Shaft for medical device and medical device

Abstract

In a cross-section orthogonal to the axial direction, if the diameter for which the length is the smallest is the smallest diameter, the diameter in the cross-section in the direction orthogonal to the direction of the smallest diameter is the orthogonal diameter, and the flatness ratio is the value obtained by dividing the difference between the orthogonal diameter and the smallest diameter by the orthogonal diameter, the medical device shaft has a specific portion in which the flatness ratio is 2-6%.

Description

Technical Field

[0001] The technology disclosed in this specification relates to a shaft for medical devices and medical devices. Background Technology

[0002] For example, catheters are widely used to treat or examine narrowed or occluded sections of blood vessels (hereinafter referred to as "lesions"). A guidewire is used to guide the catheter to the lesion within the blood vessel. The guidewire has a spindle.

[0003] The guidewire is required to have rotational homing properties, meaning that when the base is rotated by the surgeon or other operator, the tip rotates smoothly in response.

[0004] To improve the vascular selectivity of the guidewire, the surgeon performs a process called "shaping," which involves pre-bending the tip of the guidewire to a specified angle.

[0005] To ensure good rotational following while facilitating the shaping of the tip portion, known guidewires have a portion at the tip of the mandrel with a flatness ratio of 7% or more and 35% or less (see, for example, Patent Document 1). The flatness ratio of the mandrel is a percentage obtained by dividing the difference between the orthogonal diameter and the minimum diameter by the orthogonal diameter when the minimum diameter is defined as the minimum diameter in a cross section orthogonal to the axial direction of the mandrel, and the diameter in a direction orthogonal to the direction of the minimum diameter in the same cross section is defined as the orthogonal diameter.

[0006] Existing technical documents Patent documents Patent Document 1: International Publication No. 2021 / 131019 Summary of the Invention The problem that the invention aims to solve The existing technology described above suffers from the following problem: while ensuring good rotational following performance of the guidewire, it is difficult to suppress three-dimensional deformation during shaping of the guidewire's tip. Preferably, the guidewire should not undergo three-dimensional deformation even after shaping. "No three-dimensional deformation" means that the silhouette of the shaped guidewire projected onto a plane is approximately straight. It should be noted that this issue is not limited to guidewires with a mandrel, but is a common issue in medical devices with shafts for medical devices.

[0007] This specification discloses a technique that can solve the above-mentioned problems.

[0008] Methods for solving problems The techniques disclosed in this specification can be implemented, for example, in the following ways.

[0009] (1) For the shaft for medical devices disclosed in this specification, if the smallest diameter in a cross section orthogonal to the axial direction is set as the minimum diameter, and the diameter in the cross section orthogonal to the direction of the minimum diameter is set as the orthogonal diameter, and the value obtained by dividing the difference between the orthogonal diameter and the minimum diameter by the orthogonal diameter is set as the flatness ratio, then a specific portion has a flatness ratio of 2% or more and 6% or less.

[0010] The rotational following performance of a medical device is best when the cross-sectional shape of the shaft used in the medical device is as close to circular as possible. If the cross-sectional shape of the shaft is close to circular, deviations may occur in the shaping direction during molding, potentially causing three-dimensional deformation of the medical device. This medical device shaft has a specific portion with a flattening ratio of 2% to 6%. Although the cross-section of this specific portion is close to circular, the flattening to a certain extent suppresses deviations in the shaping direction. Therefore, according to this medical device shaft, good rotational following performance can be ensured while suppressing three-dimensional deformation during molding.

[0011] (2) In the above-mentioned shaft for medical devices, a front-end specific portion may be provided, wherein the front-end specific portion is located closer to the front end side than the specific portion, and the flatness ratio is 7% or more. According to this structure, in the front-end specific portion, deviation in the shaping direction can be effectively suppressed, and three-dimensional deformation during shaping can be effectively suppressed.

[0012] (3) In the aforementioned shaft for medical devices, the front-end portion may have a curved portion that bends around an axis parallel to the orthogonal diameter of the front-end portion. According to this structure, in the front-end portion, deviations in the shaping direction can be further effectively suppressed, and three-dimensional deformation during shaping can be further effectively suppressed.

[0013] (4) In the above-mentioned shaft for medical devices, the direction of the minimum diameter of the specific portion can be parallel to the direction of the minimum diameter of the front end specific portion. According to this structure, deviations in the shaping direction of the specific portion and the front end specific portion can be effectively suppressed, and three-dimensional deformation during shaping can be effectively suppressed.

