stent

Abstract

Effectively suppresses stent displacement. [Solution] The stent comprises a cylindrical part formed from braided wire, a radiopaque marker attached to the wire, and a resin cover member placed over the marker.

Description

[Technical Field]

[0001] The technology disclosed in the present specification relates to stents. [Background Art]

[0002] Stent placement is used when a stenosis or an occlusion (hereinafter collectively simply referred to as "stenosis") occurs in a body lumen. Stent placement is a procedure for securing a lumen by placing a stent at either the position of the stenosis or a position bypassing the stenosis. Examples of body lumens include digestive organs such as the bile duct, gallbladder, pancreas, esophagus, duodenum, small intestine, and large intestine, as well as blood vessels, ureters, and tracheas.

[0003] A stent has a cylindrical portion formed of braided wires (see, for example, Patent Document 1). As a method for braiding wires, for example, hook braiding, cross braiding, a mixture of both, or the like is used. When a compressive force acts on the cylindrical portion in the radial direction, the diameter of the cylindrical portion decreases; when the compressive force is released, the cylindrical portion expands back to its pre-compression state due to elasticity.

[0004] The stent is mounted on a delivery system in a diameter-reduced state and conveyed to the placement position. When released from the delivery system, the stent self-expands and is placed in that expanded state. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Unexamined Patent Publication No. 2022-177774 [Summary of the Invention] [Problem to be Solved by the Invention]

[0006] If a stent shifts position after placement, its function may be impaired, or other problems may arise. Therefore, stents are required to have the ability to stably maintain their position after placement. Known stents have room for improvement in terms of suppressing stent displacement.

[0007] This specification discloses a technology capable of solving the above-mentioned problems. [Means for solving the problem]

[0008] The stent disclosed herein comprises a tubular portion formed of braided wire, a radiopaque marker attached to the wire, and a resin cover member placed over the marker. [Brief explanation of the drawing]

[0009] [Figure 1] Explanatory diagram showing the appearance of the stent in this embodiment [Figure 2] This diagram schematically shows the longitudinal section of the stent in this embodiment. [Figure 3] Diagram illustrating the manufacturing method of a stent. [Figure 4] Diagram illustrating the manufacturing method of a stent. [Figure 5] Diagram illustrating the manufacturing method of a stent. [Figure 6] Diagram illustrating the manufacturing method of a stent. [Figure 7] Diagram illustrating the manufacturing method of a stent. [Figure 8] Diagram illustrating the manufacturing method of a stent. [Modes for carrying out the invention]

[0010] (Configuration of stent 10) Figure 1 is an explanatory diagram showing the external appearance of the stent 10 in this embodiment. Figure 2 is an explanatory diagram schematically showing the longitudinal cross-section of the stent 10 in this embodiment.

[0011] Stent 10 is a medical device that, when a narrowing occurs in an internal lumen, is placed either at the location of the narrowing or at a location that bypasses the narrowing to secure the lumen. Internal lumenes include, for example, digestive organs such as the bile duct, gallbladder, pancreas, esophagus, duodenum, small intestine, and large intestine, blood vessels, ureters, and trachea. The stent 10 in this embodiment is a self-expanding stent that shrinks in diameter when a compressive force is applied radially, and expands back to its pre-compression state by elasticity when the compressive force is released. Figures 1 and 2 show the stent 10 in an expanded state.

[0012] The stent 10 includes a cylindrical portion 110, a marker 120, a cover member 130, and a coating 200.

[0013] The cylindrical portion 110 is a member that becomes cylindrical along the central axis Ax when the stent 10 is expanded. The length of the cylindrical portion 110 along its longitudinal direction (Z-axis direction) is, for example, 20 mm or more and 250 mm or less. The cross-sectional shape of the cylindrical portion 110 is, for example, circular.

[0014] The cylindrical portion 110 has a small-diameter portion 111 and a large-diameter portion 112. The small-diameter portion 111 forms the central part of the stent 10 in the longitudinal direction. The large-diameter portions 112 are located at both ends of the small-diameter portion 111 and form both ends of the stent 10. The outer diameter of the large-diameter portion 112 is larger than the outer diameter of the small-diameter portion 111. In this embodiment, the outer diameter of the large-diameter portion 112 increases as it moves away from the boundary with the small-diameter portion 111. That is, the large-diameter portion 112 has a so-called flared shape. The outer diameter of each part of the cylindrical portion 110 is strictly the outer diameter of the cylindrical portion, and if there is a portion that protrudes outward from the outer circumference of the cylindrical portion, it is the outer diameter of the portion excluding the protruding portion. The large-diameter portion 112 mainly functions as an anchor that contacts the inner wall of the lumen when the cylindrical portion 110 expands, thereby suppressing displacement of the stent 10. The outer diameter of the small-diameter section 111 when expanded is, for example, 4 mm or more and 80 mm or less. The maximum outer diameter of the large-diameter section 112 when expanded is, for example, 6 mm or more and 100 mm or less.

