Catheter and method for producing catheter

Abstract

Provided is a catheter that exhibits continuous tensile strength from a tip end to a base end and causes no decrease in localized tensile strength. Also provided is a method for producing the catheter. A catheter 10 comprises a tubular sheath 33 having a tip end and a base end. The sheath 33 comprises: a tubular body 150 formed by a resin; and a reinforcement body 157 having a repeating structure 159 formed of a metal wire 158. The tubular body 150 and the reinforcement body 157 extend continuously over the entire length from the tip end of the sheath 33 to the base end. A traction wire 80 is fixed to a base end portion of the sheath 33, and the sheath 33 can be moved to the base end side by pulling the traction wire 80.

Description

Catheter and method for manufacturing the same

[0001] The present invention relates to a catheter to be inserted into a body lumen for treatment and a method for manufacturing the catheter.

[0002] Intravascular treatment is a method for treating lesions such as stenosis and blockages in blood vessels, in which treatment is performed from within the blood vessel using a device inserted percutaneously into the blood vessel. In intravascular treatment, a catheter is used to deliver diagnostic contrast agents, guide wires, or treatment sites to the lesion.

[0003] For example, in the treatment of myocardial infarction and angina pectoris, a stent is placed in the affected area (stenosis) of the coronary artery using a catheter to secure space within the coronary artery, and similar methods are sometimes used to improve stenosis in other body lumens, such as blood vessels, bile ducts, tracheas, esophagus, urethra, etc. Stents are classified into balloon-expandable stents and self-expandable stents depending on their function and placement method.

[0004] A balloon-expandable stent does not have an expansion function itself, and after reaching the target site, it is expanded by a balloon and becomes tightly fixed in the lumen. In contrast, a self-expandable stent has an expansion function itself, and is housed in a catheter in a pre-reduced state. After reaching the target site, a self-expandable stent is released from the catheter, expands by its own expansion force, and becomes tightly fixed in the lumen.

[0005] Patent Document 1 describes an RX (Rapid Exchange) type catheter that delivers a self-expanding stent to a target site in a lumen and fixes the self-expanding stent in close contact with the lumen. The catheter in Patent Document 1 is formed so that the outer diameter of the distal end portion that houses the stent is larger than the outer diameter of the proximal end portion, and has a tapered portion between the distal end portion and the proximal end portion that expands in diameter toward the distal end.

[0006] Patent No. 5697935

[0007] The catheter of Patent Document 1 has a mesh-like or net-like reinforcing body at the distal end where the stent is housed. The catheter also has a reinforcing body at the proximal end. The distal end where the stent is housed has a large inclination angle with respect to the longitudinal axis direction of the wires forming the reinforcing body, and therefore has high tensile strength in the radial direction. On the other hand, the proximal end has a small inclination angle with respect to the longitudinal axis direction of the wires forming the reinforcing body, and therefore has high tensile strength in the longitudinal direction.

[0008] Conventional catheters do not have a reinforcement member in the tapered section formed between the distal end and the proximal end. This results in a localized decrease in tensile strength in the section where the reinforcement member is not provided. This means that conventional catheters may break in the section where the reinforcement member is not provided when a tensile force is applied to the catheter, such as when deploying a stent.

[0009] The present invention has been made to solve the above-mentioned problems, and aims to provide a catheter that has continuous tensile strength from the tip to the base end and does not suffer from localized decreases in tensile strength, and a method for manufacturing such a catheter.

[0010] To achieve the above object, (1) a catheter is provided with a tubular sheath having a distal end and a proximal end, the sheath comprising a tubular body formed of resin and a reinforcing body having a repeating structure formed of metal wires, the tubular body and the reinforcing body extending continuously over the entire length of the sheath from the distal end to the proximal end, a pulling wire fixed to the proximal end of the sheath, and the sheath can be moved toward the proximal end by pulling the pulling wire.

[0011] (11) A method for manufacturing a catheter that achieves the above-mentioned object is a method for manufacturing a catheter equipped with a tubular sheath having a tip and a base end, and includes the steps of: forming a tube including a reinforcing body having a repeating structure formed of metal over the entire length of a resin tubular body; and inserting one side of the tube along its longitudinal axis to an intermediate position through a mold having an inner diameter smaller than the outer diameter of the tube, and increasing the pitch of the repeating structure while reducing the outer diameter of the tube that has passed through the mold.

[0012] In the catheter (1) configured as described above, the reinforcing body extends over the entire length of the sheath that is pulled by the pulling wire, so that the sheath has continuous tensile strength in the longitudinal direction from the tip to the base end, and localized reductions in tensile strength can be prevented.

[0013] (2) In the catheter of (1), the sheath may include a first region and a second region at a proximal end of the first region, the second region having a smaller outer diameter than the first region and a larger pitch of the repeating structure forming the reinforcing member, thereby increasing the tensile strength of the catheter in the longitudinal direction in the second region.

