Catheter

Abstract

To provide a catheter excellent in periphery reachability.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 plurality of (n)th external diameter parts (n=1...N) from first at the tip to Nth (N being an integer of 4 or more) toward the base end. An outer diameter of an (N-1)th external diameter part and an (N-2)th external diameter part is smaller than that of an (N)th external diameter part and an (N-3) external diameter part. The coil 40 includes a plurality of pitch regions with different pitches P along a longitudinal direction X, and includes a loosely wound part, which is a pitch region where wires are wound relatively loosely as compared to a pitch region adjacent along the longitudinal direction X, in the (N-1)th external diameter part and the (N-2)th external diameter part.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. [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, in hepatic artery embolization, there has been a demand for embolization of blood vessels that target tumors located further peripherally, and for this reason, catheters with high peripheral reachability are required.

[0007] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a catheter with high peripheral reachability. [Means for solving the problem]

[0008] The above object can be achieved by the invention described in (1) below.

[0009] (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 plurality of (n) outer diameter sections (n=1, ..., N) from No. 1 at the tip to No. N (N is an integer equal to or greater than 4) at the base end, the outer diameters of the (N-1)th and (N-2)th outer diameter sections being smaller than the outer diameters of the (N)th and (N-3)th outer diameter sections, the coil having a plurality of pitch regions with different pitches along the longitudinal direction, and the (N-1)th and (N-2)th outer diameter sections having loosely wound sections in which the wire is wound more loosely along the longitudinal direction than adjacent pitch regions along the longitudinal direction. [Effects of the Invention]

[0010] In the catheter described in (1) above, the (N-1)th outer diameter section and the (N-2)th outer diameter section have smaller outer diameters than the (N)th outer diameter section and the (N-3)th outer diameter section, thereby reducing the contact area with the blood vessel wall. This reduces the catheter's resistance to insertion into the blood vessel. Furthermore, the catheter has loosely wound sections in the (N-1)th outer diameter section and the (N-2)th outer diameter section, which improves flexibility and improves blood vessel tracking in the hepatic artery, which has a tortuous section. Therefore, the catheter can improve peripheral reachability.

[0011] (2) In the catheter described in (1) above, the (N-1)th outer diameter portion has an (N-1)th outer layer made of an (N-1)th resin, the (N-2)th outer diameter portion has an (N-2)th outer layer adjacent to the tip of the (N-2)th outer layer and made of an (N-2)th resin having a hardness lower than that of the (N-1)th resin, and the position of the boundary between the (N-1)th outer layer and the (N-2)th outer layer may overlap the position of the open coil portion in the longitudinal direction. Since the coil pitch is equal at the boundary between the first outer layer and the second outer layer, kinking at the boundary can be suppressed.

[0012] (3) In the catheter described in (1) or (2) above, the boundary between the (N) outer diameter section and the (N-1) outer diameter section may be located 350 mm to 400 mm from the most distal end of the main body. By having a highly rigid (N) outer diameter section at the proximal end, the catheter can transmit a pushing force sufficient for insertion into the peripheral blood vessel to the distal end. Furthermore, when the catheter is inserted from the femoral artery to the peripheral blood vessel of the liver, the boundary between the (N) outer diameter section and the (N-1) outer diameter section is located between the common hepatic artery and the proper hepatic artery, and closer to the common hepatic artery than a tortuous section in the proper hepatic artery. This prevents the highly rigid (N) outer diameter section from being inserted into a tortuous section, which would otherwise reduce blood vessel tracking, thereby improving insertability into the peripheral region. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a plan view showing a catheter according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing the tip of the catheter. [Figure 3] FIG. 2 is a 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

[0014] 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."

[0015] 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 and treat the tumor in the liver, and delivers an embolic coil, a drug, a contrast agent, an embolic substance, or the like.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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).

[0023] The inner layer 30 has a spiral recess 31 on its outer circumferential surface along the wire that forms the coil 40 .

[0024] The inner diameter of the inner layer 30 is, for example, 0.53 mm to 0.61 mm, for example, 0.57 mm. The thickness of the inner layer 30 is, for example, 30 μm to 40 μm. The depth of the recess 31 is, for example, 1 μm to 20 μm.

