Cryoablation catheter

Abstract

A cryoablation catheter (100) comprises: a supply lumen (31) through which a fluid can pass from the proximal side to the distal side; a discharge flow path (21) through which the fluid that has passed through the supply lumen (31) can pass from the distal side toward the proximal side; and a thermal insulation layer (12) which has an air layer (11). In a cross section perpendicular to the longitudinal direction (x) of the cryoablation catheter (100), the thermal insulation layer (12) is positioned outward in the radial direction (y) of the cryoablation catheter (100) as compared to the supply lumen (31) and the discharge flow path (21).

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] Special Publication No. 2001-524345

[0005] In the cryosurgery catheter described in Patent Document 1, a fluid for cooling a target tissue is conveyed from the proximal side to the distal side through a main lumen. After cooling the target tissue, the fluid is conveyed from the distal side to the proximal side through an outlet lumen. As a result, there is a problem in that tissues other than the target tissue may be overcooled while the fluid is passing through the main lumen and outlet lumen.

[0006] The present invention has been made in consideration of the above circumstances, and its purpose is to provide a cryoablation catheter that can more easily prevent excessive cooling of tissue other than the target tissue while the fluid is passing through the supply lumen and discharge flow path.

[0007] 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 therethrough from a proximal side to a distal side, a discharge flow path located in a region different from the supply lumen in the radial direction, extending in the longitudinal direction, and allowing a fluid that has passed through the supply lumen to pass therethrough from a distal side to a proximal side, and a heat insulating layer having an air layer and extending in the longitudinal direction, wherein, in a cross section perpendicular to the longitudinal direction, the heat insulating layer is located radially outward of the supply lumen and the discharge flow path.

[0008] In a cross section perpendicular to the longitudinal direction of the cryoablation catheter, the insulating layer is located radially outward of the supply lumen and the discharge channel, which makes it difficult for cooling by the fluid passing through the supply lumen and the discharge channel to reach parts of the cryoablation catheter that are radially outward of the insulating layer, thereby making it easier to prevent excessive cooling of tissue other than the target tissue while the fluid is passing through the supply lumen and the discharge channel.

[0009] A cryoablation catheter according to an embodiment of the present invention is preferably any one of the following [2] to

[12] . [2] The cryoablation catheter according to [1], comprising: an insulated shaft having a lumen extending in the longitudinal direction; an outer shaft disposed in the lumen of the insulated shaft and 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; the discharge flow path is a space existing between an outer surface of the inner shaft and an inner surface of the outer shaft; and the air layer is a space existing between the inner surface of the insulated shaft and the outer surface of the outer shaft. [3] The cryoablation catheter according to [1] or [2], wherein a member is disposed in the air layer. [4] The cryoablation catheter according to [3], wherein the member is a coil having a wire made of resin, and the wire is wound around the supply lumen and the discharge flow path. [5] The cryoablation catheter according to [2], wherein a member is disposed in the air layer, the member being a coil having a wire made of resin, the coil being fixed to the outer surface of the outer shaft and not fixed to the inner surface of the insulated shaft. [6] The cryoablation catheter according to [2], wherein the insulated shaft has an inner protrusion protruding radially inward of the cryoablation catheter. [7] The cryoablation catheter according to [2] or [6], wherein the outer shaft has an outer protrusion protruding radially outward of the cryoablation catheter. [8] The cryoablation catheter according to any one of [1] to [7], wherein, in a cross section perpendicular to the longitudinal direction, the cross-sectional area of ​​the air layer is 2 / 5 or more of the cross-sectional area of ​​the exhaust flow path. [9] The cryoablation catheter according to any one of [1] to [8], wherein the cryoablation catheter has a hole communicating the supply lumen with the exhaust flow path.

[10] The cryoablation catheter according to any one of [1] to [9], wherein the cryoablation catheter has a balloon, and the supply lumen and the discharge channel are in communication with each other via the interior of the balloon.

[11] The cryoablation catheter according to any one of [1] to

[10] , wherein air having a higher temperature than the fluid conveyed from the distal side to the proximal side through the discharge channel is supplied to the air layer.

[12] The cryoablation catheter according to any one of [1] to

[11] , wherein the air layer is not in communication with the supply lumen and the discharge channel.

[0010] The cryoablation catheter of the present invention can easily prevent excessive cooling of tissue other than the target tissue while the fluid is passing through the supply lumen and the discharge flow path.

