Medical device

Abstract

A medical device according to the present invention has a first region having a first characteristic, and a second region positioned closer to the base end side than the first region and having a second characteristic. For example, the medical device includes a specific member located in the first region and the second region and containing a nickel titanium alloy. The first characteristic includes a feature of the average crystal grain size of the nickel titanium alloy being a first size, and the second characteristic includes a feature of the average crystal grain size of the nickel titanium alloy being a second size smaller than the first size.

Description

medical devices

[0001] The technology disclosed herein relates to medical devices.

[0002] For example, methods using catheters are widely used to treat or examine stenosis or occlusion in blood vessels (hereinafter referred to as "lesions"). A guidewire is used to guide the catheter to the lesion in the blood vessel. To improve the blood vessel selectivity of the guidewire, the operator performs a procedure called "shaping," in which the tip of the guidewire is bent at a predetermined angle in advance (see, for example, Patent Documents 1 to 3).

[0003] JP 2015-65979 A JP 2013-544575 A JP 2011-125556 A

[0004] In guidewires, it is sometimes required to differentiate the characteristics of a first region located at the distal end from a second region located proximal to the first region. For example, in order to improve selectivity for small branched blood vessels such as peripheral blood vessels, it is sometimes required to make the curvature and bending angle of the first region of the guidewire larger than those of the second region (region proximal to the first region) during shaping. Conventional guidewires have a problem in that it is not possible to differentiate the characteristics of the first region and the second region as desired. Note that this problem is not limited to guidewires but is common to medical devices.

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

[0006] The technology disclosed in this specification can be realized, for example, in the following forms.

[0007] (1) A medical device disclosed herein includes a first region having a first characteristic and a second region located proximal to the first region and having a second characteristic, and the characteristics of the first region and the second region can be made different as desired.

[0008] (2) The above medical device may include a specific component located in the first region and the second region and containing a nickel-titanium alloy, wherein the first characteristic includes a first average crystal grain size of the nickel-titanium alloy, and the second characteristic includes a second average crystal grain size of the nickel-titanium alloy that is smaller than the first size. This configuration allows the bending angle of the first region of the medical device to be larger than the bending angle of the second region. As a result, for example, shaping can be achieved in which the bending angle of the first region of the medical device is larger than the bending angle of the second region, thereby improving selectivity for small branched blood vessels such as peripheral blood vessels.

[0009] (3) In the medical device, the first size may be 0.05 μm or more and 2.5 μm or less. This configuration can improve selectivity for small branched blood vessels such as peripheral blood vessels.

[0010] (4) In the medical device, the second size may be 0.01 μm or more and 0.05 μm or less. This configuration can improve selectivity for small branched blood vessels such as peripheral blood vessels.

[0011] (5) In the medical device, the second size may be 0.02 μm or more and 0.048 μm or less. This configuration can improve selectivity for small branched blood vessels such as peripheral blood vessels.

[0012] (6) In the above medical device, the first region may include a distal first region and a proximal first region located proximal to the distal first region, and the average crystal grain size of the nickel-titanium alloy in the distal first region may be larger than the average crystal grain size of the nickel-titanium alloy in the proximal first region. This configuration allows the distal first region of the medical device to have a larger bending angle than the proximal first region. As a result, for example, shaping can be achieved in which the distal first region of the medical device has a larger bending angle than the proximal first region, effectively improving selectivity for small branched blood vessels such as peripheral blood vessels.

[0013] (7) In the medical device, the average crystal grain size of the nickel-titanium alloy in the distal first region may be 1.0 μm or more and 2.5 μm or less. This configuration effectively improves selectivity for small branched blood vessels such as peripheral blood vessels.

[0014] (8) In the medical device, the average crystal grain size of the nickel-titanium alloy in the distal first region may be 1.5 μm or more and 2.3 μm or less. This configuration effectively improves selectivity for small branched blood vessels such as peripheral blood vessels.

[0015] (9) In the medical device, the average crystal grain size of the nickel-titanium alloy in the proximal first region may be 0.05 μm or more and 0.1 μm or less. This configuration effectively improves selectivity for small branched blood vessels such as peripheral blood vessels.

[0016] (10) In the above medical device, the specific member may be a core shaft. According to this configuration, the bending angle of the first region of the medical device including the core shaft can be made larger than the bending angle of the second region.

[0017] (11) In the above-described medical device, the medical device is pressed against a flat surface with a pin, and a load of 1 N is applied toward the flat surface via the pin. The medical device is then pulled out perpendicularly from the flat surface, thereby imparting a curved shape to the pulled-out portion. Regarding the bending angle of the medical device, the first characteristic may include the bending angle being a first angle, and the second characteristic may include the bending angle being a second angle smaller than the first angle. According to this configuration, the bending angle of the first region of the medical device can be made larger than the bending angle of the second region. As a result, for example, shaping can be achieved in which the bending angle of the first region of the medical device is made larger than the bending angle of the second region, thereby improving selectivity for small branched blood vessels such as peripheral blood vessels.