[0015] The cylindrical portion 110 is formed of a braided wire W. Any braiding method including hook braiding and cross braiding can be employed as the braiding method for the cylindrical portion 110. In the present embodiment, hook braiding is adopted throughout the entire cylindrical portion 110.

[0016] In the cylindrical portion 110, cells CE, which are substantially diamond-shaped voids surrounded by the wire W, are regularly arranged. The cylindrical portion 110 has a plurality of intersecting portions 102 and a plurality of entangled portions 101. The intersecting portions 102 are locations where the wires W intersect each other without becoming entangled with each other. The entangled portions 101 are locations where two bent portions of the wire W intersect in a hook shape and become entangled with each other. A hole 11 surrounded by the two bent portions and penetrating in the radial direction of the cylindrical portion 110 is formed in each entangled portion 101. In the entangled portion 101, the two bent portions cannot be separated. The two bent portions are connected so as to be relatively movable. Therefore, the cylindrical portion 110 can be compressed in the longitudinal direction or curved.

[0017] In the present embodiment, the cylindrical portion 110 is formed from a single wire W. However, the cylindrical portion 110 may be formed from a plurality of wires W. The wire W is formed of a superelastic alloy such as a nickel-titanium (Ni-Ti) alloy, for example. The wire W may be formed of other metals such as stainless steel, tantalum, titanium, cobalt-chromium alloy, magnesium alloy or the like, or may be formed of a resin such as polyolefin, polyester, fluororesin or the like. The outer diameter of the wire W is, for example, not less than 0.05 mm and not more than 0.5 mm.

[0018] The marker 120 is a member for improving the visibility of the stent 10 in a radioscopic image. The marker 120 is formed of a radiopaque material such as platinum, gold, tungsten, iridium, or alloys thereof. The marker 120 is attached to a wire W that forms the cylindrical portion 110. In the present embodiment, a plurality of markers 120 are arranged on the large-diameter portion 112 of the cylindrical portion 110. The marker 120 may be arranged on the small-diameter portion 111 of the cylindrical portion 110. Due to the presence of the marker 120, irregularities are provided on the outer circumferential surface of the cylindrical portion 110. The marker 120 is, for example, a cylindrical body like a coil body (see FIG. 3 and the like described later). The marker 120 is attached to the wire W in a state where the wire W penetrates through a hollow portion of the marker 120.

[0019] The cover member 130 is a member that is covered over the marker 120 to increase the diameter at the installation position of the marker 120. In the present embodiment, all the markers 120 are covered with the cover members 130. The cover member 130 is formed of a resin material. As a material for forming the cover member 130, for example, polyurethane resin or silicone resin is used. The cover member 130 is, for example, a cylindrical body, and is formed so as to cover substantially the entire outer circumference of the marker 120. Due to the presence of the cover member 130, the degree of irregularities on the outer circumferential surface of the cylindrical portion 110 increases. The thickness of the cover member 130 is, for example, 0.2 mm or more and 2.0 mm or less, and may be 0.5 mm or more and 1.0 mm or less. The thickness of the cover member 130 is larger than the film thickness of a coating 200 described later.

[0020] The coating 200 is a resin film that covers the cylindrical portion 110 and the cover member 130. As a material for forming the coating 200, for example, polyurethane resin or silicone resin is used. The film thickness of the coating 200 is, for example, 10 µm or more and 150 µm or less, and may be 20 µm or more and 100 µm or less.

[0021] The cover member 130 may contain the same type of resin material as the coating 200. For example, both the cover member 130 and the coating 200 may be formed from silicone resin. The cover member 130 may contain a resin material that is more easily hydrolyzed than the material of the coating 200. For example, if the coating 200 contains silicone resin, the cover member 130 may contain at least one of polyurethane resin, nylon resin, and nylon elastomer, which are more easily hydrolyzed than silicone resin.

