Flexible cryoprobe

Abstract

A cryoablation tool may include a catheter. The catheter may have a shaft having: a proximal end; a distal end; a shaft wall extending between the proximal end and the distal end, the shaft wall having an outer surface and an inner surface, and a vacuum gap defining a vacuum chamber between the outer surface and the inner surface, the inner surface of the shaft wall being gas permeable; a shaft cavity defined by the inner surface of the shaft wall, the shaft cavity for carrying a cryogen gas, and the vacuum chamber having a proximal opening connectable to a vacuum source, the proximal opening establishing vacuum communication between the vacuum chamber and the vacuum source.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to provisional application No. 62 / 886,858, filed August 14, 2019, which is incorporated herein by reference in its entirety. Background Art

[0002] The present invention relates to a cryoprobe for cryoablation and a system for cryoablation.

[0003] During cryosurgery, a surgeon can deploy one or more cryoprobes to ablate a target area of ​​a patient's anatomy by freezing and thawing tissue. In one example, a cryoprobe uses the Joule-Thomson effect to produce cooling or heating of the probe tip. In this case, the expansion of a cryofluid in the cryoprobe from a higher pressure to a lower pressure results in cooling the device tip to a temperature at or below the temperature at which tissue near the tip is being cryoablated. Heat transfer between the expanding cryofluid and the outer wall of the cryoprobe results in the formation of an ice ball in the tissue surrounding the tip and subsequent cryoablation of the tissue.

[0004] Some cryoprobes can be used to ablate lesions in the human lung. In this case, the cryoprobe may have to navigate through tortuous passages. Cryoprobes with rigid shafts may not be suitable for this application. Summary of the Invention

[0005] In general, various embodiments relate to devices, systems, and methods for cryoprobes, insulating sheaths, and insulated catheters. Such devices, systems, and methods may be used in exemplary applications in medical technology. These embodiments may be used in such exemplary applications, for example, when providing cryoablation. However, these embodiments may also address some of the issues mentioned above.

[0006] One aspect of the present invention relates to a cryoablation instrument comprising a shaft. The shaft may comprise a proximal end, a distal end, and a shaft wall. The shaft wall may extend between the proximal end and the distal end and further comprise an outer surface, an inner surface, and a gap defining a chamber between the outer surface and the inner surface. In some aspects, the shaft wall may be breathable. The shaft may further comprise an axial cavity defined by the inner surface of the shaft wall and a cryogen supply conduit. The cryogen supply conduit may be housed within the axial cavity and may further be configured to transport cryogen from a cryogen source to the distal portion of the cryoablation instrument. The axial cavity may additionally provide a reflux passage configured to transport cryogen gas away from the distal end of the cryoablation instrument. The chamber defined between the outer surface and the inner surface of the shaft wall may have a proximal opening that may be connected to a vacuum source. The proximal opening may establish vacuum communication between the chamber and the vacuum source. The chamber may further comprise a chamber fluid pressure therein, and the chamber fluid pressure may be regulated via the vacuum source.

[0007] Another aspect of the present invention relates to an insulating sheath suitable for use with a cryoablation tool. The sheath may include a shaft having a proximal end, a distal end, and a shaft wall. The shaft wall may extend between the proximal end and the distal end and further have an outer surface, an inner surface, and a gap defined between the outer surface and the inner surface to form a chamber. In some aspects, the shaft wall may be breathable. The shaft may also include a shaft cavity defined by the inner surface of the shaft wall. The shaft cavity may also be constructed to receive a cryoablation tool and may also be open at the proximal end and distal end. The chamber defined between the outer surface and the inner surface of the shaft wall may be sealed at the distal end and have a proximal opening that can be connected to a vacuum source. The proximal opening can be used to establish vacuum communication between the chamber and the vacuum source. The chamber may also have a chamber fluid pressure therein, and the chamber fluid pressure may be regulated via the vacuum source.

[0008] Another aspect of the present invention relates to an insulating conduit. The insulating conduit may include a tubular shaft having a proximal end, a distal end, and a shaft wall. The shaft wall may extend between the proximal end and the distal end and further have an outer surface, an inner surface, and a gap defined between the outer surface and the inner surface to form a chamber. In some aspects, the shaft wall may be breathable. The shaft may also include an axial cavity that is open at the proximal end and the distal end and defined by the inner surface of the shaft wall. The chamber defined between the outer surface and the inner surface of the shaft wall may have a proximal opening that can be connected to a vacuum source. The proximal opening can establish vacuum communication between the chamber and the vacuum source. The chamber may also have a chamber fluid pressure therein, and the chamber fluid pressure can be adjusted via the vacuum source.

[0009] Another aspect of the present invention relates to a cryoablation system. The system may include an endoscope, a vacuum source, a sheath, and a cryoablation tool. The endoscope may have a working channel. The cryoablation tool may be of any type disclosed herein. The cryoablation tool may extend from and retract into the sheath. The cryoablation tool and sheath may be inserted into the working channel. The cryoablation tool may have a shaft and chamber of any type disclosed herein. The shaft may be flexible enough to form a curve along the confines of the chamber, having a minimum radius of 20 mm. The vacuum source may be connected to the proximal opening of the chamber to actively regulate the fluid pressure in the chamber, including reducing the chamber fluid pressure.

[0010] Another aspect of the present invention relates to a cryoablation system having an endoscope, a vacuum source, an insulating sheath, and a cryoablation tool. The insulating sheath can be any type disclosed herein. The cryoablation tool can be inserted into the insulating sheath. The cryoablation tool can have a shaft and a cryogen supply conduit. The shaft can have a proximal end, a distal end, and a shaft wall. The shaft wall can extend between the proximal end and the distal end and can have an inner surface and an outer surface, and a shaft lumen defined by the inner surface of the shaft wall. The cryogen supply conduit can be housed in the shaft lumen and be configured to transport cryogen from the cryogen source to the distal portion of the cryoablation tool. The cryoablation tool can extend from and retract into the insulating sheath. The cryoablation tool and sheath can be inserted into a working channel. The shaft of the cryoablation tool can have sufficient flexibility to form a curve along the shaft, having a minimum radius of 20 mm. The vacuum source can be connected to the proximal opening of the chamber to actively regulate the chamber fluid pressure, including reducing the chamber fluid pressure.