[0014] (5) In the above-mentioned shaft for medical devices, the flatness ratio of the specific portion may be 4% or more and 6% or less. According to this structure, deviations in the shaping direction can be effectively suppressed, and three-dimensional deformation during shaping can be effectively suppressed.

[0015] It should be noted that the technology disclosed in this specification can be implemented in various ways, such as by means of shafts for medical devices, medical devices, and methods of manufacturing them. Attached Figure Description

[0016] Figure 1 This is an explanatory diagram that schematically shows the side of the guidewire in the first embodiment.

[0017] Figure 2 It is shown Figure 1 A cross-sectional view of the mandrel at position II-II.

[0018] Figure 3 It is shown Figure 1 A cross-sectional view of the mandrel at position III-III.

[0019] Figure 4 This is an illustrative diagram showing an example of a guidewire shaping method.

[0020] Figure 5 This is an explanatory diagram that schematically shows the side of the guidewire in the second embodiment.

[0021] Figure 6 This is an explanatory diagram showing the performance evaluation results of the difficulty of three-dimensional deformation when repeatedly shaping.

[0022] Figure 7 This is an explanatory diagram showing the performance evaluation results of rotational following. Detailed Implementation

[0023] A. First implementation method: A-1. Structure of guidewire 100: Figure 1 This is an explanatory diagram that schematically shows the side of the guidewire 100 in the first embodiment. Figure 1 The diagram shows the mutually orthogonal XYZ axes used to determine orientation, and also shows the side of the guidewire 100 when viewed along the X-axis. The positive Z-axis side is the distal side (the side inserted into the body), and the negative Z-axis side is the proximal side (the side manipulated by the surgeon or other operator). These points are... Figure 2 The same applies in the future. Figure 1 In the diagram, a cross-section (specifically, the YZ section) is shown for the coil body 20, which will be described later. Figure 1 Although the guidewire 100 is shown as a straight line generally parallel to the Z-axis, it is flexible enough to bend. In this specification, the end on the front end side of the guidewire 100 and its constituent components is referred to as the "front end", the front end and its vicinity as the "front end", the end on the base end side is referred to as the "base end", and the base end and its vicinity as the "base end".

[0024] Guidewire 100 is a medical device. Guidewire 100 is inserted, for example, into a blood vessel to guide other medical devices (not shown) such as catheters to a lesion in the blood vessel. Guidewire 100 has a mandrel 10. Guidewire 100 has a coil body 20. Guidewire 100 has a front-end junction 30. Guidewire 100 has a base-end junction 40.

[0025] The mandrel 10 is an elongated component. The mandrel 10 has a first part 11, a second part 12, a third part 13, a fourth part 14, a fifth part 15, a sixth part 16, and a seventh part 17. The first part 11, the second part 12, the third part 13, the fourth part 14, the fifth part 15, the sixth part 16, and the seventh part 17 are arranged sequentially from the front end to the base end. The mandrel 10 is an example of a shaft used in medical devices.

[0026] In this embodiment, the cross-sectional shapes of the first portion 11, the third portion 13, the fifth portion 15, and the seventh portion 17 are constant 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. The cross-sectional area of ​​the seventh portion 17 is larger than that of the fifth portion 15. The second portion 12, the fourth portion 14, and the sixth portion 16 smoothly connect the cross-sectional shapes of the other adjacent portions along the axial direction. The second portion 12, the fourth portion 14, and the sixth portion 16 are tapered portions whose cross-sectional area gradually increases from the front end side towards the base end side.

[0027] Materials used to form the mandrel 10 include, for example, metallic materials, and more specifically, stainless steel (SUS302, SUS304, SUS316, etc.), Ni-Ti alloys, piano wire, nickel-chromium alloys, cobalt alloys, tungsten, etc. The structure of the mandrel 10 will be described in detail later.

[0028] The coil body 20 is a hollow cylindrical component formed by winding wire into a spiral shape. The coil body 20 is configured to surround the outer periphery of the front end of the mandrel 10.

[0029] As the forming material of the coil body 20, examples include metallic materials, and more specifically, examples include radiotransmitting alloys such as stainless steel (SUS302, SUS304, SUS316, etc.), Ni-Ti alloys, piano wire, nickel-chromium alloys, or cobalt alloys, as well as radioisotope alloys such as gold, platinum, tungsten, or alloys containing these elements (e.g., platinum-nickel alloys).

