Guidewires

Abstract

To provide penetration performance in an appropriate range in which even a relatively hard affected part can be reliably penetrated while avoiding hurting a body cavity in a guide wire.SOLUTION: A guide wire includes a core shaft, a coil body covering the core shaft, and an end side bond part bonding an end of the coil body and an end of the core shaft. The end side bond part has: an outer diameter reduction part in a nearly truncated conical shape whose outer diameter becomes smaller as it goes in an end direction; and a nearly spherical endmost part which is provided at the end of the outer diameter reduction part and whose outer diameter becomes smaller as it goes in the end direction. Height r1 of the endmost part, outer diameter r2 of a bottom surface of the endmost part, and height r3 of the outer diameter reduction part satisfy the following equations (1) and (2). 0.33<r1 / r2<0.63 ...(1) 2.5<r3 / r2<3.8 ...(2).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed herein relates to a guidewire for guiding a medical device to a target location within a body cavity. [Background technology]

[0002] Methods using catheters are widely used to treat or examine stenosis or occlusion in blood vessels (hereinafter referred to as "lesions"). Generally, a guidewire is used to guide the catheter to the lesion in the blood vessel. The guidewire includes a core shaft, a coil body covering the core shaft, and a distal joint that joins the tip of the coil body to the tip of the core shaft.

[0003] For example, there are guidewires intended to penetrate relatively hard lesions such as those called chronic total occlusions (CTOs), and such guidewires are required to have high penetration performance to reliably penetrate the lesion. In order to impart high penetration performance to guidewires, there are known guidewires in which the distal end of the coil body is tapered and the distal joint is also tapered (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 6,669,652 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, a guidewire intended to penetrate a hard lesion is required to have high penetration performance. On the other hand, if the penetration performance of the guidewire is too high, there is a high risk of accidentally damaging a blood vessel. Therefore, a guidewire is required to have an appropriate range of penetration performance so that it can reliably penetrate even a relatively hard lesion while avoiding damaging the blood vessel. To date, no guidewire has been proposed that has such an appropriate range of penetration performance.

[0006] This specification discloses a technique that can solve the above-mentioned problems. [Means for solving the problem]

[0007] The technology disclosed in this specification can be realized, for example, in the following forms.

[0008] The guidewire disclosed herein includes a core shaft, a coil body covering the core shaft, and a distal joint portion joining the distal end of the coil body to the distal end of the core shaft. The distal joint portion has a generally truncated cone-shaped reduced outer diameter portion whose outer diameter decreases distally, and a generally truncated spherical tip portion provided at the distal end of the reduced outer diameter portion whose outer diameter decreases distally. The height r1 of the distal-most portion, the outer diameter r2 of the bottom surface of the distal-most portion, and the height r3 of the reduced outer diameter portion satisfy the following formulas (1) and (2): 0.33 <r1 / r2<0.63 ···(1) 2.5 <r3 / r2<3.8 ···(2)

[0009] This guidewire can achieve an appropriate range of penetration performance, such that it can reliably penetrate even relatively hard lesions while avoiding damage to the body cavity.

[0010] The techniques disclosed in this specification can be realized in various forms, for example, in the form of a guidewire or a manufacturing method thereof. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is an explanatory diagram illustrating a schematic configuration of a guide wire according to an embodiment of the present invention. [Figure 2] An explanatory diagram showing the detailed configuration of the distal joint portion of the guide wire shown in Figure 1. [Figure 3] An explanatory diagram showing the method for evaluating the penetration performance of a guidewire [Figure 4] Graph showing the results of measuring the load on the membrane when a guidewire is inserted [Figure 5] Graph showing measurement results under conditions different from those used to obtain the results in Figure 4. [Figure 6] Graph showing the measurement results under the same conditions as those used to obtain the results in Figure 4. [Figure 7] Graph showing the measurement results under the same conditions as those used to obtain the results in Figure 5. [Figure 8] A graph showing the suitability of the load applied to the membrane for each combination of the most distal portion ratio R1 and the outer diameter reduction portion ratio R2. DETAILED DESCRIPTION OF THE INVENTION

