Hollow body and medical instrument

Abstract

To provide a hollow body which has excellent rotation followability and torque transmission properties.SOLUTION: A hollow body includes a coil body and a resin coating layer arranged on an outer surface of the coil body. The coil body includes a first coil constituted by spirally winding a first element wire. The first coil is a densely wound coil in which adjacent sites of the first element wire are wound to make contact with each other, and does not have a wavy structure in which mountain parts curved or bent to protrude toward the outside and valley parts curved or bent to dent toward the inside are alternately arranged along a central axis of the first coil. The coating layer has a wavy structure in which the mountain parts curved or bent to protrude toward the outside and the valley parts curved or bent to dent toward the inside are alternately arranged along the central axis of the first coil.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology disclosed herein relates to hollow bodies and medical instruments. [Background technology]

[0002] For example, medical instruments such as catheters and guidewires that are inserted into biological lumens (blood vessels, digestive organs, ureters, tracheas, etc.) may have a hollow body formed of a coil body in which a wire is wound in a spiral shape. The coil body is often coated with a resin in order to improve sliding properties and ensure airtightness. However, the coating impedes the flexibility of the coil body, which causes a problem of reduced rotational followability (the ability of the distal end to rotate following the rotation of the proximal end when the proximal end is rotated by a doctor or other technician). In order to solve this problem, a technology has been proposed in which the coil member (coil body) arranged between a resin inner layer and an outer layer is made wavy in which contact parts (valley parts) that contact the inner layer part and separation parts (peak parts) that are separated from the inner layer part are alternately arranged (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-151380 Summary of the Invention [Problem to be solved by the invention]

[0004] With the above configuration, there is a concern that the coil body may become too flexible, resulting in a decrease in torque transmittance (the ability to smoothly transmit torque to the tip when the base end is rotated by a doctor or other technician).

[0005] It should be noted that such a problem is not limited to hollow bodies for medical instruments, but is a problem common to hollow bodies in general, including those for various piping.

[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] (1) A hollow body disclosed in the present specification comprises a coil body and a coating layer disposed on an outer surface of the coil body, wherein the coil body comprises a first coil formed by helically winding a first wire, wherein the first coil is a tightly wound coil wound such that adjacent portions of the first wire are in contact with each other, and wherein the first coil does not have a wavy structure in which peak portions that are bent or curved convexly outward and valley portions that are bent or curved concavely inward are alternately arranged along a central axis of the first coil, and the coating layer is configured in a wavy shape in which peak portions that are bent or curved convexly outward and valley portions that are bent or curved concavely inward are alternately arranged along the central axis of the first coil.

[0009] According to the above configuration, when the hollow body passes through a curved portion inside an object such as a biological lumen, the coating layer easily deforms to follow the curvature of the coil body. This makes it easy to rotate the hollow body while curving it, ensuring good rotational followability. Meanwhile, since the first coil provided in the coil body does not have a wavy configuration with peaks and valleys, the flexibility of the coil body is not so great that it hinders smooth transmission of torque. This ensures good torque transmission.

[0010] (2) In the hollow body described in (1) above, the first coil may be configured such that, in a cross section along the central axis of the first coil, the center points of multiple cross sections of the first wire are aligned in a straight line over the entire length of the first coil.

[0011] With this configuration, the flexibility of the coil body is not so great that it impedes smooth transmission of torque, thereby ensuring good torque transmission.

[0012] (3) In the hollow body described in (1) or (2) above, the first coil may be a coil having a constant inner diameter.

[0013] With this configuration, even better torque transmission can be achieved.

[0014] (4) In the hollow body described in any one of (1) to (3) above, the coil body may further include a second coil formed by spirally winding a second wire and arranged on the outer surface of the first coil, the second coil being a loosely wound coil wound so as to have gaps between adjacent portions of the second wire, and the peak portion may be arranged along the second coil.

[0015] With this configuration, a coating layer having a wavy structure can be easily formed.

[0016] (5) In the hollow body described in (4) above, an angle between a central axis of the first coil and the second wire may be 75° or more.

[0017] With this configuration, the tolerance of deformation of the coating layer can be increased, and better rotational follow-up can be achieved.

