Cryoablation catheter

Abstract

This cryoablation catheter (100) has: a supply lumen (31) through which a fluid can pass from a proximal side toward a distal side; a balloon (40) to which the fluid that has passed through the supply lumen (31) is supplied; a discharge flow path (21) through which the fluid that has passed through the inside (401) of the balloon (40) can pass from the distal side toward the proximal side; and a film-like object (70) disposed at least at one of the following positions: between the outer surface (403) and the inner surface (402) of the balloon (40), on the outer surface (403), and on the inner surface (402). The film-like object (70) has a higher thermal conductivity than that of the balloon (40).

Description

Cryoablation Catheter

[0001] The present invention relates to a cryoablation catheter.

[0002] Cryoablation is a medical technique that involves contacting a cryogenic device with the target tissue to freeze and kill the cells that make up the tissue, and is used to treat cardiac muscle tissue and tumor tissue. Methods for cryostating the device include using liquid nitrogen and using the Joule-Thomson effect with high-pressure gas.

[0003] Patent Document 1 describes a cryosurgery catheter having a catheter body with a proximal end, a distal end, and a main lumen extending therethrough. A balloon containing a cryogenic fluid supplied through the main lumen is mounted on an orifice of the catheter body constituting the cryosurgery catheter. The balloon is inflated by supplying the cryogenic fluid through the catheter body, thereby cooling the affected area. More specifically, the document discloses a configuration in which the cryogenic fluid transported from the proximal side to the distal side by a cryogenic supply tube is supplied into the balloon through a port formed in a diffuser, and the cryogenic fluid is then discharged through an outlet lumen.

[0004] Patent Document 2 describes a cryotherapy catheter having a cooling fluid supply lumen, an exhaust lumen, a first balloon, a second balloon, and a barrier disposed between the first and second balloons, and describes that a radiopaque marker having a stent-like shape is disposed on or within the barrier.

[0005] JP 2001-524345 A U.S. Pat. No. 6,648,879

[0006] In the cryosurgery catheter described in Patent Document 1, a fluid is conveyed through a main lumen to a balloon and then injected from the main lumen into the balloon to cool the target tissue. However, since the fluid has difficulty reaching locations far from the injection holes, the cooling efficiency is poor, making it difficult to uniformly cool the target tissue in both the circumferential and longitudinal directions of the balloon.

[0007] In the cryotherapy catheter described in Patent Document 2, a fluid is conveyed to the balloon through a cooling fluid supply lumen and then injected from the cooling fluid supply lumen into the balloon, thereby cooling the target tissue. However, since the fluid has difficulty reaching positions away from the injection holes and a barrier exists between the first and second balloons, the cooling efficiency is poor, making it difficult to uniformly cool the target tissue in the circumferential and longitudinal directions of the balloon.

[0008] The present invention has been made in consideration of the above circumstances, and its object is to provide a cryoablation catheter that can easily cool target tissue uniformly in the circumferential direction and longitudinal direction of the balloon.

[0009] A cryoablation catheter according to one embodiment of the present invention is as follows: [1] A cryoablation catheter having a longitudinal direction and a radial direction, comprising: a supply lumen extending in the longitudinal direction and allowing a fluid to pass from a proximal side to a distal side, a balloon to which the fluid that has passed through the supply lumen is supplied, a discharge flow path located in a region different from the supply lumen in the radial direction, extending in the longitudinal direction, and allowing the fluid that has passed through the inside of the balloon to pass from a distal side to a proximal side, and a membrane-like material disposed at least one of between an outer surface and an inner surface of the balloon, on the outer surface, and on the inner surface, wherein the membrane-like material has a higher thermal conductivity than the balloon.

[0010] By disposing a film-like material with a higher thermal conductivity than the balloon between the outer and inner surfaces of the balloon, on the outer surface, or on the inner surface, or both, heat can be easily transferred in the circumferential and longitudinal directions of the balloon via the film-like material, which makes it easier to uniformly cool the target tissue in the circumferential and longitudinal directions of the balloon.