[0011] The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is an exemplary schematic diagram of a cryoablation system including a cryoablation tool according to one non-limiting exemplary embodiment;

[0013] Figure 2 is an end view of an outer tubular member having an outer surface of a shaft wall according to one non-limiting exemplary embodiment;

[0014] Figure 3 yes Figure 1 Dimensional diagram of cryoablation tools;

[0015] Figure 3A is an exemplary schematic diagram of a system including an insulating jacket according to one non-limiting exemplary embodiment;

[0016] Figure 4 is an enlarged view of the proximal end of the shaft wall, along with components that may be part of a cryoablation system, an insulated sheath system, or an insulated catheter system; and

[0017] Figure 5 is a diagram showing details of a three-point bend test of components of an illustrative cryoablation tool. DETAILED DESCRIPTION

[0018] Figure 1A schematic diagram of an exemplary schematic diagram of a cryoablation system including a cryoablation tool 100 according to one embodiment is shown. According to some embodiments, the cryoablation tool 100 can include a catheter 102. In advantageous aspects, the catheter 102 can be inserted into a working channel of an endoscope, such as a bronchoscope 104, and can therefore be generally flexible. In some aspects, the cryoablation tool is used in conjunction with a sheath. The sheath can be disposed on the shaft of the tool. In some aspects, the outer surface of the shaft of the cryoablation tool can be thermally insulated from the inner surface of the shaft. In some aspects, the outer surface of the shaft of the sheath is thermally insulated from the inner surface. One approach to these aspects is to use Figure 3A In some aspects, the cryoablation tool 100 can be part of a cryoablation system that includes a vacuum source connectable to the cryoablation tool. In some aspects, the cryoablation tool 100 can be part of a cryoablation system that includes a sheath 160 and an endoscope, such as a bronchoscope 104, wherein the cryoablation tool is insertable into a working channel of the endoscope.

[0019] Continue to refer Figure 1 Catheter 102 may include a tubular shaft 200 having a shaft wall 106. Shaft wall 106 may extend between a proximal end 108 and a distal end 110. Shaft wall 106 may include an outer surface 112 forming the exterior of shaft wall 106 and an inner surface 114 forming the interior of shaft wall 106, defining a shaft lumen 150. In some aspects of the design, shaft wall 106 may include an inner shaft wall 201 and may include an outer shaft wall 202. Outer surface 112 may be the outer surface of outer shaft wall 202. Inner surface 114 may be the inner surface of inner shaft wall 201. Outer shaft wall 202 may have an outer shaft wall inner surface 203, and inner shaft wall 201 may have an inner shaft wall outer surface 204. A gap 206 between the outer shaft wall and the inner shaft wall forms chamber 180, which may be annular in shape. Chamber 180 may be bounded by outer shaft wall inner surface 203 and inner shaft wall outer surface 204.

[0020] In one embodiment, the inner shaft wall 201 can be formed by an inner tubular member. The outer shaft wall 202 can also be formed by an outer tubular member. The outer tubular member can be radially displaced from the inner tubular member. The outer tubular member can surround the inner tubular member. A gap 206 is defined between the outer tubular member and the inner tubular member. In this embodiment, the gap 206 forms the chamber 180.

[0021] The outer surface 112 and the inner surface 114 can each extend between the proximal end 108 and the distal end 110 of the cryoablation instrument 100. Similarly, the inner shaft wall 201 and the outer shaft wall 202 can each extend between the proximal end 108 and the distal end 110 of the cryoablation instrument 100. The distal end 110 of the shaft can terminate in a distal operating tip 116. The distal operating tip 116 can be surrounded by tissue and can cryoablate tissue in some cases. In some cases, the distal operating tip 116 can be advantageously configured to pierce tissue. For example, the distal operating tip 116 can include a sharp tip, such as a trocar tip. Alternatively, the distal operating tip 116 can be non-sharp.

[0022] In reference Figure 1 In certain optional aspects, portions of the shaft can be flexible. For example, in one aspect, the entire length of the shaft extending between the proximal end 108 and the distal end 110 can be flexible. For example, the shaft can be bent about its longitudinal axis 118, such as Figure 1 In some such embodiments, the shaft can have a shaft diameter that is configured such that the shaft can be sufficiently flexible to form a curve having a desired radius of curvature. Furthermore, in certain illustrative aspects, the entire length of the shaft can be equally flexible. In such embodiments, the curve radius of different portions of the shaft can be different.

[0023] In advantageous aspects, the material and dimensions of the shaft can be configured to provide sufficient flexibility to bend about its longitudinal axis 118. According to one aspect, the catheter shaft can comprise a polymer. For example, the inner shaft wall 201 can comprise a polymer. In one example, the polymer can comprise polyimide. In other aspects, the outer shaft wall 202 can also comprise a polymer. According to one embodiment, the outer shaft wall 202 can comprise polyimide. Additionally, the outer shaft wall 202 can comprise polytetrafluoroethylene ("PTFE"), and / or one or more polyether block amides (known under the trade name Known, hereinafter referred to as "Pebax").

[0024] exist Figure 2 In one such example shown, the outer shaft wall 202 can be formed from a generally cylindrical outer tubular member 210. In terms of the design of the outer shaft wall, the outer surface 112 can be formed on the outer layer of the outer shaft wall 202. The outer shaft wall 202 can be formed with the shaft wall 106 ( Figure 1) or it may be assembled from separate components. The outer shaft wall 202 may include one or more layers. Thus, the first layer 120 of the outer shaft wall 202 may include Pebax. The second layer 122 of the outer surface 112 may include PTFE and / or polyimide. The third layer 124 of the outer shaft wall 202 may include polyimide. The first layer 120 may be the outermost layer of the outer shaft wall. The second layer 122 may be positioned between the first layer 120 and the third layer 124. The third layer 124 may form the innermost layer of the outer shaft wall. The outer shaft wall 202 may include a hollow interior 126 defined by the third layer 124 of the outer shaft wall 202, and specifically by the outer shaft wall inner surface 203.