[0012] A. Implementation: A-1. Guidewire configuration: FIG. 1 is an explanatory diagram schematically illustrating the configuration of a guidewire according to this embodiment. FIG. 1 shows a longitudinal cross section (YZ cross section) of a guidewire 100. The positive Z-axis direction is the distal end (distal side) that is inserted into the body, and the negative Z-axis direction is the proximal end (proximal side) that is manipulated by a surgeon such as a doctor. A portion of the guidewire 100 is not shown in FIG. 1 . This also applies to the subsequent figures. In this specification, with respect to the guidewire 100 and each of its components, the distal end 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." While FIG. 1 illustrates the guidewire 100 as a whole as being linear and substantially parallel to the Z-axis direction, at least a portion of the guidewire 100 has sufficient flexibility to be bent.

[0013] The guidewire 100 is a flexible, long medical device that is inserted into a blood vessel for the main purpose of penetrating a relatively hard lesion in the blood vessel (for example, CTO). The total length of the guidewire 100 is, for example, about 1500 mm to 2000 mm.

[0014] The guidewire 100 includes a core shaft 10, a coil body 20, a distal joint 30, a proximal joint 40, an intermediate joint 50, and a coating layer 60.

[0015] The core shaft 10 is composed of a large-diameter portion 13 having a substantially constant outer diameter, a small-diameter portion 11 located distally of the large-diameter portion 13 and having a substantially constant outer diameter smaller than the outer diameter of the large-diameter portion 13, and a tapered portion 12 located between the large-diameter portion 13 and the small-diameter portion 11 and having an outer diameter that gradually decreases from the boundary with the large-diameter portion 13 toward the boundary with the small-diameter portion 11. The shape of the cross section (XY cross section) at each position of the core shaft 10 can be any shape, and is, for example, circular or flat. The outer diameter of the large-diameter portion 13 is, for example, about 0.2 to 0.8 mm, and the outer diameter of the small-diameter portion 11 is, for example, about 0.05 to 0.3 mm.

[0016] Examples of materials that can be used to form the core shaft 10 include stainless steel (SUS302, SUS304, SUS316, etc.), superelastic alloys such as Ni-Ti alloys, piano wire, etc. The core shaft 10 may be entirely made of the same material, or different portions may be made of different materials.

[0017] The coil body 20 is a coil-shaped member formed into a hollow cylinder by tightly winding a single wire in a spiral shape. The coil body 20 is disposed on the outer periphery of the core shaft 10 so as to cover the core shaft 10. In this embodiment, the coil body 20 covers the small diameter portion 11 and the tapered portion 12 of the core shaft 10.

[0018] Examples of materials that can be used to form the coil body 20 include radiolucent materials such as stainless steel (SUS302, SUS304, SUS316, etc.), superelastic alloys such as Ni-Ti alloys, and piano wire, as well as radiopaque materials such as platinum, gold, tungsten, and alloys thereof. The entire coil body 20 may be made of the same material, or different portions may be made of different materials.

[0019] The distal joint 30 is a member that joins the distal end of the coil body 20 to the distal end of the core shaft 10. That is, the distal end of the coil body 20 and the distal end of the core shaft 10 are fixedly embedded inside the distal joint 30. The proximal joint 40 is a member that joins the proximal end of the coil body 20 to the core shaft 10. The intermediate joint 50 is a member that joins a portion of the coil body 20 between the distal end and the proximal end to the core shaft 10. Examples of materials that can be used to form the distal joint 30, the proximal joint 40, and the intermediate joint 50 include metal solder (Au—Sn alloy, Sn—Ag alloy, Sn—Pb alloy, Pb—Ag alloy, etc.), brazing material (aluminum alloy brazing, silver brazing, gold brazing, etc.), adhesive (epoxy adhesive, etc.), etc. The distal joint 30, the proximal joint 40, and the intermediate joint 50 may be made of the same material or different materials. Furthermore, the distal joint 30, the proximal joint 40, and the intermediate joint 50 may be entirely made of the same material, or each part may be made of a different material.