[0022] The multiple cover members 130 of the stent 10 are arranged so that they do not come into contact with each other when the stent 10 is reduced in diameter. In other words, the first cover member 130 is arranged so that it moves away from the second cover member 130 when the stent 10 is reduced in diameter. For example, as shown in Figure 1, each cover member 130 is attached to one side of a cell CE in the cylindrical portion 110. In each cell CE of the cylindrical portion 110, there are no locations where cover members 130 are attached to both of two adjacent sides. That is, the multiple cover members 130 are arranged in the cylindrical portion 110 such that two cover members 130 are not positioned on two adjacent sides of a cell CE in the cylindrical portion 110. In other words, the first cover member 130 is positioned on the first side of a cell CE in the cylindrical portion 110, and the second cover member 130 is positioned on the second side of the cell CE, which is isolated from the first side.

[0023] (Method for manufacturing stent 10) Figures 3 to 8 are explanatory diagrams showing the manufacturing method of the stent 10.

[0024] As shown in Figure 3, the worker inserts the core rod MA into the hollow part of the cylindrical marker 120. The marker 120 is, for example, a coil. The core rod MA is, for example, made of stainless steel.

[0025] Next, as shown in Figure 4, the worker dips the marker 120 attached to the core MA into a solution LS of resin material for forming the cover member 130, thereby forming a film of the resin material solution LS on the marker 120. The solution LS is, for example, a solution of silicone resin, polyurethane resin, nylon resin, nylon elastomer, etc. After that, the worker removes the marker 120 from the container of solution LS and forms the cover member 130 on the outer circumference of the marker 120 by heat treatment to heat-cur the film of solution LS, or by heating and drying the solvent or air-drying.

[0026] Next, as shown in Figure 5, the worker makes a longitudinal slit CL in the cover member 130 and removes the cover member 130 from the marker 120. The slit CL can be formed, for example, using a feather blade. As shown in Figure 6, the removed cover member 130 has a hollow portion 132 and a longitudinal slit CL has been formed. The worker produces a large number of cover members 130 in this manner.

[0027] Next, as shown in Figure 7, the worker weaves the wire W to create a cylindrical section 110 having a small diameter section 111 and a large diameter section 112. The weaving method for the wire W is, for example, hook weaving or cross weaving. When weaving the wire W, the worker attaches the marker 120 to the wire W by passing the wire W through the hollow part of the marker 120. Once the weaving of the wire W is complete, the worker sets the shape of the cylindrical section 110 by heat treatment.

[0028] Next, as shown in Figure 8, the worker places the cover member 130, which was made by the method described above, over each marker 120 attached to the cylindrical portion 110. That is, the worker widens the slit CL of the cover member 130 and places the marker 120 into the hollow portion 132 of the cover member 130 through the slit CL, thereby placing the cover member 130 over the marker 120. Alternatively, the worker may place the cover member 130 over the marker 120 before weaving the wire W to form the cylindrical portion 110, and then attach the marker 120 with the cover member 130 over it to the wire W when weaving the wire W.

[0029] Next, the worker dips the cylindrical portion 110, to which the marker 120 and cover member 130 are attached, into a solution of resin material to form a coating 200, thereby forming a film of resin material. The solution is, for example, a silicone resin solution. After that, the worker removes the cylindrical portion 110 from the solution container and heat-treats it to thermally cure the film of solution, thereby forming a coating 200 that covers the cylindrical portion 110 and the cover member 130. For example, the stent 10 of this embodiment is manufactured by the above method.

[0030] (Effects of this embodiment) As described above, the stent 10 of this embodiment comprises a cylindrical portion 110 formed from a braided wire W, a radiopaque marker 120 attached to the wire W, and a resin cover member 130 placed over the marker 120. Therefore, according to the stent 10 of this embodiment, the diameter of the installation location of the marker 120 in the cylindrical portion 110 is increased by the cover member 130, and the degree of unevenness on the outer surface of the cylindrical portion 110 increases. Consequently, the anchoring performance of the stent 10 is improved, and displacement of the stent 10 is effectively suppressed.

[0031] In the stent 10 of this embodiment, the cylindrical portion 110 includes a small-diameter portion 111 and a large-diameter portion 112 having an outer diameter larger than the outer diameter of the small-diameter portion 111, and the marker 120 and cover member 130 are arranged at least on the large-diameter portion 112. Therefore, according to the stent 10 of this embodiment, the presence of the cover member 130 arranged on the large-diameter portion 112 increases the degree of unevenness on the outer circumferential surface of the large-diameter portion 112, effectively improving the anchoring performance of the stent 10 and further effectively suppressing displacement of the stent 10.