[0011] A cryoablation catheter according to an embodiment of the present invention is preferably any one of the following [2] to

[10] . [2] The cryoablation catheter according to [1], wherein the balloon includes an outer balloon and an inner balloon disposed inside the outer balloon and supplied with fluid that has passed through the supply lumen, and wherein the film-like material is disposed between the outer balloon and the inner balloon. [3] The cryoablation catheter according to [2], wherein the film-like material abuts against at least one of the outer balloon and the inner balloon. [4] The cryoablation catheter according to [2], wherein the film-like material abuts against the outer balloon and the inner balloon. [5] The cryoablation catheter according to any one of [2] to [4], wherein the thickness of the film-like material is thinner than the thickness of the outer balloon and thinner than the thickness of the inner balloon. [6] The cryoablation catheter according to any one of [1] to [5], wherein the film-like material is present throughout the entire circumferential direction of the balloon in a cross section perpendicular to the longitudinal direction. [7] The cryoablation catheter according to any one of [1] to [6], wherein the balloon has a straight tube portion, a distal tapered portion located distal to the straight tube portion and having an outer diameter that decreases distally, and a proximal tapered portion located proximal to the straight tube portion and having an outer diameter that decreases proximally, and the film-like material is disposed on the straight tube portion. [8] The cryoablation catheter according to any one of [1] to [7], wherein the film-like material is radiopaque. [9] The cryoablation catheter according to any one of [1] to [8], wherein the cryoablation catheter has an outer shaft having a lumen extending in the longitudinal direction and an inner shaft disposed in the lumen of the outer shaft, the supply lumen is formed in the inner shaft, and the discharge flow path is a space existing between the outer surface of the inner shaft and the inner surface of the outer shaft.

[10] The cryoablation catheter according to [9], wherein the inner shaft has a hole that communicates the supply lumen with the interior of the balloon.

[0012] The cryoablation catheter of the present invention can facilitate uniform cooling of the target tissue in the circumferential direction and longitudinal direction of the balloon.

[0013] FIG. 1 is a side view of a cryoablation catheter according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the distal portion of the cryoablation catheter shown in FIG. 1. FIG. 3 is a cross-sectional end view of the cryoablation catheter shown in FIG. 2 taken along line III-III. FIG. 4 is a cross-sectional end view showing a modified version of the cryoablation catheter shown in FIG. 3. FIG. 5 is a cross-sectional end view of the cryoablation catheter shown in FIG. 2 taken along line V-V. FIG. 6 is a cross-sectional end view showing a modified version of the cryoablation catheter shown in FIG. 5. FIG. 7 is a cross-sectional end view showing a modified version of the cryoablation catheter shown in FIG. 5.

[0014] The present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the illustrated examples, and appropriate modifications can be made within the scope of the above and below-described purpose, and all such modifications are within the technical scope of the present invention. In each drawing, hatching, symbols, etc. may be omitted for convenience. In such cases, reference should be made to the specification or other drawings. Furthermore, the dimensions of various parts in the drawings may differ from their actual dimensions, as priority is given to helping understand the features of the present invention.

[0015] A cryoablation catheter according to one embodiment of the present invention is a cryoablation catheter having a longitudinal direction and a radial direction, and comprising: a supply lumen extending in the longitudinal direction and allowing fluid to pass from the proximal side to the distal side; a balloon to which the fluid that has passed through the supply lumen is supplied; an exhaust flow path located in a region different from the supply lumen in the radial direction of the cryoablation catheter, extending in the longitudinal direction of the cryoablation catheter, allowing fluid that has passed through the interior of the balloon to pass from the distal side to the proximal side; and a membrane-like material disposed at least between the outer and inner surfaces of the balloon, on the outer surface, and on the inner surface, the membrane-like material having a higher thermal conductivity than the balloon.

[0016] The overall configuration of a cryoablation catheter 100 according to an embodiment of the present invention will be described with reference to Figures 1 to 7. These figures show the cryoablation catheter 100 including a supply lumen 31, a balloon 40, a discharge flow path 21, and a membrane-like material 70. In these figures, the longitudinal direction of the cryoablation catheter 100 is indicated by x, the radial direction by y, and the circumferential direction by c.

[0017] Each of the members and parts of the cryoablation catheter 100 also has a longitudinal direction, a radial direction, and a circumferential direction. The longitudinal, radial, and circumferential directions of the members and parts of the cryoablation catheter 100 may or may not coincide with the longitudinal direction x, radial direction y, and circumferential direction c of the cryoablation catheter 100. For ease of understanding, this specification shows an embodiment in which the longitudinal, radial, and circumferential directions of all members and parts coincide with the longitudinal direction x, radial direction y, and circumferential direction c of the cryoablation catheter 100, respectively.

[0018] In this specification, the proximal side refers to the direction toward the user's hand relative to the longitudinal direction x of the cryoablation catheter 100, and the distal side refers to the opposite side of the proximal side, i.e., the direction toward the treatment target. Furthermore, when each component or part is divided into two equal parts in the longitudinal direction x of the cryoablation catheter 100, the distal part of each component or part is referred to as the distal part of each component or part, and the proximal part of each component or part is referred to as the proximal part of each component or part. The distal end of each component or part is the most distal end of each component or part. The proximal end of each component or part is the most proximal end of each component or part. The end includes the peripheral portion of the end. In other words, the distal end refers to the distal end and the peripheral portion of the distal end, and the proximal end refers to the proximal end and the peripheral portion of the proximal end.

