Medical guide wire

Abstract

Provided is a medical guide wire comprising: a long and flexible wire body; and an outermost layer disposed on the outer side of the wire body. The outermost layer contains a siloxane-modified polyimide resin.

Description

Medical Guidewires

[0001] The present invention relates to a medical guidewire.

[0002] Various types of medical guidewires have been known. Medical guidewires are used by being inserted into blood vessels, the digestive tract, or the like. Medical guidewires are used in combination with a catheter, for example. When used in combination with a catheter, typically, the medical guidewire is first inserted into a blood vessel, the digestive tract, or the like, and then the catheter is guided to the affected area along the medical guidewire inserted into the catheter. Therefore, the surface of the medical guidewire is required to have slip properties relative to the walls of blood vessels, the digestive tract, or the like, and the inner surface of the catheter. To ensure such slip properties, in conventional medical guidewires, the outermost layer coating the metal wire body is often made of an organic fluorine-containing compound (PFAS), such as PFA or PTFE, which has a low coefficient of friction (see, for example, Patent Document 1).

[0003] International Publication No. 2019 / 155828

[0004] However, in recent years, due to concerns about the persistence, bioaccumulation, and toxicity of PFAS, various countries have been moving to restrict the use of PFAS.However, until now, it has been difficult to ensure the sufficient lubricity required for medical guidewires unless PFAS is used in the outermost layer.

[0005] An object of the present invention is to provide a medical guidewire having a highly slippery surface and from which PFAS has been eliminated.

[0006] Item 1. A medical guidewire comprising: a flexible, long wire body; and an outermost layer disposed on the outside of the wire body, wherein the outermost layer contains a siloxane-modified polyimide resin.

[0007] Item 2. The medical guide wire according to Item 1, wherein the modification amount of the siloxane-modified polyimide resin contained in the outermost layer is 2.0 wt % to 50 wt %.

[0008] Item 3. The medical guide wire according to Item 1 or 2, further comprising: a base layer covering a surface of the wire body; and a spiral layer helically disposed on the surface of the base layer along the longitudinal direction of the wire body, wherein the outermost layer is disposed on the surfaces of the base layer and the spiral layer so as to cover the surfaces of the base layer and the spiral layer.

[0009] Item 4. The medical guidewire according to Item 3, wherein the spiral layer contains a polyimide resin.

[0010] Item 5. The medical guide wire according to Item 3 or 4, wherein the underlayer contains a polyimide resin.

[0011] Item 6. The medical guide wire according to Item 1 or 2, further comprising an underlayer covering the surface of the wire body, wherein the outermost layer is spirally disposed on the surface of the underlayer along the longitudinal direction of the wire body.

[0012] Item 7. The medical guide wire according to Item 1 or 2, wherein the outermost layer is disposed on the surface of the wire body so as to cover the surface of the wire body.

[0013] Item 8. A method for producing a medical guidewire according to any one of Items 1 to 7, comprising forming the outermost layer on the outside of the wire body, wherein the siloxane-modified polyimide resin contained in the outermost layer is baked at 250°C or higher.

[0014] According to the present invention, a medical guide wire is provided which has a highly slippery surface and from which PFAS is eliminated.

[0015] 1 is a cross-sectional view of a medical guidewire according to a first embodiment. 2 is a cross-sectional view of a medical guidewire according to a second embodiment. 3 is a cross-sectional view of a medical guidewire according to a third embodiment. 4 is a cross-sectional view of a medical guidewire according to a fourth embodiment. 5 is a cross-sectional view of a medical guidewire according to a comparative example. 6 is a diagram illustrating a test method for evaluating smoothness. 7 is a diagram illustrating a test method for evaluating torque transmittance.

[0016] Hereinafter, medical guidewires according to several embodiments of the present invention will be described with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and their description will not be repeated. The drawings are also drawn in a schematic manner, with objects appropriately omitted or exaggerated, for ease of understanding.

[0017] [1. First Embodiment] [1-1. Configuration of Medical Guidewire] Fig. 1 is a cross-sectional view of a medical guidewire (hereinafter, sometimes simply referred to as a guidewire) 1 according to a first embodiment of the present invention. Fig. 1 is a cross-sectional view of the guidewire 1 cut along a plane including a central axis extending in the longitudinal direction of the guidewire 1. The guidewire 1 is used by being inserted into a blood vessel, a digestive tract, or the like. The guidewire 1 is used in combination with a hollow instrument, such as, but not limited to, a catheter or a puncture needle used in an ultrasound-guided puncture procedure, and is inserted into the lumen of such an instrument. For this reason, as will be described in detail below, the surface (outermost layer) of the guidewire 1 is configured to have high slip properties with respect to the walls of blood vessels, the digestive tract, or the like, and the inner surface of the lumen of such an instrument.

[0018] As shown in FIG. 1 , the guide wire 1 includes a wire body 2, a base layer 3, and a helical layer 4. The wire body 2 is a long core wire. The base layer 3 and the helical layer 4 are disposed on the outside of the wire body 2 and constitute covering layers that cover the surface of the wire body 2. The base layer 3 is disposed on the surface of the wire body 2 so as to cover the surface of the wire body 2 with substantially no gaps. The helical layer 4 is disposed in a spiral shape on the surface of the base layer 3 along the longitudinal direction of the wire body 2. The base layer 3 is exposed through gaps in the helical layer 4. In this embodiment, the helical layer 4 constitutes the outermost layer of the guide wire 1.