[0025] As shown in FIGS. 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 contacts the inner layer 30 and is embedded in a recess 31 formed in the outer peripheral surface of the inner layer 30. The coil 40 may also contact an outer peripheral surface of the inner layer 30 where the recess 31 is not formed. The coil 40 is disposed so as to be sandwiched between the outer layer 60 and the inner layer 30. The entire longitudinal axis direction X of the coil 40 may contact the inner layer 30, or a portion of the longitudinal axis direction X may contact the inner layer 30. A gap may be formed between the recess 31 formed in the outer peripheral surface of the inner layer 30 and the wire that forms the coil 40.

[0026] 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 of 2 or greater, and is 11 in this embodiment, but is not limited to this and may be 8, for example. The coil 40 has M (m)th pitch regions (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, a second pitch region 42, a third pitch region 43, a fourth pitch region 44, a fifth pitch region 45, a sixth pitch region 46, a seventh pitch region 47, an eighth pitch region 48, a ninth pitch region 49, a tenth pitch region 50, and an eleventh pitch region 51 that reaches approximately the base end of the main body 20.

[0027] As shown in FIG. 2, the wire in the first pitch region 41 (closely wound portion) is wound with gaps in the longitudinal direction X, but is wound more densely than the pitch region closer to the base end than the first pitch region 41. The wire in the first pitch region 41 may be wound densely without 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, 85 μm to 105 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.

[0028] 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.

[0029] 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 first pitch and the second pitch, and is, for example, 130 μm to 150 μm, and is, for example, 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, and is, for example, 1.5 mm.

[0030] The wire in the fourth pitch region 44 (increased pitch portion) is loosely wound with gaps in the longitudinal direction X. The pitch P (fourth pitch) of the fourth pitch region 44 is larger than the first to third pitches 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.

[0031] As shown in Figures 2 and 3, the wire in the fifth pitch region 45 (openly wound portion) is openly wound with gaps in the longitudinal direction X. The pitch P (fifth pitch) of the fifth pitch region 45 is larger than the first to fourth pitches and is, for example, 210 µm to 230 µm, and is, for example, 220 µm. The length L5 of the fifth pitch region 45 in the longitudinal direction X is, for example, 24.3 mm to 24.7 mm, and is, for example, 24.5 mm. The tip of the fifth pitch region 45 is preferably located 5 to 50 mm from the tip of the main body 20 toward the base end.

[0032] As shown in FIG. 3, the wire in the sixth pitch region 46 (closely wound portion) is wound with gaps in the longitudinal direction X, but is wound more densely than the fifth pitch region 45 and the seventh pitch region 47. The wire in the sixth pitch region 46 may be wound densely without gaps in the longitudinal direction X. The pitch P (sixth pitch) of the sixth pitch region 46 is smaller than the second to fifth pitches, and is, for example, 110 μm to 130 μm, and is, for example, 120 μm. The length L6 of the sixth pitch region 46 in the longitudinal direction X is, for example, 99 mm to 101 mm, and is, for example, 100 mm.

[0033] The wire in the seventh pitch region 47 (openly wound portion) is openly 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, 170 μm to 190 μm, and is, for example, 180 μm. The length L7 of the seventh pitch region 47 in the longitudinal direction X is, for example, 89 mm to 91 mm, and is, for example, 90 mm. The tip of the seventh pitch region 47 is, for example, preferably located approximately 150 mm from the tip of the main body 20 toward the base end.

[0034] The wire in the eighth pitch region 48 (densely wound portion) is wound with gaps in the longitudinal direction X, but is wound more densely than the seventh pitch region 47 and the ninth pitch region 49. The wire in the eighth pitch region 48 may be densely wound with no gaps in the longitudinal direction X. The pitch P (eighth pitch) of the eighth pitch region 48 is smaller than the seventh pitch, and is, for example, 90 μm to 110 μm, and is, for example, 100 μm. The length L8 of the eighth pitch region 48 in the longitudinal direction X is, for example, 119 mm to 121 mm, and is, for example, 120 mm. The tip of the eighth pitch region 48 is preferably located approximately 240 mm from the tip of the main body 20 toward the base end.