[0019] Fig. 1 shows a side view of a cryoablation catheter according to an embodiment of the present invention. Fig. 2 shows a cross-sectional view of the distal portion of the cryoablation catheter shown in Fig. 1. Fig. 3 shows a cross-sectional end view of the cryoablation catheter shown in Fig. 2 taken along line III-III. Fig. 4 shows a cross-sectional end view of a modified version of the cryoablation catheter shown in Fig. 3. Fig. 5 shows a cross-sectional end view of the cryoablation catheter shown in Fig. 2 taken along line V-V. Figs. 6 and 7 show cross-sectional end views of modified versions of the cryoablation catheter shown in Fig. 5.

[0020] 1 and 2, the cryoablation catheter 100 has a longitudinal direction x and a radial direction y. The cryoablation catheter 100 has a supply lumen 31, a balloon 40, an exhaust flow path 21, and a membrane 70.

[0021] As shown in FIGS. 2 to 7, the supply lumen 31 extends in the longitudinal direction x of the cryoablation catheter 100 and is a space through which a fluid can pass from the proximal side to the distal side.

[0022] The balloon 40 is supplied with fluid that has passed through the supply lumen 31. The balloon 40 has an interior 401 to which the fluid is supplied. The balloon 40 may have an inner surface 402 facing the interior 401 of the balloon 40 and an outer surface 403 facing the exterior of the balloon 40.

[0023] 1, 2, and 5 to 7 show the balloon 40 in an expanded state. The balloon 40 is preferably configured to expand in diameter when a fluid is supplied to the interior 401 of the balloon 40, and to contract in diameter when the fluid is removed. When the balloon 40 is expanded in diameter, the outer surface 403 of the balloon 40 comes into contact with the wall of a biological tract, such as a blood vessel or the digestive tract, thereby stabilizing the position of the cryoablation catheter 100 within the body cavity. Furthermore, contact of the outer surface 403 of the balloon 40 with the wall of a biological tract, such as a blood vessel or the digestive tract, facilitates localized cooling of tissue in contact with the outer surface 403 of the balloon 40.

[0024] 1, 2, and 5 to 7, the discharge channel 21 is located in a different region from the supply lumen 31 in the radial direction y of the cryoablation catheter 100. The discharge channel 21 extends in the longitudinal direction x of the cryoablation catheter 100 and is a space through which fluid that has passed through the interior 401 of the balloon 40 can pass from the distal side to the proximal side. The fluid that has been transported from the proximal side to the distal side of the cryoablation catheter 100 by passing through the supply lumen 31 is supplied to the balloon 40 and then discharged to the outside of the cryoablation catheter 100 via the discharge channel 21.

[0025] As shown in Figures 2 and 5 to 7, the film-like material 70 is disposed between the outer surface 403 and the inner surface 402 of the balloon 40, on the outer surface 403 of the balloon 40, or on the inner surface 402 of the balloon 40. Figures 2 and 5 show an embodiment in which the film-like material 70 is disposed between the outer surface 403 and the inner surface 402 of the balloon 40. Figure 6 shows an embodiment in which the film-like material 70 is disposed on the outer surface 403 of the balloon 40. Figure 7 shows an embodiment in which the film-like material 70 is disposed on the inner surface 402 of the balloon 40.

[0026] The film-like material 70 is configured to have a higher thermal conductivity than the balloon 40 .

[0027] By disposing the film-like material 70, which has a higher thermal conductivity than the balloon 40, between the outer surface 403 and the inner surface 402 of the balloon 40, on the outer surface 403, or on the inner surface 402, or both, heat can be easily transferred in the circumferential direction and longitudinal direction of the balloon 40 via the film-like material 70. This makes it easier to uniformly cool the target tissue in the circumferential direction and longitudinal direction of the balloon 40.

[0028] Cryoablation catheter 100 cools target tissue with fluid delivered by delivery lumen 31 .

[0029] The fluid is transported from the proximal side to the distal side of the cryoablation catheter 100 by passing through the supply lumen 31, and then from the distal side to the proximal side by passing through the discharge flow path 21, and is discharged outside the cryoablation catheter 100.