[0020] The coating layer 60 is disposed on the surface of the distal joint 30. Examples of materials that can be used to form the coating layer 60 include hydrophobic coating materials such as silicone oil and fluororesin, and hydrophilic coating materials such as polyvinylpyrrolidone, polyacrylic acid, polyacrylamide, polyvinyl alcohol, maleic anhydride copolymer, and hyaluronic acid. Note that, in order to improve the penetration ability of the guidewire 100 into the lesion, it is preferable that the coating layer 60 be hydrophilic.

[0021] A-2. Detailed configuration of the tip-side joint 30: 2 is an explanatory diagram showing the detailed configuration of the distal end joint 30, showing an enlarged longitudinal cross section (YZ cross section). The distal end joint 30 has a fixing portion 31, an outer diameter reduced portion 32, and a most distal portion 33. The fixing portion 31 is located at the most proximal end of the distal end joint 30 and is a portion that fixes the distal end of the coil body 20 and the distal end of the core shaft 10. The outer diameter reduced portion 32 is located distal to the fixing portion 31 in the distal end joint 30 and is a generally truncated cone-shaped portion whose outer diameter decreases toward the distal end. The most distal portion 33 is located at the distal end of the outer diameter reduced portion 32 in the distal end joint 30 and is a generally indented spherical portion whose outer diameter decreases toward the distal end.

[0022] The outer diameter at the tip of the outer diameter reducing portion 32 is the same as the outer diameter at the base end of the most-distal portion 33. Therefore, the distal-side joint 30 smoothly transitions from a shape in which the outer diameter decreases linearly toward the tip at the outer diameter reducing portion 32 to a shape in which the outer diameter decreases curvedly toward the tip at the most-distal portion 33. The cross-sectional shapes (XY cross sections) of the outer diameter reducing portion 32 and the most-distal portion 33 are substantially circular.

[0023] In the guidewire 100 of this embodiment, the height r1 (dimension in the direction from the tip to the base end) of the most-distal portion 33 of the tip-side joint 30, the outer diameter r2 of the bottom surface (base end surface) of the most-distal portion 33, and the height r3 of the reduced outer diameter portion 32 satisfy the following formulas (1) and (2). The outer diameter r2 of the bottom surface of the most-distal portion 33 is the same as the outer diameter of the top surface (tip end surface) of the reduced outer diameter portion 32. The outer diameter r2 of the bottom surface of the most-distal portion 33 may be, for example, approximately 0.1 mm to 0.5 mm. 0.33 <r1 / r2<0.63 ···(1) 2.5 <r3 / r2<3.8 ···(2)

[0024] Hereinafter, "r1 / r2" in the above formula (1) will be referred to as the "most-distal portion ratio R1," and "r3 / r2" in the above formula (2) will be referred to as the "outer diameter reduced portion ratio R2." A large value of the most-distal portion ratio R1:r1 / r2 indicates that the shape of the most-distal portion 33 is sharp (that is, the surface area is small), and a large value of the outer diameter reduced portion ratio R2:r3 / r2 indicates that the shape of the outer diameter reduced portion 32 is sharp. Therefore, guidewire 100 that satisfies the above formulas (1) and (2) can be said to have a configuration in which the shape of the most-distal portion 33 is neither too blunt nor too sharp, and the shape of the outer diameter reduced portion 32 is neither too blunt nor too sharp. Because guidewire 100 has such a configuration, it has an appropriate range of penetration performance that can reliably penetrate even a relatively hard lesion while avoiding damaging a blood vessel, as will be described later.

[0025] The distal joint 30 is preferably formed from a gold-based metal solder, such as an Au—Sn alloy. Such gold-based metal solders are known to have high rigidity, and forming the distal joint 30 from a gold-based metal solder provides the distal joint 30 with appropriate rigidity. Furthermore, since the melting point of a gold-based metal solder such as an Au—Sn alloy is 400°C or less, reduction in mechanical strength of the core shaft 10 and the coil body 20 due to thermal effects can be suppressed during formation of the distal joint 30. Furthermore, gold-based metal solder such as an Au—Sn alloy has excellent radiopacity, improving the visibility of the distal joint 30 under radioscopic imaging.