[0014] (3) In the catheter of (1), the sheath may include a first region and a second region at a proximal end of the first region, the second region having a smaller outer diameter than the first region, and the angle formed by the wires in the repeating structure forming the reinforcing body with respect to the longitudinal axis of the sheath may be smaller, thereby increasing the tensile strength of the catheter in the longitudinal direction of the second region.

[0015] (4) In the catheter of (2) or (3), the sheath may include a tapered portion between the first region and the second region that is inclined so that the diameter decreases from the first region toward the second region, and the pitch of the repeating structure in the tapered portion may be larger than the pitch of the repeating structure in the first region and smaller than the pitch of the repeating structure in the second region. This allows the catheter to continuously change the tensile strength of the sheath between the first region and the second region, thereby suppressing abrupt changes in the physical properties of the sheath and preventing breakage.

[0016] (5) In the catheter of any one of (2) to (4) above, the first region of the sheath may be a region that houses at least a portion of a stent, thereby allowing the catheter to house the stent in a state where it is securely held inside the first region of the sheath.

[0017] (6) In any of the catheters (2) to (5) above, the sheath may include a first sheath that houses the stent, and a second sheath that is connected to the proximal end of the first sheath and includes a resin tubular body and a reinforcing body formed by braiding metal wires. This allows the tensile strength of the sheath as a whole to be continuously changed along the longitudinal axis when the catheter has the first sheath that houses the stent and the second sheath that is housed in the shaft on the proximal end side as separate bodies, thereby preventing localized decreases in tensile strength.

[0018] (7) In the catheter of (6) above, the puller wire may be fixed to the proximal end of the second sheath, thereby allowing the catheter to smoothly pull the second sheath.

[0019] (8) In the catheter of (6) or (7), the second sheath may include a third region and a fourth region at a proximal end of the third region, the fourth region having a smaller outer diameter than the third region and a larger pitch of the repeating structure forming the reinforcing body, thereby increasing the tensile strength of the second sheath in the longitudinal direction in the fourth region.

[0020] (9) In any of the catheters (2) to (5) above, the sheath may include a fifth region at a proximal end of the second region, the fifth region having a smaller outer diameter than the second region, and the repeating structure forming the reinforcing body having a larger pitch. This allows the tensile strength of the entire sheath to be continuously changed along the longitudinal axis when the catheter is formed by integrating a portion that houses a stent and a portion that is housed in a proximal shaft, thereby preventing localized decreases in tensile strength.

[0021] (10) In the catheter of (2) or (3) above, a stent sheath for accommodating a stent may be connected to the distal end of the sheath, and the stent sheath may be a resin tubular body without the reinforcing body. This allows the catheter to have high flexibility in the part accommodating the stent.

[0022] (11) In the catheter of any one of (1) to (10), the puller wire may be fixed to a fixed region of the sheath, and the reinforcing member may extend over at least a portion of the fixed region. This increases the tensile strength of the catheter in the fixed region of the sheath that is pulled by the puller wire, thereby preventing the sheath from breaking.

[0023] (12) In the method for manufacturing a catheter configured as described above, a sheath is formed by reducing the diameter of a tube including a reinforcing body that is continuous from the tip to the base end of the tube. Therefore, the formed sheath has a reinforcing body that is continuous from the tip to the base end, and the sheath has continuous tensile strength from the tip to the base end in the longitudinal direction, preventing localized reduction in tensile strength.

[0024] 10 is a front view showing the entire catheter according to an embodiment. FIG. 11 is a cross-sectional view showing the distal end side of the catheter, where (a) shows the state before the stent is deployed and (b) shows the state during the stent deployment. FIG. 12 is an enlarged cross-sectional view of the first sheath near the boundary between the first and second regions. FIG. 13 is a partial front view of the first sheath reinforcement in the first region. FIG. 14 is a partial front view of the first sheath reinforcement in the second region. FIG. 15 is an enlarged cross-sectional view of the second sheath near the boundary between the third and fourth regions. FIG. 16 is a cross-sectional view showing the manufacturing process of the first sheath, where (a) shows the state after inserting a core material into the tube, (b) shows the state during insertion of the tube into the mold, and (c) shows the state after insertion of the tube into the mold is completed. FIG. 17 is a cross-sectional view showing the distal end side of a catheter according to a first modified example. FIG. 18 is a cross-sectional view showing the distal end side of a catheter according to a second modified example. FIG. 19 is an enlarged cross-sectional view of the sheath of the catheter of FIG. 9 near the boundary between the first and second regions and near the boundary between the second and fifth regions. FIG. 19 is a cross-sectional view of a sheath having a tapered portion according to a modified example.

[0025] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that dimensions in the drawings may be exaggerated for convenience of explanation and may differ from actual dimensions. Furthermore, in this specification and the drawings, components having substantially the same functions are designated by the same reference numerals, and redundant description will be omitted. In this specification, the side inserted into a lumen will be referred to as the "distal side," and the side closest to the operator will be referred to as the "proximal side."

