Guide wire

Abstract

This guide wire comprises: a core shaft; a coil body that includes a metal wire that is spirally wound around the outer periphery of the core shaft; a resin layer that is filled into the gaps between the core shaft and the coil body and that is disposed more on the inner side of the coil body than the outer peripheral surface thereof; and a hydrophilic coating layer that is disposed on the outer periphery of the coil body and the resin layer.

Description

Guidewire

[0001] The technology disclosed herein relates to guidewires.

[0002] A guidewire is a medical device that is inserted into a biological lumen such as a blood vessel. The guidewire includes a core shaft and a coil body including a metal wire wound helically around the core shaft. Known guidewires include a resin layer that fills the inner periphery of the coil body and coats the outer periphery of the coil body (see, for example, Patent Document 1).

[0003] Patent No. 5913383

[0004] The guidewire has a problem in that the flexibility is reduced due to the outer periphery of the coil body being covered with a resin layer.

[0005] This specification discloses a technique that can solve the above-mentioned problems.

[0006] The guide wire disclosed in this specification comprises a core shaft, a coil body including a metal wire wound helically around the outer periphery of the core shaft, a resin layer filled in the gap between the core shaft and the coil body and positioned inside the outer periphery of the coil body, and a hydrophilic coating layer positioned on the outer periphery of the coil body and the resin layer.

[0007] FIG. 1 is an explanatory diagram showing a schematic diagram of a guidewire 100 according to an embodiment; FIG. 2 is an explanatory diagram showing the detailed configurations of an adhesive layer 31, a resin layer 33, and a hydrophilic coating layer 35; FIG. 3 is an explanatory diagram showing the detailed configurations of an adhesive layer 31, a resin layer 33, and a hydrophilic coating layer 35; FIG. 4 is an explanatory diagram showing a schematic diagram of a guidewire 100a according to a first modified example; and FIG. 5 is an explanatory diagram showing a schematic diagram of a guidewire 100b according to a second modified example.

[0008] A. Embodiments: A-1. Configuration of Guidewire 100: FIG. 1 is an explanatory diagram schematically illustrating a guidewire 100 according to an embodiment. FIG. 1 shows a longitudinal cross section of the guidewire 100. In FIG. 1, the positive Z-axis direction is the tip end (distal side) that is inserted into the body, and the negative Z-axis direction is the base end (proximal side) that is operated by a surgeon such as a doctor. FIG. 1 omits the illustration of a portion of the guidewire 100. FIG. 1 shows a state in which the central axis AX of a core shaft 10 (described later) of the guidewire 100 is linear and parallel to the Z-axis direction, but the guidewire 100 has sufficient flexibility to be bent.

[0009] In this specification, the distal end of the guidewire 100 and each of its constituent members will be referred to as the "distal end," the distal end and its vicinity will be referred to as the "distal portion," the proximal end will be referred to as the "proximal end," and the proximal end and its vicinity will be referred to as the "proximal portion." A longitudinal cross section of the guidewire 100 and each of its constituent members refers to a cross section including the central axis AX (YZ cross section), and a transverse cross section of the guidewire 100 and each of its constituent members refers to a cross section perpendicular to the central axis AX (XY cross section). These points also apply to subsequent figures.

[0010] The guidewire 100 is a medical device that is inserted into a biological lumen such as a blood vessel. The guidewire 100 is used, for example, to guide another medical device such as a catheter to a desired position within a biological lumen. The total length of the guidewire 100 is, for example, approximately 1500 mm or more and 3000 mm or less, and the outer diameter of the guidewire 100 is, for example, approximately 0.1 mm or more and 1.2 mm or less.

[0011] The guidewire 100 includes a core shaft 10 , a coil body 20 , an adhesive layer 31 , a resin layer 33 , a hydrophilic coating layer 35 , a distal joint 51 , and a proximal joint 56 .

[0012] The core shaft 10 is an elongated member extending along the central axis AX. The core shaft 10 has a thin diameter portion 11, a first tapered portion 12, a first large diameter portion 13, a second tapered portion 14, and a second large diameter portion 15. The thin diameter portion 11 is located at the tip of the core shaft 10 and is the portion of the core shaft 10 where the outer diameter is smallest. The first tapered portion 12 is located between the thin diameter portion 11 and the first large diameter portion 13 and has a tapered shape in which the outer diameter increases from the tip side to the base end side. The first large diameter portion 13 is located between the first tapered portion 12 and the second tapered portion 14 and has an outer diameter larger than that of the thin diameter portion 11 and smaller than that of the second large diameter portion 15. The second tapered portion 14 is located between the first large diameter portion 13 and the second large diameter portion 15 and has a tapered shape in which the outer diameter increases from the tip side to the base end side. The second large diameter portion 15 is located at the base end of the core shaft 10, and is the portion where the outer diameter of the core shaft 10 is greatest. The second large diameter portion 15 is the portion that is grasped by a surgeon such as a doctor. The cross-sectional shape at each position of the core shaft 10 can be any shape, for example, a circle. The diameter and length of each portion of the core shaft 10 can be set arbitrarily.