[0018] (6) The medical device disclosed in the present specification includes the hollow body according to any one of (1) to (5) above. The hollow body has good rotational followability and torque transmission properties, and is suitable for use in the medical device.

[0019] 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 description of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view of a guidewire according to an embodiment. [Diagram 2] Enlarged cross-sectional view of a portion of the area F in FIG. [Diagram 3] FIG. 1 is a partially enlarged side view of a coil body according to an embodiment; [Figure 4] 1 is a cross-sectional view showing a manufacturing process of a guidewire according to an embodiment of the present invention; [Diagram 5] FIG. 1 is a partially enlarged cross-sectional view showing a state in which the guide wire according to the embodiment is bent. [Figure 6] Enlarged cross-sectional view of sample S2 used in performance evaluation [Figure 7] Enlarged cross-sectional view of sample S3 used in performance evaluation [Figure 8] FIG. 13 is a side view showing a schematic diagram of a rotation tracking test method. [Figure 9] A graph showing the relationship between input angle and output angle for each sample used in the performance evaluation DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] A. First embodiment: A-1. Configuration of guidewire 100: FIG. 1 is an explanatory diagram that shows a schematic configuration of a guidewire 100 according to an embodiment. FIG. 1 shows a longitudinal section (YZ section) of the guidewire 100. In FIG. 1, the positive Z-axis direction side is the tip end side (distal side) that is inserted into the body, and the negative Z-axis direction side is the base end side (proximal side) that is operated by an operator such as a doctor. These points are the same for FIG. 2 and subsequent figures. FIG. 1 shows a state in which the guidewire 100 as a whole is linear and substantially parallel to the Z-axis direction, but the guidewire 100 has flexibility to the extent that it can be curved. In the following, the tip and its vicinity of the guidewire 100 and each of the components of the guidewire 100 are referred to as the "tip portion" and the base end and its vicinity are referred to as the "base end portion."

[0022] The guidewire 100 of this embodiment is a medical device that is inserted into a biological lumen, such as a blood vessel, in order to guide a catheter (not shown) to a lesion (a narrowed or blocked portion) in the biological lumen.

[0023] 1, the guidewire 100 includes a core shaft 10, a coil body 20, a distal joint portion 30, a proximal joint portion 40, and a coating layer 50. The coil body 20 and the coating layer 50 form a hollow body 60.

[0024] (Core shaft 10) The core shaft 10 is a bendable long rod-shaped member, and includes a long round bar-shaped base 12, a round bar-shaped thin-diameter portion 11 having an outer diameter smaller than that of the base 12, and a tapered portion 13 connecting the base 12 and the thin-diameter portion 11. The base 12, the tapered portion 13, and the thin-diameter portion 11 are arranged in this order from the base end side. The tapered portion 13 has an outer diameter that gradually decreases from the base 12 toward the thin-diameter portion 11. The portion of the base 12 opposite the thin-diameter portion 11 is a gripping portion 12G that is gripped by a technician such as a doctor. The outer diameter of the thin-diameter portion 11 is, for example, about 0.03-0.085 mm, and the outer diameter of the base 12 is, for example, about 0.2-0.9 mm.

[0025] The core shaft 10 is made of a known material, for example, a metal material, more specifically, stainless steel (SUS302, SUS304, SUS316, etc.), a superelastic alloy such as a Ni-Ti alloy, a piano wire, a nickel-chromium alloy, a cobalt alloy, tungsten, etc. The core shaft 10 may be made of the same material as a whole, or may be made of different materials in different parts.

[0026] (Coil body 20) The coil body 20 includes a first coil 21 and a second coil 22 disposed on the outer surface of the first coil 21. The coil body 20 is disposed so as to surround the tip portion of the core shaft 10 (specifically, the thin-diameter portion 11, the tapered portion 13, and a part of the base portion 12). The total length of the coil body 20 is, for example, about 10 to 500 mm, and the outer diameter of the first coil 21 is, for example, about 0.2 to 0.9 mm.

