Guidewire

Abstract

This guidewire is provided with a core shaft constituted from a superelastic material, and a coil formed from wire stock spirally wound around the outer periphery of the tip section of the core shaft. Along the core shaft in the section located inside the coil, the guidewire has: a first segment comprising a thermally denatured section in which the superelastic material has been thermally metamorphosed; and a second segment located on the rear-end side of the first section. In the second segment, a thermally denatured section of length shorter than that of the first section is formed, or no thermally denatured section is formed. Provided at the tip section of the coil is a sparse-wound section where gaps are formed between neighboring wire-stock coils.

Description

Guidewire

[0001] The present invention relates to a guidewire.

[0002] Conventionally, medical guidewires using a core shaft made of a superelastic alloy have been known. Patent Document 1 describes a guidewire in which the distal end of a core shaft made of a superelastic alloy has been heat-treated.

[0003] JP 2017-153615 A ​​JP 2010-222 A JP 10-146390 A JP 2005-312987 A

[0004] A typical guidewire is sometimes "shaped" by bending the tip of the guidewire into a predetermined shape to fit the shape of a blood vessel or the like. Guidewires using a core shaft made of a superelastic material have room for improvement in "shaping performance," which refers to the ease of shaping. In particular, there has been a need for ease of "hook shaping," in which 1 to 2 millimeters of the tip of the guidewire are shaped into a hook at an approximately 45-degree angle. Furthermore, while improvements in shaping performance are required, there is also room for improvement in the durability of the guidewire against breakage, such as when the guidewire is bent during use.

[0005] An object of the present invention is to provide a guidewire that has excellent shaping performance and durability and that can be easily shaped into a hook.

[0006] The present invention has been made to solve at least part of the above-mentioned problems, and can be realized in the following aspects.

[0007] (1) One embodiment of the present invention is a guide wire comprising a core shaft made of a superelastic material and a coil formed of wire wound helically around the outer periphery of the tip of the core shaft, wherein the core shaft has a first section located inside the coil and consisting of a thermally modified portion formed by thermally modifying the superelastic material, and a second section located on the rear end side of the first section, wherein the second section has a thermally modified portion that is shorter in length than the first section, or no thermally modified portion is formed, and the coil has an openly wound section at the tip where gaps are formed between adjacent wires.

[0008] According to this configuration, the provision of the first section consisting of a heat-modified portion suppresses the superelastic properties of the core shaft, improving shaping performance. Furthermore, the provision of an openly wound portion at the distal end of the coil improves the shaping performance of the distal end of the guidewire. This makes it easy to form a hook shape. Furthermore, the provision of a heat-modified portion that is shorter than the heat-modified portion at the distal end or a portion that is not heat-modified in the second section maintains the superelastic properties of the core shaft and allows the durability of the guidewire to be maintained.

[0009] (2) In the guide wire of the above embodiment, the size of the gap between the wires in the openly wound portion in the longitudinal direction of the coil may be equal to or larger than the outer diameter of the wires.

[0010] According to this configuration, when a fixing portion made of, for example, brazing material or solder material is provided on the open winding portion at the tip end to fix the core shaft and the coil, the length of the fixing portion can be shortened.

[0011] (3) In the guidewire of the above aspect, the rear end of the first section may be located rearward of the rear end of the openly coiled portion.

[0012] When shaping a guidewire, a "body shape" that is a gently curved shape may be imparted. With this configuration, the first section, which is made of a thermally denatured portion, extends over a wider area, making it easier to impart a body shape. Furthermore, since the rear end of the first section and the rear end of the openly coiled portion are located at different positions in the longitudinal direction, the change in bending rigidity of the guidewire can be made gradual.

[0013] (4) In the guidewire of the above aspect, the rear end of the loosely wound portion may be located closer to the rear end than the rear end of the first section.

[0014] With this configuration, the openly coiled portion at the distal end extends over a wider area, making it easier to shape the body. Also, since the rear end of the openly coiled portion and the rear end of the first section are located at different positions in the longitudinal direction, the change in bending stiffness of the guidewire can be made gradual.

[0015] (5) In the guide wire of the above form, the coil further has an openly wound portion at the rear end in which gaps are formed between adjacent wires, and the size of the gaps between the wires of the openly wound portion formed at the rear end in the longitudinal direction of the coil may be equal to or greater than the outer diameter of the wires.