[0026] The catheter 10 according to this embodiment is for placing a stent 20, which is a medical deployable device, in a narrowed or blocked area in a blood vessel, bile duct, trachea, esophagus, urethra, or other biological lumen to maintain the patency of the biological lumen. The catheter 10 is an RX (Rapid Exchange) type in which a guide wire 200 is inserted only at the distal end.

[0027] 1 and 2, the catheter 10 includes a stent 20, an outer tube 30 that houses the stent 20, an inner tube 40 that is disposed inside the outer tube 30, and a proximal shaft 70 that is disposed on the proximal side of the outer tube 30. The catheter 10 further includes a puller wire 80 for pulling the outer tube 30, and an operating section 110 that is disposed at the proximal end of the catheter 10.

[0028] The outer tube 30 includes a sheath 33 that houses the stent 20, and a proximal outer tube 32 that is located on the proximal side of the sheath 33. An inner tube 40 is disposed inside the sheath 33 and the proximal outer tube 32. The sheath 33 is movable toward the proximal side relative to the proximal outer tube 32. The sheath 33 includes a first sheath 34 and a second sheath 35. The reduced-diameter stent 20 is disposed inside the first sheath 34.

[0029] The first sheath 34 includes a distal first region 151 and a proximal second region 152. The second region 152 has an outer diameter and an inner diameter smaller than those of the first region 151.

[0030] The second sheath 35 has an outer diameter and an inner diameter smaller than those of the first region 151 of the first sheath 34. The distal end of the second sheath 35 is located on the outer surface of the second region 152 of the first sheath 34 and is covered with the connection tube 60. The first sheath 34 and the second sheath 35 are connected by fusing and fixing the connection tube 60 by heating or the like. The connection tube 60 may also be fixed by an adhesive or the like.

[0031] The second sheath 35 includes a distal third region 161 and a proximal fourth region 162. The fourth region 162 has an outer diameter and an inner diameter smaller than those of the third region 161.

[0032] The third region 161 of the second sheath 35 has an outer diameter smaller than the inner diameter of the proximal outer tube 32, and the proximal side portion is located inside the proximal outer tube 32. When the sheath 33 moves toward the proximal side relative to the proximal outer tube 32, the second sheath 35 slides on the inner surface of the proximal outer tube 32 and can enter the inside of the proximal outer tube 32.

[0033] The pulling wire 80 is fixed to the fourth region 162 of the second sheath 35, which is the proximal end of the sheath 33. The pulling wire 80 is located on the outer surface of the fourth region 162, which is the proximal end of the second sheath 35, and is fixed to the second sheath 35 by being covered with the wire fixing tube 65 and fixed with an adhesive or the like. Note that the pulling wire 80 may also be fixed by being covered with the wire fixing tube 65 and fused by heating or the like.

[0034] The proximal outer tube 32 is a tubular body capable of receiving therein the second sheath 35 that moves toward the proximal side.

[0035] The outer diameter of the outer tube 30 is not particularly limited, but is, for example, 0.5 to 10.0 mm, preferably 1.0 to 5.0 mm. The inner diameter of the outer tube 30 is not particularly limited, but is, for example, 0.4 to 9.0 mm, preferably 0.8 to 4.5 mm. The axial length of the outer tube 30 is not particularly limited, but is, for example, 10 to 250 mm, preferably 20 to 100 mm.

[0036] As shown in Figure 3, the first sheath 34 includes a first sheath tubular body 150 made of resin and a first sheath reinforcing body 157 having a repeating structure 159 formed of metal wires 158. The first sheath tubular body 150 has an outer layer 150a made of flexible resin and an inner layer 150b made of low-friction resin. The first sheath reinforcing body 157 is located between the outer layer 150a and the inner layer 150b. The wires 158 can be made of stainless steel, gold, platinum, silver, iridium, tungsten, tantalum, or an alloy thereof.

[0037] The first sheath 34 has a first region 151 whose outer diameter is larger than the outer diameter of the second region 152, and between the first region 151 and the second region 152 is a first tapered portion 153 that is inclined so that the outer diameter decreases from the tip side toward the base end.

[0038] The first sheath reinforcing member 157 extends continuously over the entire length from the distal end to the proximal end of the first sheath 34. That is, the first sheath reinforcing member 157 has a repeating structure 159 formed of continuous wires 158 extending over the first region 151, the first tapered portion 153, and the second region 152.

[0039] 4, the first sheath reinforcement 157 in the first region 151 has a repeating structure 159 in which the wires 158 are braided in a mesh shape so that they intersect with each other. The pitch of the repeating structure 159 in the first region 151 is P1, and the inclination angle of the wires 158 with respect to the longitudinal axis direction is α1.

[0040] 5 , the first sheath reinforcement 157 in the second region 152 has a repeating structure 159 similar to that in the first region 157, with a pitch of P2 and an inclination angle α2 of the wires 158 relative to the longitudinal axis. The pitch P2 of the repeating structure 159 in the second region 152 is larger than the pitch P1 of the repeating structure 159 in the first region 151. The inclination angle α2 of the wires 158 in the second region 152 is smaller than the inclination angle α1 of the wires 158 in the first region 151.