[0019] The wire body 2 has low rigidity and flexibility. Furthermore, the wire body 2 typically has the property of not kinking (twisting). Furthermore, not only the wire body 2 but also the entire guidewire 1 including the wire body 2 has the same low rigidity, flexibility, and kink-free properties. Therefore, the guidewire 1 can smoothly advance through blood vessels, the digestive tract, etc. without damaging surrounding tissues, and can also smoothly advance through the lumen of instruments such as catheters and puncture needles.

[0020] The wire body 2 is typically, but not limited to, configured as a metal core wire. The wire body 2 can be made of, for example, a superelastic alloy. Examples of superelastic alloys include Ni-Ti alloys, Cu-Zn alloys, Cu-Zn-X alloys (where X is at least one of Be, Si, Sn, Al, and Ga), and Ni-Al alloys, with Ni-Ti alloys being particularly preferred. When a superelastic alloy is used for the wire body 2, the guidewire 1 exhibits sufficient flexibility and recovery against bending throughout its entire length, allowing it to conform to complex curves and bends, resulting in superior operability. Furthermore, even when the wire body 2 is repeatedly bent and bent, the wire body 2 does not develop a bending habit, thereby preventing a decrease in the operability of the guidewire 1.

[0021] The wire body 2 may also be made of, for example, stainless steel or a cobalt-based alloy. When stainless steel is used for the wire body 2, the guidewire 1 can exhibit superior pushability and torque transmission properties. When a cobalt-based alloy is used for the wire body 2, the guidewire 1 can exhibit superior torque transmission properties and is extremely unlikely to experience problems such as buckling. Any alloy containing Co as a constituent element can be used as the cobalt-based alloy. However, a Co-based alloy (an alloy with the highest Co content by weight among the elements constituting the alloy) is preferred, and a Co-Ni-Cr-based alloy is more preferred. The wire body 2 may also be made of a piano wire.

[0022] The wire body 2 may have various configurations. For example, the wire body 2 may be formed from a single steel wire, by folding and twisting a single steel wire, by twisting multiple steel wires, or by twisting steel wires and a linear resin member. The wire body 2 may also have a central portion and a surface portion formed from different materials (e.g., a multilayer structure including a metal central portion and a resin-coated surface portion). The wire body 2 may also have a substantially constant outer diameter, or may have a tapered distal end that narrows toward the distal end. The total length of the wire body 2 is not particularly limited, but is preferably approximately 2000 mm to 5000 mm. In this specification, the term "X to Y" refers to a range from X to Y.

[0023] In this embodiment, the underlayer 3 contains a pigment and a siloxane-modified polyimide resin. The same is true for the spiral layer 4, which also contains a pigment and a siloxane-modified polyimide resin. The pigment functions as a colorant, and the siloxane-modified polyimide resin can function as a binder resin. The underlayer 3 and the spiral layer 4 are colored. Note that both the underlayer 3 and the spiral layer 4 may contain various additives in addition to the pigment and the siloxane-modified polyimide resin.

[0024] The spiral layer 4 constituting the outermost layer and the base layer 3 exposed through gaps in the spiral layer 4 are visible when the guidewire 1 is viewed from the outside. The base layer 3 and the spiral layer 4 are preferably different colors, and the surface of the guidewire 1 is configured to have a spiral striped pattern. In this case, the movement of the guidewire 1 can be easily grasped through a fiberscope of an endoscope or the like, and the guidewire 1 exhibits excellent visibility. From the viewpoint of improving the visibility of the guidewire 1, it is preferable to increase the color contrast between the base layer 3 and the spiral layer 4, for example, by making the base layer 3 black and the spiral layer 4 yellow.

[0025] The pigment contained in each of the underlayer 3 and the spiral layer 4 may be an inorganic pigment or an organic pigment. Examples of pigments that can be used in each of the underlayer 3 and the spiral layer 4 include carbon black, titanium oxide, phthalocyanine blue, mica, nickel titanium yellow, Prussian blue, Milory blue, cobalt blue, ultramarine, and viridian. Each of the underlayer 3 and the spiral layer 4 may contain only one type of pigment, or two or more types may be mixed together. The average particle size of the pigment is not particularly limited, but is preferably 0.05 μm to 2 μm, and more preferably 0.1 μm to 1.5 μm.

[0026] By including a siloxane-modified polyimide resin in the base layer 3, the polyimide component contained therein ensures sufficient adhesion / bonding between the wire body 2 and the base layer 3. Similarly, by including a siloxane-modified polyimide resin in the helical layer 4, the polyimide component contained therein also ensures sufficient adhesion / bonding between the base layer 3 and the helical layer 4. Examples of siloxane-modified polyimide resins contained in the base layer 3 and the helical layer 4 include siloxane-modified polyimide, siloxane-modified polyetherimide, siloxane-modified polyamideimide, and siloxane-modified polyimide sulfone. The siloxane-modified polyimide resins contained in the base layer 3 and the helical layer 4 may be different types or the same type.