[0025] According to one example configuration, the shaft can have a shaft diameter of less than about 5 millimeters (hereinafter referred to as "mm"). Thus, the dimensions of the shaft wall can be configured to result in a shaft diameter of less than about 5 mm. In this example, the outer diameter 130 of the outer surface 112 (which can be formed by a tubular member) can be less than about 5 mm. In certain preferred embodiments, the outer diameter 130 of the outer surface 112 can be between about 1 mm and about 2 mm (e.g., about 1.75 mm). Continued reference Figure 2 , the inner diameter 132 of the outer shaft wall 202 can be between about 1 mm and about 1.8 mm (e.g., about 1.6 mm). The outer shaft wall 202 (comprising one or more layers) can have a radial thickness 134 radially defined between the inner surface 203 and the outer surface 112. In such an embodiment, the radial thickness 134 of the outer shaft wall 202 can be between about 0.01 mm and about 0.5 mm thick (e.g., about 0.07 mm).

[0026] Figure 3 Shown Figure 1 Dimensional drawing of the cryoablation tool 100. Figure 3 In the illustrative embodiment of the present invention, inner shaft wall 201 of shaft wall 106 can be formed from a generally cylindrical inner tubular member, which can be a polymer tube. The inner tubular member can be inserted into outer shaft wall 202, which can also be a generally cylindrical outer tubular member and can also be a polymer tube. In terms of design, inner surface 114 can be formed on the inner layer of the inner shaft wall, and outer surface 112 can be formed on the outer layer of the outer shaft wall. Inner shaft wall 201 and outer shaft wall 202 can be integrally formed with shaft wall 106 or they can be assembled together from separate components.

[0027] In an exemplary configuration, the inner shaft wall 201 can be substantially coaxial with the outer shaft wall 202. The inner shaft wall 201 can have an outer diameter 136, an inner diameter 138, and a radial thickness 140 defined in a radial direction between the outer diameter 136 and the inner diameter 138. The outer diameter 136 of the inner shaft wall can be smaller than the inner diameter 132 of the shaft wall 202 such that the inner shaft wall can be inserted or contained within the hollow interior of the outer shaft wall.

[0028] refer to Figure 3 In an illustrative embodiment, the outer diameter 136 of the inner polymer can be between about 0.5 mm and about 1.5 mm (e.g., 1.4 mm). The inner diameter 138 of the inner shaft wall 201 can be between about 0.5 mm and about 1.4 mm (e.g., about 1.3 mm). The radial thickness 140 of the inner shaft wall can be between about 0.01 mm and about 0.2 mm (e.g., about 0.1 mm).

[0029] In some optional embodiments, the shaft wall 106 may include at least one reinforcement layer for mechanical strength. Figure 2 , the reinforcement layer 142 can be present in particular in the outer shaft wall 202. In the outer shaft wall, the reinforcement layer can be inserted between the first layer 120 comprising Pebax and the second layer 122 comprising polyimide. In some examples, the reinforcement layer can comprise a metal (e.g., stainless steel). Furthermore, in an advantageous alternative embodiment, the reinforcement layer can comprise a braided structure, such as braided stainless steel.

[0030] The reinforcement layer can be located generally radially outward of the inner shaft wall 201, and therefore radially outward of the chamber 180, and in particular radially outward of the inner surface 203 of the outer shaft wall 202. The reinforcement layer can provide sufficient mechanical strength to withstand pressure, such as the pressure of the cryogen in the cryogen supply conduit 152 or the pressure in the cryogen return conduit 158, which acts as the shaft cavity pressure in the shaft cavity 150 defined by the inner surface 114. Figure 2 , the reinforcement layer may be substantially radially outside the second layer 122 and the third layer 124. Additionally, the reinforcement layer may be substantially radially inside the first layer 120.

[0031] The materials and dimensions of the shaft, such as those described above, can provide sufficient flexibility to be bendable about its longitudinal axis 118. For example, the shaft can be sufficiently flexible, particularly along the extent of the chamber 180, that the shaft can form a curve having a minimum radius of curvature of 20 mm measured between the center of curvature of the bent shaft and the longitudinal axis 118. The shaft can form a curve having a minimum radius of curvature of 10 mm or even 5 mm.

[0032] Return Reference Figure 1According to certain aspects of the present invention, the interior of the shaft includes a shaft lumen 150. The shaft lumen 150 can be defined by the inner surface 114 of the shaft wall. The shaft lumen 150 can receive a cryogen. For example, in one embodiment, a cryogen supply conduit 152 can be housed (e.g., annularly) within the shaft lumen 150. The cryogen supply conduit 152 can be configured to supply cryogen from a cryogen source to a distal portion (e.g., the distal end 110 or the distal operative tip 116) of the cryoablation instrument 100. In some illustrative examples, the cryogen supply conduit 152 can be a capillary tube. In alternative embodiments, the cryogen supply conduit 152 can be coaxial with the shaft. The shaft lumen 150 can provide a return passage 158 that is configured to transport refrigerant gas away from the distal end of the cryoablation instrument. The return passage 158 can be at least partially surrounded circumferentially by the inner shaft wall 201, and more particularly by the inner surface of the shaft 114. The return passage can extend coextensively with the shaft lumen 150.

[0033] In certain aspects further described below, the cryogen can pass through a cryogenic cooler 154 and reach a cryogenic temperature. At the cryogenic temperature, the cryogen can be suitable for cooling the surface of the distal portion of the shaft. For example, the cryogen can cool the outer surface 112 of the distal end 110 (and / or the distal operative tip 116) of the shaft and thereby remove heat from (e.g., and advantageously ablate) the tissue surrounding the distal end 110 (and / or the distal operative tip 116) of the shaft.

[0034] In one arrangement, the cryogen supply conduit can terminate distally in a Joule-Thomson ("JT") orifice 154. Thus, the cryogen 154 can be an open-loop cryogen cooler, such as a JT orifice 154. In embodiments, the cryogen can be a cooling fluid (e.g., nitrogen, air, argon, krypton, xenon, N2O, CO2, and CF4). In this case, the cryogen can be under pressure such that expansion through the JT orifice 154 can cause the cryogen to cool to a temperature for cryogenically ablating tissue surrounding the distal operative tip 116. In certain aspects, the pressure of the cryogen upstream of the JT orifice 154 can be between about 7 megapascals (hereinafter, "MPa") and about 15 MPa (e.g., about 12 MPa). Thus, in embodiments where the cryogen can be a cooling fluid, the temperature of the cryogen after expansion from the JT orifice 154 can be less than about 190 Kelvin.