[0041] The pitch P 3 of the repeating structures 159 in the first tapered portion 153 is larger than the pitch P 1 in the first region 151 and smaller than the pitch P 2 in the second region 152 .

[0042] 6, the second sheath 35 includes a second sheath tubular body 160 made of resin and a second sheath reinforcing body 167 having a repeating structure 169 formed of metal wires 168. The second sheath tubular body 160 includes an outer layer 160a made of a flexible resin and an inner layer 160b made of a low-friction resin. The second sheath reinforcing body 167 is located between the outer layer 160a and the inner layer 160b.

[0043] The second sheath 35 has a third region 161 whose outer diameter is larger than the outer diameter of the fourth region 162, and between the third region 161 and the fourth region 162 is a second tapered portion 163 which is inclined so that the outer diameter decreases from the tip side toward the base side.

[0044] The second sheath reinforcing body 167 extends continuously over the entire length from the distal end to the proximal end of the second sheath 35. That is, the second sheath reinforcing body 167 extends continuously over the third region 161, the second tapered portion 163, and the fourth region 162.

[0045] The repeating structure 169 of the second sheath reinforcement 167 is a mesh-like braided structure similar to the repeating structure 159 of the first sheath reinforcement 157. The pitch P5 of the repeating structure 169 in the fourth region is larger than the pitch P4 of the repeating structure 169 in the third region. Furthermore, the pitch P6 of the repeating structure 169 in the second tapered portion 163 is larger than the pitch P4 in the third region 161 and smaller than the pitch P5 in the fourth region 162.

[0046] The pulling wire 80 fixed to the proximal end of the second sheath 35 is fixed within the range of the fourth region 162, which serves as a fixing region. Since the second sheath reinforcing body 167 extends in the fourth region 162, the pulling wire 80 is fixed to the fixing region where the second sheath reinforcing body 167 extends. In this way, since the pulling wire 80 is fixed to the fixing region where the second sheath reinforcing body 167 extends, the pulling wire 80 has higher strength than when the pulling wire 80 is fixed only to a region formed of a flexible resin, and therefore the second sheath 35 is less likely to break when the pulling wire 80 is pulled.

[0047] The materials constituting the outer layers of the sheath 33 and the proximal outer tube 32 are not particularly limited, but are preferably hard and flexible, such as nylon, polyester, or fluororesin. The material constituting the inner layer is preferably a fluororesin. Examples of fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkylvinyl ether copolymer (PFA), and tetrafluoroethylene-hexafluoropropylene copolymer (FEP).

[0048] 2, the inner tube 40 is a tubular body in which a guidewire lumen 41 is formed on the distal end side of the catheter 10. The inner tube 40 is equipped with a distal tip 44 fixed to the distal end, a distal marker 45, and a proximal marker 46. The inner tube 40 and the distal tip 44 are aligned in the axial direction and form a common guidewire lumen 41.

[0049] At least a portion of the inner tube 40 is located inside the outer tube 30, and passes through the inside of the stent 20 disposed inside the outer tube 30. The distal end of the inner tube 40 is located distal to the outer tube 30.

[0050] The outer diameter of the inner tube 40 is not particularly limited, but is, for example, 0.15 to 3.0 mm, and preferably 0.3 to 1.5 mm. The inner diameter of the inner tube 40 is not particularly limited, but is, for example, 0.1 to 2.0 mm, and preferably 0.2 to 1.0 mm. The axial length of the inner tube 40 is not particularly limited, but is, for example, 50 to 2000 mm, and preferably 100 to 1000 mm.

[0051] The material of the inner tube 40 is not particularly limited, but for example, polyether ether ketone (PEEK), nylon, polyimide, etc. can be suitably used.

[0052] The distal tip 44 constitutes the distal portion of the inner tube 40. The guidewire lumen 41 opens at a distal opening 47 formed at the distal end of the distal tip 44. The distal tip 44 may be formed integrally with the inner tube 40. The proximal end surface of the distal tip 44 contacts or is close to the distal end surface of the first sheath 34 that houses the stent 20.

[0053] The distal tip 44 is preferably made of a flexible material, such as nylon elastomer, polyester elastomer, urethane elastomer, etc. The distal tip 44 may be made of a material containing a contrast agent.

[0054] The pulling wire 80 is a wire for pulling the sheath 33 toward the proximal end side to release the stent 20 from the sheath 33. One or more pulling wires 80 (two in this embodiment) are provided. The proximal end side of the pulling wire 80 is fixed to an operating unit 112 of the operation unit 110, which will be described later. The distal end side of the pulling wire 80 is fixed to the proximal end of the second sheath 35.

[0055] A wire or a plurality of twisted wires can be suitably used as the pulling wire 80. The thickness of the pulling wire 80 is not particularly limited, but is, for example, 0.05 to 1.0 mm, and preferably 0.1 to 0.5 mm. The surface of the pulling wire 80 is coated with a fluorine-based resin, which is a low-friction material.

