Medical guidewires

Abstract

Provided is a medical guidewire that exhibits excellent slip properties while ensuring adhesion of the coating layer. [Solution] The present invention relates to a medical guide wire (1) comprising a flexible, long wire body (2), at least one intermediate layer (3) covering the surface of the wire body (2), and an outermost layer (4) covering the surface of the intermediate layer (3), wherein the intermediate layer (3) is colored by containing a pigment, and the concentration of the pigment is 50 wt% or more and 90 wt% or less relative to the entire intermediate layer (3).

Description

Technical Field

[0001] The present invention relates to a medical guide wire.

Background Art

[0002] Conventionally, various medical guide wires used in the medical field are known. For example, as described in Patent Document 1, as a medical guide wire used under an endoscope, in order to ensure slipperiness inside a catheter and to be able to grasp the movement of the guide wire through the fiber scope of the endoscope, a guide wire coated with a fluororesin tube having a spiral pattern color-coded in a plurality of colors is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The above-described guide wire coated with a fluororesin tube color-coded in a plurality of colors has extremely excellent visibility under an endoscope. However, since the fluororesin tube is not chemically adhered to the metal wire of the guide wire, when used as a guide wire for passing through a puncture needle in an ultrasonic endoscope puncture procedure that has rapidly spread in recent years, there is a problem that a part of the fluororesin tube peels off and falls off due to contact with the tip of the hollow puncture needle, and it is difficult to use it as a guide wire used when passing through the puncture needle.

[0005] Furthermore, guide wires formed by coating a metal wire, which serves as the core material of the guide wire, with a resin underlayer and a fluororesin layer using a coating method are also known. However, even such guide wires are not designed to withstand sliding with metal components that have sharp points, such as puncture needles. There is a concern that the fluororesin layer coated on the resin underlayer may peel off and fall off upon contact with the tip of a hollow puncture needle, making them difficult to use as guide wires when passing through a puncture needle.

[0006] Due to these issues, metal wires without fluororesin tubing or coatings are used as guide wires for puncture needles in endoscopic ultrasound-guided puncture procedures. However, metal wires have poor lubricity, making them difficult to insert into hollow puncture needles.

[0007] The present invention was made to solve the aforementioned problems, and aims to provide a medical guide wire that exhibits excellent lubricity while ensuring adhesion of the coating layer. [Means for solving the problem]

[0008] The above objective of the present invention is achieved by a medical guide wire comprising a flexible, elongated wire body, at least one intermediate layer covering the surface of the wire body, and an outermost layer covering the surface of the intermediate layer, wherein the intermediate layer is colored by containing a pigment, and the concentration of the pigment is 50 wt% or more and 90 wt% or less of the entire intermediate layer.

[0009] In this medical guidewire, the concentration of the pigment is preferably 55 wt% or more and 85 wt% or less relative to the entire intermediate layer.

[0010] Furthermore, the intermediate layer may be configured to include a first region containing a first pigment and a second region containing a second pigment having a different color from the first pigment.

[0011] Furthermore, the average particle size of the pigment is preferably in the range of 0.05 μm to 2 μm. Also, the thickness of the intermediate layer is preferably in the range of 1 μm to 30 μm.

[0012] Furthermore, the intermediate layer preferably contains a binder resin made of a polyimide resin. The outermost layer is preferably formed from a fluororesin material. The outermost layer is preferably fused to the surface of the intermediate layer. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a medical guide wire that exhibits excellent lubricity while ensuring adhesion of the coating layer. [Brief explanation of the drawing]

[0014] [Figure 1] This is an enlarged schematic cross-sectional view of the main components of a medical guide wire according to one embodiment of the present invention. [Figure 2] (a) is an enlarged plan view of a modified medical guide wire according to Figure 1, and (b) is an enlarged cross-sectional view of the main part in section AA. [Figure 3] (a) is an enlarged plan view of a key part showing another modified example of the medical guide wire shown in Figure 1, and (b) is an enlarged cross-sectional view of a key part in the BB section thereof. [Figure 4] (a) and (b) are both enlarged plan views of key parts showing further variations of the medical guide wire shown in Figure 1. [Figure 5] Figure 1 is an enlarged schematic cross-sectional view showing a modified example of a medical guidewire. [Modes for carrying out the invention]