[0027] Known materials are used for the first coil 21 and the second coil 22, for example, metal materials, more specifically, stainless steel (SUS302, SUS304, SUS316, etc.), superelastic alloys such as Ni-Ti alloys, piano wire, nickel-chromium alloys, cobalt alloys, tungsten, etc. The materials of the first coil 21 and the second coil 22 may be the same or different.

[0028] (Tip joint 30) The tip joint 30 is a member that connects the tip of the small diameter portion 11 and the tip of the coil body 20. The tip of the core shaft 10 and the tip of the coil body 20 are fixed so as to be embedded inside the tip joint 30. The tip surface of the tip joint 30 is a smooth surface (for example, a substantially hemispherical surface). The tip joint 30 is made of, for example, a metal solder such as silver solder, gold solder, zinc, Sn-Ag alloy, Au-Sn alloy, or an adhesive such as an epoxy adhesive. By disposing the tip joint 30 at the tip of the core shaft 10, the core shaft 10 is prevented from contacting a blood vessel wall or the like, and damage to the core shaft 10 is suppressed.

[0029] (Proximal junction 40) The base end joint portion 40 is a member that joins the base end of the coil body 20 to the core shaft 10. The base end joint portion 40 is made of the same material as the tip joint portion 30 described above.

[0030] (Coating layer 50) The coating layer 50 is made of one or more types of resin material, and is a coating member that covers the outer peripheral surface of the coil body 20 and the outer surfaces of the distal joint portion 30 and the proximal joint portion 40. A known material is used as the material for the coating layer 50, such as a hydrophilic resin such as a PVA resin or a hyaluronic acid resin, or a silicone resin, PTFE (polytetrafluoroethylene), etc. The thickness of the coating layer 50 is, for example, about 0.001-0.1 mm.

[0031] A-2. Detailed configuration of hollow body 60: As described above, the coil body 20 and the coating layer 50 form the hollow body 60, and the coil body 20 includes the first coil 21 and the second coil 22.

[0032] (First coil 21) The first coil 21 is a multi-strand coil formed by winding a plurality of first wires 21W in a spiral shape. As shown in FIG. 3, the first coil 21 is a tightly wound coil in which adjacent portions of the first wire 21W are in contact with each other when no external force is applied. That is, the first coil 21 is wound so that there is no gap between one turn of the first wire 21W and another turn adjacent thereto. The first coil 21 is configured such that, in a cross section (cross section shown in FIG. 1) taken along the central axis AXc of the first coil 21, the center points Pc of the multiple cross sections 21Wc of the first wire 21W are aligned in a straight line (that is, along the straight line L in FIG. 1) over the entire length of the first coil 21. More specifically, the first coil 21 is cylindrical with a constant inner diameter over the entire length. In addition, when the center points Pc are "arranged in a straight line," this does not only mean that multiple center points Pc are arranged in a strictly straight line, but also includes cases where slight deviations inevitably occur due to manufacturing tolerances, etc.

[0033] (Second coil 22) The second coil 22 is a coil formed by winding one second wire 22W in a spiral shape. As shown in FIG. 3, the second coil 22 is disposed so as to surround the outer periphery of the first coil 21 and is in contact with the outer surface of the first coil 21. When no external force is applied, the second coil 22 is a loosely wound coil having a gap between adjacent portions of the second wire 22W. In other words, the second coil 22 is wound so that there is a gap between one turn of the second wire 22W and another turn adjacent to it. The winding direction of the second coil 22 is opposite to that of the first coil 21. FIG. 1 shows an example in which the first coil 21 is wound counterclockwise from the tip to the base end, and the second coil 22 is wound clockwise from the tip to the base end, but it is also acceptable for the first coil 21 to be wound clockwise from the tip to the base end, and the second coil 22 to be wound counterclockwise from the tip to the base end.

[0034] (Coating layer 50) As shown in FIG. 1 and FIG. 2, the coating layer 50 has a peak 50A and a valley 50B. The peak 50A is a portion of the coating layer 50 that is curved in a mountain shape convex toward the outside (direction away from the first coil 21). The peak 50A extends in a spiral shape along the second coil 22. The valley 50B is a portion of the coating layer 50 that is curved in a valley shape concave toward the inside (direction approaching the first coil 21). The valley 50B extends in a spiral shape adjacent to the peak 50A in a portion of the surface of the coil body 20 where the second coil 22 is not arranged. That is, the coating layer 50 has a wavy shape in which one turn of the peak 50A and one turn of the valley 50B are alternately arranged in a direction along the central axis AXc of the first coil 21. In this embodiment, the bottom of the valley 50B is in contact with the first coil 21.

