Catheter

Abstract

To provide a catheter in which reinforcement bodies are joined to each other in a sure manner at the end part of a reinforcement layer.SOLUTION: A catheter 1 is provided with a tube body 2 including an inner layer 10 having a lumen along a lengthwise direction, an outer layer 30 for covering an outer peripheral side of the inner layer 10, and a reinforcement layer 20 disposed between the inner layer 10 and the outer layer 30. The reinforcement layer 20 is a braided body formed by braiding a first reinforcement body 21 wound in either left or right direction with respect to the tube body 2 and a second reinforcement body 22 wound in a direction opposite to the first reinforcement body 21 with respect to the tube body 2 in a mesh shape so as to intersect with each other, The first reinforcement body 21 is composed of a tungsten flat wire 26 having a substantially square cross-sectional shape and containing tungsten as a main component, or the tungsten flat wire 26 and a stainless steel flat wire 25 having a substantially square cross-sectional shape and containing stainless steel as a main component, The second reinforcement body 22 is composed of the stainless steel flat wire 25.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] One method for treating lesions such as stenosis and blockages in blood vessels is endovascular treatment, which uses a device inserted percutaneously into the blood vessel to perform treatment from within the blood vessel. In endovascular treatment, a catheter is used to deliver diagnostic contrast agents and guide wires to the lesion.

[0003] In some catheters, a reinforcing layer is provided inside the tubular body to ensure sufficient strength even when the tubular body is thin. In this case, the tubular body has an inner layer with a lumen along the longitudinal direction, an outer layer covering the outer periphery of the inner layer, and a reinforcing layer disposed between the inner and outer layers. The reinforcing layer is formed by winding a reinforcing element, which is a metal wire, around the inner layer in both clockwise and counterclockwise directions relative to the central axis and then braiding it.

[0004] The reinforcing body that constitutes the reinforcing layer is often made of stainless steel wire, which has high strength and good workability. Furthermore, as shown in Patent Document 1, some of the reinforcing body may be made of tungsten wire. By using tungsten wire as part of the reinforcing body, it is possible to reduce anisotropy, which is the difference in torque transmission depending on the direction of rotation, and improve the kink resistance of the tube body. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-29120 Summary of the Invention [Problem to be solved by the invention]

[0006] The reinforcing layer is subjected to end treatment by applying heat to join adjacent reinforcing bodies so that the ends of the reinforcing bodies, which are element wires, do not penetrate the resin layer at the ends. Stainless steel wires can be easily joined to each other by end treatment, but tungsten wires have a high melting point, so there is a possibility that they cannot be joined to each other.

[0007] The present invention has been made to solve the above-mentioned problems, and has an object to provide a catheter in which reinforcing bodies are securely joined to each other at the ends of the reinforcing layer. [Means for solving the problem]

[0008] (1) A catheter that achieves the above-mentioned object is a catheter having a tubular body having an inner layer with a lumen along the longitudinal direction, an outer layer covering the outer periphery of the inner layer, and a reinforcing layer arranged between the inner layer and the outer layer, wherein the reinforcing layer is a braided body formed by weaving a first reinforcing body wound in either the left or right direction around the tubular body and a second reinforcing body wound in the opposite direction to the first reinforcing body around the tubular body in a mesh pattern so that they cross each other, and the first reinforcing body is composed of a tungsten flat wire having an approximately rectangular cross-sectional shape and composed primarily of tungsten, or the tungsten flat wire and a stainless steel flat wire having an approximately rectangular cross-sectional shape and composed primarily of stainless steel, and the second reinforcing body is composed of the stainless steel flat wire. [Effects of the Invention]

[0009] The catheter configured as described above contains tungsten flat wires in the reinforcing layer, which reduces anisotropy and improves kink resistance. Furthermore, because the reinforcing layer contains tungsten flat wires only in the first reinforcing element wound in one direction around the tubular body, the tungsten flat wires, which have a high melting point, do not cross and join together at the end of the reinforcing layer, and these wires can be reliably joined together by end processing.