[0026] A-3. Method of manufacturing guidewire 100: The guidewire 100 of this embodiment can be manufactured, for example, by the following method. First, a core shaft 10 whose shape has been processed by mechanical polishing or the like and a coil body 20 fabricated by winding a coil wire are prepared. The core shaft 10 is inserted into the hollow portion of the coil body 20, and a distal joint 30, a proximal joint 40, and an intermediate joint 50 that join the coil body 20 and the core shaft 10 are formed. Note that when forming the distal joint 30, a rough shape is adjusted using, for example, a soldering iron to form precursors of the outer diameter reduced portion 32 and the most distal portion 33. Thereafter, the surfaces of the precursors of the outer diameter reduced portion 32 and the most distal portion 33 are polished using, for example, a router, to form the outer diameter reduced portion 32 and the most distal portion 33 with shapes that satisfy the above formulas (1) and (2). For example, the guidewire 100 having the above configuration can be manufactured by the above method. [Example]

[0027] The penetration performance of guidewires was evaluated. For the evaluation, 30 types of guidewires were used, each having the same main configuration as the guidewire 100 of the present embodiment described above, but with different values ​​of the most-extreme portion ratio R1:r1 / r2 and the outer diameter reduced portion ratio R2:r3 / r2 at the distal joint 30. In each guidewire, the outer diameter r2 of the bottom surface of the most-extreme portion 33 was within the range of 0.1 mm to 0.5 mm.

[0028] Figure 3 is an explanatory diagram illustrating a method for evaluating the guidewire's penetration performance. A membrane ME (approximately 0.85 mm thick), representing a relatively hard lesion such as a CTO, was placed on a force analyzer FA, which measures the load. A guidewire GW (approximately 1.5 mm long) was inserted into the membrane ME from its tip at a constant speed. The force analyzer FA measured the load on the membrane ME when the guidewire GW penetrated to a penetration depth d of 0.1 mm and 0.6 mm. A penetration depth d of 0.1 mm indicates that the most distal portion 33 of the distal joint 30 was inserted into the membrane ME. A penetration depth d of 0.6 mm indicates that the most distal portion 33 and the reduced outer diameter portion 32 of the distal joint 30 were inserted into the membrane ME. The load at a penetration depth d of 0.1 mm indicates the ease with which the guidewire GW penetrates the lesion. That is, the smaller the load when the penetration depth d is 0.1 mm, the easier it is for the tip of the guidewire GW to penetrate into the lesion. Also, the load when the penetration depth d is 0.6 mm represents the ease with which the tip of the guidewire GW penetrates deeper into the lesion after penetrating it. That is, the smaller the load when the penetration depth d is 0.6 mm, the easier it is for the guidewire GW to penetrate deeper into the lesion after penetrating it.

[0029] Furthermore, based on a qualitative evaluation simulating clinical practice, appropriate load ranges RA(0.1) and RA(0.6) were established for penetration depths d of 0.1 mm and 0.6 mm, respectively. That is, using a simulated CTO lesion, a penetration test was conducted to penetrate the hard membrane on the surface of the simulated lesion, and a maneuverability test of the guidewire GW within the simulated lesion was conducted. Based on the physician's evaluation, appropriate load ranges RA(0.1) and RA(0.6) were established that corresponded to penetration performance that was neither too low nor too high.

[0030] Figures 4 to 7 are graphs showing the results of measurements of the load applied to the membrane ME during insertion of the guidewire GW. Figures 4 and 5 show the relationship between the most distal portion ratio R1:r1 / r2 and the load when the insertion depth d is 0.1 mm and 0.6 mm, respectively. Figures 6 and 7 show the relationship between the most distal portion ratio R1:r1 / r2 and the load when the insertion depth d is 0.1 mm and 0.6 mm, respectively. The horizontal axis represents the most distal portion ratio R1:r1 / r2 or the most distal portion ratio R2:r3 / r2, and the vertical axis represents the load. The graphs also show regression lines derived from the measurement results. The appropriate load ranges RA(0.1) and RA(0.6) are also shown. Plots within these ranges are indicated by black circles, and plots outside these ranges are indicated by black triangles.

