Catheter and catheter manufacturing method

Abstract

To provide a catheter capable of improving periphery reachability and improving procedural efficiency by suppressing unintended movement of the catheter, and to provide a catheter manufacturing method.SOLUTION: A catheter 10 includes a body 20 having an inner layer 30, an outer layer 60, and a coil 40 formed by winding a wire outside the inner layer 30, which extends in a longitudinal direction X. The body 20 includes a first external diameter part 21, a second external diameter part 22 adjacent to a base end side of the first external diameter part 21, and a third external diameter part 23 adjacent to a base end side of the second external diameter part 22. The first external diameter part 21 includes a first external layer 61 made of first resin, the second external diameter part 22 includes a second external layer 62 made of second resin whose hardness is higher than that of the first resin, and the third external diameter part 23 includes a third external layer 63 made of third resin whose hardness is higher than that of the second resin. The outer diameter of the third outer diameter part 23 is larger than the outer diameter of the first outer diameter part 21 and smaller than the outer diameter of the second outer diameter part 22.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a catheter for use in a lumen such as a blood vessel, and a method for manufacturing the catheter. [Background technology]

[0002] For lesions occurring in blood vessels, endovascular treatment is performed by inserting a catheter percutaneously into the blood vessel under radiographic guidance to diagnose and treat the target area. For example, for liver tumors, hepatic artery embolization is performed by inserting a catheter through the hepatic artery to the vicinity of the tumor and injecting a contrast agent or embolic substance to diagnose and treat the liver tumor.

[0003] To achieve peripheral reach, catheters used in such intravascular treatments must have a flexible tip that allows them to move along a leading guidewire through complexly curved blood vessels. Furthermore, catheters must have the pushability to transmit the pushing force applied to the proximal end by the surgeon to the distal end, and kink resistance to prevent bending even after the guidewire is removed. Catheters must also have pressure resistance to allow the injection of fluids such as contrast agents and embolic materials through the lumen.

[0004] Patent Document 1 discloses a catheter that has excellent flexibility and kink resistance at the tip, and that includes a fluororesin layer, a tubular reinforcing body arranged on the outer periphery of the base end of the fluororesin layer, a metal coil arranged on the outer periphery of the tip end of the fluororesin layer, and a resin layer arranged on the outermost periphery. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-223728 Summary of the Invention [Problem to be solved by the invention]

[0006] In recent years, there has been a demand for hepatic artery embolization to target tumors located further peripherally. The hepatic arteries have sharp branching sections and complexly curved, tortuous sections in the proper hepatic artery. Therefore, catheters used in hepatic artery embolization are required to have even greater flexibility at their tips.

[0007] However, if a catheter is too flexible, it is prone to kinking at bifurcated or meandering sections. Furthermore, the catheter's ability to transmit pushing force is reduced, making it difficult to insert into peripheral areas. Furthermore, because the catheter's pressure resistance is also reduced, when fluid is injected into the catheter, the reaction force generated by the fluid injection can cause the catheter to move from the intended position, reducing the efficiency of the procedure.

[0008] The present invention has been made to solve the above-mentioned problems, and aims to provide a catheter and a method for manufacturing a catheter that can improve the efficiency of procedures by improving peripheral reachability and suppressing unintended catheter movement. [Means for solving the problem]

[0009] The above object can be achieved by the invention described in (1) below.

[0010] (1) A catheter according to the present invention has a main body extending in a longitudinal direction and including an inner layer, an outer layer, and a coil formed by winding a wire around the inner layer, wherein the main body has a first outer diameter portion, a second outer diameter portion adjacent to the base end side of the first outer diameter portion, and a third outer diameter portion adjacent to the base end side of the second outer diameter portion, wherein the first outer diameter portion has a first outer layer made of a first resin, the second outer diameter portion has a second outer layer made of a second resin having a harder resin than the first resin, and the third outer diameter portion has a third outer layer made of a third resin having a harder resin than the second resin, and the outer diameter of the third outer diameter portion is larger than the outer diameter of the first outer diameter portion and smaller than the outer diameter of the second outer diameter portion. [Effects of the Invention]

[0011] The catheter described in (1) above uses a flexible first outer layer in the first outer diameter section, allowing it to follow the guidewire even at sharply angled branching blood vessels. Furthermore, the catheter uses a second outer diameter section adjacent to the first outer diameter section that is harder than the first outer layer in the first outer diameter section and has a larger outer diameter of the main body, thereby providing rigidity that allows insertion into peripheral branches of blood vessels. Furthermore, the catheter uses a third outer diameter section adjacent to the second outer diameter section that is harder than the second outer layer, while reducing the outer diameter of the main body, thereby providing kink resistance and pressure resistance without impeding peripheral reachability. Therefore, this catheter can improve peripheral reachability and suppress unintended movement, improving the efficiency of procedures.

[0012] (2) In the catheter described in (1) above, the coil has a plurality of pitch regions with different pitches along the longitudinal axis direction, and the first outer diameter portion has a first densely wound portion, which is a pitch region in which the wire is wound more densely than adjacent pitch regions in the longitudinal axis direction, a second densely wound portion located proximal to the first densely wound portion, which is a pitch region in which the wire is wound more densely than adjacent pitch regions in the longitudinal axis direction, and an openly wound portion located between the first densely wound portion and the second densely wound portion, which is a pitch region in which the wire is wound more loosely than the first densely wound portion and the second densely wound portion, and the position of the boundary between the first outer layer and the second outer layer may overlap the position of the second densely wound portion in the longitudinal axis direction. Thus, by having an openly wound portion between the two densely wound portions in the first outer diameter portion, the catheter can form an inflection point of rigidity near the tip, thereby improving the flexibility of the tip portion. Furthermore, by overlapping the boundary between the first and second outer diameter sections with the second densely wound section, the kink resistance and pressure resistance at the boundary can be improved. This allows the catheter to improve peripheral reachability and prevent unintended migration, improving the efficiency of the procedure.