[0011] 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 example of the cryoablation catheter shown in FIG. 3. FIG. 5 is a cross-sectional view (partial side view) showing a modified example of the cryoablation catheter shown in FIG. 2. FIG. 6 is a cross-sectional view showing a modified example of the cryoablation catheter shown in FIG. 2. FIG. 7 is a cross-sectional view showing a modified example of the cryoablation catheter shown in FIG. 2.

[0012] 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.

[0013] 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 of the cryoablation catheter and allowing fluid to pass from the proximal side to the distal side; 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, and allowing fluid that has passed through the supply lumen to pass from the distal side to the proximal side; and an insulating layer having an air layer and extending in the longitudinal direction of the cryoablation catheter, wherein the gist is that in a cross section perpendicular to the longitudinal direction of the cryoablation catheter, the insulating layer is located radially outward of the cryoablation catheter from the supply lumen and the exhaust flow path.

[0014] 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, which includes a supply lumen 31, an exhaust flow path 21, and a thermal insulating layer 12. 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.

[0015] 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.

[0016] 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.

[0017] 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 example of the cryoablation catheter shown in Fig. 3. Fig. 5 is a cross-sectional view (partially a side view) showing a modified example of the cryoablation catheter shown in Fig. 2. Figs. 6 and 7 are cross-sectional views showing modified examples of the cryoablation catheter shown in Fig. 2.

[0018] 1, 2, and 5-7, the cryoablation catheter 100 has a longitudinal direction x and a radial direction y. The cryoablation catheter 100 has a supply lumen 31, an exhaust channel 21, and a thermal insulating layer 12.

[0019] 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.

[0020] 2 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 the fluid that has passed through the supply lumen 31 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 discharged to the outside of the cryoablation catheter 100 via the discharge channel 21.

[0021] As shown in FIGS. 2-7, the thermal insulating layer 12 extends in the longitudinal direction x of the cryoablation catheter 100 .

[0022] 2 to 7, the heat insulating layer 12 only needs to have an air layer 11 containing air. Although not shown, the heat insulating layer 12 may contain air bubbles as the air layer 11. For example, the air layer 11 may be formed by the presence of a large number of spherical air bubbles.

[0023] As shown in FIGS. 2 to 4, in a cross section perpendicular to the longitudinal direction x of the cryoablation catheter 100, the heat insulating layer 12 is located outward in the radial direction y of the cryoablation catheter 100 from the supply lumen 31 and the discharge flow path 21.

[0024] In a cross section perpendicular to the longitudinal direction x of the cryoablation catheter 100, the insulating layer 12 is located further outward in the radial direction y of the cryoablation catheter 100 than the supply lumen 31 and the discharge flow path 21, which makes it difficult for cooling by the fluid passing through the supply lumen 31 and the discharge flow path 21 to reach parts of the cryoablation catheter 100 that are located further outward in the radial direction y than the insulating layer 12. This makes it easier to prevent tissues other than the target tissue from being excessively cooled while the fluid is passing through the supply lumen 31 and the discharge flow path 21.

[0025] Cryoablation catheter 100 cools target tissue with fluid delivered by delivery lumen 31 .

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 1 to 7 , the cryoablation catheter 100 has a supply lumen 31, an exhaust flow path 21, and a heat insulating layer 12. The supply lumen 31, the exhaust flow path 21, and the heat insulating layer 12 may be included in the shaft 1 of 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.

[0030] The shaft 1 may have a hollow cylindrical shape, a hollow polygonal prism shape, or the like.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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 a supply lumen 31, a discharge flow path 21 located in a region different from the supply lumen 31, and a heat insulating layer 12 having an air layer 11 located in a region different from the supply lumen 31 and the discharge flow path 21. In an embodiment in which the cryoablation catheter 100 has a guidewire lumen 32, the shaft 1 may be an integrally molded member having, in a cross section perpendicular to the longitudinal direction x of the cryoablation catheter 100, the supply lumen 31, a discharge flow path 21 located in a region different from the supply lumen 31, the heat insulating layer 12 having an air layer 11 located in a region different from the supply lumen 31 and the discharge flow path 21, and the guidewire lumen 32 located in a region different from the supply lumen 31, the discharge flow path 21, and the heat insulating layer 12.