[0035] Alternatively, the cryogen can be a heating fluid (e.g., helium, hydrogen). In this case, the cryogen can be under pressure so that expansion through the JT orifice 154 can cause the temperature of the cryogen to increase, thereby causing heating of the tissue surrounding the distal operative tip. Such an embodiment can be used to thaw frozen tissue.

[0036] Continue to refer Figure 1In an embodiment where the cryocooler 154 can be a JT orifice 154, the distal end of the shaft can further include a distal expansion chamber 156 that can be in fluid communication with the return path. The cryogen supply conduit can terminate in the JT orifice, which opens into the expansion chamber. When the cryogen leaves the cryogen supply conduit 152 via the JT orifice 154, the cryogen may undergo JT expansion and expand into the distal expansion chamber 156. The distal expansion chamber 156 can be disposed within the flexible portion of the shaft, and can particularly be disposed within the active region 172 of the shaft, and particularly within the metal portion thereof, as this improves heat exchange with the tissue, as further explained elsewhere herein.

[0037] refer to Figure 1 , the refrigerant return conduit 158 ​​transports the refrigerant away from the distal portion of the shaft. As shown, in some embodiments, the refrigerant return conduit 158 ​​can be in fluid communication with the expansion chamber. Therefore, after expansion in the distal expansion chamber 156, the refrigerant can flow through the refrigerant return conduit 158. In the illustrated embodiment, the refrigerant return conduit 158 ​​can be formed by the inner surface 114 of the shaft wall 106 and can therefore extend coextensively with the shaft cavity 150 defined by the inner wall 114. Alternatively, the refrigerant return conduit 158 ​​can be a separate physical conduit. In an exemplary aspect, the refrigerant return conduit 158 ​​can be coaxial with the refrigerant supply conduit 152. Additionally, in an advantageous aspect, the refrigerant return conduit 158 ​​can be annularly surrounding the refrigerant supply conduit 152, thereby facilitating the use of the refrigerant expanded in the refrigerant return conduit 158 ​​to pre-cool (e.g., when the refrigerant can be a cooling fluid) or pre-heat (e.g., when the refrigerant can be a heating fluid) the refrigerant in the refrigerant supply conduit 152.

[0038] Return Reference Figure 1 , the cryoablation tool 100 may include a sheath 160 that may be disposed on the shaft. In some embodiments, the sheath 160 may surround the shaft wall 106. For example, the sheath 160 may be disposed approximately coaxially with the shaft and may annularly surround the shaft. In advantageous aspects, the sheath 160 and the shaft wall 106 may be displaceable relative to each other. For example, the sheath 160 and the shaft wall 106 may be disposed as shown in FIG. Figure 1160 (parallel to the longitudinal axis 118). In one example, the distal portion of the shaft may extend beyond the sheath 160 and may be retracted into the sheath 160. The displacement of the sheath 160 relative to the shaft can be controlled from the proximal end 108 of the cryoablation instrument 100. The sheath 160 can advantageously accommodate and surround the distal (e.g., sharp) operating tip of the cryoablation instrument 100. For example, such an embodiment may be advantageous when the cryoablation instrument 100 includes a sharp tip and when the cryoablation instrument 100 can be inserted into an endoscope, such as a working channel of a bronchoscope 104. In this case, the sheath 160 can protect the distal (e.g., sharp) operating tip from protruding from the sheath 160 and accidentally damaging the working channel. In addition, advantageously, the sheath 160 can protect the outer surface 112 of the shaft from mechanical damage (e.g., wear) when inserted into the working channel of the bronchoscope 104.

[0039] The material of the sheath 160 can be configured to provide a desired degree of flexibility and other mechanical properties. According to one aspect, the catheter 160 can comprise a polymer. In one embodiment, the polymer can comprise Pebax to achieve sufficient flexibility and kink resistance. The polymer can also comprise PTFE, which can facilitate engagement of the sheath 160 with respect to the catheter 102. Additional polymer additives can be added to the material of the sheath 160 to reduce friction on the outer surface 112 of the sheath 160. Furthermore, the sheath 160 can optionally be constructed as a layered arrangement of one or more polymers.

[0040] The dimensions of the sheath 160 can be configured to provide the desired degree of flexibility and other mechanical properties. In an example configuration, reference Figure 3 The sheath 160 can be large enough to receive the catheter 102 therein and also have sufficient flexibility and kink resistance. The sheath 160 can have an outer diameter 162 between about 1 mm and about 3 mm (e.g., about 2 mm) and an inner diameter 164 between about 1 mm and about 2 mm (e.g., about 1.8 mm).

[0041] Reference again Figure 1 and Figure 3, the shaft may include a thermally insulating region 170. When a vacuum is actively drawn in the chamber 180, at least a portion of the chamber forms a thermally insulating region that provides thermal insulation around the shaft lumen. Within the thermally insulating region 170, the surface of the shaft 112 is thermally insulated from the refrigerant in the return conduit 158. The thermally insulating region may be coextensive with the chamber 180. In the example shown, the thermally insulating region 170 extends a majority of the length of the shaft. The thermally insulating region 170 may thermally insulate the shaft from the sheath 160 and / or the working channel of the bronchoscope 104. Such an embodiment may be advantageous in thermally insulating portions of the shaft outside of a desired area from areas external to the shaft. For example, the thermally insulating region may thermally insulate portions of the shaft from portions of a patient outside of a target site where a cryoablation procedure may be performed.

[0042] According to one aspect, the thermally insulating region 170 can extend over a majority of the length of the shaft. Figure 3 In some embodiments, for example, the thermal insulation region 170 extends substantially between the proximal end 108 and the distal end 110, except for an active region 172 proximate the distal end 110. The thermal insulation region 170 can extend circumferentially at least partially around the outer diameter of the shaft's inner surface 114. In certain advantageous aspects, the thermal insulation region 170 can provide thermal insulation to the shaft's outer surface 112 completely around the diameter of the shaft.

[0043] As previously mentioned, the material and size of the shaft can be selected to provide the desired flexibility. Therefore, in such an embodiment, the material of the shaft wall can be breathable. For example, the inner surface 114 of the shaft wall, the outer surface 112 of the shaft wall or both can be breathable. Inner shaft wall 201, outer shaft wall 202 or two shaft walls can be breathable. Surface and shaft wall can be breathable, particularly when the fluid pressure in chamber 180 is lower than atmospheric pressure, such as when, for example, at 0.1 Torr, partial vacuum is applied. In a kind of arrangement, shaft wall 106 (for example, such as the features of inner shaft wall, outer shaft wall, outer surface and inner surface) is configured so that when the chamber fluid pressure is reduced to 0.1 Torr, due to the fact that gas penetrates through the breathable shaft wall when not continuing to evacuate, the chamber fluid pressure will be increased to 0.9 Torr in 30 minutes.