[0030] The fluid used in the cryoablation catheter 100 may be a liquid or a gas. When the fluid is a liquid, nitrogen or chlorofluorocarbon may be used. When the fluid is a gas, argon, carbon dioxide, or nitrous oxide may be used, for example. From the viewpoint of being able to reduce pressure loss and energy loss, it is preferable that the fluid used in the cryoablation catheter 100 be a liquid.

[0031] 1 to 4, the cryoablation catheter 100 may have a guidewire lumen 32 into which a guidewire is inserted. Although not shown, the cryoablation catheter 100 does not necessarily have to have the guidewire lumen 32.

[0032] 1 to 7, the cryoablation catheter 100 has a supply lumen 31 and an exhaust flow path 21. The supply lumen 31 and the exhaust flow path 21 may be included in a shaft 1 provided in the cryoablation catheter 100. In addition to the above, the shaft 1 may have a guidewire lumen 32. The shaft 1 preferably extends in the longitudinal direction x of the cryoablation catheter 100.

[0033] The shaft 1 may have a hollow cylindrical shape, a hollow polygonal prism shape, or the like.

[0034] The shaft 1 is preferably flexible because it is inserted into the body, allowing it to be deformed to fit the shape of the body cavity. In addition, the shaft 1 is preferably elastic so as to maintain its shape.

[0035] Examples of the shaft 1 include a hollow body formed by arranging one or more wires in a predetermined pattern; a hollow body having at least one of the inner and outer surfaces coated with resin; a resin tube; or a combination thereof, such as a combination of these, connected in the longitudinal direction x. Examples of hollow bodies having wires arranged in a predetermined pattern include a tubular body having a mesh structure formed by crossing or weaving wires, and a coil formed by winding wires. The wires may be one or more solid wires or one or more twisted wires. The resin tube can be manufactured by, for example, extrusion molding. When the shaft 1 is a resin tube, it can be composed of a single layer or multiple layers. A portion of the shaft 1 in the longitudinal direction x or circumferential direction c of the cryoablation catheter 100 may be composed of a single layer, and the other portion may be composed of multiple layers.

[0036] The shaft 1 can be made of, for example, synthetic resins such as polyolefin resins (e.g., polyethylene and polypropylene), polyamide resins (e.g., nylon), polyester resins (e.g., PET), aromatic polyether ketone resins (e.g., PEEK), polyether polyamide resins, polyurethane resins, polyimide resins, and fluororesins (e.g., PTFE, PFA, and ETFE), or metals such as stainless steel, carbon steel, and nickel-titanium alloys. These may be used alone or in combination of two or more.

[0037] Although not shown, the shaft 1 may be integrally molded from a single member. For example, in a cross section perpendicular to the longitudinal direction x of the cryoablation catheter 100, the shaft 1 may be an integrally molded member having the supply lumen 31 and the discharge channel 21 located in a region different from the supply lumen 31. In an embodiment in which the cryoablation catheter 100 has a guidewire lumen 32, the shaft 1 may be an integrally molded member having the supply lumen 31, the discharge channel 21 located in a region different from the supply lumen 31, and the guidewire lumen 32 located in a region different from the supply lumen 31 and the discharge channel 21 in a cross section perpendicular to the longitudinal direction x of the cryoablation catheter 100.

[0038] As shown in FIGS. 2 to 4 , the cryoablation catheter 100 may include, as the shaft 1, an outer shaft 20 having a lumen 20a extending in the longitudinal direction x of the cryoablation catheter 100, and an inner shaft 30 disposed in the lumen 20a of the outer shaft 20. The outer shaft 20 may have an inner surface 20b facing the lumen 20a and an outer surface 20c facing the exterior of the outer shaft 20. The inner shaft 30 may have a lumen 30a extending in the longitudinal direction x of the cryoablation catheter 100 and an outer surface 30c facing the exterior of the inner shaft 30. In the above case, the supply lumen 31 may be formed in the inner shaft 30. For example, the lumen 30a of the inner shaft 30 may be the supply lumen 31. The discharge flow path 21 may be a space existing between the outer surface 30c of the inner shaft 30 and the inner surface 20b of the outer shaft 20. In an embodiment in which the cryoablation catheter 100 has a guidewire lumen 32, the guidewire lumen 32 may be formed in the inner shaft 30. For example, the inner cavity 30a of the inner shaft 30 may be the guidewire lumen 32.

[0039] The outer shaft 20 and the inner shaft 30 may be made of the same material, or may be made of different materials.