[0015] Hereinafter, a medical guide wire 1 according to an embodiment of the present invention will be described with reference to the attached drawings. Note that each figure has been partially enlarged or reduced to facilitate understanding of the structure. Figure 1 is an enlarged schematic cross-sectional view of the main part of a medical guide wire 1 according to one embodiment of the present invention. The medical guide wire 1 according to the present invention is, for example, a guide wire that is passed through a hollow puncture needle in endoscopic ultrasound-guided puncture, or a guide wire that is inserted into a catheter, and comprises a wire body 2, an intermediate layer 3, and an outermost layer 4.

[0016] The wire body 2 is a long, flexible linear member. While the wire body 2 can be constructed from various conventional materials used as core materials for medical guide wires, it is preferable to form it from a metallic material. For example, it can be constructed from stainless steel (e.g., all types of SUS, such as SUS304, SUS303, SUS316, SUS316L, SUS316J1, SUS316J1L, SUS405, SUS430, SUS434, SUS444, SUS429, SUS430F, SUS302, etc.). When stainless steel is used as the material for the wire body 2, the medical guide wire 1 can achieve superior pushability and torque transmission.

[0017] Furthermore, a pseudoelastic alloy (including a superelastic alloy) can be used as the material for the wire body 2. In particular, when the wire body 2 is constructed using a superelastic alloy, the medical guide wire 1 gains sufficient flexibility and resilience to bending throughout, improving its ability to follow complex curves and bends, and resulting in superior operability. Moreover, even if the wire body 2 undergoes repeated bending and flexing deformation, the resilience prevents the wire body 2 from developing a permanent bend, thus preventing a decrease in operability due to the wire body 2 developing a permanent bend during use of the medical guide wire 1.

[0018] Pseudoelastic alloys include those with stress-strain curves under tension of any shape, including those in which transformation points such as As, Af, Ms, and Mf can be significantly measured and those in which they cannot be measured, and all those that deform greatly under stress and almost return to their original shape when the stress is removed.

[0019] Preferred compositions of superelastic alloys include Ni-Ti-based alloys such as Ni-Ti alloys containing 49 to 52 atomic% Ni, Cu-Zn alloys containing 38.5 to 41.5 wt% Zn, Cu-Zn-X alloys (X is at least one of Be, Si, Sn, Al, Ga) containing 1 to 10 wt% X, Ni-Al alloys containing 36 to 38 atomic% Al, and the like. Among these, the Ni-Ti-based alloys are particularly preferred.

[0020] In addition, a cobalt-based alloy can also be used as the material of the wire body 2. When the wire body 2 is constituted by a cobalt-based alloy, the medical guide wire 1 is excellent in torque transmission and extremely unlikely to cause problems such as buckling. As the cobalt-based alloy, any alloy containing Co as a constituent element may be used, but an alloy containing Co as a main component (Co-based alloy: an alloy in which the content of Co is the largest in weight ratio among the elements constituting the alloy) is preferred, and a Co-Ni-Cr-based alloy is more preferably used. By using an alloy having such a composition, the above-described effects become more remarkable. In addition, an alloy having such a composition has a high elastic modulus, can be cold-formed even as a high elastic limit, and by being a high elastic limit, it can be made smaller in diameter while sufficiently preventing the occurrence of buckling, and can be provided with sufficient flexibility and rigidity for insertion into a predetermined site.

[0021] In addition to being constituted by using the above materials, the wire body 2 may be constituted by, for example, piano wire.