[0027] Furthermore, the inclusion of a siloxane-modified polyimide resin in the spiral layer 4, which is the outermost layer, ensures high lubricity inherent to silicone on the surface of the guidewire 1. Therefore, the guidewire 1 can more smoothly advance through blood vessels, the digestive tract, etc., and the lumen of instruments such as catheters and puncture needles. Similarly, the inclusion of a siloxane-modified polyimide resin in the base layer 3, which is exposed through gaps in the spiral layer 4, also enhances the lubricity of the surface of the guidewire 1. Note that, when the guidewire 1 is extended in a straight line, the base layer 3 rarely comes into contact with the walls of blood vessels, the digestive tract, etc., or the inner surface of the lumen of instruments such as catheters. However, because the base layer 3 is exposed through gaps in the spiral layer 4, it may come into contact with the walls of blood vessels, the digestive tract, etc., or the inner surface of the lumen of instruments such as catheters, when the guidewire 1 is bent. Therefore, when high lubricity is ensured not only on the surface of the spiral layer 4 but also on the surface of the base layer 3, the guidewire 1 can more smoothly advance through blood vessels, the digestive tract, etc., or the lumen of instruments such as catheters.

[0028] The weight percent concentration of the siloxane-modified polyimide resin contained in the underlayer 3 is preferably 10 wt% or more, more preferably 15 wt% or more, and even more preferably 20 wt% or more. On the other hand, the weight percent concentration of the siloxane-modified polyimide resin contained in the underlayer 3 is preferably 60 wt% or less, more preferably 50 wt% or less, and even more preferably 40 wt% or less.

[0029] The weight percent concentration of the siloxane-modified polyimide resin contained in the spiral layer 4 is preferably 10 wt% or more, more preferably 15 wt% or more, and even more preferably 20 wt% or more. On the other hand, the weight percent concentration of the siloxane-modified polyimide resin contained in the spiral layer 4 is preferably 60 wt% or less, more preferably 50 wt% or less, and even more preferably 40 wt% or less.

[0030] The modification amount of the siloxane-modified polyimide resin contained in the spiral layer 4 is preferably 2.0 wt% or more, and more preferably 5.0 wt% or more. Similarly, the modification amount of the siloxane-modified polyimide resin contained in the underlayer 3 is preferably 2.0 wt% or more, and more preferably 5.0 wt% or more. When the above numerical conditions are satisfied, the lubricity derived from silicone is effectively imparted to the surface of the guidewire 1.

[0031] Furthermore, the modification amount of the siloxane-modified polyimide resin contained in the helical layer 4 is preferably 50 wt% or less, and more preferably 40 wt% or less. Similarly, the modification amount of the siloxane-modified polyimide resin contained in the underlayer 3 is preferably 50 wt% or less, and more preferably 40 wt% or less. If the above numerical conditions are not satisfied, the rubber properties of the siloxane-modified polyimide resin may be strengthened, which may result in a decrease in the torque transmission and slip properties of the guidewire 1.

[0032] The side chain of the siloxane of the siloxane-modified polyimide resin contained in each of the underlayer 3 and the spiral layer 4 is preferably a methyl group (dimethyl), because the methyl group has low surface energy and is excellent in slipperiness and releasability.

[0033] The thickness of the base layer 3 is not particularly limited, but is preferably 0.5 μm or more, and more preferably 1 μm or more. The same applies to the thickness of the helical layer 4, which is preferably 0.5 μm or more, and more preferably 1 μm or more. On the other hand, in order to prevent the entire guidewire 1 from becoming too thick, if the base layer 3 and the helical layer 4 are made thick, the wire body 2 will become relatively thin, which may result in a decrease in torque transmission. From the viewpoint of preventing this, the thickness of the coating layer coating the wire body 2 (the total thickness of the base layer 3 and the helical layer 4) is preferably 30 μm or less, more preferably 20 μm or less, more preferably 15 μm or less, more preferably 10 μm or less, and more preferably 5 μm or less.

[0034] The method for forming the underlayer 3 is not particularly limited, and various methods can be used. For example, the underlayer 3 can be formed by immersing the wire body 2 in a solution prepared by mixing a material containing a pigment and a binder resin constituting the underlayer 3 with an appropriate solvent, drying the solution, and then performing a heat treatment to fuse the underlayer 3 onto the wire body 2 (dip method). The heat treatment may be performed using, for example, a chamber-type heat treatment device, to apply heat to the underlayer 3 from the outside. Alternatively or additionally, if the wire body 2 is made of a metal material that easily conducts electricity, the wire body 2 may be heated by applying a voltage to both ends of the wire body 2, thereby applying heat to the underlayer 3 from the inside.

[0035] Similarly, the method for forming the spiral layer 4 is not particularly limited, and various methods can be used. For example, the spiral layer 4 can be formed by applying a solution prepared by mixing a material containing a pigment and a binder resin that constitute the spiral layer 4 with an appropriate solvent to the surface of the underlayer 3, and then drying the solution to volatilize the solvent.

[0036] The guide wire 1 is manufactured by preparing the wire body 2 and forming the base layer 3 and the helical layer 4 on the outside of the prepared wire body 2. While not limited thereto, the siloxane-modified polyimide resin contained in the base layer 3 and the helical layer 4 is baked during the formation of the base layer 3 and the helical layer 4. The maximum baking temperature (the maximum temperature of the base layer 3 and the helical layer 4 during baking) is preferably 250°C or higher, more preferably 280°C or higher, and even more preferably 300°C or higher. When the above temperature conditions are satisfied, the siloxane component contained in the base layer 3 may segregate to the surface side (outer surface) of the base layer 3, and the polyimide component contained in the base layer 3 may segregate to the interface with the wire body 2. Similarly, the siloxane component contained in the helical layer 4 may segregate to the surface side (outer surface) of the helical layer 4, and the polyimide component contained in the helical layer 4 may segregate to the interface with the base layer 3. That is, the siloxane component segregates on the surface of the guidewire 1, effectively enhancing the lubricity of the surface of the guidewire 1. Furthermore, the polyimide component segregates at the interface with the adjacent inner layer, further enhancing the adhesion / bonding between the adjacent inner layer.