[0056] The constituent material of the traction wire 80 is not particularly limited, but examples thereof include stainless steel wire (preferably high-tensile stainless steel for springs), piano wire (preferably nickel-plated or chrome-plated piano wire), wires formed from various metals such as superelastic alloy wire, Ni-Ti alloy, Cu-Zn alloy, Ni-Al alloy, tungsten, tungsten alloy, titanium, titanium alloy, cobalt alloy, and tantalum, and relatively high-rigidity polymer materials such as polyamide, polyimide, ultra-high molecular weight polyethylene, polypropylene, and fluororesin, as well as appropriate combinations of these.

[0057] The stent 20 is formed in a generally cylindrical shape and is housed within the first sheath 34 in a state compressed toward the central axis, as shown in Fig. 2. When the stent 20 is pushed out from the opening at the distal end of the first sheath 34, the stress load is removed, the stent 20 expands, and it returns to its shape before being compressed. The shape of the stent 20 is not limited as long as it is a so-called self-expanding stent. As an example, the stent 20 may be formed by arranging a plurality of annular portions that are formed into annular shapes while being bent, and connected in a row to form a single generally cylindrical shape.

[0058] A superelastic alloy is preferably used as the material for the stent 20. The superelastic alloy referred to here is generally called a shape memory alloy, and exhibits superelasticity at least at body temperature (around 37°C). Suitable shape memory alloys include Ni-Ti alloys, Cu-Al-Ni alloys, and Cu-Zn-Al alloys.

[0059] As shown in FIG. 1, the operation unit 110 includes an operation main body 111, an operating unit 112, and a kink-resistant protector 113.

[0060] The operation body 111 is a part that is held by the surgeon and houses therein a mechanism for pulling the pulling wire 80, including a part of the operating unit 112.

[0061] The operating unit 112 is a part where the user performs the pulling operation of the traction wire 80. The operating unit 112 is provided with a dial 117 that is operated by the surgeon, and can rotate relative to the operation main body 111 around a rotation axis 119.

[0062] The dial 117 is a part that is rotated by the surgeon, and is formed in a disk shape and disposed within the operation body 111 so as to be partially exposed from the operation body 111. The part of the dial 117 that is exposed from the operation body 111 is the part that is operated by the surgeon. It is preferable that the surface part that the surgeon may touch when operating the dial 117 has a non-slip surface. For example, it is preferable that the outer peripheral surface of the dial 117 is knurled, embossed, or coated with a high-friction material. When the surgeon rotates the dial 117, a winding shaft (not shown) provided inside the operation body 111 rotates, and the traction wire 80 can be wound up.

[0063] The anti-kink protector 113 covers the proximal end side of the proximal shaft 70 and partially protrudes from the operation main body 111 toward the distal end side. The anti-kink protector 113 suppresses kinking of the proximal shaft 70 on the proximal end side.

[0064] Next, a method for manufacturing the sheath 33 that constitutes the catheter 10 will be described. First, a tube 300 is formed that includes a reinforcing member 312 having a repeating structure 313 formed of metal wires 314 along the entire length of a resin tubular body 310 that has a distal end and a proximal end. The tube 300 has the same outer and inner diameters along its entire length, and the pitch of the repeating structure 313 in the reinforcing member 312 is also formed to be the same along its entire length.

[0065] 7(a), a core material 330 is inserted into the formed tube 300. The core material 330 has an outer diameter that is approximately the same as the inner diameter of the second region 152 of the first sheath 34 to be manufactured. The outer diameter of the core material 330 is 1.3 mm to 1.5 mm.

[0066] Next, the tube 300 is inserted into a mold 320. As shown in Figure 7(b), the mold 320 has a second region forming portion 321 having an inner diameter smaller than the outer diameter of the tube 300, a first region forming portion 322 having an inner diameter substantially the same as the outer diameter of the tube 300, and an intermediate portion 323 that slopes so that the diameter decreases from the first region forming portion 322 toward the second region forming portion 321. The inner diameter of the second region forming portion 321 of the mold 320 is 1.6 mm to 1.8 mm. The mold 320 can be heated, and the heat from the mold 320 can be used to heat the tube 300 to a high temperature, allowing for diameter reduction processing.

[0067] When one side of tube 300 is inserted into mold 320 along its longitudinal axis and pulled toward the base end, intermediate section 323 and second region forming section 321 reduce the outer diameter of tube 300, stretch reinforcing body 312 in the longitudinal axis direction, and increase the pitch of repeating structure 313. This allows tube 300 to form a portion that will become first region 151, a portion that will become second region 152, and a portion that will become first tapered section 153. Reinforcing body 312 included in tube 300 is formed of wires 314 that are continuous from the distal end to the proximal end of tube 300, and tube 300 including reinforcing body 312 is subjected to a diameter reduction process to form sheath 33. As a result, the formed sheath 33 has reinforcing body 157 that is formed of wires 314 that are continuous from the distal end to the proximal end.

