing mechanism 1496 may have a bellows-like structure. This allows the unsealed portion of the adjustable sealing mechanism 1496 to expand or contract while maintaining the seal between the ends 1497, 1499 of the adjustable sealing mechanism and the shaft 328 by moving the return tube 326 axially 1498 relative to the insulating shaft 104.

[0169] Referring to Figure 15, schematic diagrams of some of the cryoablation shafts according to various embodiments of the present disclosure are shown. The cryoablation shaft 104 in Figure 15 is substantially the same as the cryoablation shaft 104 in Figure 14, except that the return pipe 326 is moved axially 1498 relative to the adiabatic shaft 328. In the example in Figure 15, the expansion chamber has a second length L E2 It has.

[0170] Comparing Figure 14 and Figure 15, the expansion chamber 106 in Figure 14 is the same as the expansion chamber (L) in Figure 15. E2 Length longer than (L) E1 ) has. Therefore, the cryoablation probe in Figure 14 is expected to produce more oval ice balls than the cryoablation probe in Figure 15.

[0171] By using the adjustable sealing mechanism 1496, the expansion chamber 106 can be adjusted to have any suitable length between the minimum possible expansion chamber length and the maximum possible expansion chamber length. In some embodiments, the minimum possible expansion chamber length may be 50 mm, 40 mm, 30 mm, 20 mm, or 10 mm or less, or within a range of any of these. In some embodiments, the maximum possible expansion chamber length may be 10 mm, 30 mm, 50 mm, 70 mm, 90 mm, 110 mm, 130 mm, or 150 mm or more, or within a range of any of these.

[0172] [Marker for imaging system] The joint 334 (Figure 3) and the distal tip 108 (Figures 8 and 10) are configured to appear on the imaging system. The joint 334 may include a marker band made of radiopaque material such as tungsten, platinum-iridium, or other suitable material. The material and dimensions of the distal tip 108 may be configured to appear on the imaging system. Examples of materials for the distal tip 108 include stainless steel and nitinol. Markers at each end of the device's operating area help the physician visually identify the location of the cryoablation operating area relative to the patient's anatomical structure and the target area of ​​cryoablation. Examples of imaging systems include ultrasound, fluoroscopy, cone-beam CT, and MRI systems.

[0173] [Installation Options] In one embodiment, the catheter system is delivered using a sheath introduction system. An example of a sheath introduction system is a maneuverable sheath. Alternatively, the catheter system may be maneuverable. In another embodiment, the catheter system includes a monorail lumen along a portion of the catheter to facilitate introduction.

[0174] The concepts described herein may be applied to and used in connection with the cryoablation systems and components described in the following four U.S. Patent Applications filed on 22 May 2024: U.S. Patent Application No. 18 / 671,627, entitled “Safety Devices for Cryoablation Probe,” U.S. Patent Application No. 18 / 671,677, entitled “Multiple Gas Circuit Connector and Method for Cryoablation System,” U.S. Patent Application No. 18 / 671,727, entitled “Delivery Systems for Cryoablation Device,” and U.S. Patent Application No. 18 / 671,742, entitled “Distal Tip Structure for Cryoablation Probe,” which are incorporated herein by reference in their entirety.

[0175] As used herein and in the claims, “a / an” and “the” include multiple subjects unless otherwise explicitly indicated. The term “or” is generally used to include “and / or” unless otherwise explicitly indicated.

[0176] As used herein and in the claims, the term “configured” describes a system, apparatus, or other structure that is built or configured to perform a particular process or employ a particular configuration. The term “configured” may also be used interchangeably with other similar terms such as arranged and configured, built and positioned, constructed, manufactured and positioned.

[0177] All publications and patent applications herein represent the level of skill of those skilled in the art to which the present invention pertains. All publications and patent applications are incorporated herein by reference to the same extent as if each individual publication or patent application were specifically and individually indicated by reference.