[0018] (12) In the medical device, the first angle may be equal to or greater than 10 degrees and equal to or less than 100 degrees. This configuration can improve selectivity for small branched blood vessels such as peripheral blood vessels.

[0019] (13) In the medical device, the second angle may be equal to or greater than 0 degrees and equal to or less than 20 degrees. This configuration can improve selectivity for small branched blood vessels such as peripheral blood vessels.

[0020] (14) In the above medical device, the first region may include a distal first region and a proximal first region located proximal to the distal first region, and the bending angle in the distal first region may be larger than the bending angle in the proximal first region. According to this configuration, the bending angle in the distal first region of the medical device can be larger than the bending angle in the proximal first region. As a result, for example, shaping can be achieved in which the bending angle in the distal first region of the medical device is larger than the bending angle in the proximal first region, thereby effectively improving selectivity for small branched blood vessels such as peripheral blood vessels.

[0021] (15) In the medical device, the bending angle in the distal first region may be greater than or equal to 40 degrees and less than or equal to 100 degrees. This configuration can improve selectivity for small branched blood vessels such as peripheral blood vessels.

[0022] (16) In the medical device, the bending angle in the proximal first region may be 10 degrees or more and 40 degrees or less. This configuration can improve selectivity for small branched blood vessels such as peripheral blood vessels.

[0023] (17) In the above medical device, the value obtained by dividing the bending angle in the distal first region by the bending angle in the second region may be equal to or greater than 5 and equal to or less than 10. According to this configuration, the bending angle in the distal first region of the medical device can be made larger than the bending angle in the second region by a predetermined amount.

[0024] (18) In the above medical device, the value obtained by dividing the bending angle in the distal first region by the bending angle in the proximal first region may be equal to or greater than 1 and equal to or less than 6. According to this configuration, the bending angle of the distal first region of the medical device can be made larger than the bending angle of the proximal first region by a predetermined amount.

[0025] (19) The medical device may further include a core shaft located in the first region and the second region and made of the same material. This configuration can prevent damage to the core shaft due to a gap in physical properties.

[0026] The techniques disclosed in this specification can be realized in various forms, for example, in the form of a core shaft for a medical device, a medical device, a manufacturing method thereof, etc.

[0027] FIG. 1 is an explanatory diagram showing a schematic configuration of a guide wire according to an embodiment. FIG. 2 is an explanatory diagram showing a method for determining the average crystal grain size of a nickel-titanium alloy. FIG. 3 is an explanatory diagram showing a method for determining the bending angle. FIG. 4 is an explanatory diagram showing a configuration of a guide wire according to a modified example. FIG. 5 is an explanatory diagram showing a configuration of a guide wire according to a modified example.

[0028] A. Embodiment: (Configuration of Guidewire 100) FIG. 1 is an explanatory diagram schematically illustrating the configuration of a guidewire 100 according to an embodiment. FIG. 1 illustrates mutually orthogonal X, Y, and Z axes for specifying directions, and shows a longitudinal section (YZ section) of the guidewire 100. Along a direction parallel to the central axis AX of the guidewire 100 (hereinafter referred to as the "axial direction"), the positive Z-axis direction corresponds to the distal end (distal side) that is inserted into the body, and the negative Z-axis direction corresponds to the proximal end (proximal side) that is manipulated by a surgeon such as a physician. While FIG. 1 illustrates the guidewire 100 as a whole in a linear shape that is substantially parallel to the Z-axis direction, the guidewire 100 is flexible enough to be bent. In this specification, the distal end of the guidewire 100 and each of its constituent members will be referred to as the "distal end," the distal end and its vicinity will be referred to as the "distal portion," the proximal end will be referred to as the "proximal end," and the proximal end and its vicinity will be referred to as the "proximal portion."

[0029] The guidewire 100 is a medical device that is inserted into a blood vessel to guide another medical device (not shown), such as a catheter, to a lesion in the blood vessel. The guidewire 100 includes a core shaft 10, an outer layer coil body 20, an inner layer coil body 30, a distal joint 40, a first intermediate joint 51, a second intermediate joint 52, a first base-end joint 53, a second base-end joint 54, and a coating 60.

[0030] The core shaft 10 is an elongated member. The central axis of the core shaft 10 substantially coincides with the central axis AX of the guide wire 100. The core shaft 10 has a first portion 11, a second portion 12, a third portion 13, a fourth portion 14, and a fifth portion 15. The first portion 11, the second portion 12, the third portion 13, the fourth portion 14, and the fifth portion 15 are arranged in order from the distal end toward the proximal end. The core shaft 10 is an example of a specific member.

[0031] In this embodiment, the first portion 11, the third portion 13, and the fifth portion 15 of the core shaft 10 have a constant cross-sectional shape (X-Y cross-section) at each position along the axial direction. The cross-sectional area of ​​the third portion 13 is larger than that of the first portion 11. The cross-sectional area of ​​the fifth portion 15 is larger than that of the third portion 13. Furthermore, the second portion 12 and the fourth portion 14 of the core shaft 10 smoothly connect the cross-sectional shapes of other portions adjacent to each other along the axial direction. The second portion 12 and the fourth portion 14 are tapered portions whose cross-sectional areas gradually increase from the distal end toward the proximal end.