[0035] The wire in the 9th pitch region 49 (openly wound portion) is openly wound with gaps in the longitudinal direction X. The pitch P (9th pitch) of the 9th pitch region 49 is larger than the 8th pitch and is, for example, 210 μm to 230 μm, and is, for example, 220 μm. The length L9 of the 9th pitch region 49 in the longitudinal direction X is, for example, 29 mm to 31 mm, and is, for example, 30 mm. The tip of the 9th pitch region 49 is, for example, preferably located approximately 350 mm from the tip of the main body 20 toward the base end.

[0036] The wire in the tenth pitch region 50 (openly wound portion) is openly wound with gaps in the longitudinal direction X. The pitch P (tenth pitch) of the tenth pitch region 50 is larger than the first to ninth pitches and is, for example, 270 μm to 290 μm, and is, for example, 280 μm. The length L10 of the tenth pitch region 50 in the longitudinal direction X is, for example, 29 mm to 31 mm, and is, for example, 30 mm.

[0037] The wire in the 11th pitch region 51 (openly wound portion) is openly wound with gaps in the longitudinal direction X. The pitch P (11th pitch) of the 11th pitch region 51 is larger than the first to tenth pitches and is, for example, 340 μm to 360 μm, and is, for example, 350 μm. The length L11 of the 11th pitch region 51 in the longitudinal direction X is, for example, 646 mm to 1046 mm, and is, for example, 846 mm.

[0038] As shown in Figures 2 and 3, the coil 40 has pitch increasing sections (second pitch region 42, third pitch region 43, fourth pitch region 44) between the first pitch region 41 (closely wound section) and the fifth pitch region 45 (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 largest in the pitch region (eleventh pitch region 51) 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 40 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 axis direction X. In this embodiment, the outer layer 60 has N portions with different hardness or materials. N is an integer equal to or greater than 4, 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 comprises, from the tip side to the base side, 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 ((N-3) outer layer) made of a third resin ((N-3) resin), a fourth outer layer 64 ((N-2) outer layer) made of a fourth resin ((N-2) resin), a fifth outer layer 65 ((N-1) outer layer) made of a fifth resin ((N-1) resin), and a sixth outer layer 66 ((N) outer layer) made of a sixth resin ((N) resin) that reaches the base 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) 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 the first outer layer 61, a second outer diameter portion 22 located in a region having the second outer layer 62, a third outer diameter portion 23 ((N-3)th outer diameter portion) located in a region having the third outer layer 63 ((N-3)th outer layer), a fourth outer diameter portion 24 ((N-2)th outer diameter portion) located in a region having the fourth outer layer 64 ((N-2)th outer layer), a fifth outer diameter portion 25 ((N-1)th outer diameter portion) located in a region having the fifth outer layer 65 ((N-1)th outer layer), and a sixth outer diameter portion 26 ((N)th outer diameter portion) located in a region having the sixth outer layer 66 ((N)th outer layer). Adjacent outer diameter portions in the major axis direction X have different outer diameters. Each outer diameter portion includes a portion of the outer layer 60, a portion of the coil 40, and a portion of the inner layer 30. In addition, the outer diameter portion located at the distal end or proximal end of the main body 20 may not have the coil 40.