[0044] In the embodiment of the present invention, the inner surface 114 of the shaft wall can allow the expansion refrigerant from the cryogen return conduit 158 ​​to flow through the inner surface 114 and enter the annular space between the inner surface 114 and the outer surface 112 of the shaft wall. The entry of the expansion refrigerant can reduce the thermal insulation between the inner surface 114 and the outer surface 112, thereby causing the refrigerant in the cryogen return conduit 158 ​​of the shaft cavity 150 and the part of the outer surface 112 of the shaft wall and the outer area around the outer surface 112 of the shaft wall to transfer unintentionally. The chamber fluid pressure under vacuum pressure can cause the refrigerant gas transported in the shaft cavity 158 to penetrate into the chamber through the shaft wall 106. The penetration of the refrigerant by the inner shaft wall 201 may be at least partially due to the shaft cavity fluid pressure being greater than the fluid pressure of chamber 180. Therefore, the chamber fluid pressure will increase, unless the chamber fluid pressure is regulated via a vacuum source.

[0045] Optionally, the outer surface 112 of the shaft wall and / or the outer shaft wall itself can also be gas permeable and can allow gas from the air surrounding the shaft, such as nitrogen or oxygen, to flow through the outer surface 112 and / or outer wall and into the chamber 180, particularly if the fluid pressure in the chamber is less than the pressure of the air surrounding the shaft.

[0046] Gas permeating through inner surface 114 and / or outer surface 112 and the inner and outer shaft walls may reduce the thermal insulation capabilities of the shaft walls and, if an active vacuum is not maintained, may reduce the vacuum conditions within the chamber. Thus, the illustrative embodiments may establish an active vacuum between inner and outer surfaces 114, 112 of the shaft walls or between the inner and outer shaft walls, for example, within chamber 180.

[0047] Figure 4 An enlarged view of the shaft wall is shown. Figure 3 and Figure 4 , thermally insulating region 170 can be formed by (e.g., insulated by) chamber 180 located between outer surface 112 and inner surface 114. The pressure within chamber 180, sometimes referred to as chamber fluid pressure, can be adjustable. For example, the chamber fluid pressure of chamber 180 can be maintained under vacuum to provide thermally insulating region 170. Continuing with reference to Figure 4 In certain illustrative aspects, chamber 180 can be defined between an inner shaft outer surface 203 of the shaft (e.g., the radially outermost layer of the inner tubular member) and an inner surface 204 of outer shaft 202 (e.g., the radially innermost layer of outer tubular member 112). Inner shaft 201 and outer shaft 202 can be radially spaced apart from each other such that an annular gap 206 exists therebetween and forms chamber 180. If a vacuum is applied to the chamber (as will be described further below), chamber 180 can provide thermal insulation between inner surface 114 and outer surface 112 of the shaft, such that inner surface 114 is thermally isolated from outer surface 112 and outer surface 112 is thermally isolated from inner surface 114.

[0048] According to various aspects, the chamber 180 can extend at least partially circumferentially around the shaft cavity 150. For example, in one embodiment, the chamber can extend completely circumferentially around the shaft cavity 150. Figure 4 As shown, the chamber 180 may extend annularly around the shaft cavity 150 and may be coaxial therewith in the thermally insulating region 170 of the shaft.

[0049] The cryoablation tool 100 can be proximally configured to establish vacuum communication between the chamber 180 and the vacuum source 182. Figure 4 In one embodiment shown, the cryoablation instrument 100 can be configured to be connected to a vacuum source 182 on the proximal side. For example, the chamber 180 can have a proximal opening 184 that can be connected to the vacuum source 182. The opening 184 is the only opening to the chamber 180. The chamber is closed distally. In one aspect, the vacuum source 182 can be a vacuum pump 182. The vacuum pump 182 can be operably connected to the chamber 180 (e.g., via the proximal opening 184) and can extract the gas in the chamber 180. Except for the proximal opening 184, the chamber 180 can be sealed. If the chamber is sealed except for the proximal opening 184, the extraction of gas by the vacuum source may cause the chamber fluid pressure to drop to a value below atmospheric pressure, thereby resulting in a partial vacuum. According to illustrative aspects, a partial vacuum can be actively maintained in the chamber 180. The vacuum pump 182 can continue to actively extract gas from the chamber 180, thereby maintaining the pressure in the chamber 180 to a value below atmospheric pressure.

[0050] Chamber 180 can have a radial thickness 190 between about 0.01mm and about 0.1mm (e.g., 0.05mm). According to one embodiment, vacuum source 182 can maintain a chamber fluid pressure of about 0.05 torr (about 6.6 Pascals). In an advantageous aspect, under such deep vacuum pressure, due to the relatively high pressure of the cryogen in cryogen supply conduit 152, the deep vacuum in chamber 180, one or more of the permeability of inner surface 114, outer surface 112 and outer shaft, fluid can migrate through inner surface 114 and / or outer surface 112 and through outer shaft and / or inner shaft into chamber 180. The permeability of inner surface 114, inner shaft 201, outer surface 112 and outer shaft can be the result of the materials and dimensions of these features. As described herein, in an advantageous aspect of shaft wall 106, shaft wall 106 has sufficient flexibility to bend around its longitudinal axis 118 in a manner as described herein. The materials (e.g., polymers described elsewhere herein) and dimensions (millimeter thickness described elsewhere herein) of the inner shaft 201 and outer shaft 202 can be selected, in part, to provide the shaft wall 106 with this degree of flexibility. As a result, due to one or more of the relatively high pressure of the cryogen in the cryogen supply conduit 152, the deep vacuum in the chamber 180, the permeability of the inner shaft 201 and the inner surface 114, and the permeability of the outer shaft 202 and the outer surface 112, fluid (e.g., due to the axial cavity pressure of the expanding cryogen in the cryogen return conduit 158) may migrate into the chamber 180. The vacuum source 182 actively operates to draw this migrated fluid out of the chamber 180 and actively maintains the chamber fluid pressure at the vacuum pressure, as described elsewhere herein.