[0035] A-3. Method for forming coating layer 50: The coating layer 50 having the above-mentioned shape can be formed, for example, by the following method.

[0036] First, a resin sheet S is wound around the outer circumferential surface of the coil body 20. Next, as shown in FIG. 4, the processing wire Wp is wound around the outside of the wound sheet S. At this time, the processing wire Wp is wound in a spiral shape so as to be positioned in the gap between adjacent parts of the second wire 22W. As a result, the part of the sheet S in contact with the processing wire Wp is recessed so as to approach the first coil 21 to form a valley part 50B, and the part not recessed by the processing wire Wp (the part along the second coil 22) becomes the peak part 50A. After that, the processing wire Wp is removed, and the coating layer 50 having the peak part 50A and the valley part 50B is completed.

[0037] A-4. Operation of the Guidewire 100 The operator rotates the gripping portion 12G, and the guidewire 100 advances while rotating inside the biological lumen. When the guidewire 100 passes through a curved portion of the biological lumen, the guidewire 100 rotates while curving in accordance with the curved shape of the biological lumen. At the curved portion of the guidewire 100, the coil body 20 deforms so that the portion located outside the curve stretches, as shown in FIG. 5. That is, a gap is generated between adjacent portions of the first coil 21, and the gap between adjacent portions of the second coil 22 becomes larger. In this state, the guidewire 100 is rotated, and therefore, when focusing on a specific portion of the coil body 20, the coil body 20 repeats an expanding and contracting motion.

[0038] However, if a resin layer is present on the outer surface of the coil body 20, the resin layer will hinder the expansion and contraction movement of the coil body 20. As a result, even if the operator rotates the grip portion 12G, the tip of the hollow body 60 will be prevented from rotating in response to the rotation of the grip portion 12G, which is thought to reduce rotational followability.

[0039] In this embodiment, the coating layer 50 is configured in a wavy shape in which multiple peaks 50A and multiple valleys 50B are alternately arranged in a direction along the central axis AXc of the first coil 21. With such a configuration, the curvature angles of the peaks 50A and valleys 50B change in response to the expansion and contraction movement of the coil body 20, and the coating layer 50 is easily deformed. This ensures good rotational followability.

[0040] On the other hand, if the first coil constituting the coil body itself is made to have a wavy configuration having peaks and valleys, the flexibility of the coil body becomes extremely large. As a result, it is considered that the torque applied to the gripping portion by the surgeon such as a doctor is not easily transmitted to the tip, and kinking is easily caused. In this embodiment, the first coil 21 does not have a wavy configuration. More specifically, the first coil 21 has a constant inner diameter. With such a configuration, the flexibility of the coil body 20 does not become too large, so that good torque transmission can be ensured.

[0041] In order to increase the deformation tolerance of the coating layer 50, the angle between the central axis AXc of the coil body 20 and the second wire 22W (more specifically, the angle θ between the central axis AXc of the coil body 20 and the center line AXw of the second wire 22W) is preferably 75° or greater, and more preferably 80° or greater.

[0042] A-5. Advantages of this embodiment: As described above, the hollow body 60 of this embodiment comprises a coil body 20 and a coating layer 50 arranged on the outer surface of the coil body 20, wherein the coil body 20 comprises a first coil 21 formed by spirally winding a first wire 21W, wherein the first coil 21 is a tightly wound coil in which adjacent portions of the first wire 21W are wound so as to be in contact with each other and has a constant inner diameter, and wherein the coating layer 50 is configured in a wavy shape in which peak portions 50A that are bent or curved so as to be convex outward and valley portions 50B that are bent or curved so as to be concave inward are alternately arranged along the central axis AXc of the first coil 21.