[0032] In the stent 10 of this embodiment, a resin coating 200 is further provided to cover the cylindrical portion 110 and the cover member 130, and the thickness of the cover member 130 is greater than the thickness of the coating 200. Therefore, according to the stent 10 of this embodiment, the presence of the cover member 130 effectively increases the degree of unevenness on the outer surface of the cylindrical portion 110, effectively improving the anchoring performance of the stent 10 and further effectively suppressing displacement of the stent 10.

[0033] In the stent 10 of this embodiment, the cover member 130 may contain the same type of resin material as the coating 200. This improves the adhesion between the cover member 130 and the coating 200, and suppresses peeling of the coating 200.

[0034] In the stent 10 of this embodiment, the cover member 130 may contain a resin material that is more susceptible to hydrolysis than the material of the coating 200. This reduces the resistance of the cover member 130 when removing the stent 10, improving the ease of removal of the stent 10.

[0035] In the stent 10 of this embodiment, the cover member 130 may contain at least one of polyurethane resin, nylon resin, and nylon elastomer. In this case, since these resins are relatively easy to hydrolyze, they hydrolyze over time after implantation, reducing the resistance of the cover member 130 when removing the stent 10, and improving the ease of removal of the stent 10.

[0036] The stent 10 of this embodiment includes a plurality of cover members 130, and the first cover member 130 is positioned so as to move away from the second cover member 130 when the stent 10 is reduced in diameter. Therefore, the stent 10 of this embodiment can suppress the decrease in diameter reduction caused by the presence of the cover members 130. In the stent 10 of this embodiment, a cell CE, which is a substantially rhomboid void surrounded by a wire W, is formed in the cylindrical portion 110, and the first cover member 130 may be positioned on the first side of the cell CE, and the second cover member 130 may be positioned on the second side of the cell CE, which is isolated from the first side. In this way, the plurality of cover members 130 can be positioned so as not to come into contact with each other when the stent 10 is reduced in diameter.

[0037] (modified version) The technologies disclosed herein are not limited to the embodiments described above and can be modified in various forms without departing from their essence, for example, the following modifications are possible.

[0038] The configuration of the stent 10 in the above embodiment is merely an example and can be modified in various ways. The arrangement of the marker 120 and cover member 130 in the above embodiment can be changed arbitrarily. For example, in the above embodiment, the cover member 130 may be placed over only a portion of the marker 120.

[0039] In the above embodiment, the large-diameter portion 112 of the cylindrical portion 110 may include a portion whose outer shape is substantially constant. In the above embodiment, the outer diameter of the cylindrical portion 110 may be substantially constant along its entire length.

[0040] In the above embodiment, the stent 10 does not need to have a coating 200. In the above embodiment, the forming material of each component is merely an example and can be changed in various ways. The manufacturing method of the stent 10 in the above embodiment is merely an example and can be modified in various ways.

Claims

1. A stent (10), A cylindrical part (110) formed by braided wire (W), A radiopaque marker (120) is attached to the wire (W), A resin cover member (130) is placed over the marker (120), A stent (10) equipped with [a specific feature].

2. A stent (10) according to claim 1, The cylindrical portion (110) includes a small diameter portion (111) and a large diameter portion (112) having an outer diameter larger than the outer diameter of the small diameter portion (111). The stent (10) is provided with the marker (120) and the cover member (130) positioned at least on the large diameter portion (112).

3. A stent (10) according to claim 1 or claim 2, The tubular portion (110) and the cover member (130) are further covered by a resin coating (200), A stent (10) in which the thickness of the cover member (130) is greater than the thickness of the coating (200).

4. A stent (10) according to claim 3, The cover member (130) is a stent (10) containing the same type of resin material as the coating (200).

5. A stent (10) according to claim 3, The cover member (130) is a stent (10) containing a resin material that is more susceptible to hydrolysis than the material of the coating (200).

6. A stent (10) according to any one of claims 1 to 5, The cover member (130) is a stent (10) comprising at least one of polyurethane resin, nylon resin, and nylon elastomer.

7. A stent (10) according to any one of claims 1 to 6, The cover member (130) is a first cover member, Furthermore, it is equipped with a second cover member (130), The first cover member (130) is positioned such that it separates from the second cover member when the stent (10) is reduced in diameter.

8. A stent (10) according to claim 7, The cylindrical portion (110) has a cell (CE) which is a roughly rhomboid-shaped void surrounded by the wire (W). A stent (10) wherein the first cover member (130) is positioned on a first side of the cell (CE), and the second cover member (130) is positioned on a second side of the cell (CE) that is isolated from the first side.

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