[0030] The front-end joint 30 joins the front end of the mandrel 10 to the front end of the coil body 20. The outer peripheral surface of the front end side of the front-end joint 30 is a smooth surface (e.g., approximately hemispherical). The base-end joint 40 joins the mandrel 10 to the base end of the coil body 20. Examples of materials used to form the front-end joint 30 and the base-end joint 40 include metal solders such as silver solder, gold solder, zinc solder, Sn-Ag alloy, and Au-Sn alloy, as well as adhesives such as epoxy resin adhesives.

[0031] A-2. Detailed structure of mandrel 10: Figure 2 It is shown Figure 1 A cross-sectional view of the mandrel 10 at position II-II. Figure 3 It is shown Figure 1 A cross-sectional view of the mandrel 10 at position III-III. In this specification, in a cross-section (XY section) orthogonal to the axial direction (Z-axis direction) of each part of the mandrel 10, if the diameter with the shortest length is defined as the minimum diameter Dmin, and the diameter in the direction orthogonal to the direction of the minimum diameter Dmin is defined as the orthogonal diameter Do, then the percentage obtained by dividing the difference between the orthogonal diameter Do and the minimum diameter Dmin by the orthogonal diameter Do is called the flatness ratio F of each part of the mandrel 10. That is, the flatness ratio F of each part of the mandrel 10 is defined by the following formula (1).

[0032]

[0033] like Figure 2 As shown, the first portion 11 of the mandrel 10 has a relatively flat cross-section. The cross-section of the first portion 11 is, for example, approximately elliptical. The flatness ratio F of the first portion 11 is 7% or more. The flatness ratio F of the first portion 11 can be 10% or more and 70% or less, 20% or more and 60% or less, or 30% or more and 50% or less. The direction of the minimum diameter Dmin of the first portion 11 is the Y-axis direction, and the direction of the orthogonal diameter Do of the first portion 11 is the X-axis direction. The length of the first portion 11 can be, for example, approximately 1mm to 10mm. The first portion 11 of the mandrel 10 is an example of a specific front-end portion.

[0034] like Figure 3As shown, the cross-section of the third portion 13 of the mandrel 10 is approximately circular. The flatness ratio F of the third portion 13 is 2% or more and 6% or less. The flatness ratio F of the third portion 13 can also be 4% or more. The direction of the minimum diameter Dmin of the third portion 13 is the Y-axis direction, and the direction of the orthogonal diameter Do of the third portion 13 is the X-axis direction. That is, the direction of the minimum diameter Dmin of the third portion 13 is parallel to the direction of the minimum diameter Dmin of the first portion 11, and the direction of the orthogonal diameter Do of the third portion 13 is parallel to the orthogonal diameter Do of the first portion 11. The front end of the third portion 13 is located approximately 5mm to 10mm from the front end of the mandrel 10, and the length of the third portion 13 is approximately 3mm to 15mm. The third portion 13 of the mandrel 10 is an example of a specific portion.

[0035] The flatness ratio F of the second portion 12 of the mandrel 10 is close to that of the first portion 11, for example, 7% or more. The flatness ratio F of the second portion 12 can be 10% or more, 20% or more, 30% or more, less than 70%, less than 60%, or less than 50%. Furthermore, the cross-section of the fourth portion 14 of the mandrel 10, and the cross-section of the portion closer to the base end compared to the fourth portion 14, is approximately circular. The flatness ratio F of these portions is, for example, less than 2%.

[0036] The mandrel 10 can be manufactured, for example, by producing components with circular cross-sections in each part and performing flattening processes such as stamping according to the flatness ratio set in each part.

[0037] A-3. Method for shaping guidewire 100: Figure 4 This is an illustrative diagram showing an example of a method for shaping the guidewire 100. Figure 4 The method described is as follows: When the surgeon uses guidewire 100, in order to improve vascular selectivity, a process called "shaping" is performed in which the tip of guidewire 100 is bent to a specified angle.

[0038] like Figure 4 As shown, the surgeon shapes the guidewire 100 along its tip in one direction using the shaping needle 200. At this time, the surgeon bends the guidewire 100 about an axis (X-axis) parallel to the orthogonal diameter Do of the first portion 11 and the third portion 13 of the mandrel 10. In other words, the surgeon bends the guidewire 100 along the direction of the minimum diameter Dmin of the first portion 11 and the third portion 13 of the mandrel 10 (Y-axis direction). The surgeon then inserts the guidewire 100 into the vessel to use it. For example, during vessel selection, the surgeon rotates the tip of the guidewire 100 by rotating the base of the guidewire 100 about the Z-axis.

[0039] A-4. Effects of this implementation method: As explained above, the mandrel 10 for the guide wire 100 in this embodiment has a third portion 13 with a flatness ratio F of 2% or more and 6% or less.