[0016] According to this configuration, when a fixing portion made of, for example, brazing material or solder material is provided in the loosely wound portion on the rear end side to fix the core shaft and the coil, the length of the fixing portion can be shortened.

[0017] The present invention can be realized in various aspects, for example, in the form of a guidewire, a method for manufacturing a guidewire, a method for manufacturing a catheter, an endoscope, a dilator, and the like.

[0018] FIG. 1 is an explanatory diagram illustrating the overall configuration of a guidewire of a first embodiment. FIG. 2 is an explanatory diagram illustrating a longitudinal cross section of a distal end portion of a guidewire. FIG. 3 is an explanatory diagram illustrating an A-A cross section of a guidewire. FIG. 4 is an explanatory diagram illustrating a longitudinal cross section of the most distal end portion of a guidewire. FIG. 5 is an explanatory diagram illustrating a longitudinal cross section of a rear end portion of a coil. FIG. 6 is an explanatory diagram illustrating a shaped distal end portion of a guidewire. FIG. 7 is an explanatory diagram illustrating a longitudinal cross section of a distal end portion of a guidewire of a second embodiment. FIG. 8 is an explanatory diagram illustrating a longitudinal cross section of a distal end portion of a guidewire of a third embodiment. FIG. 9 is an explanatory diagram illustrating a longitudinal cross section of a distal end portion of a guidewire of a fourth embodiment. FIG. 10 is an explanatory diagram illustrating a hook-shaped distal end portion of a guidewire. FIG. 11 is an explanatory diagram illustrating a guidewire of Modified Example 1. FIG. 12 is an explanatory diagram illustrating a guidewire of Modified Example 4. FIG. 13 is an explanatory diagram illustrating a guidewire of Modified Example 8.

[0019] 1 to 6 are illustrative only and may be expressed on a scale different from the actual size. Hereinafter, the end portion of each component of the guidewire 1A located on the distal end side will be referred to as the "distal end," and the portion including the "distal end" and extending from the distal end to partway toward the proximal end will be referred to as the "distal portion." Similarly, the end portion of each component located on the proximal end side will be referred to as the "rear end," and the portion including the "rear end" and extending from the proximal end to partway toward the distal end will be referred to as the "rear portion."

[0020] 1 is an explanatory diagram illustrating an overall view of a guidewire 1A according to a first embodiment. The guidewire 1A is a medical device used for treating blood vessels, etc. The guidewire 1A includes a core shaft 10, a coil 20A, a distal end fixing portion 30, and a proximal end fixing portion 31.

[0021] 2 is an explanatory diagram illustrating a longitudinal cross section of the distal end of the guidewire 1A of the first embodiment. The core shaft 10 is a long member extending from the distal end to the proximal end of the guidewire 1A. The core shaft 10 is formed so that the outer diameter decreases toward the distal end, and the distal end has a straight portion 11 having a substantially constant outer diameter in the longitudinal direction and a tapered portion 12 provided on the proximal end side of the straight portion 11. Details of the core shaft 10 will be described later.

[0022] The core shaft 10 is made of a superelastic material. The superelastic material is not particularly limited, but examples thereof include superelastic alloys such as Ni-Ti alloys, Ni-Ti-X (X=Fe, Cu, V, Co, Cr, Mn, Nb, etc.) alloys, and Cu-Zn-X (X=Al, Fe, etc.) alloys.

[0023] The coil 20A is a component formed from wires 21A wound in a spiral shape to cover the outer periphery of the tip end of the core shaft 10. The coil 20A has, in order from the tip end, an openly wound portion 22A, a densely wound portion 23A, and an openly wound portion 24A. The densely wound portion 23A is a portion with a small pitch where the wires 21A are wound so that they contact each other. On the other hand, the openly wound portion 22A and the openly wound portion 24A have a larger pitch than the densely wound portion 23A, and a gap G (FIGS. 4 and 5) described below is formed between adjacent wires 21A. In this embodiment, the coil 20A has the densely wound portion 23A and the openly wound portion 24A rearward of the openly wound portion 22A. However, the entire length of the coil 20A may be formed from the openly wound portion 22A. Alternatively, the entire portion of the coil 20A rearward of the openly wound portion 22A may be the densely wound portion 23A. The configuration of the openly wound portion 22A of the coil 20A is not limited to the above example, and various modifications are possible. The openly wound portion 22A and the openly wound portion 24A will be described in detail later.