[0013] (3) In the catheter described in (1) or (2) above, the coil pitch in the third outer diameter portion may be equal to that in the second outer diameter portion, thereby preventing kinking at the boundary between the second and third outer layers.

[0014] (4) In the catheter described in any one of (1) to (3) above, the coil may be embedded in the outer layer. As a result, in this catheter, the coil is spaced from the inner layer, and a resin forming the outer layer is disposed between the coil and the inner layer. Furthermore, because the coil is not embedded in the inner layer, the thickness of the inner layer does not become locally thin. Therefore, the catheter can have a thin overall inner layer thickness while maintaining pressure resistance. Therefore, this catheter can have an increased inner diameter without increasing the outer diameter, thereby improving the delivery efficiency of an embolization coil, a drug, a contrast agent, an embolic substance, or the like.

[0015] (5) A method for manufacturing a catheter that achieves the above object is a catheter having a main body extending in a longitudinal direction, the main body including an inner layer, an outer layer, and a coil formed by winding a wire around the inner layer, the main body having a first outer diameter portion, a second outer diameter portion adjacent to the base end side of the first outer diameter portion, and a third outer diameter portion adjacent to the base end side of the second outer diameter portion, the first outer diameter portion having a first outer layer made of a first resin, the second outer diameter portion having a second outer layer made of a second resin having a hardness higher than that of the first resin, the third outer diameter portion having a third outer layer made of a third resin having a hardness higher than that of the second resin, A method for manufacturing a catheter having an outer diameter of the first outer diameter portion greater than that of the first outer diameter portion and smaller than that of the second outer diameter portion includes the steps of: inserting a mandrel into an inner tube forming the inner layer; winding the wire around the outer surface of the inner tube under tension to form the coil; arranging an outer tube forming the outer layer so as to cover the coil; arranging a heat-shrinkable tube so as to cover the outer tube; and heating the heat-shrinkable tube from one direction in the longitudinal direction and shrinking it while twisting it in the direction opposite to the winding direction of the coil. This facilitates loosening of the coil by shrinking the heat-shrinkable tube while twisting it in the direction opposite to the winding direction of the coil. This separates the coil from the inner layer, allowing the resin of the outer tube to flow between the inner layer and the coil. This manufacturing method therefore enables the manufacture of a catheter with a thin inner layer while maintaining pressure resistance.

[0016] (6) In the method for manufacturing a catheter described in (5) above, the tension applied to the wire may be 60 gf to 100 gf. By winding the wire with a tension in this range, the wire forming the coil is not embedded in the inner layer, and the thickness of the inner layer is not locally reduced. Therefore, this manufacturing method makes it possible to easily manufacture a catheter with a thin inner layer while maintaining pressure resistance. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a plan view showing a catheter according to an embodiment. [Figure 2] FIG. 2 is a longitudinal cross-sectional view showing the distal end of the catheter. [Figure 3] FIG. 2 is a longitudinal cross-sectional view showing the main body of the catheter. [Figure 4] FIG. 1 is a cross-sectional view of a catheter. [Figure 5] FIG. 10 is a plan view illustrating a method for manufacturing a catheter. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the dimensional proportions in the drawings may be exaggerated for convenience of explanation and may differ from the actual proportions. In the following description, the side of the catheter that is operated will be referred to as the "proximal end" and the side that is inserted into the living body will be referred to as the "distal end."

[0019] The catheter 10 according to an embodiment of the present invention is a catheter 10 that is delivered to the vicinity of a tumor through the hepatic artery to diagnose or treat the tumor in the liver, and delivers an embolic coil, a drug, a contrast agent, an embolic substance, or the like.

[0020] As shown in FIG. 1, the catheter 10 includes a flexible tubular main body 20, a hub 70 fixed to the proximal end of the main body 20, and a kink-resistant protector 80.

[0021] 1 to 4, the main body 20 is a flexible tubular member, and a lumen 27 is formed around the axis of the main body 20 from the distal end to the proximal end. The lumen 27 opens at a distal opening 28 formed at the distal end of the main body 20. The lumen 27 functions as a passage for a guidewire, an embolization coil, a drug, a contrast agent, an embolic substance, or the like.

[0022] The hub 70 is fixed to the base end of the main body 20. The hub 70 has a hub lumen 71 that communicates with the lumen 27 and opens at the base end. The hub 70 functions as an insertion port for a guide wire or an embolization coil into the lumen 27, or as an injection port for a drug, contrast agent, embolic substance, or the like into the lumen 27. The hub 70 also functions as a gripping portion that the surgeon grips and operates.

[0023] The anti-kink protector 80 is a flexible member that is attached so as to cover the portion connecting the main body 20 and the hub 70. The anti-kink protector 80 suppresses kinking of the main body 20 at the connecting portion between the main body 20 and the hub 70.

[0024] At least the outer peripheral surface of the tip of the main body 20 may be coated with a lubricious coating 90. The lubricious coating 90 is, for example, a hydrophilic polymer, such as a cellulose-based polymer, a polyethylene oxide-based polymer, a maleic anhydride-based polymer (e.g., a maleic anhydride copolymer such as a methyl vinyl ether-maleic anhydride copolymer), an acrylamide-based polymer (e.g., a block copolymer of polyacrylamide, glycidyl methacrylate-dimethylacrylamide), water-soluble nylon, polyvinyl alcohol, polyvinylpyrrolidone, or a derivative thereof. Alternatively, the lubricious coating 90 may be formed of a fluorine-based resin such as polytetrafluoroethylene (PTFE), a low-friction material such as high-density polyethylene (HDPE), or the like.

[0025] The main body 20 includes an inner layer 30 that defines the lumen 27, a coil 40 disposed outside the inner layer 30, and an outer layer 60 that is disposed outside the inner layer 30 and covers the coil 40.