[0022] Furthermore, various forms can be adopted for the wire body 2. For example, the wire body 2 may be formed from a single steel material, or it may be formed by folding and twisting together a single linear steel material. Alternatively, the wire body 2 may be formed by twisting together multiple linear steel materials, or by twisting together a linear steel material and a linear resin member. Moreover, various configurations can be adopted, such as one in which the central part and the surface part are made of different materials (a two-layer structure, for example, a member in which the outer surface of the central part made of metal is coated with a thermosetting resin to form the surface part). The total length of the wire body 2 is not particularly limited, but it is preferably about 2000 to 5000 mm.

[0023] Furthermore, the wire body 2 may be configured such that its outer diameter is approximately constant, or the tip portion may be formed in a tapered shape where its outer diameter decreases towards the tip. When the tip portion of the wire body 2 is configured in a tapered shape where its outer diameter decreases towards the tip, the rigidity (bending rigidity, torsional rigidity) of the wire body 2 can be gradually reduced towards the tip. As a result, the medical guide wire 1 has good passage through constricted areas and flexibility at its tip, improving its conformability and safety, and also preventing bending and other problems, which is preferable.

[0024] Alternatively, the wire body 2 may be constructed by connecting the first wire body 2, which constitutes the tip portion, and the second wire body 2, which constitutes the middle and proximal portions, by welding or other means. When the wire body 2 is constructed using the first wire body 2 and the second wire body 2, it is preferable that the diameter of the first wire body 2 be smaller than the diameter of the second wire body 2. Furthermore, it is preferable that the connecting portion be tapered so that the first wire body 2 and the second wire body 2 are smoothly connected. Even when the wire body 2 is constructed in this way, the rigidity (bending rigidity, torsional rigidity) of the wire body 2 can be gradually reduced toward the tip, and as a result, the medical guide wire 1 has good passage through narrowed areas and flexibility at the tip, improving followability and safety, and also preventing bending, which is preferable.

[0025] The intermediate layer 3 is configured to cover the surface of the wire body 2 and is composed of a material containing a pigment and a binder resin. The pigment contained in the intermediate layer 3 is a coloring agent and is used to color the intermediate layer 3. This pigment can be either an inorganic pigment or an organic pigment, but it is preferable to use one with excellent heat resistance. Suitable pigments include carbon black, titanium dioxide, phthalocyanine blue, mica, nickel titanium yellow, Prussian blue, millery blue, cobalt blue, ultramarine, and viridian. The pigment may be used alone or in combination (especially mixed) of two or more types. The average particle size of the pigment is not particularly limited, but it is preferably set in the range of 0.05 μm to 2 μm, and more preferably in the range of 0.1 μm to 1.5 μm.

[0026] The binder resin included in the intermediate layer 3 is not particularly limited in type, but examples include polysulfone, polyimide, polyetheretherketone, polyallylenketone, polyphenylene sulfide, polyallylen sulfide, polyamideimide, polyetherimide, polyimide sulfone, polyallyl sulfone, polyallyl ethersulfone, polyester, and polyethersulfone. In particular, polyimide-based resins such as polyimide, polyamideimide, polyetherimide, and polyimide sulfone can be suitably used. By using such materials as the binder resin, the adhesion between the wire body 2 and the outermost layer 4 can be effectively improved.

[0027] The thickness of this intermediate layer 3 is not particularly limited, but from the viewpoint of highlighting the colored hue, it is preferable to set it to 1 μm or more. Also, from the viewpoint of preventing the medical guidewire from becoming too thick, it is preferable to set it to 30 μm or less. More preferably, the intermediate layer 3 is configured in the range of 2 μm to 20 μm.

[0028] Furthermore, in the present invention, the pigment concentration is configured to be in the range of 50 wt% to 90 wt% of the entire intermediate layer 3. More preferably, the pigment concentration is configured to be in the range of 55 wt% to 85 wt% of the entire intermediate layer 3, and even more preferably, in the range of 60 wt% to 85 wt%. By setting the pigment concentration in this manner, the surface area of ​​the surface of the intermediate layer 3 (the surface in contact with the outermost layer 4) increases, the anchoring effect on the outermost layer 4 increases, and the adhesion strength of the outermost layer 4 to the intermediate layer 3 is dramatically improved. In addition, by setting the pigment concentration in this manner, the hardness gap between the wire body 2 and the intermediate layer 3 can be reduced, so it is presumed that shear stress applied from outside the guide wire, such as when the tip of the puncture needle passes through, is less likely to concentrate at the interface between the wire body 2 and the intermediate layer 3.