[0035] 2 to 4, the shaft 1 may be composed of multiple members. For example, the cryoablation catheter 100 may include, as the shaft 1, an insulated shaft 10 having a lumen 10a extending in the longitudinal direction x of the cryoablation catheter 100, an outer shaft 20 disposed in the lumen 10a of the insulated shaft 10 and 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 insulated shaft 10 may have an inner surface 10b facing the lumen 10a and an outer surface 10c facing the exterior of the insulated shaft 10. 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 outside 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. The air layer 11 may be a space existing between the inner surface 10b of the insulated shaft 10 and the outer surface 20c of the outer shaft 20. In other words, the heat insulating layer 12 may be composed of the insulated shaft 10 and the air layer 11 existing between the inner surface 10b of the insulated shaft 10 and the outer surface 20c 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 lumen 30 a of the inner shaft 30 may be a guidewire lumen 32 .

[0036] The insulated shaft 10, the outer shaft 20, and the inner shaft 30 may be made of the same material, or may be made of different materials.

[0037] 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.

[0038] 2, the cryoablation catheter 100 may have an X-ray opaque marker portion 34 provided at the distal portion of the inner shaft 30. With this configuration, the position of the distal portion of the cryoablation catheter 100 can be visualized using an X-ray imaging device.

[0039] The shape of the radiopaque marker portion 34 is preferably cylindrical. Other shapes include a hollow cylinder, a hollow polygonal prism, a C-shaped cross section with a notch in the cylinder, and a coil shape with a wound wire.

[0040] The radiopaque marker portion 34 may be made of a radiopaque substance such as lead, barium, iodine, tungsten, gold, platinum, iridium, stainless steel, titanium, or a cobalt-chromium alloy. For example, the entire radiopaque marker portion 34 may be made of the radiopaque substance. The radiopaque substance may be included as part of the material making up the radiopaque marker portion 34. In this case, the radiopaque marker portion 34 may be made by dispersing radiopaque particles such as barium sulfate in the inner shaft 30 or a separately provided resin member.

[0041] 3 and 4 , in a cross section perpendicular to the longitudinal direction x of the cryoablation catheter 100, the cross-sectional area of ​​the air layer 11 is preferably 2 / 5 or more, more preferably 1 / 2 or more, and even more preferably 3 / 5 or more of the cross-sectional area of ​​the discharge channel 21. This makes it easier to prevent tissues other than the target tissue from being excessively cooled while the fluid passes through the supply lumen 31 and the discharge channel 21. From the viewpoint of enhancing the above-mentioned effect, it is also preferable that the cross-sectional area of ​​the air layer 11 is larger than the cross-sectional area of ​​the discharge channel 21 in a cross section perpendicular to the longitudinal direction x of the cryoablation catheter 100.

[0042] The length of the air layer 11 in the radial direction y of the cryoablation catheter 100 can be 50 μm or more, 100 μm or more, 150 μm or more, etc. The length of the air layer 11 in the radial direction y of the cryoablation catheter 100 can be 400 μm or less, 350 μm or less, 300 μm or less, etc.

[0043] The length of the exhaust channel 21 in the radial direction y of the cryoablation catheter 100 can be 50 μm or more, 150 μm or more, 200 μm or more, etc. The length of the exhaust channel 21 in the radial direction y of the cryoablation catheter 100 can be 500 μm or less, 400 μm or less, 300 μm or less, etc.

[0044] The distal end and the proximal end of the insulating layer 12 may be closed, or the distal end and the proximal end of the insulating layer 12 may be open so that the outside of the insulating layer 12 communicates with the air layer 11. One of the distal end and the proximal end of the insulating layer 12 may be closed and the other may be open.

[0045] It is preferable that the air layer 11 does not communicate with the supply lumen 31 and the discharge flow path 21. Specifically, it is preferable that the cryoablation catheter 100 is not formed with any holes or flow paths that communicate the air layer 11 with the supply lumen 31, or any holes or flow paths that communicate the air layer 11 with the discharge flow path 21. As can be seen from Figures 2 to 7, it is preferable that the outer shaft 20 is not formed with any holes or flow paths that communicate the air layer 11 with the discharge flow path 21. This makes it possible to prevent the fluid that has passed through the supply lumen 31 from flowing into the air layer 11, making it easier to prevent tissues other than the target tissue from being excessively cooled.

[0046] As shown in FIG. 5 , it is preferable that a member 13 be disposed in the air layer 11. This makes it easier to maintain the length of the air layer 11 in the radial direction y of the cryoablation catheter 100 at a predetermined length. Furthermore, by disposing the member 13 in the air layer 11, it is possible to easily prevent the air layer 11 from collapsing even when the cryoablation catheter 100 is bent within a body cavity. This makes it easier to prevent tissues other than the target tissue from being overcooled while the fluid is passing through the supply lumen 31 and the discharge flow path 21. Note that even when the member 13 is disposed in the air layer 11, air still exists in the air layer 11. That is, the air layer 11 is not entirely blocked by the member 13, resulting in a state in which no air is present at all.