[0040] As shown in FIG. 3 , the inner shaft 30 may be a single tube having a plurality of lumens 30a extending in the longitudinal direction x of the cryoablation catheter 100. In this case, one of the plurality of lumens 30a may be a supply lumen 31, and another of the lumens 30a may be a guidewire lumen 32. As shown in FIG. 4 , the inner shaft 30 may be a plurality of tubes having lumens 30a extending in the longitudinal direction x of the cryoablation catheter 100. In this case, one of the plurality of tubes may be a supply tube 35, and the lumen 30a of the supply tube 35 may be the supply lumen 31. Another of the plurality of tubes may be a guidewire tube 36, and the lumen 30a of the guidewire tube 36 may be the guidewire lumen 32. Although not shown, the inner shaft 30 may have only the supply lumen 31 without the guidewire lumen 32.

[0041] 2 and 5, the portion of the inner shaft 30 located inside the balloon 40 may include a portion having the supply tube 35 and the guidewire tube 36 disposed in the lumen 30a of the supply tube 35. As shown in Figures 2 and 3, the portion of the inner shaft 30 located proximal to the balloon 40 may be composed of a single tube having the supply lumen 31 and the guidewire lumen 32.

[0042] 2 and 5 , the inner shaft 30 may have a hole 33 that connects the supply lumen 31 with the interior 401 of the balloon 40. The hole 33 is preferably provided in the distal portion or the distal end of the inner shaft 30. The hole 33 is preferably configured to be able to eject fluid outward in the radial direction y of the cryoablation catheter 100. The fluid transported from the proximal side to the distal side by passing through the supply lumen 31 is ejected into the interior 401 of the balloon 40 through the hole 33 and is transported to the discharge flow path 21.

[0043] Examples of materials that can be used to form the balloon 40 include polyamide resins such as nylon 11 and nylon 12, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyurethane resins, thermoplastic elastomers such as polyether block amide copolymers, and combinations of these.

[0044] As shown in Fig. 2, the holes 33 are preferably located inside the balloon 40. For example, the holes 33 are preferably formed in a portion of the inner shaft 30 that is located inside the balloon 40. The holes 33 may also be formed in a portion of the inner shaft 30 that is not located inside the balloon 40. However, the holes 33 are preferably formed only in a portion of the inner shaft 30 that is located inside the balloon 40. This makes it easier to increase the distance between the holes 33 and portions other than the balloon 40, thereby making it easier to reduce the cooling efficiency in portions other than the balloon 40. This makes it easier to increase the freezing efficiency of the tissue where the balloon 40 is located.

[0045] The membrane-like object 70 has a membrane-like shape. The cryoablation catheter 100 may have only one membrane-like object 70 or may have a plurality of membrane-like objects 70.

[0046] The material of the membrane 70 is not particularly limited as long as it is configured to have a higher thermal conductivity than the balloon 40. For example, metals such as iodine, lead, barium, tungsten, tantalum, gold, platinum, iridium, stainless steel, titanium, and cobalt-chromium alloys can be used. These materials are radiopaque, and using these materials can make the membrane 70 radiopaque, thereby making the balloon 40 more visible under X-ray fluoroscopy. The entire membrane 70 may be made solely of the above-mentioned radiopaque material. The above-mentioned radiopaque material may also be included as part of the material constituting the membrane 70.

[0047] The film-like material 70 may be a sheet-like material formed from the above-mentioned material. The film-like material 70 may be a deposition product in which the above-mentioned material is vapor-deposited on the balloon 40. The film-like material 70 may be a coating product in which the above-mentioned material is applied to the balloon 40 by spraying or brushing. The film-like material 70 may be a sheet-like material in which the above-mentioned material is vapor-deposited or coated on a separately provided substrate. For example, the film-like material 70 may be gold foil, a sheet-like material in which gold is coated or vapor-deposited on a separately provided substrate, a deposition product in which gold is vapor-deposited on the balloon 40, or a coating product in which gold is coated on the balloon 40. When the film-like material 70 is disposed on the balloon 40, a linear member made of a material containing an X-ray opaque substance and having a thermal conductivity higher than that of the balloon 40 may be wrapped around the film-like material 70 and the balloon 40. When a sheet-like material such as that described above is used as the film-like material 70, the film-like material 70 may be adhered to the balloon 40 with an adhesive, or the film-like material 70 may be fixed to the balloon 40 with a string, wire, or the like.

[0048] As shown in Figures 2 and 5, the balloon 40 may have an outer balloon 46 and an inner balloon 47 that is disposed inside the outer balloon 46 and to which the fluid that has passed through the supply lumen 31 is supplied.