[0029] The method for forming the intermediate layer 3 by coating the surface of the wire body 2 with a material composed of the above-mentioned pigment and binder resin is not particularly limited, and various methods can be used. For example, it can be formed by applying a solution prepared by mixing the above-mentioned pigment and binder resin with a suitable solvent to the wire body 2, and then drying it to evaporate the solvent. The material included in the intermediate layer 3 is not limited to the above-mentioned pigment and binder resin, but may also include, for example, a fluororesin or various other additives.

[0030] The outermost layer 4 is configured to cover the intermediate layer 3, which is placed on the surface of the wire body 2, and is preferably formed from a transparent material. As the material constituting the outermost layer 4, for example, a fluorine-based resin material having lubricity is preferred. Examples of such fluorine-based resin materials include tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA, melting point 300-310°C), polytetrafluoroethylene (PTFE, melting point 330°C), tetrafluoroethylene-hexafluoropropylene copolymer (FEP, melting point 250-280°C), ethylene-tetrafluoroethylene copolymer (ETFE, melting point 260-270°C), polyvinylidene fluoride (PVDF, melting point 160-180°C), polychlorotrifluoroethylene (PCTFE, melting point 210°C), tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymer (EPE, melting point 290-300°C), etc., and fluorine-based resin materials such as copolymers containing these polymers. Among these, PFA, PTFE, FEP, ETFE, and PVDF are preferred due to their excellent sliding properties.

[0031] The thickness of the outermost layer 4 is not particularly limited, but is usually 2 μm to 30 μm, preferably 3 μm to 25 μm, and especially preferably 4 μm to 20 μm, as a dry thickness.

[0032] The method for forming the outermost layer 4 by coating the surface of the intermediate layer 3 with the above-mentioned resin material is not particularly limited, and various methods can be used. For example, one method involves immersing the wire body 2, on which the intermediate layer 3 has been formed, in a solution prepared using the above-mentioned resin material and a suitable solvent, drying it, and then performing a heat treatment to fuse the outermost layer 4 onto the intermediate layer 3. The heat treatment can be performed, for example, by using a chamber-type heat treatment device and applying heat from the outside of the outermost layer 4 formed on the wire body 2. Alternatively, if the wire body 2 is made of, for example, an electrically conductive metal material, the wire body 2 can be heated by applying a voltage to both ends of the wire body 2, and the outermost layer 4, which is placed covering the surface of the wire body 2, can be melted by this heat and fused onto the intermediate layer 3.

[0033] As described above, the medical guidewire 1 according to this embodiment is configured to have an intermediate layer 3 interposed between the wire body 2 and the outermost layer 4, and the concentration of the pigment contained in the intermediate layer 3 is configured to be 50 wt% or more and 90 wt% or less of the total intermediate layer 3. With this configuration, it is possible to achieve extremely high adhesion between the outermost layer 4 and the intermediate layer 3, and even when used as a guidewire to pass through a puncture needle in endoscopic ultrasound-guided puncture, for example, it is possible to effectively prevent the outermost layer 4 from peeling off due to contact with the tip of the hollow puncture needle.

[0034] Furthermore, since the medical guidewire 1 according to the present invention is equipped with a lubricating outermost layer 4 formed from a fluororesin material or the like, it exhibits extremely high slipperiness, ensuring good sliding properties between the inner wall of the puncture needle and the inner wall of the catheter during endoscopic ultrasound-guided puncture.