[0026] The inner layer 30 is preferably formed from a low-friction material, which can reduce the sliding resistance of the guidewire and embolization coil within the lumen 27, as well as the flow resistance of drugs, contrast media, embolic substances, etc. Examples of low-friction materials include fluorine-based resins such as polytetrafluoroethylene (PTFE) and tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA).

[0027] The inner diameter of the inner layer 30 is, for example, 0.6 mm to 0.8 mm, and is, for example, 0.7 mm. The thickness of the inner layer 30 is, for example, 30 μm to 40 μm.

[0028] 2 to 4, the coil 40 is a member that reinforces the main body 20 and is formed by spirally winding a single continuous wire. The coil 40 does not contact the inner layer 30 and is located radially outward of the inner layer 30. Therefore, the material of the outer layer 60 is disposed between the coil 40 and the inner layer 30, so that the coil 40 is embedded in the outer layer 60.

[0029] The pitch P (see FIG. 2 ) of the coil 40 varies depending on the position in the longitudinal axis direction X of the main body 20. The pitch P of the coil 40 is the distance between the central axes of adjacent wire rods of the coil 40 in a vertical cross section passing through the axis of the main body 20. In this embodiment, the coil 40 has M pitch regions with different pitches P. M is an integer equal to or greater than 3, and is 8 in this embodiment, but is not limited to this and may be 11, for example. The coil 40 has M (m)th outer layers (m=1, ..., M) from the distal end to the proximal end. That is, from the tip end to the base end, the coil 40 has a first pitch region 41 (first densely wound portion), a second pitch region 42 (increased pitch portion), a third pitch region 43 (increased pitch portion), a fourth pitch region 44 (openly wound portion), a fifth pitch region 45 (second densely wound portion), a sixth pitch region 46 (the (M-2) region), a seventh pitch region 47 (the (M-1) region), and an eighth pitch region 48 (the (M) region) that reaches approximately the base end of the main body 20.

[0030] As shown in FIG. 2, the wire in the first pitch region 41 (first densely wound portion) is wound with gaps in the longitudinal direction X, but is wound more densely than the pitch regions closer to the base end than the first pitch region 41. The wire in the first pitch region 41 may be densely wound with no gaps in the longitudinal direction X. The pitch P (first pitch) of the first pitch region 41 is determined according to the diameter of the wire, and is, for example, 30 μm to 100 μm, and is, for example, 95 μm. The tip of the first pitch region 41 is located closer to the base end than the tip of the main body 20, and the length L0 in the longitudinal direction X from the tip of the main body 20 to the tip of the first pitch region 41 is, for example, 0.8 mm to 1.2 mm, and is, for example, 1.0 mm. The length L1 in the longitudinal direction X of the first pitch region 41 is, for example, 0.7 mm to 1.1 mm, and is, for example, 0.9 mm.

[0031] The wire in the second pitch region 42 (increased pitch portion) is loosely wound with gaps in the longitudinal direction X. The pitch P (second pitch) of the second pitch region 42 is larger than the first pitch and is, for example, 100 μm to 120 μm, and is, for example, 110 μm. The length L2 of the second pitch region 42 in the longitudinal direction X is, for example, 1.1 mm to 1.5 mm, and is, for example, 1.3 mm.

[0032] The wire in the third pitch region 43 (increased pitch portion) is loosely wound with gaps in the longitudinal direction X. The pitch P (third pitch) of the third pitch region 43 is larger than the second pitch and is, for example, 130 μm to 150 μm, e.g., 140 μm. The length L3 of the third pitch region 43 in the longitudinal direction X is, for example, 1.3 mm to 1.7 mm, e.g., 1.5 mm.

[0033] The wire in the fourth pitch region 44 (openly wound portion) is openly wound with gaps in the longitudinal direction X. The pitch P (fourth pitch) of the fourth pitch region 44 is larger than the third pitch and is, for example, 180 μm to 200 μm, and is, for example, 190 μm. The length L4 of the fourth pitch region 44 in the longitudinal direction X is, for example, 1.3 mm to 1.7 mm, and is, for example, 1.5 mm. The tip of the fourth pitch region 44 is preferably located 4 mm to 6 mm from the tip of the main body 20 toward the base end.

[0034] As shown in FIGS. 2 and 3, the wire in the fifth pitch region 45 (second densely wound portion) is wound with gaps in the longitudinal direction X, but is wound more densely than the second pitch region 42, the third pitch region 43, and the fourth pitch region 44. The wire in the fifth pitch region 45 may be densely wound with no gaps in the longitudinal direction X. The pitch P (fifth pitch) of the fifth pitch region 45 is smaller than the second to fourth pitches, and is, for example, 90 μm to 110 μm, and is, for example, 100 μm. The length L5 of the fifth pitch region 45 in the longitudinal direction X is, for example, 244 mm to 246 mm, and is, for example, 245 mm.

[0035] As shown in Fig. 3, the wire in the sixth pitch region 46 is loosely wound with gaps in the longitudinal axis direction X. The pitch P (sixth pitch) of the sixth pitch region 46 is larger than the fifth pitch and is, for example, 140 µm to 160 µm, and is, for example, 150 µm. The length L6 of the sixth pitch region 46 in the longitudinal axis direction X is, for example, 79 mm to 81 mm, and is, for example, 80 mm. For example, the tip of the sixth pitch region 46 is preferably located approximately 250 mm from the tip of the main body 20 toward the base end.

[0036] The wire in the seventh pitch region 47 is loosely wound with gaps in the longitudinal direction X. The pitch P (seventh pitch) of the seventh pitch region 47 is larger than the sixth pitch and is, for example, 240 μm to 260 μm, and is, for example, 250 μm. The length L7 of the seventh pitch region 47 in the longitudinal direction X is, for example, 69 mm to 71 mm, and is, for example, 70 mm. The tip of the seventh pitch region 47 is, for example, preferably located approximately 330 mm from the tip of the main body 20 toward the base end.