[0010] (2) In the catheter of (1) above, the reinforcing layer may be configured such that 25% of the total number of the first reinforcing members plus the second reinforcing members is made of the tungsten flat wires, thereby enabling the catheter to simultaneously achieve good visibility during angiography, reduced anisotropy, and improved kink resistance. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is an overall view of a catheter according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing a portion of the tubular body of the catheter. [Figure 3] FIG. 3 is an enlarged front view showing a part of the reinforcing layer. [Figure 4] These are X-ray images of a tube, where (a) is an image of a tube with a reinforcing layer made up of only flat stainless steel wires, (b) is an image of a tube with a reinforcing layer made up of 25% flat tungsten wires and 75% flat stainless steel wires, and (c) is an image of a tube with a reinforcing layer made up of 50% flat tungsten wires and 50% flat stainless steel wires. [Figure 5] FIG. 1 is a conceptual overall view of a torque transmission test device. [Figure 6] The graphs show the results of a torque transmission test, with (a) a test specimen having a reinforcing layer made up of only stainless steel flat wires, and (b) a test specimen having a reinforcing layer made up of 25% tungsten flat wires and 75% stainless steel flat wires, showing the relationship between the base end angle and the tip angle. [Figure 7] FIG. 1 is a conceptual overall view of a kink resistance test device. [Figure 8] The graphs show the results of the kink resistance test, with (a) a test specimen having a reinforcing layer made only of stainless steel flat wires, and (b) a test specimen having a reinforcing layer containing tungsten flat wires, showing the relationship between the test force and the displacement. [Figure 9] FIG. 4 is an enlarged front view of an end portion of the reinforcing layer. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. For convenience of explanation, the dimensions of the drawings may be exaggerated and may differ from the actual dimensions. Furthermore, in this specification and the drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant explanations will be omitted. In this specification, the side of a catheter that is inserted into a blood vessel will be referred to as the "distal side," and the side that is operated will be referred to as the "proximal side."

[0013] In the description of this specification, the direction in which the catheter extends in its natural state (straight state without external force being applied) is referred to as the "longitudinal direction." The direction of rotation about the longitudinal direction of the catheter as the reference axis is referred to as the "circumferential direction." The side of the catheter that is inserted into the blood vessel is referred to as the distal end, and the end opposite the distal end is referred to as the proximal end. The portion of the catheter that extends from the distal end (the most distal end) in the longitudinal direction is referred to as the "distal portion," and the portion of the catheter that extends from the proximal end (the most proximal end) in the longitudinal direction is referred to as the "proximal end." Here, clockwise rotation when viewed from the proximal end, with the longitudinal axis as the center, is referred to as rightward rotation, and counterclockwise rotation is referred to as leftward rotation.

[0014] In this specification, the term "X to Y" indicating a range includes X and Y and means "at least X but not more than Y."

[0015] The catheter 1 according to this embodiment is a guiding catheter that is inserted into the radial artery, femoral artery, or the like, and advanced to the vicinity of a target site, such as a stenotic portion of a coronary artery. The guiding catheter is used to insert a treatment catheter, such as a balloon catheter, and guide the treatment catheter to the target site. As shown in FIG. 1 , the catheter 1 has a long tubular body 2 having a distal end and a proximal end, a hub 3 connected to the proximal end of the tubular body 2, and a kink-resistant protector 4 that surrounds the connection site between the tubular body 2 and the hub 3.

[0016] The tubular body 2 is a flexible tubular member, and has an internal cavity 5 formed from the base end to the tip end. A guide wire is inserted into the internal cavity 5 when the catheter 1 is inserted into a blood vessel. The internal cavity 5 can also be used as a passage for the treatment catheter described above.

[0017] The effective length of the tubular body 2 is not particularly limited, but is, for example, 600 mm to 2500 mm. The effective length of the tubular body 2 is the length of the portion that can be inserted into a blood vessel or a sheath. In this embodiment, the effective length is the length from the tip of the anti-kink protector 4 to the tip of the tubular body 2.