[0178] As used herein, an enumeration of numerical ranges by endpoints includes all numbers contained within that range (for example, 2 to 8 includes 2.1, 2.8, 5.3, 7, etc.). The headings used herein are for structural reference only. These headings should not be considered to limit or characterize any invention described in any claim that may arise from this disclosure. For example, with respect to the heading "Technical Field," the claims should not be limited by the language selected under that heading to describe that technical field. Similarly, the description of the technology in "Background Art" does not constitute prior art to any invention in this disclosure. Furthermore, the "Summary of the Invention" should not be considered as a characteristic of the invention described in the claims.

[0179] The embodiments described herein are not intended to be exhaustive, nor are they intended to limit the invention to the exact forms disclosed in the detailed description. Rather, the embodiments are selected and described so that those skilled in the art can recognize and understand the principles and practices. Several aspects have been described above with reference to various specific preferred embodiments and techniques. However, many changes and modifications can be made that fall within the spirit and scope of this disclosure.

Claims

1. Cryoablation probe, Precooler fluid circuit, Working fluid circuit and Vacuum circuits and, A shaft and a shaft, the shaft is supply pipe and A return pipe surrounding the supply pipe, A first polymer layer configured to contain fluid from the working fluid circuit, Reinforcement layer, The return tube includes a second polymer layer, An insulating region, wherein the vacuum circuit is defined within the insulating region between the return pipe and the insulating shaft, An expansion chamber extending distal to the adiabatic region, wherein fluid from the working fluid circuit moves through the supply pipe and expands within the expansion chamber, A cryoablation probe, including one.

2. The cryoablation probe according to any one of claims 1, 3 to 15, wherein the shaft forms a curve having a minimum radius of curvature of 30 mm or less.

3. The cryoablation probe according to any one of claims 1, 2, 4 to 15, wherein the first polymer layer comprises PTFE and the second polymer layer comprises polyether block amide.

4. The cryoablation probe according to any one of claims 1 to 3, 5 to 15, wherein the vacuum circuit terminates at the distal end of the adiabatic region, and the distal end of the adiabatic region is the proximal end of the expansion chamber.

5. The cryoablation probe according to any one of claims 1 to 4, 6 to 15, wherein the second polymer layer has a substantially constant durometer hardness along its length.

6. The cryoablation probe according to any one of claims 1 to 5, 7 to 15, wherein the second polymer layer is a thermoplastic material and comprises a plurality of regions with different durometer hardnesses along its length.

7. The cryoablation probe according to any one of claims 1 to 6, 8 to 15, wherein the second polymer layer is characterized by a decrease in hardness at at least one point from the proximal end of the shaft toward the distal end of the shaft.

8. The second polymer layer comprises at least, A first region having a first durometer hardness, A second region located proximal to the first region and having a second durometer hardness, A cryoablation probe according to any one of claims 1 to 7, 9 to 15, comprising, wherein the first durometer hardness is greater than the second durometer hardness.

9. A cryoablation probe according to any one of claims 8, 10, or 11, wherein the first durometer hardness is about 70 Shore A and the second durometer hardness is about 55 Shore A.

10. The cryoablation probe according to any one of claims 8, 9, or 11, wherein the first region and the second region are each composed of separate polymer tube portions.

11. The cryoablation probe according to any one of claims 8 to 10, wherein the first region is joined to the second region by reflow processing.

12. The cryoablation probe according to any one of claims 1 to 11, 13 to 15, wherein the first polymer layer, the reinforcing layer, and the second polymer layer extend from the first proximal end of the shaft to the second distal end of the shaft.

13. The cryoablation probe according to any one of claims 1 to 12, 14, or 15, wherein the second polymer layer of the return tube is sealed to the insulating shaft by reflow treatment.

14. The cryoablation probe according to any one of claims 1 to 13, 15, wherein the second polymer layer of the return tube is sealed to the tip of the cryoablation probe by reflow treatment.

15. The cryoablation probe according to any one of claims 1 to 14, wherein the second polymer layer of the return tube is sealed to the insulating shaft by an adjustable sealing mechanism such that the return tube is movable axially relative to the insulating shaft while maintaining a seal between the return tube and the insulating shaft.

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