[0037] [1-2. Features] In the first embodiment, the helical layer 4, which is the outermost layer, contains a siloxane-modified polyimide resin, thereby ensuring high silicone-derived slipperiness on the surface of the guidewire 1. Furthermore, the base layer 3 exposed through gaps in the helical layer 4 also contains a siloxane-modified polyimide resin, further enhancing the slipperiness of the surface of the guidewire 1.

[0038] Conventional medical guidewires often use an organic fluorine-containing compound (PFAS) such as PFA or PTFE in their outermost layer to ensure surface lubricity. However, due to concerns about the persistence, bioaccumulation, and toxicity of PFAS, various countries have recently begun restricting the use of PFAS. In this regard, in the first embodiment, a siloxane-modified polyimide resin is used in the helical layer 4 and the underlayer 3, and PFAS is not used. Therefore, the guidewire 1 will be able to fully comply with such future regulations.

[0039] Furthermore, the siloxane-modified polyimide resin contained in the base layer 3 has enhanced adhesion / bonding properties with the wire body 2 due to the polyimide component, eliminating the need for a primer or the like for bonding to the wire body 2. Similarly, the siloxane-modified polyimide resin contained in the helical layer 4 has enhanced adhesion / bonding properties with the base layer 3 due to the polyimide component, eliminating the need for a primer or the like for bonding to the base layer 3. This allows the thickness of the multiple layers (base layer 3 and helical layer 4) that coat the wire body 2 to be reduced. As a result, the wire body 2 can be made relatively thick, thereby improving the torque transmission of the guidewire 1.

[0040] 2. Second Embodiment 2-1. Configuration of Medical Guidewire Fig. 2 is a cross-sectional view of a medical guidewire (hereinafter, sometimes simply referred to as a guidewire) 101 according to a second embodiment of the present invention. Fig. 2 is a cross-sectional view of the guidewire 101 cut along a plane including a central axis extending in the longitudinal direction of the guidewire 101. As can be seen from a comparison of Figs. 1 and 2, the guidewire 101 according to the second embodiment differs from the guidewire 1 according to the first embodiment in that it additionally includes a top coat layer 5, and also differs in the materials of the base layer 3 and the helical layer 4. For simplicity's sake, the following description will mainly focus on the differences between the two embodiments, and will omit a description of the commonalities as appropriate.

[0041] As shown in FIG. 2 , the guidewire 101 includes a wire body 2, a base layer 3, and a helical layer 4, and further includes a top coat layer 5 on the outside of the base layer 3 and the helical layer 4. The wire body 2 has the same structure as in the first embodiment. The base layer 3 and the helical layer 4 are also configured in the same manner as in the first embodiment, except for the materials. The top coat layer 5 is disposed on the outside of the wire body 2 and, together with the base layer 3 and the helical layer 4, constitutes a coating layer that covers the surface of the wire body 2. The top coat layer 5 is disposed on the surfaces of the base layer 3 and the helical layer 4 so as to cover the surfaces of the base layer 3 and the helical layer 4 substantially without any gaps. The top coat layer 5 covers the surface of the helical layer 4 and the surface of the base layer 3 exposed through gaps in the helical layer 4. In this embodiment, the top coat layer 5 constitutes the outermost layer of the guidewire 101.

[0042] In this embodiment, the underlayer 3 contains a pigment and a heat-resistant resin. The same is true for the spiral layer 4, which also contains a pigment and a heat-resistant resin. The heat-resistant resin here refers to, for example, a polyimide-based resin that is not siloxane-modified, such as polyimide, polyamideimide, or polyetherimide, or a thermosetting resin, such as an epoxy resin or a phenolic resin. The pigment functions as a colorant, and the heat-resistant resin can function as a binder resin. The underlayer 3 and the spiral layer 4 are colored. The pigment contained in the underlayer 3 and the spiral layer 4 is the same as the pigment in the first embodiment. Note that both the underlayer 3 and the spiral layer 4 may contain various additives in addition to the pigment and heat-resistant resin.

[0043] In this embodiment, the top coat layer 5 contains a siloxane-modified polyimide resin. Unlike the base layer 3 and the spiral layer 4, the top coat layer 5 typically does not contain a pigment and is configured to be transparent. Therefore, although the base layer 3 and the spiral layer 4 are covered from the outside by the top coat layer 5, they remain visible when the guide wire 101 is viewed from the outside. In other words, the guide wire 101 exhibits excellent visibility due to the base layer 3 and the spiral layer 4, as in the first embodiment. Note that the top coat layer 5 may contain various additives in addition to the siloxane-modified polyimide resin.

[0044] The inclusion of the heat-resistant resin in the base layer 3 ensures sufficient adhesion / bonding between the wire body 2 and the base layer 3. Similarly, the inclusion of the heat-resistant resin in the spiral layer 4 ensures sufficient adhesion / bonding between the base layer 3 and the spiral layer 4. The heat-resistant resins contained in the base layer 3 and the spiral layer 4 may be different from each other or may be the same.