[0018] The hub 3 is fixed liquid-tightly to the proximal end of the tubular body 2 by adhesive, heat fusion, or a fastener (not shown), etc. The hub 3 functions as an insertion port for a guide wire or a treatment catheter into the lumen 5. The hub 3 also functions as a gripping portion when operating the catheter 1.

[0019] The hub 3 is formed from a resin such as, but not limited to, polycarbonate, polyamide, polysulfone, polyarylate, or methacrylate-butylene-styrene copolymer.

[0020] The anti-kink protector 4 is provided to surround the connection portion between the tubular body 2 and the hub 3, and prevents kinking of the tubular body 2 at the connection portion between the tubular body 2 and the hub 3. The anti-kink protector 4 is made of an elastic material such as elastomer, natural rubber, or silicone resin.

[0021] As shown in Figures 2 and 3, the pipe body 2 includes an inner layer 10 having an inner lumen 5, a reinforcing layer 20 arranged on the outside of the inner layer 10, and an outer layer 30 arranged on the outside of the inner layer 10 and the reinforcing layer 20.

[0022] The inner layer 10 has an inner cavity 5 formed therein. The inner layer 10 is made of a low-friction material such as a fluorine-based resin such as polytetrafluoroethylene (PTFE) or high-density polyethylene (HDPE).

[0023] The outer layer 30 is a tubular member that covers the outer periphery of the inner layer 10 and the reinforcing layer 20. The hardness of the outer layer 30 increases stepwise or gradually from the distal end to the proximal end, so that the bending rigidity of the tubular body 2 is low at the distal end and high at the proximal end.

[0024] The outer layer 30 is formed from a polymer material such as polyolefin (polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer, or a mixture of two or more thereof), polyvinyl chloride, polyamide, polyester elastomer, polyamide elastomer, polyurethane, polyurethane elastomer, polyimide, fluororesin, or a thermoplastic resin such as a mixture of these, or a thermosetting resin such as epoxy resin.

[0025] 3, the reinforcing layer 20 is formed by weaving together a first reinforcing member 21 wound clockwise or counterclockwise around the tubular body 2 and a second reinforcing member 22 wound in the other clockwise or counterclockwise direction, i.e., the opposite direction, in a mesh pattern so that they intersect with each other. The first reinforcing member 21 and the second reinforcing member 22 are wound symmetrically in the left-right direction around the tubular body 2, and the spacing in the longitudinal direction may be constant or variable.

[0026] The first reinforcing body 21 is composed of a tungsten flat wire 26 having a substantially rectangular cross section and made primarily of tungsten, and a stainless steel flat wire 25 having a substantially rectangular cross section and made primarily of stainless steel, such as SUS304 or SUS316. In this specification, "made primarily of tungsten" means that the tungsten content is 90% or more. Also, in this specification, "made primarily of stainless steel" means that the stainless steel content is 90% or more. In Figures 3 and 9, the black-colored wire is the tungsten flat wire 26, and the white-colored wire is the stainless steel flat wire 25.

[0027] The second reinforcing body 22 is entirely made up of stainless steel flat wires 25. In the first reinforcing body 21, one in two wires is a tungsten flat wire 26, so in the reinforcing layer 20, of the total number of wires in the first reinforcing body 21 plus the number of wires in the second reinforcing body 22, 25% are made up of tungsten flat wires 26, and the remaining 75% are made up of stainless steel flat wires 25. The tungsten flat wires 26 are included only in the first reinforcing body 21, and not in the second reinforcing body 22. Therefore, the reinforcing layer 20 includes tungsten flat wires 26 only in one of the clockwise and counterclockwise directions relative to the tube body 2.

[0028] The stainless steel flat wire 25 and the tungsten flat wire 26 each have a width of 0.110 mm and a thickness of 0.035 mm. However, the dimensions of the stainless steel flat wire 25 and the tungsten flat wire 26 are not limited to these, and the width can be set within the range of 0.02 to 1.00 mm, and the thickness can be set within the range of 0.01 to 0.10 mm.