[0068] In the first sheath 34 formed in this manner, in the second region 152 located at the base end of the first region 151, the pitch P2 of the reinforcing members 157 is greater than the pitch P1 in the first region 151, and the inclination angle α2 of the wires 158 with respect to the longitudinal direction is smaller than the inclination angle α1 in the first region 151. In the first region 151, when the sheath 33 is pulled by the pulling wire 80, the wires 158 move, loosening the resin around the wires 158 and making the resin more likely to peel off. On the other hand, in the second region 152, the wires 158 are already pulled in the longitudinal direction during manufacturing. Therefore, even when the sheath 33 is pulled by the pulling wire 80, the resin around the wires 158 is not loosened and the resin is less likely to peel off. Therefore, the first sheath 34 can have a higher tensile strength in the longitudinal direction in the second region 152 than in the first region 151.

[0069] While the manufacturing process for the first sheath 34 has been described here, the second sheath 35 can be manufactured in a similar manner. The core material used in manufacturing the second sheath 35 has an outer diameter of 1.2 mm to 1.4 mm. The mold used in manufacturing the second sheath 35 has a third region-forming portion having an inner diameter substantially equal to the outer diameter of the third region 161 and a fourth region-forming portion having an inner diameter substantially equal to the outer diameter of the fourth region 162, and the inner diameter of the fourth region-forming portion is 1.2 mm to 1.4 mm. The first sheath 34 and the second sheath 35 can be connected by covering them with a connection tube 60. Furthermore, the fourth region 162 of the second sheath 35 can be covered with a wire-fixing tube 65 to fix the pulling wire 80.

[0070] Next, a first modified catheter 400 will be described. As shown in Figure 8, the catheter 400 has a stent 410, an outer tube 420 that houses the stent 410, and an inner tube 430 that is placed inside the outer tube 420, and its basic structure is similar to that of the catheter 10 described above. Description of parts that have the same structure as the catheter 10 will be omitted.

[0071] The outer tube 420 has a stent sheath 424 connected to the distal end of the sheath 423 and housing the stent 410. The puller wire 440 is fixed to the proximal end of the sheath 423. The sheath 423 has a second region 451, which is smaller in diameter than the first region 450, located proximal to the distal first region 450, and a first tapered section 452 is formed between the first region 450 and the second region 451. The sheath 423 includes a reinforcing member made of a resin tubular body and braided with metal wires over the entire length from the distal end to the proximal end. The pitch of the reinforcing member in the second region 451 is greater than the pitch in the first region 450. The stent sheath 424 is a resin tubular body without a reinforcing member. In this way, the stent sheath 424 housing the distal stent 410 does not need to have a reinforcing member.

[0072] Next, a catheter 500 of a second modification will be described. As shown in Figure 9, the catheter 500 has a stent 510, an outer tube 520 that houses the stent 510, and an inner tube 530 that is placed inside the outer tube 520, and its basic structure is similar to that of the catheter 10 described above. Description of parts that have the same structure as the catheter 10 will be omitted.

[0073] The outer tube 520 has a sheath 523. The sheath 523 has a first region 550 on the distal side, a second region 551 on the proximal end side of the first region 550 and having a smaller diameter than the first region 550, and a fifth region 553 on the proximal end side of the second region 551 and having a smaller diameter than the second region 551. The sheath 523 has a first tapered portion 553 between the first region 550 and the second region 551, and a second tapered portion 554 between the second region 551 and the fifth region 553. The pulling wire 540 is fixed to the fifth region 552, which is the proximal end of the sheath 523.

[0074] 10 , the sheath 523 includes a reinforcing member 561 having a repeating structure 563 in which metal wires 562 are braided around a resin tubular body 560 over the entire length from the distal end to the proximal end. The pitch of the repeating structure 563 of the reinforcing member 561 is larger in the first tapered portion 553 than in the first region 550, larger in the second region 551 than in the first tapered portion 553, larger in the second tapered portion 554 than in the second region 551, and larger in the fifth region 553 than in the second tapered portion 554. In other words, the pitch of the repeating structure 563 increases as the diameter of the tubular body 560 decreases.

[0075] Next, a description will be given of a modified example of the first sheath 150. As shown in Fig. 11, the first sheath 150 may have a first tapered section 153 formed long along the longitudinal direction, and the first sheath tubular body 150 may gradually decrease in diameter toward the proximal end. The first sheath reinforcement body 157 is formed in the first tapered section 153 so that the pitch of the repeating structure 159 gradually increases.

[0076] As described above, the catheter 10 according to the present embodiment (1) is a catheter 10 including a tubular sheath 33 having a distal end and a proximal end, the sheath 33 including a tubular body 150 made of resin and a reinforcing body 157 having a repeating structure 159 formed of metal wires 158, the tubular body 150 and the reinforcing body 157 extending continuously over the entire length of the sheath 33 from the distal end to the proximal end, the sheath 33 has a pulling wire 80 fixed to the proximal end, and the sheath 33 can be moved toward the proximal end by pulling the pulling wire 80. In the catheter 10 configured in this manner, the reinforcing body 157 extends over the entire length of the sheath 33 pulled by the pulling wire 80, so that the sheath 33 has continuous tensile strength from the distal end to the proximal end in the longitudinal direction, and local reductions in tensile strength can be prevented.