[0040] The rotational following performance of the guidewire 100 is better when the cross-sectional shape of the mandrel 10 is closer to a circle. If the cross-sectional shape of the mandrel 10 is close to a circle, a deviation will occur in the shaping direction, and the guidewire 100 may undergo three-dimensional deformation. In this embodiment, the flatness ratio F of the third portion 13 of the mandrel 10 is 2% or more and 6% or less. Although the cross-section of the third portion 13 is close to a circle, it is flattened to a certain extent, thus suppressing the deviation in the shaping direction. Therefore, the guidewire 100 according to this embodiment can suppress three-dimensional deformation caused by shaping while ensuring good rotational following performance.

[0041] The flatness F of the third part 13 of the mandrel 10 can also be 4% or more and 6% or less. If set in this way, deviations in the shaping direction can be effectively suppressed, and three-dimensional deformation caused by shaping can be suppressed.

[0042] The mandrel 10 for the guide wire 100 in this embodiment has a first portion 11, which is located closer to the front end side than the third portion 13, and has a flatness ratio F of 7% or more. Therefore, according to the mandrel 10 of this embodiment, deviations in the shaping direction can be effectively suppressed in the first portion 11, and three-dimensional deformation caused by shaping can be effectively suppressed.

[0043] In the mandrel 10 for the guide wire 100 of this embodiment, the direction of the minimum diameter Dmin of the third portion 13 is parallel to the direction of the minimum diameter Dmin of the first portion 11. Therefore, the mandrel 10 according to this embodiment can effectively suppress deviations in the shaping direction in the first portion 11 and the third portion 13, and can effectively suppress three-dimensional deformation during shaping.

[0044] B. Second implementation method: Figure 5 This is an explanatory diagram that schematically shows the side view of the guidewire 100A in the second embodiment. Hereinafter, in the structure of the guidewire 100A in the second embodiment, the description of structures that are the same as those of the guidewire 100 in the first embodiment will be omitted by using the same reference numerals.

[0045] In the mandrel 10A of the guide wire 100A in the second embodiment, the first portion 11 has a bent portion 11a. The bent portion 11a is around a diameter Do (refer to) that is orthogonal to the first portion 11. Figure 2The portion that is pre-bent along a parallel axis (X-axis). The coil body 20 is joined to the mandrel 10A by the presence of a bent portion 11a in the mandrel 10A. Figure 1 The guide wire 100A is also bent at the position of the bend 11a. The bending angle of the bend 11a can be, for example, more than 10 degrees and less than 70 degrees, more than 20 degrees and less than 60 degrees, or more than 30 degrees and less than 50 degrees. The position of the bend 11a can be located at a distance of, for example, about 0.5 mm to 5 mm from the front end of the mandrel 10.

[0046] The guide wire 100A of the second embodiment can be manufactured by bending a bent portion 11a after the coil body 20 is joined to the spindle 10A.

[0047] In the mandrel 10A for guide wire 100A in the second embodiment, since the first part 11 has a bent portion 11a, it is possible to further effectively suppress deviations in the direction of shaping in the first part 11, and to further effectively suppress three-dimensional deformation caused by shaping.

[0048] C. Performance Evaluation: For mandrels used as guidewires, the difficulty of three-dimensional deformation during repeated shaping and their rotational following performance were evaluated.

[0049] Figure 6 This is an explanatory diagram illustrating the performance evaluation results showing the difficulty of three-dimensional deformation during repeated shaping. In actual surgery, shaping is usually performed only once. In this performance evaluation, shaping and reshaping were repeated for the evaluation of three-dimensional deformation. Figure 6 As shown, in this performance evaluation result, multiple mandrels 10 with different flatness ratios F at their front ends (the third part 13 in the above embodiment) were prepared. Samples of guide wires 100 equipped with these mandrels 10 were fabricated. Samples S1-S4 included mandrels 10 without the bend 11a (mandrels corresponding to the first embodiment described above). Samples S5-S8 included mandrels 10 with the bend 11a (mandrels corresponding to the second embodiment described above). Execution Figure 6 The following processing was repeated for the number of times shown: Each sample was used as the object, initially shaped from a straight state (guidewire 100) to a height of 5 mm, and then further shaped to a height of less than 1 mm. The shape of the guidewire 100 after the repeated processing is shown below. Figure 6 . Figure 6 The shape shown represents the silhouette obtained by projecting guide wire 100 onto the ZX plane. This silhouette is a straight line before shaping. After shaping and reshaping, if no three-dimensional deformation occurs, the silhouette remains a straight line.

