Stent

Abstract

To provide a stent that can reduce stimulation to a body cavity wall and be readily and safely removed.SOLUTION: A stent 1 includes: a cylindrical body part 2 capable of expanding and contracting in a radial direction; and a coil 3 helically wound around a lateral face of the body part 2. The coil 3 is made of a shape memory wire. The coil 3 includes: a first part 31 wound around a center part of the body part 2; and a second part 32 wound around end parts of the body part 2. The second part 32 has an outer diameter r2 that is larger than an outer diameter r1 of the first part 31.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a stent. [Background technology]

[0002] Conventionally, when a stenosis or blockage occurs in a body cavity such as a blood vessel or a digestive organ, a technique is known in which a stent is placed in the affected area to expand the stenosis, etc. For example, Patent Document 1 proposes an invention of a stent provided with an anchoring mechanism that prevents the stent from shifting (migrating) from the placement position. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. WO2020 / 194506 Summary of the Invention [Problem to be solved by the invention]

[0004] However, according to the invention of Patent Document 1, a stent is formed by weaving metal wires, and a portion of the stent is provided with no hook weaving, which is raised to form a claw shape, and the claw shape is anchored to the body cavity to hold the stent in place. At this time, there is a problem that the edge of the metal wire forming the claw shape irritates the body cavity wall, causing bleeding or perforation. In addition, when removing and replacing the stent, there is a problem that the claw shape digs into the body cavity in the opposite direction to the removal direction, damaging the body cavity.

[0005] Additionally, biliary stents used to expand the bile duct are covered stents, in which the entire stent is coated with resin. However, when covered stents are used for a long period of time, insoluble bile, known as "bile sludge," gradually accumulates, causing re-obstruction. This makes it necessary to remove the covered stent and replace it with a new one. For this reason, there has been a demand for a covered stent that can be removed easily and safely.

[0006] Therefore, an object of the present disclosure is to provide a stent that can reduce irritation to the body cavity wall and can be easily and safely removed. [Means for solving the problem]

[0007] In order to solve the above problems, the stent disclosed herein comprises a cylindrical main body portion that is radially expandable and contractable, and a coil wound spirally around a side of the main body portion, the coil including a first portion wound around a central portion of the main body portion and a second portion wound around an end portion of the main body portion, and the outer diameter of the second portion is larger than the outer diameter of the first portion. Effect of the Invention

[0008] According to the stent of the present disclosure, the outer diameter of the second portion of the coil is made larger than the outer diameter of the first portion of the coil, so that as the main body and the first portion expand in diameter, the second portion expands in diameter and is anchored to the body cavity. At this time, the second portion is anchored, so that irritation to the body cavity can be reduced.

[0009] Furthermore, according to the stent of the present disclosure, the second portion is reduced in diameter by pulling the end portion, so that the anchoring can be automatically released and the stent can be easily and safely removed from the body cavity. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram of a stent according to a first embodiment. [Diagram 2]2A is a schematic cross-sectional view of the stent in FIG. 1 taken along line AA, (b) a schematic cross-sectional view of line BB, and (b) a schematic cross-sectional view of line CC. [Diagram 3] FIG. 1 is a schematic diagram showing (a) a method for inserting a stent, (b) a stent in an indwelling state, and (c) a method for removing the stent. [Figure 4] FIG. 1 is a schematic diagram of a stent according to a second embodiment. [Diagram 5] 5A is a schematic cross-sectional view of the stent in FIG. 4 taken along line DD, and FIG. 5B is a schematic cross-sectional view of the stent taken along line EE. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the stent of the present disclosure will be described with reference to the drawings. In each embodiment, the same components are given the same reference numerals and the description will be omitted. In addition, in Figs. 2, 3, and 5, the resin film 4 is omitted for the sake of simplicity. EXAMPLES