[0031] As shown in Figures 4 and 5, at both the penetration depth d of 0.1 mm and 0.6 mm, it was confirmed that the load tended to decrease as the value of the most-extremely-proximal portion ratio R1:r1 / r2 increased. As described above, it is believed that when the most-extremely-proximal portion ratio R1:r1 / r2 increased, the shape of the most-extremely-proximal portion 33 became sharper, thereby reducing the load that the membrane ME received from the guidewire GW. Similarly, as shown in Figures 6 and 7, at both the penetration depth d of 0.1 mm and 0.6 mm, it was confirmed that the load tended to decrease as the value of the outer diameter reducing portion ratio R2:r3 / r2 increased. As described above, it is believed that when the outer diameter reducing portion ratio R2:r3 / r2 increased, the shape of the outer diameter reducing portion 32 became sharper, thereby reducing the load that the membrane ME received from the guidewire GW.

[0032] 8 is a graph showing the suitability of the load applied to the membrane ME for each combination of the most-extremely-proximal portion ratio R1 and the outer diameter reducing portion ratio R2. This graph plots the measured values ​​for each guidewire, with the most-extremely-proximal portion ratio R1:r1 / r2 on the horizontal axis and the outer diameter reducing portion ratio R2:r3 / r2 on the vertical axis. For each combination of the most-extremely-proximal portion ratio R1 and the outer diameter reducing portion ratio R2, the plots for which the load fell within the appropriate load ranges RA(0.1) and RA(0.6) at both a penetration depth d of 0.1 mm and 0.6 mm are indicated by black circles, and the plots for which the load fell outside the appropriate load range at either or both a penetration depth d of 0.1 mm and 0.6 mm are indicated by black triangles. 8, when the value of the most distal portion ratio R1:r1 / r2 was greater than 0.33 and less than 0.63 and the value of the outer diameter reduced portion ratio R2:r3 / r2 was greater than 2.5 and less than 3.8, the load fell within the appropriate range at both the penetration depth d of 0.1 mm and 0.6 mm. In other words, it can be said that the above-mentioned formulas (1) and (2) were not satisfied, the load fell within the appropriate range, and the penetration performance of the guidewire GW was within the appropriate range.

[0033] Thus, in the guide wire 100, if the height r1 of the most distal portion 33 of the tip-side joint 30, the outer diameter r2 of the bottom surface of the most distal portion 33, and the height r3 of the outer diameter reducing portion 32 satisfy the above formulas (1) and (2), an appropriate range of penetration performance can be achieved, such that the guide wire can reliably penetrate even relatively hard lesions while avoiding damage to blood vessels.

[0034] B. Variations: The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified into various forms without departing from the spirit thereof, for example, the following modifications are also possible.

[0035] The configuration of the guidewire 100 in the above embodiment is merely an example and can be modified in various ways. For example, in the above embodiment, the core shaft 10 is configured from the small diameter portion 11, the tapered portion 12, and the large diameter portion 13, but the core shaft 10 may not have at least one of these three portions, or may have other portions in addition to the three portions.

[0036] In the guidewire 100 of the above embodiment, the proximal joint portion 40 and the intermediate joint portion 50 are provided, but at least one of these may be omitted.

[0037] In the guidewire 100 of the above embodiment, the coating layer 60 covers the surface of the distal joint 30, but the coating layer 60 may also cover the surfaces of the coil body 20 and the core shaft 10. Also, the coating layer 60 may be omitted.

[0038] In the above embodiment, the coil body 20 covers the small diameter portion 11 and the tapered portion 12 of the core shaft 10, but the portion of the core shaft 10 that is covered by the coil body 20 can be changed as desired. For example, the coil body 20 may cover only the small diameter portion 11 of the core shaft 10, or the coil body 20 may cover not only the small diameter portion 11 and the tapered portion 12 of the core shaft 10 but also part or all of the large diameter portion 13.