[0051] Continue to refer Figure 4 , if a vacuum is to be actively maintained in chamber 180, the shaft may include a structure for increasing mechanical strength. In one embodiment, the shaft may include one or more support elements 192. In an advantageous aspect, the support element 192 may be maintained in an annular spacing between the inner shaft wall 201 (which may be an inner tubular member) and the outer shaft wall 202 (which may be an outer tubular member). The support element 192 may be disposed within the chamber. Advantageously, it may not occupy the entire volume of chamber 180 and may partially occupy the available space in chamber 180, which may be annular. If gas is evacuated from chamber 180, such an embodiment may be configured to facilitate preventing collapse of chamber 180.

[0052] According to one aspect, support element 192 may include support filaments 192. Support filaments 192 may include a polymer. In one embodiment, the polymer may include polyetheretherketone ("PEEK"). Support filaments 192 may be formed by winding a filament, such as a polymer filament (e.g., PEEK), 192 in a series of turns around the inner shaft wall, more specifically around the outer surface 204 of inner shaft wall 20. According to some embodiments, filaments 192 may have a diameter between approximately 0.01 mm and approximately 0.1 mm (e.g., approximately 0.05 mm). Winding support filaments 192 may advantageously maintain a coaxial arrangement between inner shaft wall 201 and outer shaft wall. Fibers 192 may advantageously prevent direct contact between inner surface 203 of outer shaft wall 202 (e.g., outer tubular member) and outer surface 204 of inner shaft wall (e.g., inner tubular member), counteracting forces caused by vacuum pressure and thereby increasing the mechanical strength of catheter 102.

[0053] In an advantageous embodiment, the return Figure 1 , the distal end 110 of the catheter shaft can include an active region 172 over which the expanded refrigerant can exchange heat with an area external to the shaft (e.g., tissue). Thus, the active region 172 can be non-thermally insulating. The thermally insulating region 170 can extend over a majority of the length of the catheter shaft excluding the active region 172. The active region 172 can include a metal portion disposed distal to the thermally insulating region 170. The active region 172 can facilitate heat exchange between the expanded refrigerant flowing in the refrigerant return conduit 158 ​​and an area external to the shaft (e.g., tissue).

[0054] According to certain aspects of the present invention, the active region 172 can also be substantially flexible. The active region 172 can have substantially the same degree of flexibility as the thermally insulating region 170. The active region 172 can include one or more bellows, grooves, etc., and can provide a satisfactory degree of bendability without kinking within the metal region. Thus, the shaft can include a flexible metal region disposed at the distal end 110 of the shaft 200. The flexible metal region can terminate in a distal top operative tip 116, which can be configured to penetrate tissue.

[0055] Return Reference Figure 1 and Figure 3According to certain embodiments, the catheter 102 can include a heat exchange coil 194 that is wound at least distally above the cryogen supply conduit 152. The heat exchange coil 194 can enhance the circulation and / or residence time of the cryogen (e.g., during expansion) and can additionally help maintain a coaxial arrangement between the cryogen supply conduit 152 and the active metal region. In one embodiment, the heat exchange coil 194 can be formed by a metal (e.g., tinned copper) wire wound around the distal end 110 of the cryogen supply conduit 152 (e.g., a capillary tube). The heat exchange coil 194 can have a desired pitch (e.g., between about 1 mm and about 10 mm, e.g., about 4 mm).

[0056] In another embodiment, the axial wall of the thermally insulating region of the cryoablation instrument can be used as the axial wall of the insulating sheath, or can also be used as the axial wall of the insulating catheter. The insulating sheath can be used with the cryoablation instrument as further described herein.

[0057] Cryoablation tools may lack thermal insulation areas but may still be used in conjunction with endoscopes, such as bronchoscopes or similar devices. In one embodiment, the cryoablation tool may be used in conjunction with an insulating sheath to provide protection for the working channel of the endoscope from the cryogenic temperatures that may be found in the cryoablation tool. The sheath may also provide protection for tissue that is not intended to be ablated.

[0058] refer to Figure 3A , the sheath (or catheter) has a shaft wall 106 that is generally tubular and has a proximal end 108 and a distal end 230. The shaft is provided with the same features as the shafts of the cryoablation instruments described elsewhere herein.

[0059] The shaft wall 106 extends between the proximal end and the distal end. The shaft wall has an outer surface 112 and an inner surface 114. A gap 206 can be defined between the outer surface of the shaft 112 and the inner surface of the shaft 114. The gap 206 can define a chamber 180 between the two surfaces. The chamber can be sealed at the distal end 230, such as by a closure 231.

[0060] The shaft can include an inner shaft wall 201 and can also include an outer shaft wall 202. The outer surface of the outer shaft wall 202 can provide the shaft's outer surface 112. The inner surface of the inner shaft wall 201 can provide the shaft's inner surface 114. A chamber 180 can be defined between the outer shaft wall 202 and the inner shaft wall 201. More specifically, the chamber 180 can be defined between an outer shaft wall inner surface 203 and an inner shaft wall outer surface 204.

[0061] The components, construction, materials, and permeability properties of the shaft wall are the same as those of the cryoablation tools described elsewhere herein.

[0062] The sheath or catheter has a lumen 232 defined by the inner surface of the shaft wall 114, the lumen of the sheath being configured to receive the cryoablation tool 300. The lumen of the sheath or catheter can be open at the distal end 230 and can be open at the proximal end. Figure 4 Similarly, the chamber defined between the inner surface 114 and the outer surface 112 of the shaft can have a proximal opening 184 connectable to a vacuum source 182, the proximal opening 184 being configured to establish vacuum communication between the chamber 180 and the vacuum source, with the chamber having a chamber fluid pressure therein. The connection of the chamber 180 to the vacuum source 182 allows the chamber fluid pressure to be regulated by the vacuum source, similar to the manner discussed elsewhere herein with respect to cryoablation tools.