[0050] like Figure 6As shown, in both samples without the curved portion 11a (S1-S4) and samples with the curved portion 11a (S5-S8), the three-dimensional deformation during repeated shaping was well suppressed in samples with a flattening ratio of 2% or more and 6% or less (S2-S4, S6-S8). In particular, the three-dimensional deformation during repeated shaping was further well suppressed in samples with a flattening ratio of 4% or more and 6% or less (S3-S4, S7-S8). Furthermore, when samples with the same flattening ratio F are compared with each other, the three-dimensional deformation of samples with the curved portion 11a (S6-S8) is well suppressed during repeated shaping compared to samples without the curved portion 11a (S2-S4).

[0051] Figure 7 This is an explanatory diagram showing the performance evaluation results of rotational following. (Example) Figure 7 As shown, in this performance evaluation, the relationship between the angle at which the base of the guidewire 100 rotates (input rotation angle) and the angle at which the tip of the guidewire 100 rotates (output rotation angle) is evaluated. The closer the line is to the point where the input rotation angle and the output rotation angle coincide (…), the better. Figure 7 The "ideal" line in the equation indicates a higher degree of rotational following. This performance evaluation was conducted using a sample with a bend 11a.

[0052] like Figure 7 As shown, the larger the flatness F of the front end of the mandrel 10, the lower the rotational following performance. In the sample with a flatness F of 8% at the front end of the mandrel 10, a whipping occurred, meaning that the input rotational torque was stored as strain, and then the front end rotated suddenly. Since the presence or absence of the bend 11a can be considered to have almost no effect on the rotational following performance, the same result can be expected in the mandrel 10 without the bend 11a.

[0053] Based on the above performance evaluation results, if the mandrel 10 used for the guidewire 100 has a third portion 13 with a flatness ratio F of 2% or more and 6% or less, it can suppress three-dimensional deformation during shaping while ensuring good rotational following performance. Specifically, if the flatness ratio F of the third portion 13 of the mandrel 10 is 4% or more and 6% or less, it can effectively suppress three-dimensional deformation during shaping. Furthermore, if the first portion 11 of the mandrel 10 has a bent portion 11a, it can further effectively suppress three-dimensional deformation caused by shaping.

[0054] D. Variation example: The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified into various forms without departing from its spirit, such as the following modifications.

[0055] The structure of the guide wire 100 in the above embodiment is only one example and can be modified in various ways. For example, the mandrel 10 may not have a portion with a flatness ratio of more than 7% near the front end compared to the third part 13.

[0056] The spindle 10 may have a third part 13 with a flatness ratio of 2% or more and 6% or less, or it may not have at least one of the first part 11 to the seventh part 17.

[0057] The direction of the minimum diameter Dmin of the third part 13 of the mandrel 10 may not be parallel to the direction of the minimum diameter Dmin of the first part 11.

[0058] The technology disclosed in this specification is not limited to the mandrel 10 used in the guidewire 100, but can be widely applied to shafts used in medical devices.

[0059] Explanation of reference numerals in the attached figures 10: Mandrel, 11: First part, 11a: Bending part, 12: Second part 13: Part Three, 14: Part Four, 15: Part Five, 16: Part Six 17: Part 7; 20: Coil body; 30: Front end side joint; 40: Base end side joint. 100: guidewire, 200: shaping needle, Dmin: minimum diameter, Do: orthogonal diameter.

Claims

1. A shaft for a medical device, wherein, If the smallest diameter in a cross section orthogonal to the axial direction is defined as the minimum diameter, and the diameter in the cross section orthogonal to the direction of the minimum diameter is defined as the orthogonal diameter, and the difference between the orthogonal diameter and the minimum diameter is divided by the orthogonal diameter as the flatness ratio, then the shaft for medical devices has a specific portion with a flatness ratio of 2% or more and 6% or less.

2. The shaft for medical devices according to claim 1, wherein, The shaft for the medical device has a front-end specific portion, which is located closer to the front end than the specific portion, and the flatness ratio is 7% or more.

3. The shaft for medical devices according to claim 2, wherein, The front end portion has a curved portion that bends about an axis parallel to the orthogonal diameter of the front end portion.

4. The shaft for medical devices according to claim 2 or 3, wherein, The direction of the minimum diameter of the specific portion is parallel to the direction of the minimum diameter of the front end specific portion.

5. The shaft for medical devices according to any one of claims 1 to 4, wherein, The flatness of the specific portion is above 4% and below 6%.

6. A medical device, wherein, The medical device comprises a shaft for medical devices as described in any one of claims 1-5.

Images