[0045] By including a siloxane-modified polyimide resin in the top coat layer 5, the polyimide components contained therein ensure sufficient adhesion / bonding between the top coat layer 5 and the underlayer 3 and the spiral layer 4. Examples of siloxane-modified polyimide resins that can be used in the top coat layer 5 include siloxane-modified polyimides, siloxane-modified polyetherimides, siloxane-modified polyamideimides, and siloxane-modified polyimide sulfones.

[0046] Furthermore, since the top coat layer 5, which is the outermost layer, contains a siloxane-modified polyimide resin, the high lubricity inherent to silicone is ensured on the surface of the guide wire 101. Therefore, the guide wire 101 can more smoothly advance through blood vessels, the digestive tract, etc., and within the lumen of instruments such as catheters and puncture needles.

[0047] The weight percent concentration of the heat-resistant resin contained in the underlayer 3 is preferably 10 wt% or more, more preferably 15 wt% or more, and even more preferably 20 wt% or more, while the weight percent concentration of the heat-resistant resin contained in the underlayer 3 is preferably 60 wt% or less, more preferably 50 wt% or less, and even more preferably 40 wt% or less.

[0048] The weight percent concentration of the heat-resistant resin contained in the spiral layer 4 is preferably 10 wt% or more, more preferably 15 wt% or more, and even more preferably 20 wt% or more. On the other hand, the weight percent concentration of the heat-resistant resin contained in the spiral layer 4 is preferably 60 wt% or less, more preferably 50 wt% or less, and even more preferably 40 wt% or less.

[0049] The weight percent concentration of the siloxane-modified polyimide resin contained in the top coat layer 5 is preferably 70 wt % or more, more preferably 80 wt % or more, and even more preferably 90 wt % or more.

[0050] The modification amount of the siloxane-modified polyimide resin contained in the top coat layer 5 is preferably 2.0 wt% or more, and more preferably 5.0 wt% or more. When these numerical conditions are met, the surface of the guide wire 101 is effectively imparted with silicone-derived slipperiness. Furthermore, the modification amount of the siloxane-modified polyimide resin contained in the top coat layer 5 is preferably 50 wt% or less, and more preferably 40 wt% or less. If these numerical conditions are not met, the rubber properties exhibited by the siloxane-modified polyimide resin may be strengthened, which may result in a decrease in the torque transmission and slipperiness of the guide wire 101.

[0051] The side chain of the siloxane of the siloxane-modified polyimide resin contained in the top coat layer 5 is preferably a methyl group (dimethyl), because the methyl group has low surface energy and provides excellent slip properties and releasability.

[0052] The preferred ranges for the thicknesses of the base layer 3 and the spiral layer 4 are the same as those in the first embodiment. The thickness of the top coat layer 5 (the distance from the surface of the spiral layer 4 to the surface of the top coat layer 5) is not particularly limited, but is preferably 0.5 μm or more, and more preferably 1 μm or more. On the other hand, from the viewpoint of ensuring a certain degree of thickness for the wire body 2 and preventing a decrease in torque transmissibility, the thickness of the coating layer coating the wire body 2 (the total thickness of the base layer 3, spiral layer 4, and top coat layer 5) is preferably 50 μm or less, more preferably 40 μm or less, more preferably 30 μm or less, more preferably 20 μm or less, and more preferably 15 μm or less.

[0053] The methods for forming the base layer 3 and the spiral layer 4 are the same as those in the first embodiment, except for the materials used. The method for forming the top coat layer 5 is also not particularly limited, and various methods can be used. For example, the top coat layer 5 can be formed by immersing the wire body 2 on which the base layer 3 and the spiral layer 4 have been formed in a solution prepared by mixing a material constituting the top coat layer 5 with an appropriate solvent, drying the solution, and then performing a heat treatment to fuse the top coat layer 5 onto the base layer 3 and the spiral layer 4 (dip method). For example, a chamber-type heat treatment device may be used to apply heat to the top coat layer 5 from the outside. Alternatively or additionally, if the wire body 2 is made of a metal material that is highly conductive, the wire body 2 may be heated by applying a voltage to both ends of the wire body 2, and the top coat layer 5 may be heated from the inside.

[0054] The guidewire 101 is manufactured by preparing a wire body 2 and then forming an underlayer 3, a helical layer 4, and a topcoat layer 5 on the outer surface of the prepared wire body 2. While not limited thereto, the siloxane-modified polyimide resin contained in the topcoat layer 5 is baked during the formation of the topcoat layer 5. The maximum baking temperature (the maximum temperature of the topcoat layer 5 during baking) is preferably 250°C or higher, more preferably 280°C or higher, and even more preferably 300°C or higher. When the above temperature conditions are satisfied, the siloxane component contained in the topcoat layer 5 segregates to the surface side (outer surface) of the topcoat layer 5, and the polyimide component contained in the topcoat layer 5 segregates to the interface with the underlayer 3 and the helical layer 4. That is, the segregation of the siloxane component on the surface of the guidewire 101 effectively enhances the lubricity of the surface of the guidewire 101. Furthermore, the segregation of the polyimide component at the interface with the adjacent inner layer further enhances the adhesion / bonding between the adjacent inner layer.