[0037] The wire in the eighth pitch region 48 is loosely wound with gaps in the longitudinal direction X. The pitch P (eighth pitch) of the eighth pitch region 48 is larger than the seventh pitch and is, for example, 340 μm to 360 μm, and is, for example, 350 μm. The length L8 of the eighth pitch region 48 in the longitudinal direction X is, for example, 656 mm to 1158 mm, and is, for example, 963 mm. The tip of the eighth pitch region 48 is, for example, preferably located approximately 400 mm from the tip of the main body 20 toward the base end.

[0038] As shown in Figures 2 and 3, the coil 40 has pitch increasing sections (second pitch region 42, third pitch region 43) between the first pitch region 41 (first densely wound section) and the fourth pitch region 44 (openly wound section) where the pitch P increases stepwise or continuously.

[0039] The pitch P of the coil 40 is smallest in the pitch region (first pitch region 41) located at the most distal end of the coil 40, and is largest in the pitch region (eighth pitch region 48) located at the most proximal end.

[0040] The diameter of the wire that forms the coil 40 is, for example, 30 μm to 50 μm, and is 50 μm as an example.

[0041] The coil 40 may be made of a metal or a non-metal. Metals may include, for example, stainless steel, nickel-titanium alloy, platinum, gold, silver, iridium, and tungsten, either singly or in combination. Non-metals may include, for example, carbon, polyamide, polyethylene terephthalate, and polybutylene terephthalate, either singly or in combination. If the coil 40 is made of a radiopaque material, the densely wound portion of the coil 40 can function as a radiopaque marker. Radiopaque materials include tungsten, platinum, gold, silver, iridium, and alloys containing these. The cross-sectional shape of the wire forming the coil 40 is circular in this embodiment, but is not particularly limited and may be, for example, elliptical, oval, rectangular, square, or the like.

[0042] The outer layer 60 has hardness that varies stepwise or continuously in the longitudinal direction X. In this embodiment, the outer layer 60 has N portions with different hardness or materials. N is an integer of 2 or greater, and is 6 in this embodiment, but is not limited to this. The outer layer 60 has N (n)th outer layers (n = 1, ..., N) from the distal end to the proximal end. That is, the outer layer 60 includes, from the distal end to the proximal end, a first outer layer 61 made of a first resin, a second outer layer 62 made of a second resin, a third outer layer 63 made of a third resin, a fourth outer layer 64 made of a fourth resin, a fifth outer layer 65 ((N-1)th outer layer) made of a fifth resin ((N-1)th resin), and a sixth outer layer 66 ((N)th outer layer) made of a sixth resin ((N)th resin) that reaches the proximal end of the main body 20.

[0043] The main body 20, formed by the inner layer 30, the coil 40, and the outer layer 60, has N (n)th outer diameter portions (n ​​= 1, ..., N) from the distal end to the proximal end. That is, the main body 20 includes a first outer diameter portion 21 located in a region having a first outer layer 61, a second outer diameter portion 22 located in a region having a second outer layer 62, a third outer diameter portion 23 located in a region having a third outer layer 63, a fourth outer diameter portion 24 located in a region having a fourth outer layer 64, a fifth outer diameter portion 25 (the (N-1)th outer diameter portion) located in a region having a fifth outer layer 65 (the (N-1)th outer layer), and a sixth outer diameter portion 26 (the (N)th outer diameter portion) located in a region having a sixth outer layer 66 (the (N)th outer layer). The outer diameter portions adjacent to each other in the longitudinal axis direction X have different outer diameters. Note that the outer diameter portions adjacent to each other in the longitudinal axis direction X may have the same outer diameter. Each outer diameter portion has a part of the outer layer 60, a part of the coil 40, and a part of the inner layer 30. Note that the outer diameter portions located at the distal end or proximal end of the main body 20 may not have the coil 40.

[0044] The length L11 of the first outer diameter portion 21 in the longitudinal direction X is, for example, 7 mm to 13 mm, and is, for example, 10 mm. The base end of the first outer diameter portion 21 is located midway within the fifth pitch region 45 in the longitudinal direction X. The length L12 of the second outer diameter portion 22 in the longitudinal direction X is, for example, 25 mm to 35 mm, and is, for example, 30 mm. The tip and base ends of the second outer diameter portion 22 are located midway within the fifth pitch region 45 in the longitudinal direction X. The length L13 of the third outer diameter portion 23 in the longitudinal direction X is, for example, 55 mm to 65 mm, and is, for example, 60 mm. The tip and base ends of the third outer diameter portion 23 are located midway within the fifth pitch region 45 in the longitudinal direction X. The length L14 of the fourth outer diameter portion 24 in the longitudinal direction X is, for example, 95 mm to 105 mm, and is, for example, 100 mm. The tip and base ends of the fourth outer diameter portion 24 are located midway through the fifth pitch region 45 in the longitudinal axis direction X. The length L15 of the fifth outer diameter portion 25 in the longitudinal axis direction X is, for example, 95 mm to 105 mm, and is, for example, 100 mm. The tip of the fifth outer diameter portion 25 is located midway through the fifth pitch region 45 in the longitudinal axis direction X, and the base end of the fifth outer diameter portion 25 is located midway through the sixth pitch region 46 in the longitudinal axis direction X. The length L16 of the sixth outer diameter portion 26 in the longitudinal axis direction X is, for example, 695 mm to 1205 mm, and is, for example, 1000 mm. The tip of the sixth outer diameter portion 26 is located midway through the sixth pitch region 46 in the longitudinal axis direction X. The change position of the pitch P differs from the change position of the outer diameter portion (outer layer 60). The boundary between the fifth outer diameter portion 25 and the sixth outer diameter portion 26 is located at a position 250 mm to 400 mm from the tip of the main body 20, and more preferably at a position 250 mm to 300 mm.