[0032] A core shaft 10 having such a shape can be manufactured, for example, by pressing a precursor having a constant cross section along the axial direction at a press rate corresponding to the shape of each part of the core shaft 10.

[0033] Examples of materials for forming the core shaft 10 include metal materials, more specifically, stainless steel (SUS302, SUS304, SUS316, etc.), nickel-titanium alloys, piano wire, nickel-chromium alloys, cobalt alloys, and tungsten. In this embodiment, the core shaft 10 includes a nickel-titanium alloy, and more specifically, is formed from a nickel-titanium alloy. In this embodiment, the entire core shaft 10 is formed from the same material. This configuration can suppress damage to the core shaft 10 due to a gap in physical properties.

[0034] The outer layer coil body 20 is a hollow cylindrical member formed by spirally winding a wire. The outer layer coil body 20 is, for example, a tightly wound coil. The outer layer coil body 20 is arranged so as to surround the outer periphery of the tip end of the core shaft 10. In the axial direction, the position of the tip 21 of the outer layer coil body 20 is approximately the same as the position of the tip end of the core shaft 10.

[0035] The inner layer coil body 30 is a hollow cylindrical member formed by spirally winding a wire. The inner layer coil body 30 is, for example, a tightly wound coil. The inner layer coil body 30 is arranged in the space between the core shaft 10 and the outer layer coil body 20 so as to surround the outer periphery of the tip end of the core shaft 10. In the axial direction, the position of the tip end 31 of the inner layer coil body 30 is approximately the same as the position of the tip end of the core shaft 10, and the position of the base end 32 of the inner layer coil body 30 is further tip-side than the position of the base end 22 of the outer layer coil body 20.

[0036] The outer diameter and inner diameter of the outer layer coil body 20 and the inner layer coil body 30 may be constant along the axial direction, or may vary along the axial direction.

[0037] Examples of materials for forming the outer layer coil body 20 and the inner layer coil body 30 include metal materials, more specifically, radiolucent alloys such as stainless steel (SUS302, SUS304, SUS316, etc.), nickel-titanium alloys, piano wire, nickel-chromium alloys, or cobalt alloys, and radiopaque alloys such as gold, platinum, tungsten, or alloys containing these elements (e.g., platinum-nickel alloys).

[0038] The distal joint 40 joins the distal end of the core shaft 10 to the distal ends of the outer layer coil body 20 and the inner layer coil body 30. The distal outer peripheral surface of the distal joint 40 is smooth (e.g., approximately hemispherical). The first proximal joint 53 joins the core shaft 10 to the proximal end of the outer layer coil body 20. The second proximal joint 54 joins the core shaft 10 to the proximal end of the inner layer coil body 30. The first intermediate joint 51 joins the core shaft 10 to the intermediate portion of the outer layer coil body 20 (a portion excluding the distal and proximal ends; the same applies below) and the intermediate portion of the inner layer coil body 30. The second intermediate joint 52 is located closer to the proximal end than the first intermediate joint 51 and joins the core shaft 10 to the intermediate portion of the outer layer coil body 20. Examples of materials for forming these joints 40, 51, 52, 53, and 54 include metal solders such as silver solder, gold solder, zinc, Sn--Ag alloy, and Au--Sn alloy, and adhesives such as epoxy adhesives.

[0039] The coating 60 covers the outer peripheral surfaces of the distal joint 40 and the outer coil body 20 from the distal end of the distal joint 40 to the proximal end 22 of the outer coil body 20. Examples of materials for forming the coating 60 include hydrophilic coating materials such as polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, polyvinyl alcohol, maleic anhydride copolymer, and hyaluronic acid.

[0040] (Characteristics of the average crystal grain size of the nickel-titanium alloy contained in the core shaft 10) The guide wire 100 has a first region R1 and a second region R2 located closer to the base end than the first region R1. The first region R1 is a region along the axial direction, for example, from the tip of the core shaft 10 to the middle of the third portion 13. The first region R1 is a region that has been heat treated. The second region R2 is a region that has not been heat treated. The base end of the first region R1 is adjacent to the tip of the second region R2. The length of the second region R2 is predetermined taking into account the length over which the doctor will perform shaping. Along the axial direction, the length of the first region R1 is, for example, 12 mm. The length of the second region R2 is, for example, 5 mm.