[0024] The material of the coil 20A is not particularly limited, but examples thereof include stainless steel (SUS302, SUS304, SUS316, etc.), superelastic alloys such as Ni-Ti alloys, piano wire, nickel-chromium alloys, cobalt alloys, tungsten, platinum, etc.

[0025] The tip fixing portion 30 is a member that fixes the tip of the core shaft 10 and the tip of the coil 20A. The rear end fixing portion 31 is a member that fixes the middle portion of the core shaft 10 and the rear end of the coil 20A. For example, the tip fixing portion 30 and the rear end fixing portion 31 are formed by applying molten brazing material or solder material to the core shaft 10 and the coil 20A and then cooling and solidifying the material.

[0026] The material of the tip fixing portion 30 and the rear end fixing portion 31 is not particularly limited, but for example, soldering material (aluminum alloy solder, silver solder, gold solder, etc.), metal solder (Ag-Sn alloy, Au-Sn alloy, etc.), adhesive (epoxy adhesive, etc.), etc. can be used.

[0027] <Details of Core Shaft 10> The details of the core shaft 10 will be described. The core shaft 10 has a first section S1 and a second section S2 inside the coil 20A. The first section extends from the tip to the rear end of the core shaft 10 and is composed of a thermally denatured portion 13A. The portion of the core shaft 10 that is not thermally denatured other than the thermally denatured portion 13A is referred to as the "non-thermally denatured portion 15A." The thermally denatured portion 13A is a portion in which the properties of the superelastic material forming the core shaft 10 are changed by heating the core shaft 10. In this embodiment, the thermally denatured portion 13A is a portion in which the superelastic properties of the core shaft 10 are suppressed compared to the non-thermally denatured portion 15A. Furthermore, a rear end 14A of the first section S1 (rear end of the thermally denatured portion 13A) marks the boundary between the thermally denatured portion 13A and the non-thermally denatured portion 15A. The rear end 14A of the first section S1 is located rearward of a rear end 25A of the openly wound portion 22A, which will be described later. As a result, the rear end 14A of the first section S1 and the rear end 25A of the tip-side open coil portion 22A are located at different positions in the longitudinal direction of the core shaft 10. In Fig. 2, the length of the first section S1 in the longitudinal direction from the tip to the rear end 14A is indicated as Ls1. The length Ls1 of the first section is not particularly limited, but may be, for example, 2 to 7 millimeters.

[0028] The second section S2 is located inside the coil 20A and closer to the rear end than the first section S1. The second section S2 does not have a thermally denatured portion 13A and is formed only by a non-thermally denatured portion 15A. In this embodiment, the second section S2 does not have a thermally denatured portion 13A, but may have a thermally denatured portion 13A formed in the second section S2 as in a second embodiment described later. In this case, the length in the major axis direction of the thermally denatured portion 13A formed in the second section S2 is shorter than the length of the thermally denatured portion 13A in the first section S1.

[0029] The method for producing the thermally modified portion 13A is not particularly limited, but for example, the thermally modified portion 13A can be formed by irradiating the surface of the core shaft 10 with a laser to heat the core shaft 10 to approximately 600 degrees to approximately 1000 degrees.

[0030] FIG. 3 is an explanatory diagram illustrating an example of an A-A cross section of the guidewire 1A of the first embodiment. The straight portion 11 of the core shaft 10 is formed by a flat surface 16, a flat surface 17 opposite the flat surface 16, and curved surfaces 18 and 19 connecting the flat surfaces 16 and 17. The cross section of the straight portion 11 has a flattened shape extending elongated in a predetermined direction. In this embodiment, the length of the cross section of the straight portion 11 in the direction Dx parallel to the flat surface 16 is greater than the length of the cross section in the direction Dy perpendicular to the flat surface 16. This causes the straight portion 11 to bend more easily depending on the direction of stress applied to the straight portion 11. For example, the straight portion 11 is more likely to bend when stress is applied to the straight portion 11 in the direction Dy perpendicular to the flat surface 16 than when stress is applied in the direction Dx parallel to the flat surface 16. Here, the length of the straight portion 11 in the longitudinal direction of the guidewire 1A is not particularly limited, but may be, for example, 10 to 20 millimeters. Although not shown, the cross section of the tapered portion 12 and the portion of the core shaft 10 proximal to the tapered portion 12 are circular.

[0031] The method for manufacturing the straight portion 11 is not particularly limited, but for example, it can be manufactured by pressing the tip end of the core shaft 10 formed into a cylindrical shape using a mold with a flat portion.