[0063] Continue to refer Figure 3A , the cryoablation tool 300 has a shaft 340 having a proximal end 108 and a distal end 110. A shaft wall 341 extends between the proximal end 108 and the distal end 110. The shaft wall has an inner surface 342 and an outer surface 343. The shaft wall is generally polymeric in nature and, in some embodiments, can be constructed from a series of layers in a manner similar to that described elsewhere herein and in reference to Figure 2 The outer shaft wall of the described cryoablation instrument is identical. In particular, the shaft wall may include a reinforcement layer 142, which may include a braided layer, particularly a stainless steel braid as described elsewhere herein. The instrument may have an axial cavity 158 defined by the inner surface 342 of the shaft wall. A cryogen supply conduit 152 may be housed in the axial cavity, which is configured to transport cryogen from a cryogen source to the distal portion 110 of the cryoablation instrument. The instrument may be provided with a cryogen return passage for evacuating cryogen, which, for the devices discussed elsewhere herein, is typically evacuated proximally or may be recirculated. A reflux passage may be provided by the axial cavity, which may be configured to transport cryogen gas away from the distal end of the cryoablation instrument.

[0064] The distal end 110 of the cryoablation tool can terminate in a distal operating tip 116. The distal operating tip 116 can advantageously be configured to pierce tissue. For example, the distal operating tip 116 can include a sharp tip, such as a trocar tip. Alternatively, the distal operating tip 116 can be non-sharp.

[0065] In one arrangement, the cryogen supply conduit can terminate distally in a Joule-Thomson ("JT") orifice 154. The distal end of the shaft can also include a distal expansion chamber 156, which can be in fluid communication with the return path. The cryogen supply conduit can terminate in the JT orifice, which opens into the expansion chamber. Illustrative Examples

[0066] Figure 5The flexibility of various components of the catheter 102 according to one embodiment is shown. The flexibility of the components can be quantified by a three-point bend test. The tested components are supported between two points separated by a distance of about 25 mm. Figure 5 The force (in pounds) required to deflect the component under test by approximately 3 mm is plotted in FIG.

[0067] Continue to refer Figure 5 In one embodiment, the outer shaft wall 202 is configured to have an inner diameter 132 of approximately 1.6 mm, an outer diameter 130 of approximately 1.75 mm, and The outer shaft wall 202 of this embodiment can have a bend radius of about 12.7 mm and a burst pressure of about 27 MPa.

[0068] refer to Figure 5 In another embodiment, the inner shaft wall 201 is configured to have an inner diameter 138 of approximately 1.32 mm, an outer diameter 136 of approximately 1.45 mm, and comprises polyimide. The force required to deflect the inner shaft wall 201 by 3 mm is approximately 0.14 pounds (approximately 0.6228 Newtons).

[0069] Reference again Figure 5 In another embodiment, the sheath 160 is configured to have an inner diameter 164 of 1.8 mm and an outer diameter 162 of approximately 2 mm. The sheath 160 includes multiple layers, wherein the first layer 120 of the sheath 160 includes PTFE, the second layer 122 of the sheath 160 includes stainless steel, and the third layer 124 of the sheath 160 includes Pebax The bend radius of the sheath 160 is about 12.7 mm. The force required to deflect the sheath 160 by about 3 mm is about 0.3 pounds (about 1.334 N).

[0070] In another embodiment, the cryogen supply conduit 152 comprises a nitinol capillary tube having an outer diameter of approximately 0.57 mm. According to this embodiment, the force required to deflect the capillary tube by 3 mm is approximately 0.38 pounds (approximately 1.69 Newtons). The combined force required to deflect the sheath 160, outer surface 112, inner surface 114, and capillary tube by approximately 3 mm can be approximately 0.954 pounds (approximately 4.244 Newtons).

[0071] Another embodiment provides an insulating sheath. The insulating sheath may be used with a cryoablation tool as further described herein, or it may be suitable for use as an insulating catheter.

[0072] Cryoablation tools may lack thermal insulation areas but may still be used in conjunction with endoscopes, such as bronchoscopes or similar devices. In one embodiment, the cryoablation tool may be used in conjunction with an insulating sheath to provide protection for the working channel of the endoscope from the cryogenic temperatures that may be found in the cryoablation tool. The sheath may also provide protection for tissue that is not intended to be ablated.

[0073] refer to Figure 3A , the sheath or catheter has a shaft wall 106 that is generally tubular and has a proximal end 108 and a distal end 230. The shaft is provided with the same features as the shafts of the cryoablation tools described elsewhere herein.

[0074] The shaft wall 106 extends between the proximal end and the distal end. The shaft wall 106 has an outer surface 112 and an inner surface 114. A gap 206 can be defined between the outer surface of the shaft 112 and the inner surface of the shaft 114. The gap 206 can define a chamber 180 between the two surfaces. The chamber can be sealed at the distal end 230, such as by a closure 231.

[0075] The shaft can include an inner shaft wall 201 and can also include an outer shaft wall 202. The outer surface of the outer shaft wall 202 can provide the shaft's outer surface 112. The inner surface of the inner shaft wall 201 can provide the shaft's inner surface 114. A chamber 180 can be defined between the outer shaft wall 202 and the inner shaft wall 201. More specifically, the chamber 180 can be defined between an outer shaft wall inner surface 203 and an inner shaft wall outer surface 204.

[0076] The components, construction, materials, and gas permeability properties of the shaft wall are the same as those of the cryoablation tool described in detail elsewhere herein.

[0077] The sheath or catheter has a lumen 232 defined by the inner surface of the shaft wall 114, the lumen of the sheath being configured to receive the cryoablation tool 300. The lumen of the sheath or catheter can be open at the distal end 230 and can be open at the proximal end. Figure 4 Similarly, the chamber defined between the inner surface 114 and the outer surface 112 of the shaft can have a proximal opening 184 connectable to a vacuum source 182, the proximal opening 184 being configured to establish vacuum communication between the chamber 180 and the vacuum source, with the chamber having a chamber fluid pressure therein. The connection of the chamber 180 to the vacuum source 182 allows the chamber fluid pressure to be regulated by the vacuum source, similar to the manner discussed elsewhere herein with respect to cryoablation tools.