[0041] As described above, the core shaft 10 contains a nickel-titanium alloy. The average crystal grain size D of the nickel-titanium alloy contained in the core shaft 10 ａｖｅ is different between the first region R1 and the second region R2 of the guide wire 100. Specifically, the average crystal grain size D ａｖｅ is the average crystal grain size D of the nickel-titanium alloy in the first region R1 ａｖｅ The average crystal grain size D of the nickel-titanium alloy in the first region R1 is smaller than ａｖｅ The average crystal grain size D of the nickel-titanium alloy in the second region R2 is, for example, 0.05 μm or more and 2.5 μm or less. ａｖｅ The average crystal grain size D of the nickel-titanium alloy in the second region R2 is, for example, 0.01 μm or more and 0.05 μm or less. ａｖｅ The average crystal grain size D of the nickel-titanium alloy in the first region R1 is preferably 0.02 μm or more and 0.048 μm or less. ａｖｅ is the average crystal grain size D of the nickel-titanium alloy in the second region R2 ａｖｅ The larger value (first value) is an example of the first characteristic, and the average crystal grain size D of the nickel-titanium alloy in the second region R2 is ａｖｅ is the average crystal grain size D of the nickel-titanium alloy in the first region R1 ａｖｅ The smaller value (second value) is an example of the second characteristic.

[0042] The first region R1 of the guidewire 100 has a distal first region R1d and a proximal first region R1p located proximal to the distal first region R1d. The distal first region R1d is, for example, a region extending from the distal end of the core shaft 10 to the proximal end of the first portion 11 along the axial direction. The proximal first region R1p is, for example, a region extending from the proximal end of the distal first region R1d to the intermediate portion of the third portion 13 along the axial direction. The distal first region R1d has a length of, for example, 4 mm, and the proximal first region R1p has a length of, for example, 8 mm along the axial direction.

[0043] Average crystal grain size D of the nickel-titanium alloy in the tip-side first region R1d ａｖｅis the average crystal grain size D of the nickel-titanium alloy in the base end side first region R1p ａｖｅ The average crystal grain size D of the nickel-titanium alloy in the front-end first region R1d is larger than ａｖｅ The average crystal grain size D of the nickel-titanium alloy in the tip-side first region R1d is, for example, 1.0 μm or more and 2.5 μm or less. ａｖｅ is preferably 1.5 μm or more and 2.3 μm or less. ａｖｅ is, for example, 0.05 μm or more and 0.1 μm or less.

[0044] The average crystal grain size D of the nickel-titanium alloy contained in the core shaft 10 in each region of the guide wire 100 ａｖｅ is specified as follows: ａｖｅ FIG.

[0045] First, the vicinity of the surface of the core shaft 10 to be measured is cut out as an observation sample. This vicinity of the surface is the portion that has been heat-treated in the first region R1. The cut-out observation sample is processed using an FIB (focused ion beam processing and observation device, such as the FB2000 manufactured by Hitachi High-Technologies Corporation), and the sample is observed using a TEM (transmission electron microscope, such as the JEM-2100F manufactured by JEOL Ltd.) to obtain a TEM image IM.

[0046] Next, in the TEM image IM, the radius r ０ , area S ０ (For example, ０ A test circle TC of 75 nm (or 75 nm) is set, and the number of crystal grains CP (number of equivalent crystals N) contained within the test circle TC is counted. Specifically, the number of crystal grains CP (for example, crystal grain CP1) whose entirety is contained within the test circle TC is counted as N. １ The number of grains (for example, grain CP2 in FIG. 2) intersecting the test circle TC is N ２ Then, the number of equivalent crystal grains N is calculated by the following formula (1): Number of crystal grains per unit area N ０ and the average grain area S ａｖｅ are calculated by the following formulas (2) and (3), respectively.ａｖｅ is calculated by the following formula (4).

[0047] (Characteristics Regarding Bending Angle θ) The first region R1 of the guidewire 100 is more susceptible to bending during shaping than the second region R2. That is, with regard to the bending angle θ, which is an index value representing the susceptibility to bending during shaping (described later), the bending angle θ in the first region R1 is greater than the bending angle θ in the second region R2. The bending angle θ in the first region R1 is, for example, 10 degrees or greater and 100 degrees or less. The bending angle θ in the second region R2 is, for example, 0 degrees or greater and 20 degrees or less. The bending angle θ in the first region R1 being a value (first angle) greater than the bending angle θ in the second region R2 is an example of a first characteristic, and the bending angle θ in the second region R2 being a value (second angle) smaller than the bending angle θ in the first region R1 is an example of a second characteristic.

[0048] The bending angle θ in the distal first region R1d of the guidewire 100 is larger than the bending angle θ in the proximal first region R1p. The bending angle θ in the distal first region R1d is, for example, 40 degrees or more and 100 degrees or less. The bending angle θ in the proximal first region R1p is, for example, 10 degrees or more and 40 degrees or less.

[0049] The value obtained by dividing the bending angle θ in the distal first region R1d by the bending angle θ in the second region R2 is equal to or greater than 5 and equal to or less than 10. The value obtained by dividing the bending angle θ in the distal first region R1d by the bending angle θ in the proximal first region R1p is equal to or greater than 1 and equal to or less than 6.

[0050] The curvature angle θ in each region of the guidewire 100 is determined as follows. Fig. 3 is an explanatory diagram showing a method for determining the curvature angle θ. Fig. 3 shows a measuring device 200 for the curvature angle θ. The measuring device 200 has a base 211, a flat plate 213 placed on the base 211 and having a flat surface 212 on its upper surface, a pin 215 supported on a support column 214 erected on the base 211 so as to be slidable in the vertical direction, and a clamp mechanism 217 supported on a support rod 216 erected on the base 211 so as to be slidable in the vertical direction.