[0039] In the above embodiment, the coil body 20 is configured to be formed into a hollow cylindrical shape by tightly winding a single wire. However, the coil body 20 may also be configured to be formed into a hollow cylindrical shape by loosely winding a single wire, or by spirally winding multiple wires. Furthermore, the coil body 20 may be configured to be formed into a hollow cylindrical shape by spirally winding a single stranded wire formed by twisting multiple wires, or by spirally winding multiple stranded wires formed by twisting multiple wires.

[0040] The materials of the components in the above-described embodiment are merely examples and can be modified in various ways. Furthermore, the manufacturing method of the guidewire in the above-described embodiment is merely an example and can be modified in various ways. For example, in the above-described embodiment, the outer diameter reduced portion 32 and the most-extremely-proximal portion 33 in the distal joint portion 30 are integrally formed. However, after the outer diameter reduced portion 32 is formed, a precursor of the most-extremely-proximal portion 33 may be formed at the tip of the outer diameter reduced portion 32 using metal solder or the like, and the most-extremely-proximal portion 33 may be formed by polishing the precursor. Furthermore, in the above-described embodiment, the outer diameter reduced portion 32 and the most-extremely-proximal portion 33 having a predetermined shape are formed by polishing. However, the outer diameter reduced portion 32 and the most-extremely-proximal portion 33 may also be formed by other known methods (e.g., casting).

[0041] In the above embodiment, a guidewire for guiding a catheter to a target location within a blood vessel has been used as an example, but the technology disclosed in this specification is similarly applicable to a guidewire for guiding a medical device to a target location within a body cavity (blood vessel, digestive tract, urinary tract, etc.). [Explanation of symbols]

[0042] 10: Core shaft 11: Thin section 12: Tapered section 13: Large diameter part 20: Coil body 30: Distal joint 31: Fixed part 32: Reduced outer diameter part 33: Cutting edge section 40: Proximal junction 50: Middle joint 60: Coat layer 100: Guidewire FA: Force analyzer GW: Guidewire ME: membrane

Claims

1. A guidewire comprising: A core shaft; A coil body covering the core shaft; a tip-side joint portion that joins a tip of the coil body and a tip of the core shaft, The tip side joint portion is an outer diameter reducing portion having a generally truncated cone shape in which the outer diameter decreases toward the tip; a tip end portion having a generally spherical shape, the tip end portion being provided at a tip end of the outer diameter reducing portion and having an outer diameter that decreases toward the tip end; having a height r1 of the most-end portion, an outer diameter r2 of a bottom surface of the most-end portion, and a height r3 of the outer diameter reduced portion satisfy the following formulas (1) and (2): 0.33<r1 / r2<0.63...(1) 2.5<r3 / r2<3.8...(2)

2. The guidewire according to claim 1, further comprising: The guidewire further comprises a coating layer covering the distal joint.

3. A guidewire as described in claim 2, The coating layer and the tip-side joint portion cooperate to completely surround the tip of the coil body and the tip of the core shaft.

4. A guidewire according to any one of claims 1 to 3, The tip of the coil body and the tip of the core shaft are embedded in the tip side joint portion.

5. A guidewire according to any one of claims 1 to 4, The core shaft includes: a first portion having a substantially constant first outer diameter; a second portion located distally of the first portion and having a substantially constant second outer diameter smaller than the first outer diameter; a third portion located between the first portion and the second portion, the third portion having an outer diameter gradually decreasing from a boundary position with the first portion toward a boundary position with the second portion; A guidewire comprising:

6. The guidewire according to claim 5, further comprising: The guidewire comprises a proximal joint portion that joins a proximal end of the coil body and the first portion.

7. A guidewire as claimed in claim 6, The proximal bond is located on the first portion adjacent the third portion of the guidewire.

8. A guidewire according to any one of claims 5 to 7, further comprising: The guidewire further comprises an intermediate joint that joins the second portion and a portion of the coil body between the distal end and the proximal end.

9. A guidewire according to any one of claims 1 to 5, further comprising: The guidewire comprises a proximal joint portion that joins a proximal end of the coil body and the core shaft.

10. A guidewire according to any one of claims 1 to 7, further comprising: The guidewire comprises an intermediate joint that joins the core shaft and a portion of the coil body between the distal end and the proximal end.

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