[0045] The material of the outer layer 60 is, for example, polyamide, polyamide elastomer, thermoplastic polyurethane elastomer, or the like, and polyester elastomer may be mixed with polyamide.

[0046] The material of the first outer layer 61 preferably has a Shore D hardness of 30 or less (Young's modulus of 30 MPa). The material of the first outer layer 61 is, for example, a polyamide elastomer with a Shore D hardness of 27. The Shore D hardness of the material of the second outer layer 62 is greater than the Shore D hardness of the material of the first outer layer 61, but may be approximately the same as the Shore D hardness of the material of the first outer layer 61. The material of the second outer layer 62 is, for example, a polyamide elastomer with a Shore D hardness of 33. The Shore D hardness of the material of the third outer layer 63 is greater than the Shore D hardness of the material of the second outer layer 62, but may be approximately the same as the Shore D hardness of the material of the second outer layer 62. The material of the third outer layer 63 is, for example, a polyamide elastomer with a Shore D hardness of 42. The Shore D hardness of the material of the fourth outer layer 64 may be greater than, but approximately the same as, the Shore D hardness of the material of the third outer layer 63. The material of the fourth outer layer 64 may be, for example, a polyamide elastomer with a Shore D hardness of 56. The Shore D hardness of the material of the fifth outer layer 65 may be greater than, but approximately the same as, the Shore D hardness of the material of the fourth outer layer 64. The material of the fifth outer layer 65 may be, for example, a polyamide elastomer with a Shore D hardness of 62. The Shore D hardness of the material of the sixth outer layer 66 may be greater than, but approximately the same as the Shore D hardness of the material of the fifth outer layer 65. The material of the sixth outer layer 66 may be, for example, a polyamide elastomer with a Shore D hardness of 73 or a thermoplastic polyurethane elastomer with a Shore D hardness of 75. The fifth outer layer 65 and the sixth outer layer 66 preferably have a Shore D hardness of 55 or more.

[0047] The rigidity of the main body 20 preferably increases stepwise or continuously from the distal end to the proximal end. In this embodiment, the rigidity of the main body 20 can be expressed as the bending load required to support the main body 20 at two fulcrums 5 mm apart in the longitudinal axis direction X and press the main body 20 0.5 mm from the opposite side at the force point at the center of the two fulcrums in a three-point bending test. The bending load of the main body 20 in the three-point bending test is 20 gf or less for the first outer diameter portion 21 and the second outer diameter portion 22, and 20 gf or more for the third outer diameter portion 23 to the sixth outer diameter portion 26. The bending load of the second outer diameter portion 22 is 10 gf to 25 gf, for example, 20 gf. The bending load of the third outer diameter portion 23 is 25 gf to 50 gf, for example, 40 gf. The bending load of the fourth outer diameter portion 24 is 50 gf to 100 gf, for example, 90 gf. The bending load of the fifth outer diameter portion 25 is 100 gf to 140 gf, for example, 120 gf. The bending load of the sixth outer diameter portion 26 is 140 gf to 180 gf, for example, 150 gf.

[0048] The outer diameter of the main body 20 (outer layer 60) is so-called 2.7 Fr (approximately 0.9 mm) to 3.0 Fr (1.0 mm) and varies along the longitudinal axis direction X within a range compatible therewith. The outer diameter of the second outer diameter portion 22 is larger than the outer diameter of the first outer diameter portion 21. The outer diameter of the third outer diameter portion 23 is larger than the outer diameter of the first outer diameter portion 21 and smaller than the outer diameter of the second outer diameter portion 22. The outer diameter of the fourth outer diameter portion 24 is larger than the outer diameter of the third outer diameter portion 23. The outer diameter of the fourth outer diameter portion 24 is smaller than the outer diameter of the second outer diameter portion 22. The outer diameter of the fifth outer diameter portion 25 is equal to or larger than the first outer diameter portion 21 and smaller than the outer diameters of the third outer diameter portion 23 and the fourth outer diameter portion 24. The outer diameter of the sixth outer diameter portion 26 is larger than the outer diameter of the fifth outer diameter portion 25. The outer diameter of the sixth outer diameter portion 26 is preferably 105% to 120% of the outer diameter of the fifth outer diameter portion 25. The outer diameter of the first outer diameter portion 21 is preferably smaller than the outer diameter of any of the second outer diameter portion 21 to the sixth outer diameter portion 26. In addition, the outer diameter of the sixth outer diameter portion 26 is preferably larger than the outer diameter of any of the first outer diameter portion 21 to the fifth outer diameter portion 25.

[0049] The length of the main body 20 in the longitudinal direction X is preferably a length that can reach the vicinity of the liver through the femoral or radial artery and is, for example, 1000 mm to 1500 mm, for example 1300 mm.

[0050] Next, a method for manufacturing the catheter 10 according to this embodiment will be described.

[0051] First, as shown in Figure 5, the manufacturer inserts a mandrel 103 into the inner layer tube 100 on which the inner layer 30 is to be formed. The inner layer 30 and the mandrel 103 may be formed by coating the mandrel 103 with the inner layer 30. Next, the manufacturer forms the coil 40 by winding the wire that will form the coil 40 around the outer surface of the inner layer tube 100 while applying tension. The tension applied to the wire is preferably 60 gf to 100 gf, and is 80 gf, for example. The tension applied to the wire is constant, but may be varied depending on the position in the longitudinal axis direction X of the inner layer tube 100.

[0052] Next, the manufacturer arranges a plurality of outer tubes 101 that form the outer layer 60 so as to cover the inner tube 100 and the coil 40. The outer tubes 101 correspond to the first outer layer 61 to the sixth outer layer 66, respectively.