[0035] In the configuration shown in Figure 1, a single intermediate layer is provided. However, as shown in the enlarged plan view of the main part in Figure 2(a) and the enlarged cross-sectional view of the main part in the AA section of Figure 2(a), as shown in Figure 2(b), the intermediate layer may be configured to include a first region 31 containing a first pigment and a second region 32 containing a second pigment having a different color from the first pigment. In the medical guide wire shown in Figure 2, the intermediate layer is configured to have a two-layer structure, with the second region 32 provided on the first region 31. Furthermore, the second region 32 is provided on the first region 31 so as to form a spiral pattern along the longitudinal direction of the medical guide wire.

[0036] Such an intermediate layer 3 is constructed by, for example, preparing a first solution by mixing a first pigment, a binder resin, and a solvent, and separately preparing a second solution by mixing a second pigment, a binder resin, and a solvent, applying and drying the first solution onto the wire body 2 to form a first region 31, and then applying the second solution in a spiral pattern onto the first region 31 and drying it to form a second region 32.

[0037] Even with an intermediate layer 3 having a first region 31 and a second region 32, the aforementioned effect of improved adhesion can be obtained by configuring the concentration of pigment contained in the intermediate layer 3 (the combined concentration of the first and second pigments) to be between 50 wt% and 90 wt% of the entire intermediate layer 3. Furthermore, by configuring the intermediate layer 31 and the second region 32 to have different colors from each other, the movement of the guidewire can be easily observed through an endoscope fiberscope, etc., so the medical guidewire shown in Figure 2 has excellent visibility.

[0038] Furthermore, while Figure 2 shows the configuration of a two-layer intermediate layer 3 in which a second region 32 is formed in a spiral pattern on the first region 31, as shown in the enlarged plan view of the main part in Figure 3(a) and the enlarged cross-sectional view of the main part in the BB section in Figure 3(a), the first region 31 and the second region 32 may be arranged alternately on the wire body 2 along the longitudinal direction of the wire body 2 in a double helix structure (a form in which a spiral pattern is formed by a single intermediate layer 3). Also, when configuring the first region 31 and the second region 32 to have different colors from each other, the configuration is not limited to forming a spiral pattern as shown in Figures 2 and 3. For example, as shown in the enlarged plan view of the main part in Figure 4(a), the second region 32 may be formed in a dot shape, or, as shown in the enlarged plan view of the main part in Figure 4(b), the ring-shaped first region 31 and the second region 32 may be arranged alternately along the longitudinal direction of the wire member.

[0039] The inventors of the present invention have created prototypes relating to the medical guide wires according to the present invention, including examples (Examples 1-4) and comparative examples (Comparative Examples 1-4), and have conducted tests to confirm the above-mentioned effects (effects related to improved adhesion), which are described below.

[0040] First, the structures of Examples 1-4 and Comparative Examples 1-4 will be described. As shown in Figures 2(a) and 2(b), Examples 1-4 and Comparative Examples 1-4 are constructed by forming a two-layer intermediate layer 3 (an intermediate layer 3 comprising a first region 31 and a second region 32) on a wire body 2, and then forming an outermost layer 4 on the formed intermediate layer 3. In all of Examples 1-4 and Comparative Examples 1-4, a metal wire with a diameter of 0.55 mm (material: Ni-Ti alloy from Furukawa Techno Material Co., Ltd.) is used as the wire body 2. In all of Examples 1-4 and Comparative Examples 1-4, the outermost layer 4 is constructed using tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). The thickness of the outermost layer 4 is 10 μm.

[0041] Furthermore, the thickness of the first region 31 constituting the intermediate layer 3 is 4 μm. The thickness of the second region 32 formed on the first region 31 is 8 μm. The second region 32 is configured such that its dimension in the direction along the longitudinal direction of the wire body 2 is 3 mm. Furthermore, when viewed in the direction along the longitudinal direction of the wire body 2, the spacing between adjacent second regions 32 is 6 mm.