[0049] 2 and 5 , the film-like material 70 may be disposed between the outer balloon 46 and the inner balloon 47. Only the film-like material 70 may be disposed between the outer balloon 46 and the inner balloon 47, or the film-like material 70 may be disposed together with a component other than the film-like material 70. However, from the viewpoint of easily improving heat transfer efficiency, when a component other than the film-like material 70 is disposed between the outer balloon 46 and the inner balloon 47, it is preferable that the thermal conductivity of the component be higher than that of the outer balloon 46 and higher than that of the inner balloon 47. In other words, it is preferable that no component with a lower thermal conductivity than the outer balloon 46 and the inner balloon 47 is disposed between the outer balloon 46 and the inner balloon 47.

[0050] The film-like material 70 is preferably in contact with at least one of the outer balloon 46 and the inner balloon 47. The film-like material 70 may be in contact only with the outer balloon 46. This makes it easier to improve the efficiency of heat transfer from the film-like material 70 to the outer balloon 46. The film-like material 70 may be in contact only with the inner balloon 47. This makes it easier to improve the efficiency of heat transfer from the inner balloon 47 to the film-like material 70. As shown in FIGS. 2 and 5 , it is more preferable that the film-like material 70 be in contact with the outer balloon 46 and the inner balloon 47. By having the film-like material 70 in contact with the outer balloon 46 and the inner balloon 47, it is easier to improve the efficiency of heat transfer from the inner balloon 47 to the outer balloon 46, making it easier to efficiently cool the target tissue.

[0051] The film-like material 70 may be fixed to at least one of the outer balloon 46 and the inner balloon 47. This prevents the film-like material 70 from coming off the balloon 40 or from shifting its position relative to the balloon 40 during treatment. The film-like material 70 may be fixed only to the outer balloon 46. This makes it easier to improve the efficiency of heat transfer from the film-like material 70 to the outer balloon 46. The film-like material 70 may be fixed only to the inner balloon 47. This makes it easier to improve the efficiency of heat transfer from the inner balloon 47 to the film-like material 70. The film-like material 70 may be fixed to both the outer balloon 46 and the inner balloon 47. Fixing the film-like material 70 to the outer balloon 46 and the inner balloon 47 makes it easier to improve the efficiency of heat transfer from the inner balloon 47 to the outer balloon 46, thereby making it easier to efficiently cool the target tissue.

[0052] 2 and 5, the thickness of the film-like material 70 may be thinner than the thickness of the outer balloon 46 and thinner than the thickness of the inner balloon 47. Although not shown, the thickness of the film-like material 70 may be thicker than the thickness of the outer balloon 46 and thicker than the thickness of the inner balloon 47.

[0053] The material constituting the outer balloon 46 and the material constituting the inner balloon 47 may be the same or different.

[0054] 2 and 5 to 7, in a cross section perpendicular to the longitudinal direction x of the cryoablation catheter 100, the membrane-like material 70 is preferably present over the entire circumferential direction of the balloon 40. This allows heat to be easily transferred in the circumferential direction of the balloon 40 via the membrane-like material 70. This makes it easier to uniformly cool the target tissue in the circumferential direction of the balloon 40. Although not shown, an embodiment in which the membrane-like material 70 is present only over a portion of the circumferential direction of the balloon 40 in a cross section perpendicular to the longitudinal direction x of the cryoablation catheter 100 is also acceptable.

[0055] 2 , when the balloon 40 is in an expanded diameter state, the balloon 40 may have a cylindrical straight tube portion 41, a distal tapered portion 42 located distal to the straight tube portion 41 and having an outer diameter that decreases distally, and a proximal tapered portion 43 located proximal to the straight tube portion 41 and having an outer diameter that decreases proximally. Furthermore, the balloon 40 may have a distal sleeve portion 44 located distal to the distal tapered portion 42 and fixed to the outer surface 30 c of the inner shaft 30, and a proximal sleeve portion 45 located proximal to the proximal tapered portion 43 and fixed to the outer surface 20 c of the outer shaft 20.

[0056] 2, the film-like material 70 is preferably disposed on the straight pipe portion 41. The film-like material 70 may be disposed only on the straight pipe portion 41. The film-like material 70 may be disposed only on the straight pipe portion 41, the distal tapered portion 42, and the proximal tapered portion 43. This makes it easier to uniformly cool the target tissue in the straight pipe portion 41 of the balloon 40.

[0057] 1 and 2 , the cryoablation catheter 100 may further include a distal tip 50 having a lumen 51 extending in the longitudinal direction x of the cryoablation catheter 100 and having an outer diameter that decreases from the proximal end to the distal end. The distal tip 50 is preferably connected to the distal end of the shaft 1. In an embodiment in which the cryoablation catheter 100 has a guidewire lumen 32, the distal tip 50 is preferably connected to the shaft 1 so that the guidewire lumen 32 and the lumen 51 of the distal tip 50 communicate with each other. By including the distal tip 50 whose outer diameter decreases from the proximal side to the distal side, the distal end of the cryoablation catheter 100 can be more easily inserted into a body cavity.