[0055] [2-2. Features] In the second embodiment, the top coat layer 5, which is the outermost layer, contains a siloxane-modified polyimide resin, thereby ensuring high silicone-derived slipperiness on the surface of the guide wire 101. Also, in the second embodiment, PFAS is not used in the helical layer 4 and the base layer 3, nor in the top coat layer 5. Therefore, the guide wire 101 will be able to fully comply with PFAS regulations that are being implemented in various countries in the future.

[0056] 3. Third Embodiment 3-1. Configuration of Medical Guidewire Fig. 3 is a cross-sectional view of a medical guidewire (hereinafter, sometimes simply referred to as a guidewire) 201 according to a third embodiment of the present invention. Fig. 3 is a cross-sectional view of the guidewire 201 cut along a plane including a central axis extending in the longitudinal direction of the guidewire 201. As can be seen from a comparison of Figs. 1 and 3, the guidewire 201 according to the third embodiment differs from the guidewire 1 according to the first embodiment in that the helical layer 4 is omitted. For simplicity's sake, the following description will mainly focus on the differences between the two embodiments, and will omit a description of the commonalities as appropriate.

[0057] As shown in Fig. 3, the guide wire 201 includes a wire body 2 and an underlayer 3. The wire body 2 and the underlayer 3 are configured in the same manner as in the first embodiment. The underlayer 3 is disposed on the outside of the wire body 2 and constitutes a covering layer that covers the surface of the wire body 2. The underlayer 3 is disposed on the surface of the wire body 2 so as to cover the surface of the wire body 2 substantially without any gaps. In this embodiment, the underlayer 3 constitutes the outermost layer of the guide wire 201, and no additional layer is laminated on the surface of the underlayer 3. Therefore, hereinafter, the underlayer 3 will be referred to as a topcoat layer 3 while retaining the same reference numeral.

[0058] In this embodiment, the top coat layer 3 contains a siloxane-modified polyimide resin, as in the first embodiment. However, the top coat layer 3 may or may not contain a pigment. That is, the top coat layer 3 is typically transparent, but may also be colored. Note that the top coat layer 3 may contain various additives in addition to the siloxane-modified polyimide resin (and the pigment, if any).

[0059] The thickness of the top coat layer 3 is not particularly limited, but is preferably 0.5 μm or more, and more preferably 1 μm or more. On the other hand, from the viewpoint of ensuring a certain thickness of the wire body 2 and preventing a decrease in torque transmissibility, the thickness of the coating layer coating the wire body 2 (thickness of the top coat layer 3) is preferably 30 μm or less, more preferably 20 μm or less, more preferably 15 μm or less, more preferably 10 μm or less, more preferably 5 μm or less, more preferably 3 μm or less, and more preferably 2 μm or less.

[0060] [3-2. Features] In the third embodiment, the top coat layer 3, which is the outermost layer, contains a siloxane-modified polyimide resin, thereby ensuring high lubricity derived from silicone on the surface of the guide wire 201. Furthermore, in the third embodiment, the top coat layer 3 uses a siloxane-modified polyimide resin, but does not use PFAS. Therefore, the guide wire 201 can fully comply with PFAS regulations that are being implemented in various countries in the future.

[0061] Furthermore, the siloxane-modified polyimide resin contained in the top coat layer 3 has enhanced adhesion / bonding to the wire body 2 due to the polyimide component, eliminating the need for a primer or the like for bonding to the wire body 2. This allows the thickness of the multilayer (top coat layer 3) covering the wire body 2 to be reduced. As a result, the wire body 2 can be made relatively thick, thereby improving the torque transmission of the guide wire 201.

[0062] 4. Fourth Embodiment 4-1. Configuration of Medical Guidewire Fig. 4 is a cross-sectional view of a medical guidewire (hereinafter, sometimes simply referred to as a guidewire) 301 according to a fourth embodiment of the present invention. Fig. 4 is a cross-sectional view of the guidewire 301 cut along a plane including a central axis extending in the longitudinal direction of the guidewire 301. As can be seen from a comparison of Figs. 1 and 4, the guidewire 301 according to the fourth embodiment differs from the guidewire 1 according to the first embodiment in that it additionally includes a primer layer 6. For simplicity's sake, the following description will mainly focus on the differences between the two embodiments, and will omit a description of the commonalities as appropriate.

[0063] As shown in FIG. 4 , the guidewire 301 includes a wire body 2, a base layer 3, and a spiral layer 4, and further includes a primer layer 6 between the wire body 2 and the base layer 3. The wire body 2, base layer 3, and spiral layer 4 are configured in the same manner as in the first embodiment. The primer layer 6 is disposed on the outside of the wire body 2 and, together with the base layer 3 and the spiral layer 4, constitutes a coating layer that coats the surface of the wire body 2. The primer layer 6 is disposed on the surface of the wire body 2 so as to cover the surface of the wire body 2 substantially without gaps. The base layer 3 is disposed on the surface of the primer layer 6 so as to cover the surface of the primer layer 6 substantially without gaps. The base layer 3 indirectly coats the surface of the wire body 2 via the primer layer 6, which directly coats the surface of the wire body 2. In this embodiment, the spiral layer 4 constitutes the outermost layer of the guidewire 301.