[0042] Furthermore, for the intermediate layer 3, the pigments and binder resins contained in the first region 31 and the second region 32 were varied in each of Examples 1 to 4 and Comparative Examples 1 to 4, and the pigment concentration for the entire intermediate layer 3 (first region 31 and second region 32) was also changed. Details of the types of binder resins, pigments, and pigment concentrations contained in the intermediate layer 3 (first region 31 and second region 32) are shown in Table 1 below. Note that the pigment concentration for Example 1 is 85 wt%, for Example 2 it is 70 wt%, for Example 3 it is 60 wt%, and for Example 4 it is 50 wt%. Also, the pigment concentration for Comparative Example 1 is 30 wt%, for Comparative Example 2 it is 40 wt%, for Comparative Example 3 it is 95 wt%, and for Comparative Example 4 it is 40 wt%.

[0043] [Table 1]

[0044] For each of the guidewires in Examples 1-4 and Comparative Examples 1-4, configured as described above, an adhesion test was conducted to determine whether the outermost layer 4 peeled off by inserting them into a hollow puncture needle (NEOLUS (1.20 x 38 mm) manufactured by Terumo Corporation) actually used in endoscopic ultrasound-guided puncture. More specifically, each guidewire was inserted from the proximal end of a horizontally placed hollow puncture needle, and the guidewire was pulled out 50 mm from the tip of the puncture needle at a 45-degree angle upwards. Then, the guidewire was pulled from the tip side of the puncture needle. The guidewire was pulled at a constant speed toward the proximal end. A microscope was used to check whether or not delamination of the outermost layer 4 had occurred on the guidewire. The results are shown in Table 2 below. Regarding the adhesion check results, "×" indicates that the outermost layer 4 has delaminated and fallen off, "△" indicates that the outermost layer 4 has not fallen off but has delaminated in layers, "○" indicates that there is damage to the outermost layer 4 but no delamination or detachment has occurred, and "◎" indicates that there is no damage or delamination to the outermost layer 4.

[0045] Furthermore, the inventors also conducted visibility tests for each of Examples 1-4 and Comparative Examples 1-4, and the results are shown in Table 2. The visibility tests were conducted by inserting each guidewire into a PTFE cannula and observing the movement of the guidewire under an endoscopic fiberscope. In Table 2, "×" indicates that the movement of the guidewire could not be confirmed, "△" indicates that the movement of the guidewire could be confirmed but was unclear, and "◎" indicates that the movement of the guidewire was clearly confirmed.

[0046] [Table 2]

[0047] As shown in the adhesion confirmation results in Table 2 above, it can be confirmed that in Examples 1 to 4 and Comparative Example 3, where the pigment concentration in the intermediate layer 3 (first region 31 and second region 32) is in the range of 50 wt% or more relative to the entire intermediate layer 3, the outermost layer 4 does not peel off or fall off. In particular, in Examples 1, 2, and 3, where the pigment concentration is in the range of 60 wt% to 85 wt% relative to the entire intermediate layer 3, there is no peeling or fall-off of the outermost layer 4 in any case, indicating that the adhesion of the outermost layer 4 is extremely excellent.

[0048] On the other hand, in Comparative Examples 1, 2, and 4, where the pigment concentration was 40 wt% or less of the entire intermediate layer 3, a portion of the outermost layer 4 detached in all cases, confirming that the adhesion of the outermost layer 4 was poor.

[0049] Furthermore, based on the adhesion test results in Table 2, it is considered that the lower limit of pigment concentration at which the outermost layer can withstand use without detaching is 50 wt% as in Example 4. In particular, it is thought that the lower limit of pigment concentration at which adhesion to the outermost layer 4 is high lies between 50 wt% in Example 3 and 60 wt% in Example 4, and the arithmetic mean of the two, 55 wt%, is presumed to be the boundary. Therefore, in order to ensure sufficient adhesion between the intermediate layer 3 and the outermost layer 4, it is preferable to set the pigment concentration in the intermediate layer 3 to 55 wt% or higher relative to the entire intermediate layer 3.