[0058] The shape of the distal tip 50 can be, for example, a hollow cone, a hollow polygonal pyramid, a hollow truncated cone, a hollow polygonal pyramid, or a hemisphere with a lumen formed therein.

[0059] The material constituting the distal tip 50 can be any of the materials exemplified as materials constituting the shaft 1. The material constituting the distal tip 50 and the material constituting the shaft 1 may be the same or different.

[0060] As shown in FIG. 1 , a hub 2 may be connected to the proximal portion of the shaft 1. The shaft 1 and the hub 2 may be fixed together. For example, the shaft 1 and the hub 2 can be fixed together by bonding with an adhesive, welding, screws, or the like. Among these, it is preferable that the shaft 1 and the hub 2 are fixed together by bonding. By fixing the shaft 1 and the hub 2 together by bonding, the strength of the connection between the shaft 1 and the hub 2 can be increased even when the shaft 1 and the hub 2 are made of different materials, for example, when the shaft 1 is made of a highly flexible material and the hub 2 is made of a highly rigid material, and so on. This makes it easier to improve the durability of the cryoablation catheter 100.

[0061] The hub 2 may be provided with a fluid injection section 3 capable of injecting a fluid passing through a supply lumen 31 from the proximal side to the distal side. The fluid injection section 3 may be connected to a fluid supply device 4. Examples of the fluid supply device 4 include a regulator, a flow rate controller, and a pump connected to a container in which the fluid is stored.

[0062] FIG. 1 discloses an embodiment in which a guidewire port 5 is formed midway from the distal end to the proximal end of the shaft 1. The guidewire port 5 is in communication with the guidewire lumen 32 of the shaft 1. FIG. 1 illustrates a so-called rapid exchange type cryoablation catheter 100. The shaft 1 may have a distal shaft portion 1a and a proximal shaft portion 1b located proximal to the distal shaft portion 1a. The distal shaft portion 1a and the proximal shaft portion 1b may be separate members, with the proximal end of the member constituting the distal shaft portion 1a connected to the distal end of the member constituting the proximal shaft portion 1b. Alternatively, the distal shaft portion 1a and the proximal shaft portion 1b may be formed from a single member.

[0063] Although not shown, the cryoablation catheter 100 may be of a so-called over-the-wire type in which a guidewire lumen 32 is formed from the distal end to the proximal end of the shaft 1. When the cryoablation catheter 100 is of the over-the-wire type, the guidewire lumen 32 preferably extends in the longitudinal direction x of the cryoablation catheter 100 to the position where the hub 2 is located.

[0064] Regardless of whether the cryoablation catheter 100 is a rapid exchange type or an over-the-wire type, the supply lumen 31 and the discharge channel 21 preferably extend to the position where the hub 2 is located in the longitudinal direction x of the cryoablation catheter 100.

[0065] The outer surface of the shaft 1 and the outer surface of the distal tip 50 may be coated. As shown in FIG. 1 , when the cryoablation catheter 100 is a rapid exchange type, the outer surface of at least one of the distal shaft portion 1a and the proximal shaft portion 1b may be coated, or the outer surfaces of both the distal shaft portion 1a and the proximal shaft portion 1b may be coated. When the cryoablation catheter 100 is an over-the-wire type, only a portion or the entire outer surface of the shaft 1 may be coated. Only a portion or the entire outer surface of the distal tip 50 may be coated.

[0066] The coating applied to the outer surface of the shaft 1 or the outer surface of the distal tip 50 can be a hydrophilic coating or a hydrophobic coating depending on the purpose. The coating can be applied by immersing the shaft 1 or the distal tip 50 in a hydrophilic or hydrophobic coating agent, by applying a hydrophilic or hydrophobic coating agent to the outer surface of the shaft 1 or the outer surface of the distal tip 50, or by covering the outer surface of the shaft 1 or the outer surface of the distal tip 50 with a hydrophilic or hydrophobic coating agent. Drugs or additives may be added to the coating agent.

[0067] Examples of hydrophilic coating agents include hydrophilic polymers such as polyvinyl alcohol, polyethylene glycol, polyacrylamide, polyvinylpyrrolidone, and methyl vinyl ether-maleic anhydride copolymer, and hydrophilic coating agents composed of combinations of these.