[0077] (2) In the catheter 10 described in (1) above, the sheath 33 may include a first region 151 and a second region 152 at the proximal end of the first region 151, and the second region 152 may have a smaller outer diameter than the first region 151 and a larger pitch of the repeating structure 159 forming the reinforcing member 157. This allows the catheter 10 to have high tensile strength in the longitudinal direction of the second region 152.

[0078] (3) In the catheter 10 described in (1) above, the sheath 33 may include a first region 151 and a second region 152 at the proximal end of the first region 151, the second region 152 having a smaller outer diameter than the first region 151, and the angle formed by the wires 158 in the repeating structure 159 forming the reinforcing body 157 with respect to the longitudinal axis direction of the sheath 33 may be smaller. This allows the catheter 10 to have high tensile strength in the longitudinal direction of the second region 152.

[0079] (4) In the catheter 10 described above in (2) or (3), the sheath 33 may include a tapered portion 153 between the first region 151 and the second region 152, the tapered portion 153 being inclined so that the diameter decreases from the first region 151 toward the second region 152, and the pitch of the repeating structures 159 in the tapered portion 153 may be larger than the pitch of the repeating structures 159 in the first region 151 and smaller than the pitch of the repeating structures 159 in the second region 152. This allows the catheter 10 to continuously change the tensile strength of the sheath 33 between the first region 151 and the second region 152, thereby suppressing abrupt changes in the physical properties of the sheath 33 and preventing breakage.

[0080] (5) In the catheter 10 of any of (2) to (4) above, the first region 151 of the sheath 33 may be a region that houses at least a portion of the stent 20. This allows the catheter 10 to house the stent 20 inside the first region 151 of the sheath 33 in a state where the stent 20 is securely held therein.

[0081] (6) In the catheter 10 of any of (2) to (5) above, the sheath 33 may include a first sheath 34 that houses the stent 20, and a second sheath 35 that is connected to the proximal end of the first sheath 34 and includes a resin tubular body 150 and a reinforcing body 167 formed by braiding metal wires 158. In this way, when the catheter 10 includes the first sheath 34 that houses the stent 20 and the second sheath 35 that is housed in the shaft on the proximal end side as separate bodies, the tensile strength of the sheath 33 as a whole can be continuously changed along the longitudinal direction, and localized decreases in tensile strength can be prevented.

[0082] (7) In the catheter 10 described above in (6), the pulling wire 80 may be fixed to the proximal end of the second sheath 35. This allows the catheter 10 to smoothly pull the second sheath 35.

[0083] (8) In the catheter 10 described in (6) or (7) above, the second sheath 35 may include a third region 161 and a fourth region 162 located proximal to the third region 161, and the fourth region 162 may have a smaller outer diameter than the third region 161 and a larger pitch of the repeating structure 169 forming the reinforcing member 167. This allows the catheter 10 to have high tensile strength in the longitudinal direction of the fourth region 162 of the second sheath 35.

[0084] (9) In the catheter 500 of any of (2) to (5) above, the sheath 523 may include a fifth region 553 at the proximal end of the second region 551, and the fifth region 553 may have a smaller outer diameter than the second region 551 and may have a larger pitch of the repeating structure 563 forming the reinforcing member 561. As a result, when the catheter 500 is formed by integrating the portion that houses the stent 510 and the portion that is housed in the shaft on the proximal side, the tensile strength of the sheath 523 as a whole can be continuously changed along the longitudinal axis, and localized decreases in tensile strength can be prevented.

[0085] (10) In the catheter 400 of (2) or (3) above, a stent sheath 424 that houses the stent 410 may be connected to the distal end of the sheath 423, and the stent sheath 424 may be a resin tube without a reinforcing member. This allows the catheter 400 to have high flexibility in the portion that houses the stent 410.

[0086] (11) In the catheter 10 of any of (1) to (10) above, the pulling wire 80 may be fixed to a fixing region of the sheath 33, and the fixing region may have the reinforcing member 167 extending over at least a portion thereof. This increases the tensile strength of the catheter 10 in the fixing region of the sheath 33 that is pulled by the pulling wire 80, thereby preventing the sheath 33 from breaking.