[0053] Next, the manufacturer places the heat-shrinkable tube 102 so as to cover the outer tube 101. The heat-shrinkable tube 102 has, for example, a molecular orientation that is circumferential and inclined with respect to the longitudinal axis direction X. The heat-shrinkable tube 102 having such a molecular orientation can be manufactured, for example, by applying a rotational force by a screw during extrusion molding.

[0054] Next, the manufacturer heats the heat-shrinkable tube 102 by moving a heating means 110, such as a heater, from one side (the distal end or the proximal end) of the heat-shrinkable tube 102 in the longitudinal direction X toward the opposite side. During this process, the heat-shrinkable tube 102 shrinks while twisting in accordance with its molecular orientation, as indicated by the dashed-dotted arrow in FIG. 5 . The manufacturer shrinks the heat-shrinkable tube 102 while twisting it in the direction opposite to the winding direction of the coil 40. This causes the coil 40 to loosen in the unwinding direction, and the wire forming the coil 40 moves radially outward from the inner tube 100. The resin of the outer tube 101, softened by heating, flows into the gap between the inner tube 100 and the wire forming the coil 40 as the heat-shrinkable tube 102 shrinks. As a result, the coil 40 moves away from the inner layer 30 and becomes embedded in the outer layer 60. It is possible that the resin of the outer layer 60 will not flow into the gap between the inner layer 30 and the wire that forms the coil 40, resulting in the formation of a void. This completes the manufacture of the main body 20. Next, the manufacturer attaches the hub 70 and the anti-kink protector 80 to the main body 20, and coats the outer surface of the outer layer 60 with a lubricating coat 90. This completes the manufacture of the catheter 10.

[0055] As described above, the catheter 10 according to this embodiment is a catheter 10 having a main body 20 extending in the longitudinal axis direction X, which includes an inner layer 30, an outer layer 60, and a coil 40 formed by winding a wire around the inner layer 30, the main body 20 having a first outer diameter portion 21 and a second outer diameter portion 22 adjacent to the base end side of the first outer diameter portion 21, the first outer diameter portion 21 having a first outer layer 61 made of a first resin, and the second outer diameter portion 22 having a second outer layer 62 made of a second resin having a higher hardness than the first resin, the coil 40 having a plurality of pitch regions with different pitches P along the longitudinal axis direction X, and the first outer diameter portion 21 has a first outer layer 61 made of a first resin and a second outer layer 62 made of a second resin having a higher hardness than the first resin. the first outer layer 61 and the second outer layer 62 are wound in a relatively more densely wound pitch region than the adjacent pitch region (second pitch region), the second densely wound portion (fifth pitch region 45) is located proximally of the first densely wound portion and is wound more densely than the adjacent pitch regions (fourth pitch region 44 and sixth pitch region 46), and the loosely wound portion (fourth pitch region 44) is located between the first densely wound portion and the second densely wound portion and is wound more loosely than the first densely wound portion and the second densely wound portion, and the position of the boundary between the first outer layer 61 and the second outer layer 62 overlaps with the position of the second densely wound portion in the longitudinal axis direction X. As a result, the catheter 10 has an loosely wound portion between the two densely wound portions of the first outer diameter portion 21, which allows an inflection point of bending rigidity to be formed near the tip, thereby improving the flexibility of the tip portion. Furthermore, since the boundary between the first outer diameter portion 21 and the second outer diameter portion 22 overlaps with the second densely wound portion, the kink resistance at the boundary can be improved. As a result, the catheter 10 can improve peripheral reachability and prevent unintended movement, improving the efficiency of the procedure.

[0056] The outer diameter of the second outer diameter portion 22 is larger than the outer diameter of the first outer diameter portion 21. As a result, the catheter 10 is provided with kink resistance and pressure resistance that can suppress unintended movement during fluid injection, thanks to the second outer diameter portion 22 having an outer diameter larger than that of the first outer diameter portion 21.

[0057] The coil 40 has increasing pitch regions (second pitch region 42 and third pitch region 43) between the first densely wound portion (first pitch region 41) and the loosely wound portion (fourth pitch region 44), in which the pitch P increases from the first densely wound portion to the loosely wound portion. This allows the catheter 10 to gradually reduce the change in stiffness along the longitudinal axis direction X of the distal end by increasing the pitch P of the coil 40 from the distal end to the proximal end in the flexible first outer diameter portion 21. This allows the catheter 10 to bend easily without localized kinking, improving its ability to follow the guidewire. This allows the catheter 10 to improve its peripheral reachability.

[0058] The first densely wound portion (first pitch region 41), the loosely wound portion (fourth pitch region 44), and the second densely wound portion (fifth pitch region 45) of the coil 40 are formed from a single continuous wire. This allows the catheter 10 to have a gradual transition in pitch P at the boundary between the loosely wound portion and the densely wound portion of the coil 40, making it less likely to develop kinks due to local changes in rigidity.

[0059] The coil 40 is embedded in the outer layer 60. As a result, in the catheter 10, the coil 40 is spaced from the inner layer 30, and the resin that forms the outer layer 60 is disposed between the coil 40 and the inner layer 30. Furthermore, because the coil 40 is not embedded in the inner layer 30, the thickness of the inner layer 30 does not become locally thin. This allows the catheter 10 to have a thin overall thickness of the inner layer 30 while maintaining pressure resistance. Therefore, the catheter 10 can have an increased inner diameter without increasing its outer diameter, thereby improving the delivery efficiency of an embolic coil, a drug, a contrast agent, an embolic substance, or the like.