[0044] The length L21 of the first outer diameter portion 21 in the longitudinal direction X is, for example, 1 mm to 11 mm, and is, for example, 10 mm. The base end of the first outer diameter portion 21 is located midway through the fifth pitch region 45 in the longitudinal direction X. The length L22 of the second outer diameter portion 22 in the longitudinal direction X is, for example, 39 mm to 41 mm, and is, for example, 40 mm. The tip end of the second outer diameter portion 22 is located midway through the fifth pitch region 45 in the longitudinal direction X, and the base end of the second outer diameter portion 22 is located near the tip end of the sixth pitch region 46 in the longitudinal direction X. The length L23 of the third outer diameter portion 23 in the longitudinal direction X is, for example, 49 mm to 51 mm, and is, for example, 50 mm. The tip end of the third outer diameter portion 23 is located near the tip end of the sixth pitch region 46 in the longitudinal direction X, and the base end of the third outer diameter portion 23 is located midway through the sixth pitch region 46 in the longitudinal direction X. The length L24 of the fourth outer diameter portion 24 in the longitudinal direction X is, for example, 90 mm to 110 mm, and is, for example, 100 mm. The tip of the fourth outer diameter portion 24 is located midway through the sixth pitch region 46 in the longitudinal direction X, and the base end of the fourth outer diameter portion 24 is located midway through the seventh pitch region 47 in the longitudinal direction X. The length L25 of the fifth outer diameter portion 25 in the longitudinal direction X is, for example, 190 mm to 210 mm, and is, for example, 200 mm. The tip of the fifth outer diameter portion 25 is located midway through the seventh pitch region 47 in the longitudinal direction X, and the base end of the fifth outer diameter portion 25 is located midway through the ninth pitch region 49 in the longitudinal direction X. The length L26 of the sixth outer diameter portion 26 in the longitudinal direction X is, for example, 840 mm to 1240 mm, and is, for example, 1040 mm. The tip of the sixth outer diameter portion 26 is located midway through the ninth pitch region 49 in the longitudinal direction X. The change position of the pitch P is different 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 350 mm to 400 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 33. 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 42. 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 56. 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 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 to the third outer diameter portion 23 and 20 gf or more for the fourth outer diameter portion 24 to the sixth outer diameter portion 26. The bending load of the second outer diameter portion 22 is 10 gf to 20 gf, for example, 15 gf. The bending load of the third outer diameter portion 23 is 10 gf to 20 gf, for example, 17 gf. The bending load of the fourth outer diameter portion 24 is 30 gf to 60 gf, for example, 37 gf. The bending load of the fifth outer diameter portion 25 is 60 gf to 80 gf, for example, 75 gf. The bending load of the sixth outer diameter portion 26 is 80 gf to 140 gf, for example, 130 gf.

[0048] The outer diameter of the main body 20 (outer layer 60) is generally 2.2 Fr to 2.4 Fr (approximately 0.73 to 0.79 mm) to 3.0 Fr (approximately 1.0 mm), and varies along the longitudinal axis direction X within a range consistent therewith. The outer diameter of the second outer diameter portion 22 is smaller 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 diameters of the first outer diameter portion 21 and the second outer diameter portion 22. The outer diameter of the fourth outer diameter portion 24 is smaller than the outer diameter of the third outer diameter portion 23 and larger than the outer diameters of the first outer diameter portion 21 and the second outer diameter portion 22. The outer diameter of the fifth outer diameter portion 25 is smaller than the outer diameter of the third outer diameter portion 23 and larger than the outer diameter of 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 second outer diameter portion 22 is preferably smaller than the outer diameter of any of the first 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 FIG. 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 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 wire that forms the coil 40 penetrates the outer surface of the inner layer tube 100, forming a spiral recess 31 in the inner layer tube 100. The tension applied to the wire is, for example, 170 gf to 180 gf in the first pitch region 41 to the fourth pitch region 44 located in the first outer diameter portion 21. The tension applied to the wire may be varied depending on the position in the longitudinal axis direction X of the inner layer tube 100. The tension applied to the wire decreases from 180 gf to 170 gf in the fifth pitch region 45 located at the proximal end of the first outer diameter section 21, and decreases from 170 gf to 151 gf in the fifth pitch region 45 located at the second outer diameter section 22. In the sixth pitch region 46 to the eleventh pitch region 51, the tension applied to the wire is constant at 151 gf. By decreasing the tension applied to the wire from the distal end toward the proximal end at the distal end (first outer diameter section 21 or second outer diameter section 22) of the catheter 10, the amount of penetration of the wire into the outer circumferential surface of the inner-layer tube 100 can be decreased from the distal end toward the proximal end. Note that the tension applied to the wire may be constant 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 to cover the inner tube 100 and the coil 40. The plurality of outer tubes 101 correspond to the first outer layer 61 to the sixth outer layer 66, respectively. Next, the manufacturer arranges a heat-shrinkable tube 102 to cover the outer tubes 101.