[0087] (12) A method for manufacturing a catheter 10 according to this embodiment is a method for manufacturing a catheter 10 equipped with a tubular sheath 33 having a distal end and a proximal end, and includes the steps of: forming a tube including a reinforcing body having a repeating structure 159 formed of metal over the entire length of a resin tubular body 150; and inserting one side of the tube along its longitudinal direction to an intermediate position through a mold having an inner diameter smaller than the outer diameter of the tube, and increasing the pitch of the repeating structure 159 while reducing the outer diameter of the tube that has passed through the mold. In this method for manufacturing a catheter 10 configured in this manner, the sheath 33 is formed by reducing the diameter of a tube including a reinforcing body that is continuous from the distal end to the proximal end of the tube. Therefore, the formed sheath 33 has a reinforcing body that is continuous from the distal end to the proximal end, and the sheath 33 has continuous tensile strength from the distal end to the proximal end in the longitudinal direction, preventing localized reductions in tensile strength.

[0088] The present invention is not limited to the above-described embodiment, and various modifications can be made by those skilled in the art within the technical spirit of the present invention. In the above-described embodiment, a catheter for placing a stent was described, but the present invention can be applied to other types of catheters as long as they have a tubular sheath, such as an ultrasound catheter.

[0089] In the sheath 33, in the second region 152 located at the base end of the first region 151, the pitch P2 of the reinforcing members 157 is larger than the pitch P1 in the first region 151, and the inclination angle α2 of the wires 158 relative to the longitudinal axis direction is smaller than the inclination angle α1 in the first region 151; however, in the second region 152, the pitch P2 of the reinforcing members 157 may be smaller than the pitch P1 in the first region 151, and the inclination angle α2 of the wires 158 relative to the longitudinal axis direction may be larger than the inclination angle α1 in the first region 151.

[0090] This application is based on Japanese Patent Application No. 2023-163653, filed on September 26, 2023, the disclosures of which are incorporated herein by reference in their entirety.

[0091] DESCRIPTION OF SYMBOLS 10 Catheter 20 Stent 30 Outer tube 32 Proximal outer tube 33 Sheath 34 First sheath 35 Second sheath 36 Stent sheath 37 Sheath 40 Inner tube 70 Proximal shaft 80 Pulling wire 110 Control section 150 First sheath tubular body 151 First region 152 Second region 153 First tapered section 157 First sheath reinforcing body 158 Wire 159 Repeated structure 160 Second sheath tubular body 161 Third region 162 Fourth region 163 Second tapered section 167 Second sheath reinforcing body 168 Wire 169 Repeated structure

Claims

1. A catheter having a tubular sheath with a distal end and a proximal end, the sheath comprising a tubular body formed of resin and a reinforcing body having a repeating structure formed of metal wires, the tubular body and the reinforcing body extending continuously over the entire length of the sheath from the distal end to the proximal end, a pulling wire fixed to the proximal end of the sheath, and the sheath can be moved toward the proximal end by pulling the pulling wire.

2. The catheter according to claim 1, wherein the sheath comprises a first region and a second region at a proximal end of the first region, the second region having a smaller outer diameter than the first region and a larger pitch for the repeating structure forming the reinforcing body.

3. A catheter as described in claim 1, wherein the sheath comprises a first region and a second region at a base end of the first region, the second region having an outer diameter smaller than that of the first region, and the angle that the wires in the repeating structure forming the reinforcing body make with respect to the longitudinal axis direction of the sheath is smaller than that of the first region.

4. A catheter as described in claim 2, wherein the sheath has a tapered section between the first region and the second region, the tapered section having a diameter that decreases from the first region toward the second region, and the pitch of the repeating structure in the tapered section is greater than the pitch of the repeating structure in the first region and is smaller than the pitch of the repeating structure in the second region.

5. The catheter of claim 2, wherein said first region of said sheath is a region that accommodates at least a portion of a stent.

6. A catheter as described in claim 5, wherein the sheath comprises a first sheath that houses the stent, and a second sheath that is connected to the base end side of the first sheath and has a resin tube body and a reinforcing body made of braided metal wires.

7. The catheter of claim 6, wherein said puller wire is fixed to the proximal end of said second sheath.

8. A catheter as described in claim 6 or 7, wherein the second sheath comprises a third region and a fourth region at the base end of the third region, the fourth region having a smaller outer diameter than the third region and a larger pitch of the repeating structure forming the reinforcing body.

9. A catheter as claimed in claim 2 or 3, wherein the sheath is provided with a fifth region at the base end of the second region, the fifth region having a smaller outer diameter than the second region and a larger pitch for the repeating structure forming the reinforcing body.

10. A catheter as claimed in claim 2 or 3, wherein a stent sheath housing a stent is connected to the distal end of said sheath, said stent sheath being a resin tube having no reinforcing member.

11. A catheter according to claim 2 or 3, wherein the puller wire is fixed to a fixing region of the sheath, and the fixing region extends at least in part through the reinforcement body.

12. A method for manufacturing a catheter equipped with a tubular sheath having a distal end and a proximal end, comprising the steps of: forming a tube including a reinforcing body having a repeating structure formed of metal over the entire length of a resin tubular body; and inserting one side of the tube along the longitudinal direction to a midpoint through a mold having an inner diameter smaller than the outer diameter of the tube, thereby reducing the outer diameter of the tube that has passed through the mold while increasing the pitch of the repeating structure.

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