[0060] Furthermore, the catheter 10 according to this embodiment is a catheter 10 having a main body 20 extending in the longitudinal axis direction X and including an inner layer 30, an outer layer 60, and a coil 40 formed by winding a wire around the inner layer 30, wherein the main body 20 has a first outer diameter portion 21, a second outer diameter portion 22 adjacent to the base end of the first outer diameter portion 21, and a third outer diameter portion 23 adjacent to the base end of the second outer diameter portion 22, wherein the first outer diameter portion 21 has a first outer layer 61 made of a first resin, the second outer diameter portion 22 has a second outer layer 62 made of a second resin having a harder hardness than the first resin, and the third outer diameter portion 23 has a third outer layer 63 made of a third resin having a harder hardness than the second resin, and the outer diameter of the third outer diameter portion 23 is larger than the outer diameter of the first outer diameter portion 21 and smaller than the outer diameter of the second outer diameter portion 22. Thus, by using a flexible first outer layer 61 in the first outer diameter section 21, the catheter 10 can follow the guidewire even at sharply angled branching blood vessels. Furthermore, by using a second outer diameter layer 62 in the second outer diameter section 22 adjacent to the first outer diameter section 21 that is harder than the first outer layer 61 of the first outer diameter section 21 and by increasing the outer diameter of the main body 20, the catheter 10 can be provided with rigidity that allows insertion into peripheral branches of blood vessels. Furthermore, by using a third outer diameter layer 63 in the third outer diameter section 23 adjacent to the second outer diameter section 22 that is harder than the second outer layer 62 while reducing the outer diameter of the main body 20, the catheter 10 can be provided with kink resistance and pressure resistance without impeding peripheral reachability. Therefore, the catheter 10 can improve peripheral reachability and suppress unintended migration, thereby improving the efficiency of the procedure.

[0061] The pitch P of the coil 40 is equal in the third outer diameter portion 23 and the second outer diameter portion 22. This allows the catheter 10 to suppress kinking at the boundary between the second outer layer 62 and the third outer layer 63.

[0062] The method for manufacturing the catheter 10 described above includes the steps of inserting a mandrel 103 into the inner-layer tube 100 that forms the inner layer 30; winding a wire around the outer surface of the inner-layer tube 100 under tension to form the coil 40; arranging an outer-layer tube 101 that forms the outer layer 60 to cover the coil 40; arranging a heat-shrinkable tube 102 to cover the outer-layer tube 101; and heating the heat-shrinkable tube 102 from one direction to shrink it while twisting it in the direction opposite to the winding direction of the coil 40. This shrinking of the heat-shrinkable tube 102 while twisting it in the direction opposite to the winding direction of the coil 40 facilitates loosening of the coil 40. This separates the coil 40 from the inner layer 30, allowing the resin of the outer-layer tube 101 to flow between the inner layer 30 and the coil 40. This manufacturing method therefore enables the manufacture of a catheter 10 with a thin inner layer 30 while maintaining pressure resistance.

[0063] In the above-described method for manufacturing catheter 10, the tension applied to the wire is 60 gf to 100 gf. By winding the wire with a tension within this range, the wire forming coil 40 is not embedded in the inner layer 30, preventing localized thinning of the thickness of the inner layer 30. Therefore, this manufacturing method makes it possible to easily manufacture a catheter 10 having a thin inner layer 30 while maintaining pressure resistance.

[0064] Furthermore, the catheter 10 according to this embodiment is a catheter 10 having a main body 20 extending in a longitudinal axis direction X and including an inner layer 30, an outer layer 60, and a coil 40 formed by winding a wire around the inner layer 30, wherein the main body 20 has a plurality of (n)th outer diameter portions (n=1, ..., N) from a first outer diameter portion at the tip to an Nth outer diameter portion (N is an integer of 2 or more) toward the base end, the (N-1)th outer diameter portion having an outer diameter smaller than the (N)th outer diameter portion closest to the base end, the (N)th outer diameter portion having an (N)th outer layer made of an (N)th resin, and the (N-1)th outer diameter portion having an (N)th outer layer made of an (N)th resin. The coil 40 has an (N-1)th outer layer adjacent to the tip of the outer layer and made of an (N-1)th resin having a lower hardness than the (N)th resin, and the coil 40 has a plurality of (m)th pitch regions (m = 1, ..., M) from the tip No. 1 to the base end No. M (M is an integer of 3 or more), the (M-1)th pitch region has a smaller pitch P than the (M)th pitch region closest to the base end, the (M-2)th pitch region has a smaller pitch P than the (M-1)th pitch region, and the position of the boundary between the (N)th outer layer and the (N-1)th outer layer overlaps with the position of the (M-2)th pitch region in the long axis direction X. The (N)th outer diameter portion includes an (N)th outer layer made of an (N)th resin, and the (N-1)th outer diameter portion includes an (N-1)th outer layer made of an (N-1)th resin with a lower hardness than the (N)th resin, resulting in a higher rigidity of the (N)th outer diameter portion than the (N-1)th outer diameter portion. Because the (N)th outer diameter portion has a higher rigidity than the (N-1)th outer diameter portion, the (N)th outer diameter portion can have sufficient pressure resistance even if the pitch P of the coil 40 is increased. This reduces the time required to wind the wire per length of the catheter 10 during formation of the coil 40, thereby improving manufacturing efficiency. Furthermore, by making the pitch P of the coil 40 equal at the boundary between the (N)th outer layer and the (N-1)th outer layer, the catheter 10 can suppress kinking at the boundary. Therefore, the catheter 10 can improve peripheral reachability and suppress unintended migration, thereby improving procedural efficiency.

[0065] The boundary between the (N)th outer diameter portion and the (N-1)th outer diameter portion is located 250 mm to 400 mm from the tip of the main body 20. As a result, the catheter 10 has a highly rigid (N)th outer diameter portion at its base end, and therefore can transmit a pushing force sufficient for insertion into the periphery of a blood vessel to the tip. Furthermore, when the catheter 10 is inserted into the periphery of the liver's blood vessels, the boundary between the (N)th outer diameter portion and the (N-1)th outer diameter portion is located between the common hepatic artery and the proper hepatic artery, and closer to the common hepatic artery than a tortuous portion of the proper hepatic artery. As a result, the catheter 10 can prevent a decrease in blood vessel tracking ability due to the highly rigid (N)th outer diameter portion being inserted into a tortuous portion.