[0032] <Details of the Distal-Side Openly Coated Portion 22A> Figure 4 is an explanatory diagram illustrating a longitudinal cross section of the distal end of the guidewire 1A of the first embodiment. Details of the openly coiled portion 22A will be described. The coil 20A has an openly coiled portion 22A in which, of the spirally wound wires 21A, a gap G is provided between adjacent wires 21A. The openly coiled portion 22A is formed from the distal end toward the proximal end of the coil 20A, and its distal end is embedded in the distal end fixing portion 30. A proximal end 25A of the openly coiled portion 22A marks the boundary between the openly coiled portion 22A and the densely coiled portion 23A. The length of the openly coiled portion 22A in the major axis direction is not limited, but can be, for example, approximately 0.5 to 2 millimeters.

[0033] When the outer diameter of the wires 21A constituting the openly wound portion 22A is D and the size of the gaps G between the wires 21A in the major axis direction is Lg, the size Lg of the gaps G between the wires 21A is equal to or greater than the outer diameter D of the wires 21A. Here, the outer diameter D of the wires 21A refers to the size of the wires 21A in the major axis direction of the coil 20A. Furthermore, when the wires 21A are circular and the size of the wires 21A in the major axis direction of the coil 20A is not constant in cross section, as in the case of the wires 21A of this embodiment, the outer diameter D of the wires 21A is defined as "the size in the major axis direction of the portion of the wires 21A that is largest in the major axis direction of the coil 20A." In other words, the outer diameter D is the maximum outer diameter of the wires 21A. Here, a configuration in which the size Lg of the gap G and the outer diameter D of the wire 21A are approximately the same can be rephrased as a configuration in which the pitch of the openly wound portion 22A is approximately 200% of the pitch of the densely wound portion 23A, in which the wires 21A are wound so that they contact each other. Therefore, "the size Lg of the gap G is equal to or greater than the outer diameter D of the wire 21A" can be rephrased as meaning that the pitch of the openly wound portion 22A is 200% or greater of the pitch of the densely wound portion 23A. When a gap G is formed between adjacent wires 21A, as in the openly wound portion 22A shown in FIG. 4 , the brazing material or solder material of the tip fixing portion 30 is fixed in place by flowing into the gap G of the openly wound portion 22A.

[0034] <Details of the Openly Coated Portion 24A on the Rear End Side> FIG. 5 is an explanatory diagram illustrating a longitudinal cross section of the rear end portion of the coil 20A of the guidewire 1A of the first embodiment. The details of the openly coiled portion 24A will be described. The openly coiled portion 24A is formed at the rear end of the coil 20A. The openly coiled portion 24A is formed from the rear end of the coil 20A toward the front end, and its rear end is embedded in the rear end fixing portion 31. Similar to the openly coiled portion 22A formed at the front end, the openly coiled portion 24A formed at the rear end has gaps G formed between adjacent wires 21A. The length of the openly coiled portion 24A in the longitudinal direction is not limited, but can be, for example, approximately 0.5 to 2 millimeters. When the pitch of the densely coiled portion 23A is taken as 100%, the pitch of the openly coiled portion 24A shown in FIG. 5 is 200% or more.

[0035] In this embodiment, the size Lg of the gap G between the open coiled portion 22A and the open coiled portion 24A is set to be equal to or larger than the outer diameter D of the wire 21A. However, the size Lg of the gap G between the open coiled portion 22A and the open coiled portion 24A may be smaller than the outer diameter D of the wire 21A. As described above, when the pitch of the densely coiled portion 23A is set to 100%, the size of the pitch of the open coiled portion 22A and the open coiled portion 24A can be set to approximately 150% to 500%. By setting the pitch of the open coiled portion 22A and the open coiled portion 24A to approximately 150% or larger, adjacent wires 21A are sufficiently spaced apart, reducing the thermal conductivity between the wires 21A. This reduces the amount of molten brazing or solder flowing along the wire 21A in the longitudinal direction when brazing or solder is used for the tip fixing portion 30.