[0050] Furthermore, from the adhesion confirmation results in Table 2, it is considered that the upper limit of pigment concentration that can withstand use without the outermost layer falling off is 95 wt% in Comparative Example 3. However, in the case of Comparative Example 3, there is a risk that problems may occur in the adhesion between the wire body 2 and the intermediate layer 3 due to the excessive amount of pigment contained in the intermediate layer 3 (the adhesion confirmation results in Table 2 are marked as "△~×" because there is a risk of problems in the adhesion between the wire body 2 and the intermediate layer 3). Therefore, it is considered that the upper limit of pigment concentration that provides excellent adhesion between the wire body 2 and the intermediate layer 3, and also high adhesion to the outermost layer 4, lies between 85 wt% in Example 1 and 95 wt% in Comparative Example 3, and it is estimated that the arithmetic mean of the two, 90 wt%, is the boundary. In other words, in order to sufficiently ensure adhesion between the wire body 2 and the intermediate layer 3, and between the intermediate layer 3 and the outermost layer 4, it is preferable to set the pigment concentration contained in the intermediate layer 3 to 90 wt% or less of the entire intermediate layer 3.

[0051] Furthermore, from the visibility test results in Table 2, it can be seen that Examples 1 to 4 and Comparative Example 3, in which the pigment concentration in the intermediate layer 3 (first region 31 and second region 32) is in the range of 50 wt% or more relative to the entire intermediate layer 3, all have good visibility, allowing the movement of the guide wire to be clearly observed. On the other hand, in Comparative Examples 1, 2, and 4, in which the pigment concentration is 40 wt% or less relative to the entire intermediate layer 3, the movement of the guide wire could not be observed or was unclear in all cases.

[0052] From the above, it can be seen that by setting the concentration of the pigment contained in the intermediate layer 3 (first region 31 and second region 32) to a range of 50 wt% to 90 wt% relative to the entire intermediate layer 3, visibility under the fiberscope of the endoscope can be improved, and sufficient adhesion of the outermost layer 4 can also be ensured.

[0053] The medical guide wire 1 according to the present invention has been described above, but the specific configuration is not limited to the above embodiments. For example, as shown in the cross-sectional view of Figure 5, the medical guide wire 1 may be constructed by spirally winding a wire 5 around the surface of the outermost layer 4. The medical guide wire 1 shown in Figure 5 shows a configuration in which the wire 5 is wound around the medical guide wire shown in Figure 2. It is preferable that this wire 5 is made from the same material as the material forming the outermost layer 4. Furthermore, the wire 5 is formed to have a substantially uniform thickness along its longitudinal direction before being wound on the outermost layer 4, and its maximum diameter can preferably be in the range of, for example, 10 μm to 200 μm, and more preferably in the range of 80 μm to 200 μm. Here, pitch is a concept that represents the distance between the centers of adjacent wires 5 in the longitudinal direction of the wire body 2, as shown in the cross-sectional view of Figure 5. In Figure 5, the wires 5 are wound spirally so that the distance between the centers (pitch) of the wires 5 are equal. The distance between the centers (pitch) of the wires 5 can be set to any dimension, but for example, it is 15 μm to 5000 μm, preferably 30 μm to 1000 μm, and particularly preferably 50 μm to 700 μm. Note that the distance between the centers (pitch) of the wires 5 may be configured to be partially different.

[0054] The method for winding the wire 5 onto the outermost layer 4 is not particularly limited, and examples include winding it using a covering device used to manufacture covering yarn.