[0013] The core shaft 10 is formed from, for example, stainless steel (SUS302, SUS304, SUS316, etc.), Ni-Ti alloy, piano wire, nickel-chromium alloy, cobalt alloy, tungsten, or the like.

[0014] The coil body 20 is a coil-shaped member formed into a hollow cylinder extending along the central axis AX. More specifically, the coil body 20 is a cylindrical member having an inner circumferential surface SI facing the radially inward direction of the coil body 20 and an outer circumferential surface SO facing the radially outward direction of the coil body 20 (see FIG. 2 ). The coil body 20 includes a metal wire 21 wound in a spiral shape around the outer periphery of the core shaft 10. In a longitudinal cross section of the guidewire 100, an imaginary line connecting points on the wire 21 that are the shortest distance from the central axis AX defines the inner circumferential surface SI of the coil body 20, and an imaginary line connecting points on the wire 21 that are the longest distance from the central axis AX defines the outer circumferential surface SO of the coil body 20 (see FIG. 2 ). The coil body 20 is disposed on the outer periphery of the core shaft 10 so as to cover the core shaft 10. The core shaft 10 and the coil body 20 are disposed spaced apart in the radial direction of the guidewire 100. That is, a gap SPr is formed between the core shaft 10 and the coil body 20. The coil body 20 is a loosely wound coil in which the wires 21 are loosely wound, thereby forming a gap SPa between adjacent wires 21 in the axial direction (i.e., the Z-axis direction) (see FIGS. 2 and 3 ). More specifically, the gap SPa refers to the gap between the wires 21 in the axial direction of the guidewire 100. In this embodiment, the coil body 20 covers the small diameter portion 11, the first tapered portion 12, and the first large diameter portion 13 of the core shaft 10. In this embodiment, the cross section of the wires 21 is circular. The wire diameter of the wires 21 and the average coil diameter of the coil body 20, which is the average diameter of the outer diameter and inner diameter of the coil body 20, can be set as desired.

[0015] The wire 21 may be formed from a radiotransparent material such as stainless steel (SUS302, SUS304, SUS316, etc.), Ni-Ti alloy, or piano wire, or may be formed from a radiopaque material such as platinum, gold, tungsten, cobalt alloy, or nickel-chromium alloy.

[0016] The adhesive layer 31 is disposed between the core shaft 10 and the resin layer 33 in the radial direction of the guidewire 100. The adhesive layer 31 is disposed in the axial direction of the guidewire 100 from the distal joint 51 to the proximal joint 56. The adhesive layer 31 covers the thin diameter portion 11, the first tapered portion 12, and the first large diameter portion 13 of the core shaft 10. By covering the core shaft 10, the adhesive layer 31 connects the thin diameter portion 11 and the first tapered portion 12 to each other and also connects the first tapered portion 12 and the first large diameter portion 13 to each other.

[0017] The resin layer 33 is disposed on the outer periphery of the adhesive layer 31 in the radial direction of the guidewire 100. The resin layer 33 is disposed in the axial direction of the guidewire 100 from the distal joint 51 to the proximal joint 56. The resin layer 33 covers the outer periphery of the adhesive layer 31. The resin layer 33 fills the gap SPr between the core shaft 10 and the coil body 20 (see FIGS. 2 and 3 ), and is disposed inside the outer periphery SO of the coil body 20. It can also be said that the resin layer 33 fills the gaps SPa between the wires 21 in the coil body 20.

[0018] The hydrophilic coating layer 35 is disposed on the outer periphery of the coil body 20 and the resin layer 33 in the radial direction of the guidewire 100. The hydrophilic coating layer 35 covers the outer periphery of the coil body 20 and the resin layer 33 over the entire length of the coil body 20. Furthermore, the hydrophilic coating layer 35 covers the distal surface of the distal joint 51 and the proximal surface of the proximal joint 56. The hydrophilic coating layer 35 swells by absorbing moisture in the human body, improving the lubricity of the guidewire 100.