[0043] According to the above configuration, when the hollow body 60 passes through a curved portion inside an object such as a biological lumen, the coating layer 50 easily deforms to follow the curvature of the coil body 20. This makes it easy to rotate the hollow body 60 while curving it, ensuring good rotational followability. Meanwhile, since the first coil 21 constituting the coil body 20 does not have a wavy configuration with peaks and valleys, the flexibility of the coil body 20 is not so great that it hinders the smooth transmission of rotational operations by an operator such as a doctor. This ensures good torque transmission.

[0044] The coil body 20 further includes a second coil 22 configured by helically winding a second wire 22W and disposed on the outer surface of the first coil 21, the second coil 22 being a loosely wound coil wound so as to have gaps between adjacent portions of the second wire 22W, and the peaks 50A are disposed along the second coil 22. With this configuration, the coating layer 50 having a wavy configuration can be easily formed.

[0045] In addition, the angle between the central axis AXc of the first coil 21 and the second wire 22W is equal to or greater than 75°. With this configuration, the tolerance of deformation of the coating layer 50 can be increased, and better rotational followability can be ensured.

[0046] A-6.Performance evaluation: The performance evaluation performed using the following three guidewire samples S1, S2, and S3 will be described below.

[0047] (Sample S1) A guidewire having the same configuration as in the above embodiment was prepared and designated as sample S1. An eight-strand multi-strand coil was used as the first coil, and PeBax5533 (manufactured by Tokyo Materials Co., Ltd.) was used as the material for the coating layer 50.

[0048] (Sample S2) A guide wire similar to sample S1 was prepared as sample S2, except that after the sheet that would become coating layer 50S2 was wound around coil body 20, no processing wire was wound around it. As shown in Fig. 6, in coating layer 50S2 of sample S2, the portion along second coil 22 became peak portion 50A2, and the portion where second coil 22 was not disposed became valley portion 50B2, gently recessed so as to approach first coil 21.

[0049] (Sample S3) As shown in FIG. 7, a first coil 21 without a second coil 22 wound thereon was used as a coil body, and after a sheet to become the coating layer 50S3 was wound around the first coil 21, a guide wire similar to sample S1 was prepared, except that no processing wire was wound around it, and this was designated sample S3.

[0050] (Rotational tracking test) As shown in Fig. 8, a circular ring with a radius of 50 mm was made using tube C, and a test path was created with a straight line in front of and behind the ring. Sample S1 was inserted from one opening of this test path (the opening on the right side in Fig. 8) and the tip FR was made to protrude from the other opening of tube C. In this state, the gripping portion 12G of sample S1 was gripped and rotated, and the number of degrees the tip FR had rotated was measured. Samples S2 and S3 were also tested in the same manner.

[0051] (result) The relationship between the rotation angle of the gripper (input angle) and the rotation angle of the tip (output angle) for each of samples S1, S2, and S3 is shown in Figure 9. In Figure 9, the thin solid line is an ideal straight line that shows the ideal state in which the input angle and output angle are the same, that is, the tip completely follows the rotation of the gripper.

[0052] In sample S3, in which coating layer 50S3 does not have peaks and valleys, the tip hardly rotates for a while even when the gripping part starts to rotate, and then when the gripping part is rotated beyond a certain level, the tip suddenly rotates significantly. This phenomenon is thought to be repeated in sample S3. The rotation of the gripping part is not smoothly transmitted to the tip, and torque accumulates for a while, and when the accumulated torque reaches a certain level or more, it is suddenly released.

[0053] In sample S2, the difference in the rotation angle between the gripping portion and the tip was smaller than in sample S3. Also, when the gripping portion was rotated beyond a certain degree, the tip suddenly rotated a lot, but the movement was gentler than in sample S3. From this, it is considered that the rotation tracking ability is improved by configuring coating layer 50S2 to have peaks 50A2 and valleys 50B2.

[0054] In sample S1, the input angle and output angle were almost equal, and the tip followed the rotation of the gripping part well. Sample S1 had a larger depression in the valley portion 50B compared to sample S2, which was not wrapped with a processing wire. This is thought to have made the coating layer more easily deformable, further improving the rotation tracking ability.