[0029] As shown in Figure 4(a), a reinforcing layer made up only of stainless steel flat wires 25 has poor visibility under X-ray contrast, while a reinforcing layer made up of 50% tungsten flat wires has a darker tungsten contrast but is more expensive as shown in Figure 4(c). As shown in Figure 4(b), a reinforcing layer made up of 25% tungsten flat wires 26 has fewer tungsten flat wires 26, but the overlapping of the wires makes it more visible.

[0030] A torque transmissibility test was conducted on a tube 2 having a reinforcing layer 20 of this embodiment. As shown in Fig. 5, a torque transmissibility test device 50 has a rotation transmission unit 53 that transmits a rotational force to a base end 55 of a test piece 51, which is the tube 2, and a holding unit 52 that holds the center portion of the test piece 51 in a U-shape in the longitudinal direction. The radius R of the holding unit 52 is 70 mm, and the distance L from the base end 55 of the tube 2 to the lowest point of the holding unit 52 is 400 mm.

[0031] The torque transmissibility testing device 50 can test the torque transmissibility of the test specimen 51 by rotating the base end 55 of the test specimen 51 with the rotation transmission unit 53 and measuring the difference between the rotation angle of the base end 55 and the rotation angle of the tip end 54 of the test specimen 51. During the test, the test specimen 51 is rotated both clockwise and counterclockwise to evaluate the difference in torque transmissibility in each direction. When changing the rotation direction of the test specimen 51, the torque on the test specimen 51 is temporarily released before the test is conducted.

[0032] As shown in Figure 6(a), the test specimen 51 with a reinforcing layer composed only of stainless steel flat wires 25 exhibited a large difference in torque transmissibility of approximately 80° between clockwise and counterclockwise rotations. In other words, the test specimen 51 with a reinforcing layer composed only of stainless steel flat wires 25 exhibited a large anisotropy in torque transmission. In contrast, as shown in Figure 6(b), the test specimen 51 with a reinforcing layer composed of 25% tungsten flat wires 26 exhibited a small difference in torque transmissibility of approximately 20° between clockwise and counterclockwise rotations. In other words, the test specimen 51 with a reinforcing layer containing tungsten flat wires 26 exhibited a small anisotropy in torque transmission. When treating the left and right coronary arteries, the surgeon first engages the distal end of the tubular body 2 with one of the left and right coronary arteries, and then engages the distal end of the tubular body 2 with the other coronary artery. At this time, the surgeon rotates the hub 3 at hand to change the orientation of the distal end of the tubular body 2. The tube 2 having the reinforcing layer 20 of this embodiment has small anisotropy in torque transmission, which reduces the discomfort felt by the surgeon during rotational operations, allowing the surgeon to perform the operations reliably.

[0033] The kink resistance of a pipe 2 having a reinforcing layer 20 of this embodiment was tested. As shown in FIG. 7 , a kink resistance test device 60 has a holding part 62 that supports a test piece 61, which is the pipe 2, from below, and a pressing body 63 that presses the U-shaped bent test piece 61 from above. The pressing body 63 has a groove for accommodating the test piece 61 on its lower surface that presses the test piece 61. The kink resistance test device 60 presses the U-shaped bent test piece 61 downward with the pressing body 63, and can measure the relationship between the amount of displacement and the test force.

[0034] As shown in Figure 8, it was confirmed that the specimen 61 having a reinforcing layer including tungsten flat wire 26 had a larger displacement and test force at which kinking began than the specimen 61 having a reinforcing layer composed only of stainless steel flat wire 25, and was less likely to kink.