[0047] The member 13 may be a coil 15 wound with a wire 14, a foamed material, a porous material, a mesh, or the like.

[0048] The porosity of the porous material is preferably 50% or more, more preferably 55% or more, and even more preferably 60% or more, and is preferably 95% or less, more preferably 90% or less, and even more preferably 85% or less.

[0049] As the material for forming the member 13, the materials exemplified as the materials for forming the shaft 1 may be used.

[0050] A foamed resin insulating material or a fiber insulating material can also be used as the member 13. Examples of foamed resin insulating materials that can be used include rigid urethane foam, phenol foam, and bead-method polystyrene foam. Examples of fiber insulating materials that can be used include glass wool, rock wool, and cellulose fiber.

[0051] In particular, as shown in Fig. 5, the member 13 is preferably a coil 15 having a wire 14 made of resin. By making the wire 14 of the coil 15 out of resin, it is possible to easily reduce the heat transfer efficiency. Therefore, it is possible to easily prevent excessive cooling of tissues other than the target tissue while the fluid is passing through the supply lumen 31 and the discharge flow path 21. In this case, it is preferable that the wire 14 is wound around the supply lumen 31 and the discharge flow path 21. The wire 14 may be disposed between the insulated shaft 10 and the outer shaft 20.

[0052] A member 13 is disposed in the air layer 11. The member 13 is a coil 15 having wires 14 made of resin. The coil 15 is preferably fixed to the outer surface 20c of the outer shaft 20 and not fixed to the inner surface 10b of the insulated shaft 10. By not fixing the coil 15 to the inner surface 10b of the insulated shaft 10, the efficiency of heat transfer to the insulated shaft 10 can be easily reduced. This makes it easier to prevent tissues other than the target tissue from being excessively cooled while the fluid is passing through the supply lumen 31 and the discharge flow path 21.

[0053] As shown in FIG. 5, the wire 14 is arranged to wrap around the outer shaft 20, and the coil 15 has a spiral shape.

[0054] The wire 14 has a tip and a base in the longitudinal direction. The wire 14 may be composed of a single linear member from the tip to the base. Alternatively, the wire 14 may be composed of a plurality of linear members connected to each other in the longitudinal direction. The wire 14 may have a solid structure or a hollow structure. Furthermore, the number of turns of the wire 14 is not particularly limited.

[0055] The wire diameter of the wire 14 can be, for example, 30 μm or more, 80 μm or more, 130 μm or more, etc. The wire diameter of the wire 14 can be, for example, 380 μm or less, 330 μm or less, 280 μm or less, etc. In this specification, the "wire diameter of the wire 14" is measured in a cross section perpendicular to the longitudinal direction x of the cryoablation catheter 100. Furthermore, if the outer shape of the wire 14 in the cross section perpendicular to the longitudinal direction x of the cryoablation catheter 100 is other than a perfect circle, the "wire diameter of the wire 14" is defined as the diameter of a circle circumscribing the outer shape of the wire 14 in the cross section perpendicular to the longitudinal direction x of the cryoablation catheter 100.

[0056] The coil 15 has a pitch. The pitch is the spacing between turns of the spirally wound wire 14. The coil 15 may have a pitch equal to or greater than the wire diameter of the wire 14, a pitch greater than the wire diameter of the wire 14, or a pitch 50 times or more the wire diameter of the wire 14. The coil 15 may have a pitch 100 times or less the wire diameter of the wire 14, a pitch 300 times or less the wire diameter of the wire 14, or a pitch 8 times or less the wire diameter of the wire 14.

[0057] As shown in Figures 2 to 4, the member 13 does not have to be disposed in the air layer 11. The distal and proximal ends of the insulating layer 12 may be open so that the air layer 11 communicates with the outside of the insulating layer 12. The distal and proximal ends of the insulating layer 12 may be closed to prevent air leakage. One of the distal and proximal ends of the insulating layer 12 may be closed and the other open. When the distal and proximal ends of the insulating layer 12 are closed, the air layer 11 within the insulating layer 12 may be decompressed to a near-vacuum state, or may be at normal pressure.