[0012] As shown in Figs. 1 and 2, the stent 1 of the present disclosure includes a cylindrical main body 2 that can expand and contract in the radial direction, and a coil 3 wound in a spiral shape on the side of the main body 2. The coil 3 is a shape-memory wire that is separate from the main body 2. The coil 3 includes a first portion 31 wound around the center of the main body 2 and a second portion 32 wound around an end of the main body 2. The outer diameter of the second portion 32 is larger than the outer diameter of the first portion 31. In other words, the second portion 32 is wound in a state spaced apart radially outward from the main body 2. On the other hand, the first portion 31 is wound so as to follow the outer diameter of the main body 2. By making the outer diameter of the second portion 32 larger than the outer diameter of the first portion 31, when the affected area is expanded by the stent 1, the second portion 32 is automatically anchored to the body cavity 52, and the placement position of the stent 1 is maintained. The stent 1 of the present disclosure is used to maintain an open state of a stenosed or obstructed area by being placed in a body lumen 52 such as a blood vessel, a digestive organ, or a bile duct.

[0013] The stent 1 is covered with a resin film 4. By covering the stent 1 with the resin film 4, the stent 1 does not come into direct contact with the body cavity 52, and the body cavity 52 is less likely to be damaged. Also, obstructing substances such as cells and thrombi that constitute the body cavity 52 can be prevented from entering the stent 1. Resins used for the resin film 4 include silicone, polyurethane, and the like. The thickness of the resin film 4 is 100 μm or more and 800 μm or less.

[0014] The main body 2 is made of a single metal wire made of a shape memory alloy that is woven together to form a hook shape. When the main body 2 is pulled in the axial direction, the woven mesh is crushed and the diameter is reduced.

[0015] The metal wire constituting the main body 2 is a round wire with a diameter of about 0.13 mm. For example, the metal wire constituting the main body 2 may be made of tungsten, stainless steel (SUS302, SUS304, SUS316, etc.), platinum-iridium (Pt-Ir), a superelastic alloy such as a Ni-Ti alloy, piano wire, platinum, gold, or an alloy thereof.

[0016] Here, the pitch p2 of the second portion 32 may be smaller than the pitch p1 of the first portion 31 (pitch p1>pitch p2). By making the pitch p1>pitch p2, the surface density with which the coil 3 of the second portion 32 presses against the body cavity 52 is increased, and anchoring can be performed more reliably. Here, the pitch refers to the width between adjacent coils in the axial direction in the coil 3 wound around the main body portion 2.

[0017] The second portion 32 is formed at both ends of the coil 3. Here, the outer diameter r2' of the second portion 32' wound around one end of the main body 2 is made larger than the outer diameter r2 of the second portion 32 wound around the other end (outer diameter r2<outer diameter r2'). For example, the outer diameter r2' of the second portion 32' at the base end 1b of the stent 1 is made larger than the outer diameter r2 of the second portion 32 at the tip 1a. This configuration can prevent the stent 1 from moving toward the tip 1a, i.e., toward the back of the body cavity 52. ​​Taking a bile duct stent used in a procedure called EUS-HGS (Endoscopic Ultrasonography Guided-Hepaticogastrostomy) in which the stent is placed from the stomach to the intrahepatic bile duct via an ultrasonic endoscope as an example, the bile duct stent is inserted toward the bile duct from an opening opened in the stomach wall, so that the second portion 32' is placed on the stomach wall side and the second portion 32 is placed in the bile duct, thereby preventing the bile duct stent from moving toward the back of the bile duct.

[0018] At this time, it is also possible to set the pitch p2' of the second portion 32' smaller than the pitch p2 of the second portion 32 (pitch p2'<pitch p2). By setting the pitch p2'<pitch p2, the surface density of the second portion 32' pressing against the body cavity 52 is configured to be higher than the surface density of the second portion 32 pressing against the body cavity 52, and migration of the stent 1 into the depth of the body cavity 52 can be prevented.

[0019] The metal wire of the coil 3 may be made of, for example, tungsten, stainless steel (SUS302, SUS304, SUS316, etc.), platinum-iridium (Pt-Ir), superelastic alloys such as Ni-Ti alloys, piano wire, and alloys such as platinum and gold.

[0020] Next, a method for placing the stent 1 in the affected area will be described with reference to Fig. 3. First, the stent 1 is stretched to reduce its diameter, and then cooled and fixed in the reduced diameter state by a cooling spray. Then, the stent 1 is housed in a catheter 51 of a stent delivery system. Next, as shown in Fig. 3(a), the catheter 51 is inserted into a body cavity, and the stent 1 is delivered to the affected area.