[0036] FIG. 6 is an explanatory diagram illustrating the shaped distal end of the guidewire 1A. As mentioned above, in this specification, the hook-shaped portion of the guidewire 1A, approximately 1 to 2 millimeters from the distal end, is referred to as a "hook shape" at an angle of approximately 45 degrees, and the gently curved portion of the guidewire 1A, approximately 20 millimeters from the distal end, is referred to as a "body shape." In FIG. 6, the hook-shaped portion is designated as a hook-shaped portion Sa, and the body-shaped portion is designated as a body-shaped portion Sb. The hook-shaped portion Sa is a portion where the thermally denatured portion 13A and the loosely wound portion 22A overlap. The body-shaped portion Sb also has a thermally denatured portion 13A. Furthermore, the cross section of the straight portion 11 has a flattened shape, and therefore has a direction that makes it easy to bend. As such, the guidewire 1A has a portion at the distal end that is easiest to shape, and also has a portion that is easy to shape further proximal to the distal end. In other words, the ease of shaping of the guidewire 1A changes stepwise from the distal end side to the proximal end side.

[0037] According to the guidewire 1A of this embodiment described above, the guidewire 1A has a first section S1 made of a thermally denatured portion 13A. The thermally denatured portion 13A has reduced superelastic properties compared to the non-thermally denatured portion 15A, and therefore has a reduced force that causes the guidewire 1A to return to its original shape when deformed. This makes it easy to shape the guidewire 1A in the intended direction.

[0038] The guidewire 1A has an openly coiled portion 22A, and the size Lg of the gap G between adjacent wires 21A is equal to or greater than the outer diameter D of the wires 21A. In other words, while the coil pitch of a typical guidewire is approximately 100% to 120%, the pitch of the openly coiled portion 22A is wider than 200%. Because adjacent wires 21A in the openly coiled portion 22A are sufficiently spaced apart, thermal conductivity between the wires 21A is reduced. This reduces the amount of molten brazing material or solder flowing along the wires 21A in the longitudinal direction when brazing or solder is used in the distal end fixing portion 30. This allows the longitudinal length of the distal end fixing portion 30 to be shortened, improving the flexibility of the distal end of the guidewire 1A. By loosely winding the coil 20A to make it flexible and shortening the length of the distal end fixing portion 30, the distal end of the guidewire 1A can be made flexible, making it easier for the user to shape the guidewire 1A in the direction intended. In particular, when the length of the loosely coiled portion 22A in the longitudinal direction is set to about 1 to 2 millimeters, it becomes easy to form a hook shape of about 1 to 2 millimeters. By forming a hook shape, even when the guidewire 1A is inserted into a bifurcation of a blood vessel with a small diameter (for example, a blood vessel with a diameter of about 1 to 2 millimeters), the user of the guidewire 1A can easily advance the guidewire 1A in the intended direction.

[0039] The rear end 14A of the first section S1 is positioned more rearward than the rear end 25A of the loosely wound portion 22A. This allows the portion of the core shaft 10 that is easy to shape to be more widely distributed, making body shaping easier. For example, by setting the longitudinal length Ls1 (FIG. 2) of the first section S1 to approximately 20 millimeters, body shaping of approximately 20 millimeters can be easily performed. By performing body shaping, even when the guidewire 1A is inserted into a bifurcation of a blood vessel with a large diameter (e.g., a blood vessel with a diameter of approximately 2 to 10 millimeters), the user of the guidewire 1A can easily advance the guidewire 1A in the intended direction. Furthermore, even when the length of the first section S1 is set to 2 to 7 millimeters, the provision of the thermally denatured portion 13A in the distal end portion of the body shaping section Sb, which is subject to greater deformation during shaping, makes body shaping easier. By shortening the length Ls1 of the first section S1, the length of the second section S2 becomes relatively longer, improving the durability of the core shaft 10 against bending and breaking, making it easier to achieve both shaping performance and maintaining durability.

[0040] Because the rear end 14A of the first section S1 is located more rearward than the rear end 25A of the openly coiled portion 22A, the rear end 14A of the first section S1 and the rear end 25A of the distal openly coiled portion 22A are located at different positions in the longitudinal direction of the core shaft 10. As a result, the change in bending rigidity of the core shaft 10 at the boundary between the thermally denatured portion 13A and the non-thermally denatured portion 15A and the change in bending rigidity of the coil 20A at the boundary between the openly coiled portion 22A and the densely coiled portion 23A (the rear end 15A of the openly coiled portion 22A) occur at different positions. This makes it possible to suppress a sudden change in bending rigidity in the longitudinal direction of the guidewire 1A.