[0064] The material of the primer layer 6 can be appropriately selected depending on the materials contained in the wire body 2 and the base layer 3 with which the primer layer 6 comes into contact. For example, the primer layer 6 is configured to contain a heat-resistant resin. The heat-resistant resin referred to here includes, for example, non-siloxane-modified polyimide resins such as polyimide, polyamideimide, and polyetherimide, as well as thermosetting resins such as epoxy resins and phenolic resins. The primer layer 6 preferably contains the heat-resistant resin exemplified here as its main component, and may contain various additives in addition to the heat-resistant resin as the main component. The term "main component" refers to the component with the highest weight percent concentration among all the components contained in the primer layer 6.

[0065] The thickness of the primer layer 6 is not particularly limited, but is preferably 0.5 μm or more, and more preferably 1 μm or more. On the other hand, from the viewpoint of ensuring a certain thickness of the wire body 2 and preventing a decrease in torque transmission, the thickness of the coating layer that coats the wire body 2 (the total thickness of the primer layer 6, the base layer 3, and the spiral layer 4) is preferably 30 μm or less, more preferably 20 μm or less, more preferably 15 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less.

[0066] The method for forming the primer layer 6 is not particularly limited, and various methods can be used. For example, the primer layer 6 can be formed by immersing the wire body 2 in a solution prepared by mixing a material constituting the primer layer 6 with an appropriate solvent, drying the solution, and then performing a heat treatment to fuse the primer layer 6 onto the wire body 2 (dip method). During the heat treatment, for example, a chamber-type heat treatment device may be used to apply heat to the primer layer 6 from the outside. Alternatively or additionally, if the wire body 2 is made of a metal material that easily conducts electricity, a voltage may be applied to both ends of the wire body 2 to heat the wire body 2, thereby applying heat to the primer layer 6 from the inside.

[0067] [4-2. Features] In the fourth embodiment, the helical layer 4, which is the outermost layer, contains a siloxane-modified polyimide resin, thereby ensuring high silicone-derived slipperiness on the surface of the guidewire 301. Furthermore, the base layer 3 exposed through gaps in the helical layer 4 also contains a siloxane-modified polyimide resin, further enhancing the slipperiness of the surface of the guidewire 301.

[0068] Furthermore, in the fourth embodiment, PFAS is not used not only in the spiral layer 4 and the base layer 3 but also in the primer layer 6. Therefore, the guide wire 301 can fully comply with PFAS regulations that are being implemented in various countries in the future.

[0069] [5. Modifications] Although several embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the present invention. For example, the following modifications are possible. Furthermore, the gist of the following modifications can be combined as appropriate.

[0070] [5-1] In the first and fourth embodiments, the underlayer 3 does not have to contain a siloxane-modified polyimide resin. For example, the underlayer 3 may be configured to contain a heat-resistant resin. The heat-resistant resin here includes, for example, polyimide, polyamideimide, polyetherimide, and other polyimide resins that are not siloxane-modified, as well as thermosetting resins such as epoxy resins and phenolic resins.

[0071] [5-2] In the second embodiment, either or both of the underlayer 3 and the spiral layer 4 may contain a siloxane-modified polyimide resin instead of the heat-resistant resin described above.

[0072] [5-3] In the first, second, and fourth embodiments, either or both of the base layer 3 and the spiral layer 4 may not contain a pigment. Furthermore, the top coat layer 5 of the second embodiment may contain a pigment.

[0073] Examples of the present invention will be described below, but the present invention is not limited to the following examples.

[0074] Guidewires of Examples 1 to 10 and Comparative Examples 1 and 2 were prepared. The layer configurations of the guidewires of Examples 1 to 10 and Comparative Examples 1 and 2 were as shown in Tables 1 and 2. That is, the guidewires of Examples 1 to 6 had the same layer configuration as that shown in FIG. 1 (first embodiment), the guidewires of Examples 7 and 8 had the same layer configuration as that shown in FIG. 3 (third embodiment), the guidewire of Example 9 had the same layer configuration as that shown in FIG. 2 (second embodiment), the guidewire of Example 10 had the same layer configuration as that shown in FIG. 4 (fourth embodiment), the guidewire of Comparative Example 1 had the layer configuration shown in FIG. 5, and the guidewire of Comparative Example 2 had the same layer configuration as that shown in FIG. 1 (first embodiment). The materials of each layer constituting the coating layer of the guidewires of Examples 1 to 10 and Comparative Examples 1 and 2 were as shown in Tables 1 and 2. However, although not shown in Tables 1 and 2, the primer layer and spiral layer also contained pigments. Note that PI stands for polyimide, and PEI stands for polyetherimide. The material of the wire body of the guide wires of Examples 1 to 10 was a Ni-Ti alloy.

[0075]

[0076]

[0077] The modification amount and siloxane side chain of the siloxane-modified PI or siloxane-modified PEI used in Examples 1 to 10 were as shown in Tables 1 and 2. The maximum baking temperature of the siloxane-modified PI or siloxane-modified PEI layer and the thickness of the coating layer were also as shown in Tables 1 and 2.