[0021] 3(b), when the stent 1 is placed in the affected area and the catheter 51 is removed from the body cavity 52, the stent 1 is warmed by body heat and returns to its original shape. At this time, the main body 2 expands in diameter to expand the affected area, and the coil 3 expands in diameter to anchor the second portion 32 to the body cavity 52. ​​The temperature at which the stent 1 returns to its original shape is about 20°C to 37°C, and preferably 24°C±3°C.

[0022] As shown in Fig. 3(c), when the stent 1 is to be removed from the affected area, the base end 1b of the stent 1 is pulled, and the stent 1 is stretched. At this time, the main body 2 and the coil 3 are contracted in diameter, and the anchoring of the second portion 32 is released. In this way, the anchoring is automatically released by pulling the base end 1b of the stent 1, so that the stent 1 can be easily removed.

[0023] According to the stent 1 having the above configuration, the outer diameter r2 of the second portion 32 of the coil 3 is set to be larger than the outer diameter r1 of the first portion 31 of the coil 3, so that the second portion 32 expands in diameter as the main body portion 2 and the first portion 31 expand in diameter, and is anchored to the body cavity 52. ​​At this time, the side surface of the second portion 32 contacts the body cavity 52 and is anchored, so that irritation to the body cavity 52 can be reduced compared to when the edge contacts the body cavity 52 and is anchored. In addition, since the stent 1 is covered with the resin film 4, the body cavity 52 can be protected. Furthermore, according to the stent 1 of the present disclosure, the second portion 32 contracts in diameter by pulling the end portion 1b, so that the anchoring can be automatically released, and the stent 1 can be easily and safely removed from the body cavity. EXAMPLES

[0024] 4 and 5, the coil 3 of the stent 1 of Example 2 is formed from a flat metal wire having a rectangular cross-sectional shape. The coil 3 is inserted through the hook-braided holes 21 of the main body 2 and is braided into the main body 2 in a spiral shape.

[0025] The coil 3 includes multiple bent portions 33 formed by bending a flat wire in a mountain fold. Since the coil 3 is formed from a flat wire, it can be easily bent. The bent portions 33 function as anchors that hold the placement position of the stent 1. The bent portions 33 contact the body cavity 52 on the front or back surface of the flat wire, so that irritation to the body cavity 52 can be reduced compared to anchoring by a claw shape. In addition, the coil 3 with a rectangular cross section also contracts in diameter by pulling the base end portion 1b, like the coil 3 with a circular cross section, so that the body cavity 52 is not damaged when removed.

[0026] The cross-sectional area of ​​the flat wire is 0.01 mm2 to 0.03 mm2, the vertical length of the cross section of the flat wire is 0.05 mm to 0.15 mm, and the horizontal length of the cross section of the flat wire is 0.1 mm to 0.3 mm.

[0027] The present disclosure is not limited to the above-described embodiment, and the shape and configuration of each part can be appropriately modified without departing from the spirit of the present disclosure. [Explanation of symbols]

[0028] 1. Stent (a: distal end, b: proximal end) 2 Main unit 3 Coil 4. Resin Film 21 holes 31 Part 1 32 Part 2 33 Bend 51 Catheter 52 Body cavity r1 Outer diameter (1st part) r2 Outer diameter (second part) p1 pitch (first part) p2 pitch (second part)

Claims

1. The coil includes a cylindrical main body portion that is expandable and contractable in a radial direction, and a coil that is wound in a spiral shape around a side surface of the main body portion. A stent characterized in that the coil includes a first portion wound around the center of the main body and a second portion wound around an end of the main body, and the outer diameter of the second portion is larger than the outer diameter of the first portion.

2. The stent of claim 1 , wherein the pitch of the second portion is less than the pitch of the first portion.

3. The stent according to claim 1 , wherein an outer diameter of the second portion wound around one end of the main body is larger than an outer diameter of the second portion wound around the other end.

4. The stent of claim 1 , wherein the coil is rectangular in cross section.

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