[0053] Next, the manufacturer heats the heat-shrinkable tube 102 by moving the heating means 110, such as a heater, from one side (the distal end or the proximal end) in the longitudinal direction X of the heat-shrinkable tube 102 to the opposite side. As a result, the resin of the outer layer tube 101, which has been heated and softened, is tightly adhered to and fixed to the inner layer tube 100 and the coil 40 as the heat-shrinkable tube 102 shrinks. 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 peripheral surface of the outer layer 60 with a lubricating coating 90. This completes the manufacture of the catheter 10.

[0054] As described above, the catheter 10 according to this embodiment has 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. The main body 20 has a first outer diameter section 21 located at the tip, a second outer diameter section 22 adjacent to the base end of the first outer diameter section 21, and a third outer diameter section 23 adjacent to the base end of the second outer diameter section 22. The first outer diameter section 21 has an increasing pitch section in which the pitch P (first pitch to fifth pitch) of the coil 40 increases from the tip side to the base end side. In the second outer diameter section 22, the pitch P (fifth pitch) of the coil 40 is equal to the pitch P of the coil 40 at the base end of the first outer diameter section 21. The outer diameter of the second outer diameter section 22 is smaller than the outer diameters of the first outer diameter section 21 and the third outer diameter section 23. As a result, the catheter 10 has a pitch P of the coil 40 that increases from the distal end toward the proximal end in the first outer diameter section 21, and the pitch P of the coil 40 is equal at the boundary between the first outer diameter section 21 and the second outer diameter section 22, thereby enabling a gradual change in rigidity along the longitudinal axis direction X of the distal end. This allows the catheter 10 to bend easily without localized kinking, improving its ability to follow the guidewire. Furthermore, the second outer diameter section 22 has a smaller outer diameter than the first outer diameter section 21 and the third outer diameter section 23, providing flexibility and reducing the contact area with the blood vessel wall. This improves the catheter 10's peripheral reachability.

[0055] The first outer diameter section 21 may include a first outer layer 61 made of a first resin, the second outer diameter section 22 may include a second outer layer 62 made of a second resin having a higher hardness than the first resin, and the third outer diameter section 23 may include a third outer layer 63 made of a third resin having a hardness equal to that of the second resin. This allows the catheter 10 to have a gradual change in stiffness along the longitudinal axis direction X of the tip portion. Furthermore, by using a resin having a hardness equal to that of the second outer diameter section 22 for the third outer diameter section 23, it is possible to have an outer diameter larger than that of the second outer diameter section 22 while maintaining flexibility, thereby preventing the catheter 10 from moving due to a reaction force generated by the injection of a fluid into the lumen 27 of the catheter 10.

[0056] The pitch P (sixth pitch) of the coil 40 in the third outer diameter portion 23 is smaller than the pitch P (fifth pitch) of the coil 40 in the second outer diameter portion 22. This increases the outer diameter of the catheter 10 and reduces its flexibility, improving its stability within the blood vessel, thereby preventing the catheter 10 from moving due to a reaction force generated by the injection of fluid into the lumen 27 of the catheter 10.

[0057] The main body 20 has a constant inner diameter from the distal end to the proximal end, which reduces the insertion resistance of a device such as the embolic coil 40 when it is inserted into the lumen 27 of the catheter 10, and also prevents the device from clogging the lumen 27 of the catheter 10.

[0058] Furthermore, the catheter 10 according to this embodiment has 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. The main body 20 has a plurality of (n) outer diameter portions (n=1, ..., N) from a first portion at the tip to an Nth portion (N is an integer equal to or greater than 4) toward the base end, with the outer diameters of the (N-1)th and (N-2)th outer diameter portions being smaller than the outer diameters of the (N)th and (N-3)th outer diameter portions. The coil 40 has, in the (N-1)th and (N-2)th outer diameter portions, loosely wound portions (seventh pitch region 47) in which the wire is wound more loosely along the longitudinal axis direction X than in the adjacent pitch regions (sixth pitch region 46 and eighth pitch region 48). The (N-1)th outer diameter section and the (N-2)th outer diameter section have smaller outer diameters than the (N)th outer diameter section and the (N-3)th outer diameter section, and therefore the contact area with the blood vessel wall is reduced. This allows the catheter 10 to reduce resistance to insertion into the blood vessel. Furthermore, the catheter 10 has loosely wound sections in the (N-1)th outer diameter section and the (N-2)th outer diameter section, which improves flexibility and improves blood vessel tracking in the hepatic artery, which has a tortuous section. Therefore, the catheter 10 can improve peripheral reachability.