[0051] The guidewire 100 to be measured is set in the measuring device 200. Specifically, a position a predetermined distance (approximately 250 mm to 300 mm) from the tip of the guidewire 100 is fixed to the clamping mechanism 217, and the guidewire 100 extends downward from the position fixed to the clamping mechanism 217, abuts against the flat surface 212, and then extends horizontally on the flat surface 212 from that position. A portion of the guidewire 100 that abuts against the flat surface 212 is pressed toward the flat surface 212 by the pin 215, and a weight 218 is placed on the pin 215, thereby applying a load of 1 N to the guidewire 100 toward the flat surface 212 via the pin 215. In this state, the clamping mechanism 217 is moved upward along the support rod 216, and the guidewire 100 is pulled out perpendicular to the flat surface 212. The pulling distance is approximately 2 mm. For example, when measuring the bending angle θ of the distal first region R1d, the bending angle θ is measured by pulling out the central portion of the distal first region R1d. This imparts a curved shape to the pulled-out portion of the guidewire 100. The bending angle at the distal end of the guidewire 100 at this time is measured as the bending angle θ. To measure the bending angle θ, as shown in FIG. 4 , tangent lines TL1 and TL2 are drawn to the distal portion 110 and the proximal portion 120 of the pulled-out portion, respectively, and the angle at which the tangent lines intersect is determined.

[0052] (Manufacturing Method of Guidewire 100) For example, by subjecting the portion of the core shaft 10 located in the first region R1 to heat treatment while not subjecting the portion located in the second region R2 to heat treatment, the average crystal grain size D of the nickel-titanium alloy described above can be reduced between the first region R1 and the second region R2. ａｖｅ It is possible to manufacture guide wires 100 having different curvature angles θ. It is believed that the heat treatment causes the crystal grains of the nickel-titanium alloy contained in the core shaft 10 to become coarse, making the core shaft more susceptible to deformation and increasing the curvature angle θ.

[0053] In addition, for example, by setting the temperature of the heat treatment for the portion of the core shaft 10 located in the tip side first region R1d to be higher than the temperature of the heat treatment for the portion located in the base side first region R1p, the average crystal grain size D of the nickel-titanium alloy described above can be reduced between the tip side first region R1d and the base side first region R1p. ａｖｅ It is possible to manufacture guide wires 100 having different lengths and bending angles θ. It is believed that by performing heat treatment at a higher temperature, the crystal grains of the nickel-titanium alloy contained in the core shaft 10 become coarser, making it easier for the core shaft 10 to become bent, resulting in a larger bending angle.

[0054] (Effects of this embodiment) As described above, the guidewire 100 of this embodiment has a first region R1 and a second region R2 located closer to the proximal end than the first region R1. The guidewire 100 includes a core shaft 10. The core shaft 10 is located in the first region R1 and the second region R2 and contains a nickel-titanium alloy. The average crystal grain size D of the nickel-titanium alloy contained in the core shaft 10 in the first region R1 ａｖｅ is the average crystal grain size D of the nickel-titanium alloy contained in the core shaft 10 in the second region R2 ａｖｅTherefore, according to the guidewire 100 of this embodiment, it is possible to differentiate the characteristics of the first region R1 and the second region R2 as desired. For example, the bending angle θ of the first region R1 of the guidewire 100 can be made larger than the bending angle θ of the second region R2. As a result, it is possible to achieve shaping in which the bending angle θ of the first region R1 of the guidewire is made larger than the bending angle θ of the second region R2, thereby improving selectivity for small branched blood vessels such as peripheral blood vessels.

[0055] In general, in guidewires, the outer diameter of the core shaft may be tapered toward the tip to reduce tip load, or the outer diameter of the coil body may be tapered toward the tip to improve penetration. In such cases, the bending strain is reduced due to the reduction in metal thickness, resulting in a shaped shape with a smaller curvature and bending angle toward the tip of the guidewire. Even if the outer diameters of the core shaft and coil body are made uniform, this merely results in a shaped shape with a uniform curvature and bending angle. Therefore, conventional guidewires often have a shaped shape with a smaller curvature and bending angle toward the tip or a uniform curvature and bending angle. In the guidewire 100 of this embodiment, as described above, the bending angle θ of the first region R1 of the guidewire 100 can be made larger than the bending angle θ of the second region R2. Therefore, the selectivity of the guidewire 100 to small branched blood vessels, such as peripheral blood vessels, can be improved.

[0056] In the guidewire 100 of this embodiment, the first region R1 includes a distal first region R1d and a proximal first region R1p located closer to the proximal end than the distal first region R1d. ａｖｅ is the average crystal grain size D of the nickel-titanium alloy in the base end side first region R1p ａｖｅTherefore, according to the guidewire 100 of this embodiment, it is possible to differentiate the characteristics of the distal first region R1d and the proximal first region R1p as desired. More specifically, the bending angle θ of the distal first region R1d of the guidewire 100 can be made larger than the bending angle θ of the proximal first region R1p. As a result, it is possible to effectively improve the selectivity of fine branched blood vessels such as peripheral blood vessels.