[0058] As shown in Fig. 6, the insulated shaft 10 preferably has an inner protrusion 16 that protrudes inward in the radial direction y of the cryoablation catheter 100. This makes it easier to maintain the length of the air layer 11 in the radial direction y of the cryoablation catheter 100 at a predetermined length. Furthermore, the provision of the inner protrusion 16 makes it easier to prevent the air layer 11 from collapsing even when the cryoablation catheter 100 is bent within a body cavity. This makes it easier to prevent tissues other than the target tissue from being excessively cooled while the fluid is passing through the supply lumen 31 and the discharge flow path 21.

[0059] The insulated shaft 10 may have only one inner protrusion 16, but from the viewpoint of enhancing the above-mentioned effect, it is preferable that the insulated shaft 10 have multiple inner protrusions 16.

[0060] Each inner protrusion 16 may be elongated and extend in the circumferential direction c of the cryoablation catheter 100, or may be elongated and extend in the longitudinal direction x of the cryoablation catheter 100. Each inner protrusion 16 may be elongated and extend in a spiral shape so as to wind around the outer shaft 20. Each inner protrusion 16 may be in the shape of a polygonal pyramid, a polygonal truncated pyramid, a cone, a truncated cone, or a hemisphere, and multiple inner protrusions 16 having these shapes may be scattered.

[0061] 7 , the outer shaft 20 preferably has an outer protrusion 26 that protrudes outward in the radial direction y of the cryoablation catheter 100. This makes it easier to maintain the length of the air layer 11 in the radial direction y of the cryoablation catheter 100 at a predetermined length. Furthermore, the provision of the outer protrusion 26 makes it easier to prevent the air layer 11 from collapsing even when the cryoablation catheter 100 is bent within a body cavity. This makes it easier to prevent tissues other than the target tissue from being excessively cooled while the fluid is passing through the supply lumen 31 and the discharge flow path 21.

[0062] The outer shaft 20 may have only one outer protrusion 26, but from the viewpoint of enhancing the above-mentioned effects, it is preferable that the outer shaft 20 have multiple outer protrusions 26.

[0063] One outer protrusion 26 may be elongated and extend in the circumferential direction c of the cryoablation catheter 100, or may be elongated and extend in the longitudinal direction x of the cryoablation catheter 100. One outer protrusion 26 may be elongated and extend in a spiral shape so as to wind around the inner shaft 30. Furthermore, one outer protrusion 26 may be in the shape of a polygonal pyramid, a polygonal truncated pyramid, a cone, a truncated cone, or a hemisphere, and a plurality of outer protrusions 26 having these shapes may be scattered.

[0064] As shown in Figures 2 and 5 to 7, the cryoablation catheter 100 preferably has a hole 33 that connects the supply lumen 31 to the discharge channel 21. The hole 33 is preferably provided in the distal portion or distal end of the cryoablation catheter 100. Fluid transported from the proximal side to the distal side by passing through the supply lumen 31 is transported to the discharge channel 21 via the hole 33. As shown in Figures 2 and 5 to 7, the hole 33 may be formed in the inner shaft 30.

[0065] The cryoablation catheter 100 preferably has a balloon 40, and the supply lumen 31 and the discharge channel 21 are in communication with each other via an interior 401 of the balloon 40. The balloon 40 is preferably provided at the distal portion or distal end of the cryoablation catheter 100. The balloon 40 may be connected to the distal portion or distal end of the shaft 1.

[0066] The balloon 40 is preferably supplied with fluid via the supply lumen 31. The balloon 40 may have an interior 401 to which the fluid is supplied, an inner surface 402 facing the interior 401 of the balloon 40, and an outer surface 403 facing the exterior of the balloon 40.

[0067] 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.

[0068] As shown in FIG. 2 , the hole 33 is preferably located inside 401 of the balloon 40. For example, the hole 33 is preferably formed in a portion of the inner shaft 30 that is located inside 401 of the balloon 40. The hole 33 may also be formed in a portion of the inner shaft 30 that is not located inside 401 of the balloon 40. However, the hole 33 is preferably formed only in a portion of the inner shaft 30 that is located inside 401 of the balloon 40. This makes it easier to increase the distance between the hole 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 and to make it easier to prevent excessive cooling of tissue other than the target tissue via portions other than the balloon 40.

[0069] 2 and 5 to 7, 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 30c 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 20c of the outer shaft 20.

[0070] 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.

[0071] 1, 2, and 5 to 7, 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 a 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.

[0072] 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.

[0073] 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.

[0074] 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.