[0019] The distal joint portion 51 is a member that joins the distal end of the coil body 20 to the distal end (thin diameter portion 11) of the core shaft 10. The proximal joint portion 56 is a member that joins the proximal end of the coil body 20 to the core shaft 10 (first large diameter portion 13). The distal joint portion 51 and the proximal joint portion 56 are formed, for example, from metal solder (Au—Sn alloy, Sn—Ag alloy, Sn—Pb alloy, Pb—Ag alloy, etc.), brazing material (aluminum alloy brazing, silver brazing, gold brazing, etc.), adhesive (epoxy adhesive, etc.), etc. The materials that form the distal joint portion 51 and the proximal joint portion 56 may be the same or different from each other.

[0020] A-2. Detailed Configurations of Adhesive Layer 31, Resin Layer 33, and Hydrophilic Coating Layer 35: The adhesive layer 31, resin layer 33, and hydrophilic coating layer 35 will be described in more detail below. Figures 2 and 3 are explanatory diagrams showing the detailed configurations of the adhesive layer 31, resin layer 33, and hydrophilic coating layer 35. Figures 2 and 3 are enlarged longitudinal cross-sections of the guidewire 100 at portion X1 in Figure 1. Figure 2 shows the hydrophilic coating layer 35 in a normal state (dry state), and Figure 3 shows the hydrophilic coating layer 35 in a swollen state. In this specification, the swollen state refers to a state in which the hydrophilic coating layer 35 is immersed in physiological saline for 10 seconds or more.

[0021] As shown in FIG. 2 , the resin layer 33 does not cover a portion of the wire 21 located on the outer peripheral surface SO of the coil body 20, but does cover a portion of the wire 21 located closer to the central axis AX of the guidewire 100 than the outer peripheral surface SO of the coil body 20. An outer peripheral surface 33S, which is the outer peripheral surface of the resin layer 33, is located between a center position CL, which is the center between the inner peripheral surface SI and the outer peripheral surface SO of the coil body 20, and the outer peripheral surface SO of the coil body 20 in the radial direction of the guidewire 100. More specifically, the distance from the inner peripheral surface SI to the outer peripheral surface 33S in the radial direction of the guidewire 100 is preferably 50% or more and 90% or less, and more preferably 60% or more and 70% or less, of the distance from the inner peripheral surface SI to the outer peripheral surface SO in the radial direction of the guidewire 100. As such, the guidewire 100 can be said to have a smaller step on the outer peripheral surface compared to, for example, a guidewire not having the resin layer 33. The hydrophilic coating layer 35 covers the surface of the coil body 20 that is not covered by the resin layer 33, and the outer peripheral surface 33S of the resin layer 33. Therefore, the hydrophilic coating layer 35 is also formed in the gaps SPa between the wires 21 in the coil body 20, and can be said to be continuously formed from the tip end side to the base end side of the coil body 20.

[0022] 3 , when the hydrophilic coating layer 35 of the guidewire 100 is immersed in water, the hydrophilic coating layer 35 swells and transitions to a swollen state. As a result, the outer peripheral surface 35S of the hydrophilic coating layer 35 expands to a position farther away from the central axis AX of the guidewire 100 than in the normal state. The outer peripheral surface 35S is formed continuously from the distal joint 51 to the proximal joint 56.

[0023] The material for forming the resin layer 33 is not particularly limited, but may be, for example, polyurethane, polyester, polyimide, polyamide elastomer, nylon, vinyl chloride, polyethylene, polypropylene, etc. The Shore hardness of the material for forming the resin layer 33 is preferably 60D or less.

[0024] The adhesive layer 31 is a resin member that has higher adhesion to metal than the resin layer 33. The level of adhesion to metal can be measured, for example, by the following method. First, a resin material is adhered to the metal that forms the core shaft 10. Next, a cutter knife is used to make grid-like cuts in the resin material, for example, at intervals of 1 mm. Next, transparent adhesive tape is attached to the cut resin material, and the state of the grid is observed after the transparent adhesive tape is peeled off. The level of adhesion to metal can be measured by checking the peeling state of the resin material.

[0025] The material for forming the adhesive layer 31 is not particularly limited as long as it is a resin that has higher adhesion to metal than the resin layer 33, but for example, adhesives such as epoxy-based, urethane-based, silicone-based, and cyanoacrylate-based adhesives, resins with carboxylic acid groups, resins with thiol groups, and resins with amine groups can be used.