[0035] The reinforcing layer 20 of this embodiment, which includes the tungsten flat wires 26 in the first reinforcing body 21, has been confirmed to have small anisotropy in torque transmission and high kink resistance. Furthermore, since the reinforcing layer 20 includes the tungsten flat wires 26 only in one of the clockwise and counterclockwise directions relative to the pipe body 2, as shown in FIG. 9 , at the end of the reinforcing layer 20, the tungsten flat wires 26 of the first reinforcing body 21 intersect and are joined to the stainless steel flat wires 25 of the second reinforcing body 22. Furthermore, the stainless steel flat wires 25 of the first reinforcing body 21 intersect and are joined to the stainless steel flat wires 25 of the second reinforcing body 22. This prevents the tungsten flat wires 26 from intersecting and being joined to each other, allowing these wires to be reliably joined to each other by end processing. Therefore, the wires can be prevented from breaking through the inner layer 10 or the outer layer 30 at the end of the reinforcing layer 20.

[0036] The proportion of the tungsten flat wires 26 in the first reinforcing body 21 can be set arbitrarily. The first reinforcing body 21 may be configured entirely of the tungsten flat wires 26.

[0037] As described above, the catheter 1 (1) according to this embodiment is a catheter 1 comprising a tubular body 2 having an inner layer 10 with a lumen along the longitudinal direction, an outer layer 30 covering the outer periphery of the inner layer 10, and a reinforcing layer 20 arranged between the inner layer 10 and the outer layer 30, and the reinforcing layer 20 is a braided body formed by weaving a first reinforcing body 21 wound around the tubular body 2 in either the left or right direction and a second reinforcing body 22 wound around the tubular body 2 in the opposite direction to the first reinforcing body 21 in a mesh pattern so that they cross each other, and the first reinforcing body 21 is composed of a tungsten flat wire 26 having an approximately rectangular cross-sectional shape and made primarily of tungsten, or a tungsten flat wire 26 and a stainless steel flat wire 25 having an approximately rectangular cross-sectional shape and made primarily of stainless steel, and the second reinforcing body 22 is composed of a stainless steel flat wire 25. The catheter 1 configured in this manner can reduce anisotropy and improve kink resistance because the reinforcing layer 20 contains the tungsten flat wires 26. Furthermore, the catheter 1 contains the tungsten flat wires 26 only in the first reinforcing body 21 where the reinforcing layer 20 is wound in one direction around the tubular body 2. Therefore, the tungsten flat wires 26, which have a high melting point, do not cross and join together at the end of the reinforcing layer 20, and these wires can be reliably joined together by end processing.

[0038] (2) In the catheter 1, the reinforcing layer 20 may be configured such that 25% of the total number of first reinforcing members 21 plus the number of second reinforcing members 22 are made up of tungsten flat wires 26. This allows the catheter 1 to achieve both good visibility during angiography, reduced anisotropy, and improved kink resistance.

[0039] 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 concept of the present invention. [Explanation of symbols]

[0040] 1 catheter 2. Body 3. Hub 4 Anti-kink protector 5 lumens 10 Inner layer 20 Reinforcement layer 21 First Reinforcement 22 Second Reinforcement 25 Stainless steel flat wire 26 Tungsten flat wire 30 outer layer 50 Torque transmission test equipment 51 Test specimen 52 Holding part 53 Rotation transmission part 54 Tip 55 Proximal end 60 Kink Resistance Test Equipment 61 Test specimen 62 Holding part 63 Pressurizing body

Claims

1. A catheter comprising a tubular body having an inner layer having a lumen along the longitudinal direction, an outer layer covering the outer periphery of the inner layer, and a reinforcing layer disposed between the inner layer and the outer layer, the reinforcing layer is a braided body formed by weaving a first reinforcing body wound around the tubular body in either the left or right direction and a second reinforcing body wound around the tubular body in the opposite direction to the first reinforcing body in a mesh pattern so that the first reinforcing body and the second reinforcing body cross each other; the first reinforcing body is composed of a tungsten flat wire containing tungsten as a main component and having a substantially rectangular cross section, or the tungsten flat wire and a stainless steel flat wire containing stainless steel as a main component and having a substantially rectangular cross section, A catheter in which the second reinforcing body is made of the stainless steel flat wire.

2. 2. The catheter according to claim 1, wherein the reinforcing layer is made up of 25% of the total number of the first reinforcing members plus the number of the second reinforcing members, the number of which is the tungsten flat wire.

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