[0055] B. Variations: The technology disclosed in this specification is not limited to the above-described embodiments, and can be modified in various forms without departing from the spirit of the invention. For example, the following modifications are also possible. (1) In the above embodiment, the first coil 21 has a constant inner diameter, but the first coil does not necessarily have a constant inner diameter as long as it does not have a wavy structure in which peaks and valleys are alternately arranged, and may be configured, for example, such that the inner diameter of the portion closer to the tip of the first coil gradually decreases as it approaches the tip. Also, "in a cross section of the first coil taken along the central axis, the center points of a plurality of cross sections of the first wire are arranged in a straight line over the entire length of the first coil" includes, for example, a case in which the first coil is configured such that the inner diameter gradually decreases from the base end to the tip, or a case in which the inner diameter gradually increases from the base end to the tip. (2) In the above embodiment, the first coil 21 is a multi-strand coil. However, the first coil may be a coil in which a single wire is wound in a spiral shape. (3) In the above embodiment, the coil body includes a first coil 21 and a second coil 22. However, the coil body does not have to include a second coil. For example, a plurality of rings may be arranged at intervals on the outer surface of the first coil, and a coating layer may be arranged on the outside thereof, thereby forming peaks and valleys in the coating layer. (4) In the above embodiment, the second coil 22 is wound in the opposite direction to the first coil 21. However, the second coil may be wound in the same direction as the first coil. (5) In the above embodiment, an example was shown in which the coating layer 50 having the peaks 50A and the valleys 50B was formed by winding the processing wire Wp. However, the method of forming the coating layer is not limited to the above method. For example, a coating layer having peaks and valleys may be formed by inserting a coil body into a heat shrink tube and heating it. (6) The wire constituting the first coil may be a solid wire or a twisted wire in which a number of thin wires are twisted together. The same applies to the second coil. (7) There are no particular limitations on the shape of the wire that constitutes the first coil. For example, it may be a round wire with a circular cross section, a wire with an elliptical cross section, or a flat wire with a flat cross section. (8) In the above embodiment, the guidewire 100 is exemplified as a medical device having a hollow body 60, but the medical device having a hollow body may be, for example, a catheter, an endoscopic treatment tool, etc. Furthermore, the hollow body may be used for purposes other than medical use (for example, piping). [Explanation of symbols]

[0056] 10: Core shaft 11: Thin diameter section 12: Base section 12G: Grip section 13: Tapered section 20: Coil body 21: First coil 21W: First strand 22: Second coil 22W: Second strand 30: Tip joint 40: Base joint 50: Coating layer 50A: Peaks 50B: Valleys 60: Hollow body 100: Guidewire (medical device) AXc: Center axis of first coil AXw: Center line of second strand

Claims

1. A coil body and A coating layer disposed on the outer surface of the coil body, Equipped with, The coil body comprises a first coil formed by winding a first strand of wire in a spiral shape, The first coil, A tightly wound coil in which adjacent portions of the first strands are wound in contact with each other, A coil that does not have a wave-like structure in which peaks that are bent or curved so as to be convex outwards and valleys that are bent or curved so as to be concave inwards are alternately arranged along the central axis. The aforementioned coating layer The first coil is configured in a wave-like manner, with peaks that are bent or curved so as to be convex outwards and valleys that are bent or curved so as to be concave inwards, arranged alternately along the central axis of the first coil. hollow body.

2. The first coil, In a cross-section of the first coil along its central axis, the center points of the multiple cross-sections of the first strands are arranged in a straight line along the entire length of the first coil. The hollow body according to claim 1.

3. The first coil is a coil having a constant inner diameter. The hollow body according to claim 1 or claim 2.

4. The coil body, The second coil is further configured by winding a second strand of wire in a spiral shape and is arranged on the outer surface of the first coil, The second coil is a loosely wound coil in which there is a gap between adjacent portions of the second strands. The aforementioned peaks are arranged along the second coil, The hollow body according to claim 1 or claim 2.

5. The angle between the central axis of the first coil and the second wire is 75° or greater. The hollow body according to claim 4.

6. A medical device comprising a hollow body according to claim 1 or claim 2.

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