[0055] Furthermore, the wire is wound in a spiral pattern on the outermost layer 4. 5The wire is fused and integrated onto the outermost layer 4 over its entire surface. One method for fusing the wire 5 onto the outermost layer 4 is to first spirally wind the wire 5 around the outer surface of the outermost layer 4, and then heat it to melt the wire 5 and the outermost layer 4, thereby fusing the wire 5 to the surface of the outermost layer 4. One heating method is to use a chamber-type heat treatment apparatus to melt the wire wound around the outermost layer 4 on the wire body 2. 5 This can be done by applying heat from the outside. Furthermore, if the wire body 2 is made of, for example, an electrically conductive metal material, the wire body 2 can be heated by applying a voltage to both ends of the wire body 2. This heat melts the outermost layer 4 and the wire 5 on the wire body 2, thereby fusing the wire 5 onto the outermost layer 4. Note that when the wire 5 is placed on the outermost layer 4, the heat treatment when forming the outermost layer 4 on the intermediate layer 3 can be omitted. Instead, the heat treatment performed after placing the wire 5 on the outermost layer 4 can simultaneously fuse the outermost layer 4 to the intermediate layer 3 and the wire 5 to the outermost layer 4.

[0056] By incorporating such a wire 5, the durability of the outermost layer 4 is further improved. Furthermore, when the medical guidewire 1 is inserted into a hollow puncture needle or catheter, the part of the wire 5 that comes into contact with the inner wall of the hollow puncture needle is the outermost part (top), thus reducing the contact area between the medical guidewire 1 and the hollow puncture needle or catheter, and ensuring even higher sliding properties. In particular, by constructing the wire 5 from a fluororesin material, even higher sliding properties can be ensured.

[0057] Furthermore, as shown in the cross-sectional view of Figure 5, the wire 5 that is heat-fused onto the outermost layer 4 has a cross-sectional shape that is either a semi-cylindrical lens shape or a plano-convex lens shape (a capital "D" shape). It is preferable that the height of the wire 5 after heat fusion (the dimension from the surface of the outermost layer 4 to the top of the wire) be in the range of 4 μm to 80 μm. By configuring the fused wire 5 to have a height within this numerical range, particularly 6 μm or more, when moving the medical guidewire 1 inside a hollow puncture needle or catheter, the sliding properties are improved by point contact. Moreover, vibrations caused by the movement of the uneven surface are transmitted to the fingertips of the user (practitioner) of the medical guidewire. Therefore, in addition to visual information from the endoscope and normal insertion sensation information, it becomes possible to grasp the insertion status from this unique vibration sensation information, thereby improving user convenience.

[0058] In the configuration shown in Figure 5, a single wire 5 is wound spirally on the outermost layer 4. However, for example, two wires 5 of different thicknesses may be wound spirally (double helix) on the outermost layer 4. [Explanation of symbols]

[0059] 1. Medical guide wire 2 Wire body 3. Middle Class 31 First area 32 Second area 4 Outermost layer 5 wire rod

Claims

1. A long, flexible wire body, At least one intermediate layer covering the surface of the wire body, The intermediate layer comprises an outermost layer that covers the surface of the intermediate layer, The wire body is made of a metal wire material made of a Ni-Ti alloy, The outermost layer is made of a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer. The aforementioned intermediate layer is colored by containing a pigment and also contains a binder resin. The aforementioned pigment includes carbon black or titanium oxide. The binder resin comprises polyamide-imide or polyether-imide. The concentration of the pigment is 70 wt% or more and 85 wt% or less relative to the entire intermediate layer. A medical guide wire in which the wire body and the outermost layer are not in direct contact.

2. The intermediate layer comprises a first region containing a first pigment and a second region containing a second pigment having a different color from the first pigment. The first pigment comprises carbon black or titanium dioxide. The medical guide wire according to claim 1, wherein the second pigment comprises titanium dioxide or cobalt blue.

3. The medical guide wire according to claim 1 or claim 2, wherein the average particle size of the pigment is 0.05 μm or more and 2 μm or less.

4. The medical guide wire according to any one of claims 1 to 3, wherein the thickness of the intermediate layer is 2 μm or more and 30 μm or less.

5. The medical guide wire according to any one of claims 1 to 4, wherein the intermediate layer comprises a binder resin made of a polyimide resin.

6. The medical guide wire according to any one of claims 1 to 5, wherein the outermost layer is made of a fluororesin material.

7. The medical guide wire according to any one of claims 1 to 6, wherein the outermost layer is fused to the surface of the intermediate layer.

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