[0059] The (N-1)th outer diameter portion has an (N-1)th outer layer made of an (N-1)th resin, and the (N-2)th outer diameter portion has an (N-2)th outer layer adjacent to the tip of the (N-2)th outer layer and made of an (N-2)th resin having a lower hardness than the (N-1)th resin, and the position of the boundary between the (N-1)th outer layer and the (N-2)th outer layer overlaps the position of the open winding portion (seventh pitch region 47) in the longitudinal axis direction X. In the catheter 10, the pitch P of the coil 40 is equal at the boundary between the first outer layer 61 and the second outer layer 62, thereby preventing kinking at the boundary.

[0060] The boundary between the (N)th outer diameter portion and the (N-1)th outer diameter portion is located 350 mm to 400 mm from the tip of the main body 20. By having the highly rigid (N)th outer diameter portion at the base end, the catheter 10 can transmit a pushing force sufficient for insertion into the peripheral blood vessels to the tip. Furthermore, when the catheter 10 is inserted from the femoral artery to the peripheral blood vessels of the liver, 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 the tortuous portion of the proper hepatic artery. This prevents the highly rigid (N)th outer diameter portion from being inserted into the tortuous portion, which would otherwise reduce blood vessel tracking, thereby improving insertability into the peripheral vessels.

[0061] 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]

[0062] 10 Catheter 20 Main Unit 21 1st outer diameter section 22 Second outer diameter section 23 Third outer diameter section (No. (N-3) outer diameter section) 24 4th outer diameter section (No. (N-2) outer diameter section) 25 5th outer diameter section (No. (N-1) outer diameter section) 26 6th outer diameter section (No. (N) outer diameter section) 27 lumen 30 inner layer 31 Recess 40 coils 41 First pitch area 42 Second pitch area 43 Third pitch area 44 Fourth Pitch Area 45 5th pitch area 46 6th pitch area 47 7th pitch area 48 8th pitch area 49 9th Pitch Area 50 10th pitch area 51 11th pitch area 60 outer layer 61 1st outer layer 62 2nd outer layer 63 Third outer layer ((N-3) outer layer) 64 4th outer layer ((N-2) outer layer) 65 5th outer layer ((N-1) outer layer) 66 6th outer layer ((N) outer layer)

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 plurality of (n) outer diameter portions (n=1, . . . , N) from a first outer diameter portion at the distal end to an N outer diameter portion (N is an integer of 4 or more) toward the proximal end, the outer diameters of the (N-1)th outer diameter portion and the (N-2)th outer diameter portion are smaller than the outer diameters of the (N)th outer diameter portion and the (N-3)th outer diameter portion; The coil has a plurality of pitch regions with different pitches along the longitudinal axis direction, and the (N-1) outer diameter portion and the (N-2) outer diameter portion have loosely wound portions, which are pitch regions in which the wire is wound relatively loosely compared to adjacent pitch regions in the longitudinal axis direction.

2. the (N-1)th outer diameter portion has an (N-1)th outer layer made of an (N-1)th resin, the (N-2)th outer diameter portion has an (N-2)th outer layer adjacent to a tip of the (N-2) outer layer and made of an (N-2)th resin having a hardness lower than that of the (N-1)th resin, The catheter according to claim 1, characterized in that the position of the boundary between the (N-1) outer layer and the (N-2) outer layer overlaps the position of the loosely wound portion in the longitudinal direction.

3. 3. The catheter according to claim 1, wherein the boundary between the (N) outer diameter portion and the (N-1) outer diameter portion is located 350 mm to 400 mm from the tip of the main body.

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