[0075] As shown in FIG. 1, the hub 2 may have a bifurcated structure.

[0076] 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.

[0077] The cryoablation catheter 100 may be configured to supply air to the air layer 11 at a temperature higher than that of the fluid passing through the discharge channel 21 from the distal side to the proximal side. For example, the hub 2 may be provided with an air injection unit 6 capable of injecting air to be supplied to the air layer 11, and air at a temperature higher than that of the fluid passing through the discharge channel 21 from the distal side to the proximal side may be supplied to the air layer 11 via the air injection unit 6. This makes it difficult for cooling by the fluid passing through the supply lumen 31 and the discharge channel 21 to reach portions located outside the air layer 11 in the radial direction y of the cryoablation catheter 100. This makes it easier to prevent excessive cooling of tissues other than the target tissue while the fluid is passing through the supply lumen 31 and the discharge channel 21. The air injection unit 6 may be connected to an air supply device 7. Examples of the air supply device 7 include a regulator, a flow rate controller, and a pump.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] This application claims the benefit of priority based on Japanese Patent Application No. 2024-028385, filed February 28, 2024. The entire contents of the specification of Japanese Patent Application No. 2024-028385, filed February 28, 2024, are incorporated herein by reference.

[0088] DESCRIPTION OF SYMBOLS 1: Shaft 1a: Distal shaft portion 1b: Proximal shaft portion 2: Hub 3: Fluid injection portion 4: Fluid supply device 5: Guidewire port 6: Air injection portion 7: Air supply device 10: Insulated shaft 10a: Lumen 10b: Inner surface 10c: Outer surface 11: Air layer 12: Insulation layer 13: Member 14: Wire 15: Coil 16: Inner protrusion 20: Outer shaft 20a: Lumen 20b: Inner surface 20c: Outer surface 21: Discharge flow path 26: Outer protrusion 30: Inner shaft 30a: Lumen 30c: Outer surface 31: Supply lumen 32: Guidewire lumen 33: Hole 34: Radiopaque marker portion 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 401: Interior 402: Inner surface 403: Outer surface 50: Distal tip 51: Lumen 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; an exhaust flow path located in a region different from the supply lumen in the radial direction, extending in the longitudinal direction, and allowing a fluid that has passed through the supply lumen to pass from the distal side to the proximal side; and an insulating layer having an air layer and extending in the longitudinal direction, wherein, in a cross section perpendicular to the longitudinal direction, the insulating layer is located radially outward of the supply lumen and the exhaust flow path.

2. The cryoablation catheter according to claim 1, wherein the cryoablation catheter comprises an insulated shaft having a lumen extending in the longitudinal direction, an outer shaft disposed in the lumen of the insulated shaft and 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, the discharge flow path is a space existing between the outer surface of the inner shaft and the inner surface of the outer shaft, and the air layer is a space existing between the inner surface of the insulated shaft and the outer surface of the outer shaft.

3. A cryoablation catheter according to claim 1 or 2, wherein a member is disposed in the air layer.

4. A cryoablation catheter according to claim 3, wherein the member is a coil having a wire made of resin, the wire being wound around the supply lumen and the discharge flow path.

5. A cryoablation catheter as described in claim 2, wherein a member is disposed in the air layer, the member being a coil having a wire made of resin, the coil being fixed to the outer surface of the outer shaft and not fixed to the inner surface of the insulated shaft.

6. A cryoablation catheter according to claim 2, wherein the insulated shaft has an inner protrusion that protrudes radially inward of the cryoablation catheter.

7. A cryoablation catheter according to claim 2, wherein the outer shaft has an outer protrusion that protrudes radially outward from the cryoablation catheter.

8. A cryoablation catheter according to claim 1 or 2, wherein the cross-sectional area of ​​the air layer in a cross section perpendicular to the longitudinal direction is 2 / 5 or more of the cross-sectional area of ​​the discharge flow path.

9. A cryoablation catheter according to claim 1 or 2, having a hole communicating said supply lumen with said discharge channel.

10. A cryoablation catheter according to claim 1 or 2, wherein the cryoablation catheter has a balloon, and the supply lumen and the discharge flow path communicate with each other through the inside of the balloon.

11. A cryoablation catheter according to claim 1 or 2, wherein air having a higher temperature than the fluid conveyed from the distal side to the proximal side through the discharge channel is supplied to the air layer.

12. A cryoablation catheter according to claim 1 or 2, wherein the air layer is not in communication with the supply lumen and the discharge flow path.

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