[0078] The guidewire of Comparative Example 1 had a layer structure similar to that of the guidewire disclosed in FIG. 5 of Patent Document 1. Specifically, as shown in FIG. 5, the guidewire of Comparative Example 1 had a layer structure in which a base layer was disposed on the surface of the wire body, a spiral layer was disposed on the surface of the base layer, a top coat layer was disposed on the surfaces of the base layer and the spiral layer, and a wire rod was spirally wound on the surface of the top coat layer. The wire rod was wound using a covering device and then fused to the surface of the top coat layer by heat treatment. The base layer and spiral layer of Comparative Example 1 were composed of a material containing a pigment and PEI. The top coat layer and wire rod were composed of a material containing PFA (perfluoroalkoxyalkane), a type of PFAS (organofluorine compound). The wire body was made of a Ni-Ti alloy. As described in Patent Document 1, the wire rod of Comparative Example 1 serves to reduce the contact area between the guidewire and the inner surface of the lumen of an instrument such as a catheter or puncture needle, thereby improving slipperiness against the inner surface.

[0079] The maximum firing temperature (maximum temperature of the wire during firing) and the thickness of the coating layer (total thickness of the primer layer, spiral layer, top coat layer, and wire) in Comparative Example 1 were also as shown in Table 2. The maximum firing temperature (maximum temperature of the primer layer and spiral layer during firing) and the thickness of the coating layer (total thickness of the primer layer and spiral layer) in Comparative Example 2 were also as shown in Table 2.

[0080] The guidewires of Examples 1 to 10 and Comparative Examples 1 and 2 were evaluated for smoothness and torque transmission. The results are shown in Tables 1 and 2.

[0081] The lubricity was evaluated using the following method. First, a PTFE (polytetrafluoroethylene) tube with an inner diameter of 0.9 mm, through which each of the guidewires of Examples 1 to 10 and Comparative Examples 1 and 2 was passed, was bent as shown in Figure 6A. The smaller loop in Figure 6A had a diameter of 60 mm, and the larger loop had a diameter of 110 mm. The PTFE tube was then fixed, and the guidewire inserted into the tube was pulled upward at a rate of 500 mm / min using a tensile tester, at which point the test force (N) was measured and used as an index of lubricity. Note that a smaller test force (N) indicates higher lubricity.

[0082] Torque transmission was evaluated using the following method. First, a 0.9 mm inner diameter PTFE (polytetrafluoroethylene) tube through which each of the guidewires of Examples 1 to 10 and Comparative Examples 1 and 2 was passed was bent as shown in Figure 6B. The loop in Figure 6B had a diameter of 110 mm. The PTFE tube was then fixed, and a flag was attached to the tip of the guidewire inserted into the tube. The proximal end of the guidewire, opposite the tip, was rotated, and the ability of the flag to follow the rotation was visually confirmed. "Good" indicates that there was no whip in the rotation of the tip with the flag. In other words, "Good" indicates that sufficient followability was obtained and torque transmission was very good. "Average" indicates that there was some whip in the rotation of the tip with the flag. In other words, "Average" indicates that good followability was obtained and torque transmission was good, although inferior to the "Good" case. "Poor" indicates that there was a clear whip at the tip with the flag. In other words, "Poor" indicates that sufficient followability was not obtained and torque transmission was poor.

[0083] The evaluation results in Tables 1 and 2 confirmed that all of Examples 1 to 10, in which the outermost layer was a siloxane-modified polyimide resin, exhibited slip properties equivalent to or superior to those of Comparative Example 1, in which the outermost layer was PFA. Furthermore, all of Examples 1 to 10 exhibited slip properties superior to those of Comparative Example 2, in which the outermost layer was PEI. Furthermore, as can be seen from a comparison of Examples 1 to 5, slip properties were particularly improved when the siloxane modification amount was between 5 wt% and 40 wt%. Furthermore, as can be seen from a comparison of Example 6 with the other Examples, it was confirmed that dimethyl siloxane side chains were preferred. Furthermore, as can be seen from a comparison of Examples 7 and 8, it was confirmed that slip properties were particularly improved by setting the maximum baking temperature of the siloxane-modified polyimide resin to 250°C or higher. Furthermore, good torque transmission was confirmed in all of Examples 1 to 10.

[0084] 1, 101, 201, 301 Guide wire 2 Wire body 3 Base layer (top coat layer) 4 Spiral layer 5 Top coat layer 6 Primer layer

Claims

1. A medical guidewire comprising: a flexible, long wire body; and an outermost layer disposed on the outside of the wire body, wherein the outermost layer contains a siloxane-modified polyimide resin.

2. The medical guidewire according to claim 1, wherein the amount of modification of the siloxane-modified polyimide resin contained in the outermost layer is 2.0 wt% to 50 wt%.

3. The medical guide wire according to claim 1, further comprising: a base layer covering the surface of the wire body; and a spiral layer arranged in a spiral shape on the surface of the base layer along the longitudinal direction of the wire body, wherein the outermost layer is arranged on the surfaces of the base layer and the spiral layer so as to cover the surfaces of the base layer and the spiral layer.

4. The medical guidewire according to claim 3, wherein the spiral layer contains a polyimide resin.

5. The medical guidewire according to claim 3 or 4, wherein the underlayer contains a polyimide resin.

6. The medical guide wire according to claim 1 or 2, further comprising a base layer covering the surface of the wire body, the outermost layer being spirally disposed on the surface of the base layer along the longitudinal direction of the wire body.

7. The medical guide wire according to claim 1 or 2, wherein the outermost layer is disposed on the surface of the wire body so as to cover the surface of the wire body.

8. A method for manufacturing a medical guidewire according to any one of claims 1 to 4, comprising forming the outermost layer on the outside of the wire body, and the siloxane-modified polyimide resin contained in the outermost layer is baked at 250°C or higher.

Images