[0066] As the catheter advances toward the periphery of a blood vessel, its contact area with the blood vessel wall increases, increasing insertion resistance. Therefore, as the catheter 10 advances toward the periphery of the blood vessel, a stronger pushing force must be applied. By providing a high-rigidity portion at its proximal end, the catheter 10 can apply a sufficient pushing force for insertion into the periphery of the blood vessel, and the pushing force applied to the proximal end can be transmitted to the distal end. However, when the high-rigidity portion of the catheter is inserted into a tortuous portion of the blood vessel, the catheter cannot follow the tortuous portion of the blood vessel, increasing insertion resistance. Therefore, the catheter's insertability into the periphery is hindered. By providing the boundary between the (N)th outer diameter portion and the (N-1)th outer diameter portion at the above-described position, the high-rigidity (N)th outer diameter portion can be positioned so as not to extend beyond the tortuous portion, thereby improving insertability into the periphery.

[0067] The outer diameter of the (N)th outer diameter portion is 105% to 120% of the outer diameter of the (N-1)th outer diameter portion. By making the outer diameter of the (N)th outer diameter portion larger than the outer diameter of the (N-1)th outer diameter portion, the catheter 10 can improve the pushing force transmission and pressure resistance of the base end without increasing the outer diameter more than necessary, and can suppress unintended movement during fluid injection, thereby improving the efficiency of the procedure with this catheter 10.

[0068] The present invention is not limited to the above-described embodiment, and various modifications may be made by those skilled in the art within the technical spirit of the present invention. For example, the main body 20 may have a curved portion in its natural state when no external force is applied. Furthermore, the use of the catheter 10 is not limited to hepatic artery embolization. [Explanation of symbols]

[0069] 10 Catheter 20 Main Unit 21 1st outer diameter section 22 Second outer diameter section 23 Third outer diameter section 24 4th outer diameter section 25 5th outer diameter section (No. (N-1) outer diameter section) 26 6th outer diameter section (No. (N) outer diameter section) 30 inner layer 40 coils 41 First pitch area (first dense winding) 42 Second pitch region (pitch increase section) 43 Third pitch region (pitch increase section) 44 4th pitch area (open winding) 45 5th pitch area (2nd dense winding area) 46 6th pitch region ((M-2)th pitch region) 47 7th pitch region ((M-1)th pitch region) 48 8th pitch area (Mth pitch area) 60 outer layer 61 1st outer layer 62 2nd outer layer 63 Third outer layer 64 4th outer layer 65 5th outer layer ((N-1) outer layer) 66 6th outer layer ((N) outer layer) 100 Inner layer tube 101 outer tube 102 Heat shrink tubing 103 Core 110 Heating means

Claims

1. A catheter having a longitudinally extending body including an inner layer, an outer layer, and a coil formed by winding a wire around the inner layer, the main body has a first outer diameter portion, a second outer diameter portion adjacent to a base end side of the first outer diameter portion, and a third outer diameter portion adjacent to a base end side of the second outer diameter portion, the first outer diameter portion has a first outer layer made of a first resin, the second outer diameter portion has a second outer layer made of a second resin having a higher hardness than the first resin, and the third outer diameter portion has a third outer layer made of a third resin having a higher hardness than the second resin, A catheter characterized in that the outer diameter of the third outer diameter portion is larger than the outer diameter of the first outer diameter portion and smaller than the outer diameter of the second outer diameter portion.

2. The coil has a plurality of pitch regions with different pitches along the longitudinal axis direction, and in the first outer diameter portion, has a first densely wound portion which is a pitch region in which the wire is wound relatively more densely than an adjacent pitch region in the longitudinal axis direction, a second densely wound portion which is located closer to the base end than the first densely wound portion and is a pitch region in which the wire is wound relatively more densely than an adjacent pitch region, and an openly wound portion which is located between the first densely wound portion and the second densely wound portion and is a pitch region in which the wire is wound relatively more loosely than the first densely wound portion and the second densely wound portion, The catheter according to claim 1, wherein a position of a boundary between the first outer layer and the second outer layer overlaps a position of the second densely wound portion in the longitudinal direction.

3. 3. The catheter according to claim 1, wherein the coil pitch in the third outer diameter portion is equal to that in the second outer diameter portion.

4. 3. The catheter according to claim 1, wherein the coil is embedded in the outer layer.

5. A method for manufacturing a catheter having a main body extending in a longitudinal direction, the main body including an inner layer, an outer layer, and a coil formed by winding a wire around the inner layer, the main body having a first outer diameter portion, a second outer diameter portion adjacent to a base end side of the first outer diameter portion, and a third outer diameter portion adjacent to the base end side of the second outer diameter portion, the first outer diameter portion having a first outer layer made of a first resin, the second outer diameter portion having a second outer layer made of a second resin having a hardness higher than that of the first resin, the third outer diameter portion having a third outer layer made of a third resin having a hardness higher than that of the second resin, the outer diameter of the third outer diameter portion being larger than that of the first outer diameter portion and smaller than that of the second outer diameter portion, a step of inserting a mandrel into an inner layer tube forming the inner layer; a step of winding the wire around the outer circumferential surface of the inner tube while applying tension to form the coil; placing an outer layer tube that forms the outer layer so as to cover the coil; a step of placing a heat shrinkable tube so as to cover the outer tube; a step of heating the heat-shrinkable tube from one direction in the longitudinal direction and shrinking it while twisting it in the direction opposite to the winding direction of the wire.

6. 6. The method for manufacturing a catheter according to claim 5, wherein the tension applied to the wire is 60 gf to 100 gf.

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