[0026] The hydrophilic coating layer 35 is typically formed of a material with higher swellability (hydrophilicity) than the resin layer 33. In this specification, "high swellability" means that the resin material expands more (holds more water) when impregnated with physiological saline. The degree of swellability can be measured, for example, by the following method. That is, the degree of swellability can be measured by the swollen film thickness, which is the change in film thickness measured using a laser microscope or the like. The swollen film thickness can be measured using a VFX series laser microscope (manufactured by Keyesence), an OPTELICS series white light confocal microscope (manufactured by Lasertec), or an F40 series optical interference film thickness meter (manufactured by Filmetrics). The thickness of the hydrophilic coating layer 35 after swelling may be, for example, 105 to 10,000%, or 110 to 5,000%, of the film thickness before swelling. The thickness (dry film thickness) of the hydrophilic coating layer 35 is not particularly limited, but may be, for example, 0.1 to 10 μm.

[0027] Examples of materials that can be used to form the hydrophilic coating layer 35 include polymers such as hyaluronic acid, polyvinylpyrrolidone, and polyethylene glycol, and homopolymers or copolymers obtained by polymerizing monomers such as maleic acid, acrylic acid, methacrylic acid, dimethylacrylamide, carboxybetaine, phosphobetaine, sulfobetaine, methoxyethyl acrylate, hydroxyethyl methacrylate, and 2-hydroxypropyl methacrylate.

[0028] A-3. Advantages of the Present Embodiment: As described above, the guidewire 100 of the present embodiment comprises the core shaft 10, the coil body 20 including the metal wire 21 wound helically around the outer periphery of the core shaft 10, the resin layer 33 that fills the gap SPr between the core shaft 10 and the coil body 20 and is disposed inside the outer periphery SO of the coil body 20, and the hydrophilic coating layer 35 that is disposed on the outer periphery of the coil body 20 and the resin layer 33. According to the guidewire 100 of the present embodiment, the resin layer 33 is disposed inside the outer periphery SO of the coil body 20, thereby improving the flexibility of the guidewire 100. Furthermore, according to the guidewire 100 of the present embodiment, the provision of the hydrophilic coating layer 35 improves the lubricity of the guidewire 100.

[0029] In the guidewire 100 of this embodiment, the outer peripheral surface 33S of the resin layer 33 is located between the center position CL between the inner peripheral surface SI and the outer peripheral surface SO of the coil body 20 in the radial direction of the guidewire 100 and the outer peripheral surface SO of the coil body 20. According to the guidewire 100 of this embodiment, the flexibility of the guidewire 100 is improved, and the coil body 20 can be firmly fixed by the resin layer 33.

[0030] The guidewire 100 of this embodiment further includes an adhesive layer 31 made of resin, which is disposed between the core shaft 10 and the resin layer 33 and has higher adhesion to metal than the resin layer 33. According to the guidewire 100 of this embodiment, when the core shaft 10 includes multiple sections arranged in parallel in the axial direction, as in this embodiment, the multiple sections can be connected to each other by the adhesive layer 31. This eliminates the need for brazing or the like to connect the multiple sections of the core shaft 10, and the rigidity gap of the guidewire 100 can be reduced.

[0031] Furthermore, according to the guidewire 100 of this embodiment, the resin layer 33 fills the gaps SPa between the wires 21 in the coil body 20, and the hydrophilic coating layer 35 coats the outer peripheries of the coil body 20 and the resin layer 33. Therefore, compared to a guidewire in which the coil body includes loosely wound wires and no resin layer is provided, for example, the smoothness of the outer periphery 35S of the hydrophilic coating layer 35 is improved when the hydrophilic coating layer 35 swells, thereby improving the lubricity of the guidewire 100. Furthermore, according to the guidewire 100 of this embodiment, the hydrophilic coating layer 35 is continuously formed from the distal end toward the proximal end of the coil body 20. Therefore, even if the guidewire 100 is bent, for example, the hydrophilic coating layer 35 is prevented from being interrupted midway from the distal end toward the proximal end, and the lubricity of the guidewire 100 can be more effectively improved.

[0032] B. Modifications: The technology disclosed in this specification is not limited to the above-described embodiment, and can be modified in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0033] 4 is an explanatory diagram schematically illustrating a guidewire 100a according to a first modified example. In the following, the same components of the guidewire 100a according to the first modified example as those of the guidewire 100 according to the above-described embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0034] In the guidewire 100a of the first modified example, the adhesive layer 31a, the resin layer 33a, and the hydrophilic coating layer 35a are disposed in a portion of the guidewire 100a from the distal bonded portion 51 to the proximal bonded portion 56 in the axial direction. Specifically, the adhesive layer 31a, the resin layer 33a, and the hydrophilic coating layer 35a are not disposed in the distal portion of the guidewire 100a. As in the first modified example, the adhesive layer, the resin layer, and the hydrophilic coating layer may be disposed in a portion of the guidewire axial direction from the distal bonded portion to the proximal bonded portion. In other words, it is sufficient that the resin layer fills a portion of the entire length of the coil body. Since the adhesive layer 31a, the resin layer 33a, and the hydrophilic coating layer 35a are not disposed in the distal portion of the guidewire 100a, the flexibility of the distal portion can be improved.