[0041] The second section S2 does not include the thermally denatured portion 13A, and is formed solely from the non-thermally denatured portion 15A. This maintains the superelastic properties of the core shaft 10 in the second section S2, preventing the guidewire 1A from unintentionally breaking or bending. This improves the shaping performance of the guidewire 1A and also enhances its durability.

[0042] The coil 20A has an openly coiled portion 24A at its rear end, and the size Lg of the gap G between adjacent wires 21A is equal to or greater than the outer diameter D of the wires 21A. While the coil pitch of a typical guidewire is 100% to 120%, the pitch of the openly coiled portion 24A is wider than 200%. As a result, similar to the openly coiled portion 22A described above, adjacent wires 21A are sufficiently spaced apart in the openly coiled portion 24A, reducing the thermal conductivity between the wires 21A. This reduces the amount of molten brazing or solder flowing along the gap G between the wires 21A in the longitudinal direction when brazing or solder is used in the rear end fixed portion 31. This shortens the longitudinal length of the rear end fixed portion 31, improving the flexibility of the guidewire 1A. This suppresses an increase in bending rigidity near the rear end fixed portion 31 of the guidewire 1A, reducing the likelihood of breakage, such as bending or breaking, of the guidewire 1A near the rear end fixed portion 31.

[0043] The cross section of the straight portion 11 of the core shaft 10 has a flattened shape that extends elongatedly in a predetermined direction. As a result, the direction in which the straight portion 11 bends easily varies depending on the direction of stress applied to the straight portion 11. When shaping the core shaft 10, the straight portion 11 tends to bend in the direction in which it bends easily, thereby enabling the guidewire 1A to be bent uniformly in a certain direction. In this embodiment, it is easy to uniformly bend and shape the distal end of the guidewire 1A in the Dy direction shown in FIG. 3 . For example, if the cross section of the straight portion 11 had a circular shape rather than a flattened shape, the bendability would be constant regardless of the direction, making it difficult to bend the guidewire 1A uniformly in a certain direction, and the guidewire 1A would be more likely to be shaped in a twisted manner.

[0044] 7 is an explanatory diagram illustrating a longitudinal cross section of a distal end portion of a guidewire 1B according to a second embodiment. The guidewire 1B differs from the guidewire 1A according to the first embodiment in that a thermally denatured portion 13B is provided in the second section S2. A description of the configuration of the guidewire 1B that is common to the guidewire 1A will be omitted.

[0045] A thermally denatured portion 13B is provided in a portion of the second section S2, and a non-thermally denatured portion 15B is provided in the portion other than the thermally denatured portion 13B. The length Ls2 of the thermally denatured portion 13B in the second section S2 in the longitudinal direction is shorter than the length Ls1 of the first section S1 in the longitudinal direction.

[0046] Even in a configuration in which a thermally modified portion 13B is provided in the second section S2, as in the guide wire 1B, the longitudinal length Ls2 of the thermally modified portion 13B provided in the second section S2 is shorter than the longitudinal length Ls1 of the first section S1, thereby improving the durability of the core shaft 10 against breaking and bending.

[0047] 8 is an explanatory diagram illustrating a longitudinal cross section of the distal end portion of a guidewire 1B according to a third embodiment. The guidewire 1C differs from the guidewire 1A according to the first embodiment in that the rear end 25C of the openly coiled portion 22C is located more rearward than the rear end 14C of the first section S1. A description of the configuration of the guidewire 1C that is common to the guidewire 1A will be omitted.

[0048] The guidewire 1C has an openly coiled portion 22C extending more toward the rear end and provided over a wider range, which facilitates body shaping. Also in this embodiment, the rear end 14C of the first section S1 and the rear end 25C of the distal openly coiled portion 22C are provided at different positions along the longitudinal axis of the core shaft 10. This makes it possible to suppress a sudden change in bending rigidity that occurs when the position where the bending rigidity of the core shaft 10 changes overlaps with the position where the bending rigidity of the coil 20C changes.

[0049] 9 is an explanatory diagram illustrating a longitudinal cross section of a distal end portion of a guidewire 1D according to a fourth embodiment. The guidewire 1D differs from the guidewire 1A according to the fourth embodiment in that a rear end 14D of the first section S1 and a rear end 25D of the openly wound portion 22D are located at substantially the same position in the longitudinal direction of the coil 20C. A description of the configuration of the guidewire 1D that is common to the guidewire 1A will be omitted.