[0057] (Example) An operator created multiple samples of the guide wire 100 according to the above-described embodiment. Specifically, regarding the heat treatment of the core shaft 10 used to create the guide wire 100, the core shaft 10 was heat-treated in the first region R1. The core shaft 10 was not heat-treated in the second region R2. For the five samples (SA1 to SA5) created in this manner, the average crystal grain size D of the nickel-titanium alloy contained in the core shaft 10 was measured. ａｖｅ were measured. The measurement results are shown in Table 1. In this example, the distal first region R1d is a region extending from the distal end of the core shaft 10 to a position 4 mm toward the proximal end, the proximal first region R1p is a region extending from the proximal end of the distal first region R1d to a position 8 mm toward the proximal end, and the second region R2 is a region extending from the proximal end of the proximal first region R1p to a position 5 mm toward the proximal end. Furthermore, measurement of the distal first region R1d was not performed for sample SA4, and measurement of the first region R1 was not performed for sample SA5.

[0058]

[0059] As shown in Table 1, in all samples measured, the average crystal grain size D of the nickel-titanium alloy in the second region R2 ａｖｅ is the average crystal grain size D of the nickel-titanium alloy in the first region R1 ａｖｅ The average crystal grain size D of the nickel-titanium alloy in the first region R1 was smaller than that ａｖｅ The average crystal grain size D of the nickel-titanium alloy in the second region R2 was 0.05 μm or more and 2.5 μm or less. ａｖｅ The average crystal grain size D of the nickel-titanium alloy in the second region R2 was 0.01 μm or more and 0.05 μm or less. ａｖｅMore specifically, the thickness was 0.02 μm or more and 0.048 μm or less.

[0060] In addition, in all samples for which measurements were performed, the average crystal grain size D of the nickel-titanium alloy in the front-end first region R1d was ａｖｅ is the average crystal grain size D of the nickel-titanium alloy in the base end side first region R1p ａｖｅ The average crystal grain size D of the nickel-titanium alloy in the tip-side first region R1d was larger than ａｖｅ The average crystal grain size D of the nickel-titanium alloy in the tip-side first region R1d was 1.0 μm or more and 2.5 μm or less. ａｖｅ More specifically, the average crystal grain size D of the nickel-titanium alloy in the base-side first region R1p was 1.5 μm or more and 2.3 μm or less. ａｖｅ was 0.05 μm or more and 0.1 μm or less.

[0061] The bending angle θ was also measured for four other samples (SA11 to SA14). The measurement results are shown in Table 2. While samples SA11 to SA13 were produced according to the manufacturing method of the above-described embodiment, sample SA14 (comparative example) was not subjected to heat treatment in either the first region R1 or the second region R2 of the core shaft 10 used to produce the guide wire 100.

[0062]

[0063] As shown in Table 2, in samples SA11 to SA13 (Examples), the curvature angle θ in the first region R1 was larger than the curvature angle θ in the second region R2. The curvature angle θ in the first region R1 was 10 degrees or more and 100 degrees or less. The curvature angle θ in the second region R2 was 0 degrees or more and 20 degrees or less. On the other hand, in sample SA14 (Comparative Example), the curvature angle θ in the first region R1 was smaller than the curvature angle θ in the second region R2.

[0064] Furthermore, in samples SA11 to SA13 (examples), the bending angle θ in the distal first region R1d was larger than the bending angle θ in the proximal first region R1p. The bending angle θ in the distal first region R1d was 40 degrees or more and 100 degrees or less. The bending angle θ in the proximal first region R1p was 10 degrees or more and 40 degrees or less. On the other hand, in sample SA14 (comparison example), the bending angle θ in the distal first region R1d was smaller than the bending angle θ in the proximal first region R1p.

[0065] In addition, in samples SA11 to SA13 (examples), the value obtained by dividing the curvature angle θ in the distal first region R1d by the curvature angle θ in the second region R2 was 5 or more and 10 or less, and the value obtained by dividing the curvature angle θ in the distal first region R1d by the curvature angle θ in the proximal first region R1p was 1 or more and 6 or less.

[0066] The ease of blood vessel selection was evaluated for the above samples using a blood vessel model that mimics peripheral blood vessels. As a result, the ease of blood vessel selection was good for samples SA11 to SA13 (Examples). As a result of the evaluation, the ease of blood vessel selection for sample SA14 was at the same level as the conventional product.

[0067] B. Modifications: The technology disclosed in this specification is not limited to the above-described embodiment, and can be modified in various forms without departing from the spirit of the invention. For example, the following modifications are also possible.

[0068] The configuration of the guidewire 100 in the above embodiment is merely an example, and various modifications are possible. Figures 5 and 6 are explanatory diagrams showing the configurations of modified guidewires 100 (guidewires 100a to 100f).