[0068] Examples of hydrophobic coating agents include polytetrafluoroethylene (PTFE), fluorinated ethylene propylene (FEP), perfluoroalkoxyalkane (PFA), silicone oil, hydrophobic urethane resin, carbon coat, diamond coat, diamond-like carbon (DLC) coat, ceramic coat, and substances terminated with alkyl groups or perfluoroalkyl groups and having low surface free energy.

[0069] In the longitudinal direction x of the cryoablation catheter 100, the length of the cryoablation catheter 100 can be 80 cm or more, 100 cm or more, 120 cm or more, etc. In the longitudinal direction x of the cryoablation catheter 100, the length of the cryoablation catheter 100 can be 250 cm or less, 230 cm or less, 210 cm or less, etc.

[0070] In the radial direction y of the cryoablation catheter 100, the length of the cryoablation catheter 100 can be 1.0 mm or more, 2.0 mm or more, 3.0 mm or more, etc. In the radial direction y of the cryoablation catheter 100, the length of the cryoablation catheter 100 can be 6.0 mm or less, 5.0 mm or less, 4.0 mm or less, etc.

[0071] This application claims the benefit of priority based on Japanese Patent Application No. 2024-028387, filed on February 28, 2024. The entire contents of the specification of Japanese Patent Application No. 2024-028387, filed on February 28, 2024, are incorporated herein by reference.

[0072] 1: Shaft 1a: Distal shaft portion 1b: Proximal shaft portion 2: Hub 3: Fluid injection portion 4: Fluid supply device 5: Guidewire port 20: Outer shaft 20a: Lumen 20b: Inner surface 20c: Outer surface 21: Discharge flow path 30: Inner shaft 30a: Lumen 30c: Outer surface 31: Supply lumen 32: Guidewire lumen 33: Hole 35: Supply tube 36: Guidewire tube 40: Balloon 41: Straight tube portion 42: Distal tapered portion 43: Proximal tapered portion 44: Distal sleeve portion 45: Proximal sleeve portion 46: Outer balloon 47: Inner balloon 401: Interior 402: Inner surface 403: Outer surface 50: Distal tip 51: Lumen 70: Membrane-like material 100: Cryoablation catheter

Claims

1. A cryoablation catheter having a longitudinal direction and a radial direction, comprising: a supply lumen extending in the longitudinal direction and allowing a fluid to pass from the proximal side to the distal side; a balloon to which the fluid that has passed through the supply lumen is supplied; a discharge flow path located in a region different from the supply lumen in the radial direction, extending in the longitudinal direction, and allowing the fluid that has passed through the inside of the balloon to pass from the distal side to the proximal side; and a membrane-like material disposed at least between the outer and inner surfaces of the balloon, on the outer surface, and on the inner surface, wherein the membrane-like material has a higher thermal conductivity than the balloon.

2. A cryoablation catheter as described in claim 1, wherein the balloon comprises an outer balloon and an inner balloon disposed inside the outer balloon and supplied with fluid that has passed through the supply lumen, and the membrane-like material is disposed between the outer balloon and the inner balloon.

3. A cryoablation catheter according to claim 2, wherein the membrane-like material abuts against at least one of the outer balloon and the inner balloon.

4. A cryoablation catheter according to claim 2, wherein the membrane abuts against the outer balloon and the inner balloon.

5. A cryoablation catheter according to claim 2, wherein the thickness of the membrane is thinner than the thickness of the outer balloon and thinner than the thickness of the inner balloon.

6. A cryoablation catheter according to any one of claims 1 to 5, wherein the membrane-like material is present over the entire circumference of the balloon in a cross section perpendicular to the longitudinal direction.

7. A cryoablation catheter according to any one of claims 1 to 5, wherein the balloon has a straight tube portion, a distal tapered portion located distal to the straight tube portion and having an outer diameter that decreases toward the distal side, and a proximal tapered portion located proximal to the straight tube portion and having an outer diameter that decreases toward the proximal side, and the membrane-like object is disposed on the straight tube portion.

8. A cryoablation catheter according to any one of claims 1 to 5, wherein the membrane-like material is radiopaque.

9. A cryoablation catheter according to any one of claims 1 to 5, comprising an outer shaft having a lumen extending in the longitudinal direction, and an inner shaft disposed in the lumen of the outer shaft, wherein the supply lumen is formed in the inner shaft, and the discharge flow path is a space existing between the outer surface of the inner shaft and the inner surface of the outer shaft.

10. The cryoablation catheter of claim 9, wherein the inner shaft has a hole communicating the supply lumen with the interior of the balloon.

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