[0050] In the guidewire 1D, the thermally denatured portion 13D and the loosely coiled portion 22A can easily be shaped into a hook shape. Even in a configuration in which the thermally denatured portion 13D does not extend further rearward than the rear end 25D of the loosely coiled portion 22D, as in this embodiment, the core shaft 10 can be easily shaped into a body shape by having the straight portion 11 with a flattened cross-sectional shape. Furthermore, by shortening the thermally denatured portion 13D, the range over which the durability of the core shaft 10 is maintained can be ensured to be wider.

[0051] Fig. 10 is an explanatory diagram illustrating a hook-shaped distal end portion of a guidewire 1D according to the fourth embodiment. In Fig. 10, the hook-shaped portion is shown as a hook-shaped portion Sa. In the guidewire 1D described above, the portion where the thermally denatured portion 13D and the loosely wound portion 22D are overlapped is easy to shape, and therefore, the hook shape can be easily formed.

[0052] <Modifications> The present invention is not limited to the above-described embodiment, and can be embodied in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0053] <Modification 1> FIG. 11 is an explanatory diagram illustrating a guidewire 1E of Modification 1. The guidewire 1E differs from the guidewires of the other embodiments in the position of the rear end 14E of the first section S1. In the guidewire 1A of the first embodiment, the rear end 14A of the first section S1 is located rearward of the rear end 25E of the openly coiled portion 22A and extends along the entire length of the straight portion 11. However, as in the guidewire 1E, the rear end 14E of the first section S1 may be located rearward of the rear end 25E of the openly coiled portion 22E and midway along the straight portion 11. The guidewire 1E also facilitates the hook shape using the thermally modified portion 13E and the openly coiled portion 22E. Furthermore, the straight portion 11 allows the body shape to be uniformly formed in a predetermined direction. Furthermore, by shortening the thermally modified portion 13E, the durability of the core shaft 10 can be maintained over a wider range.

[0054] <Modification 2> In the guide wires (1A, 1B, 1C, 1D) of the first to fourth embodiments, the first section S1 is formed from the leading end toward the proximal end of the core shaft 10, but it does not have to be formed from the leading end of the core shaft 10. The first section S1 only needs to be formed inside the coil (20A, 20B, 20C, 20D), and for example, the leading end of the first section S1 may be provided closer to the proximal end than the leading end of the core shaft 10.

[0055] <Modification 3> The first section S1 and the second section S2 may be provided with a portion in which the characteristics of the core shaft 10 are changed other than the thermally modified portions (13A, 13B, 13C, 13D). For example, a portion in which the surface condition of the core shaft 10 is changed by electrolytic polishing, shot peening, or the like may be provided.

[0056] 12 is an explanatory diagram illustrating a guidewire 1F of Modification 4. The guidewire 1F has a plurality of thermally denatured portions 13F in the second section S2. As in the guidewire 1F, two thermally denatured portions 13F may be provided in the second section S2.

[0057] <Variation 5> In the guide wires (1A, 1B, 1C, 1D) of the first to fourth embodiments, the portion of the core shaft 10 located more rearward than the second section S2 did not have a thermally modified portion (13A, 13B, 13C, 13D), but a thermally modified portion (13A, 13B, 13C, 13D) may be provided.

[0058] <Modification 6> In the guide wires (1A, 1B, 1C, 1D) of the first to fourth embodiments, the cross section of the wires (21A, 21B, 21C, 21D) is circular, but it may be rectangular, such as square or oblong.

[0059] <Variation 7> In the guidewires (1A, 1B, 1C, 1D) of the first to fourth embodiments, the coils (20A, 20B, 20C, 20D) are formed from a single wire (21A, 21B, 21C, 21D). However, the coils may be formed by spirally winding a plurality of wires (21A, 21B, 21C, 21D). In this case, the outer diameter D of the wire (21A, 21B, 21C, 21D) refers to the outer diameter D of the wire with the largest outer diameter D among the plurality of wires (21A, 21B, 21C, 21D). Alternatively, the coils (20A, 20B, 20C, 20D) may be formed by bundling a plurality of wires (21A, 21B, 21C, 21D) to form a strand, and then spirally winding the strand. In this case, the gap between adjacent strands is defined as gap G, and the outer diameter of the strand is defined as outer diameter D of the wire (21A, 21B, 21C, 21D).