[0078] Continue to refer Figure 3A, the cryoablation tool 300 has a shaft 340 having a proximal end 108 and a distal end 110. A shaft wall 341 extends between the proximal end 108 and the distal end 110. The shaft wall has an inner surface 342 and an outer surface 343. The shaft wall is generally polymeric in nature and, in some embodiments, can be constructed from a series of layers in a manner similar to that described elsewhere herein and in reference to Figure 2 The outer shaft wall of the described cryoablation instrument is identical. In particular, the shaft wall may include a reinforcement layer 142, which may include a braided layer, particularly a stainless steel braid as described elsewhere herein. The instrument may have an axial cavity 158 defined by the inner surface 342 of the shaft wall. A cryogen supply conduit 152 may be housed in the axial cavity, which is configured to transport cryogen from a cryogen source to the distal portion 110 of the cryoablation instrument. The instrument may be provided with a cryogen return passage for evacuating cryogen, which, for the devices discussed elsewhere herein, is typically evacuated proximally or may be recirculated. A reflux passage may be provided by the axial cavity, which may be configured to transport cryogen gas away from the distal end of the cryoablation instrument.

[0079] The distal end 110 of the cryoablation tool can terminate in a distal operating tip 116. The distal operating tip 116 can advantageously be configured to pierce tissue. For example, the distal operating tip 116 can include a sharp tip, such as a trocar tip. Alternatively, the distal operating tip 116 can be non-sharp.

[0080] In one arrangement, the cryogen supply conduit can terminate distally in a Joule-Thomson ("JT") orifice 154. The distal end of the shaft can also include a distal expansion chamber 156, which can be in fluid communication with the return path. The cryogen supply conduit can terminate in the JT orifice, which opens into the expansion chamber.

Claims

1. A catheter comprising: A shaft having: proximal, remote, a shaft wall extending between the proximal end and the distal end, the shaft wall having an outer surface and an inner surface, and a gap defining a chamber between the outer surface and the inner surface, the shaft wall being gas permeable, a shaft lumen open at the proximal and distal ends and defined by the inner surface of the shaft wall; the chamber being sealed at the distal end and having a proximal opening connectable to a vacuum source, the proximal opening establishing vacuum communication between the chamber and the vacuum source, the chamber having a chamber fluid pressure therein, the chamber fluid pressure being adjustable via the vacuum source; and The air-permeable shaft wall is configured such that when the shaft cavity fluid pressure is greater than the chamber fluid pressure, the refrigerant transported in the shaft cavity penetrates into the chamber through the inner surface of the shaft wall.

2. The catheter of claim 1, further comprising a cryogen supply conduit housed within the shaft lumen, the cryogen supply conduit being configured to deliver the cryogen from a cryogen source to a distal portion of the cryoablation tool.

3. The catheter according to claim 2, wherein The shaft lumen provides a return flow passage configured to transport the cryogen away from the distal end of the cryoablation tool.

4. The catheter of claim 1 or any preceding claim, wherein: The shaft wall includes an inner shaft wall and an outer shaft wall, wherein the inner surface is an inner surface of the inner shaft wall and the outer surface is an outer surface of the outer shaft wall, and wherein a gap defined between the outer shaft wall and the inner shaft wall forms the chamber.

5. The catheter of claim 1 or any preceding claim, comprising one or more support elements configured to prevent the chamber from collapsing when gas is withdrawn from the chamber.

6. The catheter of claim 1 or any preceding claim, wherein: The outer surface of the shaft wall has an outer diameter of less than 5 mm.

7. The catheter of claim 1 or any preceding claim, wherein: The shaft is flexible enough to form a curve along the extent of the chamber, having a minimum radius of 20 mm.

8. The catheter of claim 1 or any preceding claim, wherein When a vacuum is actively drawn in the chamber, at least a portion of the chamber forms a thermally insulating region that provides thermal insulation around the shaft cavity.

9. The catheter of claim 1 or any preceding claim, wherein: The shaft wall is permeable to gas, and penetrates into the chamber through the inner surface of the shaft wall, causing the chamber fluid pressure to increase toward the shaft lumen fluid pressure over time unless the chamber fluid pressure is regulated via the vacuum source.

10. The catheter of claim 1 or any preceding claim, wherein When the shaft cavity fluid pressure is greater than the chamber fluid pressure, refrigerant transported in the shaft cavity permeates through the inner surface of the shaft wall into the chamber, causing the chamber fluid pressure to increase toward the shaft cavity fluid pressure over time unless the chamber fluid pressure is regulated via the vacuum source.

11. A cryoablation system, comprising: an endoscope having a working channel; Vacuum source; as well as A cryoablation tool insertable into the working channel, the cryoablation tool comprising: A shaft having: proximal, remote, a shaft wall extending between the proximal end and the distal end, the shaft wall having an outer surface and an inner surface, and defining a gap forming a chamber between the outer surface and the inner surface, the shaft wall being gas permeable, and A shaft cavity defined by the inner surface of the shaft wall, wherein The chamber has a proximal opening connectable to the vacuum source, the proximal opening establishing vacuum communication between the chamber and the vacuum source, and the chamber having a chamber fluid pressure therein, the chamber fluid pressure being adjustable via the vacuum source; and The air-permeable shaft wall is configured such that when the shaft cavity fluid pressure is greater than the chamber fluid pressure, the refrigerant transported in the shaft cavity penetrates into the chamber through the inner surface of the shaft wall.

12. The cryoablation system of claim 11, further comprising a cryogen supply conduit housed within the shaft lumen, the cryogen supply conduit being configured to deliver the cryogen from a cryogen source to the distal portion of the cryoablation tool.

13. The cryoablation system according to claim 11 or 12, wherein: The shaft wall includes an inner shaft wall and an outer shaft wall, wherein the inner surface is an inner surface of the inner shaft wall and the outer surface is an outer surface of the outer shaft wall, and wherein a gap defined between the outer shaft wall and the inner shaft wall forms the chamber.

14. The cryoablation system according to any one of claims 11 to 13, wherein: The outer surface of the shaft wall has an outer diameter of less than 5 mm.

15. The cryoablation system according to any one of claims 11 to 14, wherein: When a vacuum is actively drawn in the chamber, at least a portion of the chamber forms a thermally insulating region that provides thermal insulation around the shaft cavity.

16. The cryoablation system of any one of claims 11 to 15, further comprising a sheath disposed on the shaft, the sheath and the shaft being displaceable relative to each other such that the distal end of the shaft is extendable beyond and retractable into the sheath.

17. The cryoablation system according to any one of claims 11 to 16, wherein: When the shaft cavity fluid pressure is greater than the chamber fluid pressure, refrigerant transported in the shaft cavity permeates through the inner surface of the shaft wall into the chamber, causing the chamber fluid pressure to increase toward the shaft cavity fluid pressure over time unless the chamber fluid pressure is regulated via the vacuum source.

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