[0069] The guidewire 100a of the first modified example shown in section A of Figure 5 has the same characteristic as the guidewire 100 of the above embodiment, in that the bending angle θ in the first region R1 is greater than the bending angle θ in the second region R2. However, the guidewire 100a of the first modified example achieves this characteristic by adopting a configuration in which the tendency of the coil body to become twisted increases toward the distal end, regardless of the configuration of the core shaft 10. More specifically, the tendency of the inner layer coil body 30 to become twisted in the distal first region R1d is greater than the tendency of the inner layer coil body 30 in the proximal first region R1p. As a result, the bending angle θ in the distal first region R1d is greater than the bending angle θ in the proximal first region R1p. Furthermore, no inner layer coil body 30 is disposed in the second region R2. As a result, the bending angle θ in the first region R1 is greater than the bending angle θ in the second region R2. The tendency of the coil body to become bent can be adjusted, for example, by changing the temperature at which the coil body is heat treated or by changing the diameter of the wire that makes up the coil body.

[0070] A guidewire 100b of a second modified example shown in section B of Figure 5 employs an inner layer coil body 30a that is prone to becoming twisted. Furthermore, a second inner layer coil body 30b that is less prone to becoming twisted is disposed inside the inner layer coil body 30a. The proximal end of the second inner layer coil body 30b is located at the proximal end of the proximal first region R1p, and the distal end of the second inner layer coil body 30b is located at the distal end of the proximal first region R1p. By employing this configuration, the bending angle θ of the first region R1 is greater than the bending angle θ of the second region R2, and the bending angle θ of the distal first region R1d is greater than the bending angle θ of the proximal first region R1p.

[0071] The guidewire 100c of the third modified example shown in section C of Figure 5 employs an inner layer coil body 30a that is prone to becoming twisted, similar to the guidewire 100b of the second modified example. Furthermore, a third inner layer coil body 30c that is prone to becoming twisted is disposed inside the inner layer coil body 30a. The distal end of the third inner layer coil body 30c is located at the distal end of the first region R1, and the proximal end of the third inner layer coil body 30c is located at the proximal end of the distal first region R1d. By employing this configuration, the bending angle θ of the first region R1 is greater than the bending angle θ of the second region R2, and the bending angle θ of the distal first region R1d is greater than the bending angle θ of the proximal first region R1p.

[0072] In addition, by imparting a uniform tendency to bend to the core shaft 10 and adopting a configuration in which the reaction force of the coil body becomes smaller toward the tip, it is possible to achieve a characteristic in which the bending angle θ of the first region R1 is greater than the bending angle θ of the second region R2.

[0073] A guidewire 100d of a fourth modified example shown in section A of Figure 6 imparts uniform curlability to the core shaft 10 and employs a configuration in which the reaction force of the coil body decreases toward the distal end. Specifically, the distal end of the inner layer coil body 33 is located at the distal end of the proximal first region R1p. Furthermore, the reaction force of the inner layer coil body 33 in the proximal first region R1p is smaller than the reaction force of the inner layer coil body 33 in the second region R2. By employing this configuration, the bending angle θ of the first region R1 is greater than the bending angle θ of the second region R2, and the bending angle θ of the distal first region R1d is greater than the bending angle θ of the proximal first region R1p. In the guidewire 100d of the fourth modified example, the distal portion of the core shaft 10 is formed separately from the other portions and is composed of a ribbon body 18 fixed to the distal ends of the other portions. The ribbon body 18 may be made of a material (e.g., stainless steel) different from the material (e.g., nickel-titanium alloy) used to form the other portions of the core shaft 10. This also applies to the following fifth modified example.

[0074] The guidewire 100e of the fifth modified example shown in section B of Figure 6, like the guidewire 100d of the fourth modified example, imparts uniform curlability to the core shaft 10 and employs a configuration in which the reaction force of the coil body decreases toward the distal end. Specifically, the distal end of the inner layer coil body 34 is located at the distal end of the second region R2. Furthermore, a fourth inner layer coil body 34e, which has a smaller outer diameter than the inner layer coil body 34, is disposed in the first region R1. The reaction force of the fourth inner layer coil body 34e in the distal first region R1d is smaller than the reaction force of the fourth inner layer coil body 34e in the proximal first region R1p. Furthermore, the reaction force of the fourth inner layer coil body 34e is smaller than the reaction force of the inner layer coil body 34. By adopting such a configuration, the bending angle θ of the first region R1 becomes larger than the bending angle θ of the second region R2, and the bending angle θ of the distal first region R1d becomes larger than the bending angle θ of the proximal first region R1p.

[0075] A guidewire 100f according to a sixth modification shown in section C of Fig. 6 imparts uniform curlability to the inner layer coil body 35 and employs a configuration in which the reaction force of the core shaft 10 decreases toward the distal end. Specifically, the distal portion of the core shaft 10 has a tapered shape that increases in diameter toward the proximal end. Therefore, the outer diameter of the core shaft 10 in the proximal first region R1p is smaller than the outer diameter of the core shaft 10 in the second region R2, and the outer diameter of the core shaft 10 in the distal first region R1d is smaller than the outer diameter of the core shaft 10 in the proximal first region R1p. By employing such a configuration, the bending angle θ of the first region R1 is larger than the bending angle θ of the second region R2, and the bending angle θ of the distal first region R1d is larger than the bending angle θ of the proximal first region R1p.