[0035] 5 is an explanatory diagram schematically illustrating a guidewire 100b according to a second modified example. In the following, the same components of the guidewire 100b according to the second modified example as those of the guidewire 100 according to the above-described embodiment are denoted by the same reference numerals, and descriptions thereof will be omitted as appropriate.

[0036] In the guidewire 100b of the second modified example, the adhesive layer 31b, the resin layer 33b, and the hydrophilic coating layer 35b are disposed in a portion of the guidewire 100b from the distal bond 51 to the proximal bond 56 in the axial direction. Specifically, the adhesive layer 31b, the resin layer 33b, and the hydrophilic coating layer 35b are not disposed in the distal and proximal ends of the guidewire 100b. As in the second modified example, the adhesive layer, the resin layer, and the hydrophilic coating layer may be disposed in a portion of the guidewire axial direction from the distal bond to the proximal bond. In other words, the resin layer only needs to fill a portion of the entire length of the coil body. Because the adhesive layer 31b, the resin layer 33b, and the hydrophilic coating layer 35b are not disposed in the distal and proximal ends of the guidewire 100b, the flexibility of the distal and proximal ends can be improved.

[0037] In the above embodiment, the cross section of the wire 21 is circular, but the shape of the cross section of the wire is not limited to this and may be, for example, rectangular or the like.

[0038] In the above embodiment, the coil body 20 is a single wire coil made of a single wire, but the coil body may be a stranded wire coil made of a stranded wire made by twisting together a plurality of wires.

[0039] In the above embodiment, the outer surface 33S of the resin layer 33 is located in the radial direction of the guide wire 100 between the center position CL, which is located at the center between the inner surface SI and the outer surface SO of the coil body 20, and the outer surface SO of the coil body 20, but this is not necessarily limited to this.

[0040] In the above embodiment, the guidewire 100 includes the adhesive layer 31, but the guidewire does not necessarily need to include an adhesive layer.

[0041] In the above embodiment, the coil body 20 and the adhesive layer 31 are spaced apart, but a portion of the surface of the coil body may be covered with the adhesive layer.

[0042] The guidewire may also include a resin coating thinner than the resin layer, located between the coil body and the hydrophilic coating layer and between the resin layer and the hydrophilic coating layer. The thin resin coating is preferably disposed as a base layer to improve adhesion between the hydrophilic coating layer and the coil body or the resin layer. The material for the thin resin coating is not limited, but examples thereof include polyvinyl alcohol (PVA), hydrophilic urethane resins (e.g., Hydro Thane (Mitsubishi Chemical), Hydro MED (Mitsubishi Chemical), Bionate (DSM), Tecophilic (Lubrizol), HPU (Dainichiseika Chemicals)), modified polyolefin resins (e.g., polyethylene-acrylic acid (Unitika), BONDINE (Tokyo Materials)), and the like. The thickness of the thin resin coating layer may be, for example, 0.1 to 10 μm, and preferably about 1 to 5 μm.

Claims

1. A guide wire (100, 100a, 100b) comprising: a core shaft (10); a coil body (20) including a metallic wire (21) wound helically around the outer periphery of the core shaft (10); a resin layer (33, 33a, 33b) filled in a gap (SPr) between the core shaft (10) and the coil body (20) and disposed inside the outer peripheral surface (SO) of the coil body (20); and a hydrophilic coating layer (35, 35a, 35b) disposed on the outer periphery of the coil body (20) and the resin layer (33, 33a, 33b).

2. The guide wire (100, 100a, 100b) according to claim 1, wherein an outer peripheral surface (33S) of the resin layer (33, 33a, 33b) is located in a radial direction of the guide wire (100, 100a, 100b) between a central position (CL) of an inner peripheral surface (SI) and the outer peripheral surface (SO) of the coil body (20) and the outer peripheral surface (SO) of the coil body (20).

3. The guide wire (100, 100a, 100b) according to claim 1 or claim 2, further comprising an adhesive layer (31, 31a, 31b) made of resin, disposed between the core shaft (10) and the resin layer (33, 33a, 33b), and having a higher adhesion to metal than the resin layer (33, 33a, 33b).

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