[0060] <Modification 8> Fig. 13 is an explanatory diagram illustrating a guidewire 1G of Modification 8. The guidewire 1G has multiple coils (20G, 40). In the guidewires (1A, 1B, 1C, 1D) of the first to fourth embodiments, the outer periphery of the core shaft 10 is covered with only one coil (20A, 20B, 20C, 20D). However, another coil 40 may be provided around the outer periphery of the coil (20A, 20B, 20C, 20D). In the guidewire 1G shown in Fig. 13, the outer periphery of the coil 20G that covers the outer periphery of the core shaft 10 is further covered with a coil 40. The coil 40 is formed by spirally winding a wire 41 that is separate from the wire 21G that constitutes the coil 20G.

[0061] <Modification 9> In the guidewire 1A of the first embodiment, the straight portion 11 has a flattened shape and is formed by a flat surface 16, a flat surface 17 opposite the flat surface 16, and a curved surface 18 and a curved surface 19 connecting the flat surfaces 16 and 17. However, the straight portion 11 does not have to be formed by the flat surfaces 16, 17, the curved surfaces 18, and 19. For example, the straight portion 11 may be formed by four flat surfaces. In this case, the width of any of the flat surfaces can be adjusted to make the straight portion 11 flattened. Furthermore, the straight portion 11 does not have to be flattened. For example, the cross section of the straight portion 11 may be rectangular, such as a square or a rectangle, or may be circular. Furthermore, the tapered portion 12 or the rear end portion of the core shaft 10 may have a flattened shape.

[0062] DESCRIPTION OF THE SYMBOLS 1A...Guide wire 10...Core shaft 11...Straight portion 12...Tapered portion 13A...Heat-modified portion 14A...Rear end of heat-modified portion 15A...Non-heat-modified portion 16...Flat surface 17...Flat surface 18...Curved surface 19...Curved surface 20A...Coil 21A...Elemental wire 22A...Openly wound portion 23A...Densely wound portion 24A...Openly wound portion 25A...Rear end of openly wound portion 30...Tip fixing portion 31...Rear end fixing portion Ls1...Length of first section Ls2...Length of heat-modified portion of second section D...Outer diameter of elemental wire G...Gap between elemental wires Lg...Length of gap Sa...Hook-shaped portion Sb...Body-shaped portion

Claims

1. A guidewire, a core shaft made of a superelastic material; a coil formed by a wire wound in a spiral shape around the outer periphery of the tip end portion of the core shaft; Equipped with the core shaft has a first section, located inside the coil, that is made of a heat-modified portion formed by heat-modifying the superelastic material, and a second section located on the rear end side of the first section, In the second section, the thermally denatured portion is formed to a length shorter than that of the first section, or the thermally denatured portion is not formed, the coil has an openly wound portion at a tip end thereof in which gaps are formed between adjacent wires, a rear end of the first section is located rearward of a rear end of the openly wound portion; Guide wire.

2. 2. The guidewire of claim 1, A guide wire, wherein the size of the gaps between the wires in the openly wound portion in the longitudinal direction of the coil is equal to or greater than the outer diameter of the wires.

3. The guide wire according to claim 1 or 2, The coil further has an open winding portion at a rear end portion in which gaps are formed between adjacent wires, A guide wire, wherein the size of the gaps between the wires in the open winding portion formed at the rear end portion in the longitudinal direction of the coil is equal to or greater than the outer diameter of the wires.

4. A guide wire according to claim 1 or claim 2, The core shaft is a straight portion whose width in a direction perpendicular to the longitudinal direction is constant along the longitudinal direction; a tapered portion provided on a rear end side of the straight portion, the width of which in a direction perpendicular to the longitudinal direction increases toward the rear end side, The rear end of the thermally modified portion is located closer to the rear end than the front end of the tapered portion.

5. A guide wire according to claim 1 or claim 2, the openly wound portion of the coil is a first openly wound portion, The coil is a densely wound portion provided on a rear end side of the first loosely wound portion; a second loosely wound portion provided on the rear end side of the densely wound portion, The rear end of the first section is located between the front end of the densely wound portion and the rear end of the densely wound portion.

6. The guide wire according to claim 1 or claim 2 further comprises: a hook-shaped portion curved at a first angle; a body-shaped portion provided on the rear end side of the hook-shaped portion and curved at a second angle smaller than the first angle.

7. A guide wire as described in claim 6, The guide wire, wherein the hook-shaped portion is a portion where the thermally denatured portion and the loosely wound portion overlap.