[0076] In the above embodiment, the average crystal grain size D of the nickel-titanium alloy contained in the core shaft 10 in each region of the guide wire 100 ａｖｅ The numerical ranges and magnitude relationships are merely examples and can be changed in various ways.

[0077] In the above embodiment, the numerical ranges and magnitude relationships of the bending angle θ in each region of the guidewire 100 are merely examples and can be variously changed.

[0078] In the above embodiment, the characteristics imparted to each region (first region R1 and second region R2) of the guidewire 100 are merely examples, and other characteristics may be imparted.

[0079] The technology disclosed in this specification is applicable not only to the guidewire 100 but also to percutaneous medical devices in general, including dilators. Furthermore, the technology disclosed in this specification is applicable not only to percutaneous medical devices but also to medical devices in general.

Claims

1. A medical device (100) having a first region (R1) having a first characteristic; and a second region (R2) located proximal to the first region (R1) and having a second characteristic.

2. A medical device (100) as described in claim 1, comprising a specific component (10) located in the first region (R1) and the second region (R2) and containing a nickel-titanium alloy, wherein the first characteristic includes an average crystal grain size of the nickel-titanium alloy being a first size, and the second characteristic includes an average crystal grain size of the nickel-titanium alloy being a second size smaller than the first size.

3. A medical device (100) according to claim 2, wherein the first dimension is greater than or equal to 0.05 μm and less than or equal to 2.5 μm.

4. A medical device (100) according to claim 2 or 3, wherein the second size is greater than or equal to 0.01 μm and less than or equal to 0.050 μm.

5. A medical device (100) according to any one of claims 2 to 4, wherein the second dimension is greater than or equal to 0.02 μm and less than or equal to 0.048 μm.

6. A medical device (100) as described in any one of claims 2 to 5, wherein the first region (R1) has a distal first region (R1d) and a proximal first region (R1p) located proximal to the distal first region (R1d), and the average crystal grain size of the nickel-titanium alloy in the distal first region (R1d) is larger than the average crystal grain size of the nickel-titanium alloy in the proximal first region (R1p).

7. A medical device (100) according to claim 6, wherein the average crystal grain size of the nickel-titanium alloy in the distal first region (R1d) is 1.0 μm or more and 2.5 μm or less.

8. A medical device (100) as described in claim 6 or 7, wherein the average crystal grain size of the nickel-titanium alloy in the distal first region (R1d) is 1.5 μm or more and 2.3 μm or less.

9. A medical device (100) as described in any one of claims 6 to 8, wherein the average crystal grain size of the nickel-titanium alloy in the base end first region (R1p) is 0.05 μm or more and 0.1 μm or less.

10. A medical device (100) according to any one of claims 2 to 9, wherein the specific member (10) is a core shaft (10).

11. A medical device (100) as claimed in any one of claims 1 to 10, wherein the medical device (100) is pressed against a plane (212) by a pin (215), a load of 1 N is applied toward the plane (212) via the pin (215), and the medical device (100) is pulled out in a direction perpendicular to the plane (212) to impart a curved shape to the pulled-out portion, with respect to a bending angle of the medical device (100), wherein the first characteristic includes that the bending angle is a first angle, and the second characteristic includes that the bending angle is a second angle smaller than the first angle.

12. The medical device (100) of claim 11, wherein the first angle is greater than or equal to 10 degrees and less than or equal to 100 degrees.

13. The medical device (100) according to claim 11 or 12, wherein the second angle is greater than or equal to 0 degrees and less than or equal to 20 degrees.

14. A medical device (100) as claimed in any one of claims 11 to 13, wherein the first region (R1) has a distal first region (R1d) and a proximal first region (R1p) located proximal to the distal first region (R1d), and the curvature angle in the distal first region (R1d) is greater than the curvature angle in the proximal first region (R1p).

15. A medical device (100) according to claim 14, wherein the curvature angle in the distal first region (R1d) is greater than or equal to 40 degrees and less than or equal to 100 degrees.

16. A medical device (100) according to claim 14 or 15, wherein the curvature angle in the base end first region (R1p) is greater than or equal to 10 degrees and less than or equal to 40 degrees.

17. A medical device (100) as described in any one of claims 14 to 16, wherein the value obtained by dividing the curvature angle in the distal first region (R1d) by the curvature angle in the second region (R2) is 5 or more and 10 or less.

18. A medical device (100) as described in any one of claims 14 to 17, wherein a value obtained by dividing the curvature angle in the distal first region (R1d) by the curvature angle in the proximal first region (R1p) is greater than or equal to 1 and less than or equal to 6.

19. A medical device (100) according to any one of claims 11 to 18, comprising a core shaft (10) located in the first region (R1) and the second region (R2) and formed from the same material.

Images