Tube Stent

Abstract

Provided is a tube stent (1) that is a tube made from a resin material, that has a distal end (10a) and a proximal end (10b), and that has, along the lengthwise direction and in order from the distal end (10a), a first part (21), a second part (22), and a third part (23). The tube stent (1) is provided with a first edge (11) which is the proximal end of the first part (21), and a second edge (12) which is the proximal end of the second part (22). The thickness of the proximal end of the first part (21) is greater than the thickness of the distal end of the second part (22). The thickness of the second part (22) increases with increasing distance from the distal end side toward the proximal end side. The thickness of the distal end of the third part (23) is less than the thickness of proximal end of the second part (22).

Description

[Technical field]

[0001] The present invention relates to a tube stent having a flap for placement in a living body. [Background technology]

[0002] Tube stents such as indwelling tubes, particularly stents for bile ducts or pancreatic ducts, are medical devices for treating various diseases such as biliary atresia, jaundice, and biliary cancer, which are caused by narrowing or obstruction of the lumen of the body, such as the bile duct or pancreatic duct. Tube stents are placed in the lumen of the body for the purpose of draining bile from the bile duct to the duodenal side, and maintaining the inner diameter of the lumen by expanding the lesion at the narrowed or obstructed site from the inside. When tissue from the lesion, such as cancer cells, enters the lumen of the tube stent and the lumen of the tube is obstructed or narrowed, the tube must be replaced.

[0003] The tube stent may be made of either a metal material or a resin material. In the above-mentioned treatment, an in-vivo indwelling tube made of a resin material may be used.

[0004] First, a conventional tube stent will be described with reference to FIG. 2. As shown in FIG. 2, a tube stent 201 made of a resin material has a distal end 210a and a proximal end 210b, and extends in the longitudinal direction. The tube 201 is generally formed with a distal flap 231 by making a cut on the outer surface on the distal side, and a proximal flap 232 by making a cut on the outer surface on the proximal side (for example, Patent Documents 1 and 2). The proximal flap 232 and the distal flap 231 have a function of fixing the tube stent 201 at a predetermined position in a lumen in a living body. When the tube stent 201 is a bile duct stent, for example, the distal flap 231 is arranged distal to a narrowed portion (obstructed portion) of the bile duct so that the tube stent 201 does not fall off from the bile duct to the duodenal side, and the proximal flap 232 is arranged near the duodenal papilla outside the bile duct so that the tube stent 201 does not enter the bile duct. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2013-507185 [Patent Document 2] JP 2005-230415 A Summary of the Invention [Problem to be solved by the invention]

[0006] The purpose of tube stents is to perform bile drainage for narrowed areas of the bile duct. Conventional tube stents use flaps to prevent the tube stent from shifting from its designated position in the bile duct. However, the effect of the flaps in preventing the stent from shifting is not sufficient, and the current situation is that the tube stent does shift.

[0007] The tube stent disclosed in Patent Document 1 includes a magnetic element and a stopper member on a tube. The outer diameter of the stopper member is larger than the outer diameter of the portion from the end of the tube to the end of the stopper member, and the magnetic element and the stopper member protrude from the surface of the tube, making it difficult to deliver the stent to a desired placement site.

[0008] The tube stent disclosed in Patent Document 2 has multiple grooves formed on the outer surface of the tube body along the longitudinal direction. These grooves are intended to ensure the flow of bodily fluids outside the tube and to enable probabilistic use for a longer period of time than conventional stents. However, these grooves are not provided for the purpose of preventing the stent from shifting out of position relative to the narrowed area in the body, and there is a problem in that some measure is required to prevent the stent from shifting out of position after placement.

[0009] The present invention has been made in consideration of the above-mentioned circumstances, and its object is to provide a tube stent that can prevent the tube stent from moving without increasing the outer diameter of the tube stent placed in the living body too much, and can smoothly pass through a lesion such as a stenosis. [Means for solving the problem]

[0010] The tube stent that can solve the above problem is a tube formed of a resin material and has a distal end and a proximal end, and has, in the longitudinal direction from the distal end, a first part, a second part, and a third part, with a first edge at the proximal end of the first part and a second edge at the proximal end of the second part, the thickness of the proximal end of the first part is thicker than the thickness of the distal end of the second part, the thickness of the second part is thicker from the distal end side to the proximal end side, and the thickness of the distal end of the third part is thinner than the thickness of the proximal end of the second part.

[0011] The tube stent of the present invention preferably has a plurality of second portions in the longitudinal direction. The first edge and the second edge are preferably provided around the entire circumference of the outer surface of the tube.

[0012] In addition, the difference between the maximum outer diameter and the minimum outer diameter of the tube of the tube stent of the present invention is preferably 30% or less. It is preferable that the outer diameter of the proximal end of the first part or the outer diameter of the proximal end of the second part is the maximum outer diameter, and the outer diameter of the distal end of the first part or the outer diameter of the distal end of the second part is the minimum outer diameter. Alternatively, it is preferable that the outer diameter of any part of the third part is the maximum outer diameter, and the outer diameter of the distal end of the first part or the outer diameter of the distal end of the second part is the minimum outer diameter. Effect of the Invention

[0013] In the tube stent of the present invention, the wall thickness of the proximal end of the first section is thicker than the wall thickness of the distal end of the second section, the wall thickness of the second section increases from the distal end side to the proximal end side, and the wall thickness of the distal end of the third section is thinner than the wall thickness of the proximal end of the second section, so that an edge that catches on a stenosis can be provided without making the outer diameter of the tube stent placed in the living body too large. Therefore, the tube stent can be prevented from moving after placement and can be smoothly passed through a lesion such as a stenosis. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a side view according to an embodiment of the present invention. [Diagram 2] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention will be described in more detail below based on the following embodiments, but the present invention is not limited to the following embodiments, and can be modified as long as it meets the purpose described above and below, and all of these modifications are included in the technical scope of the present invention. In addition, hatching and component symbols may be omitted in each drawing for convenience, but in such cases, the specification and other drawings should be referred to. In addition, the dimensions of various components in the drawings may differ from the actual dimensions because priority is given to helping understand the features of the present invention.

[0016] In order to deliver the tube stent to the affected area, the tube stent is attached to a delivery system (delivery device) such as a catheter having a site for placing the tube stent.

[0017] In the present invention, the proximal end refers to the direction toward the user (operator) with respect to the extending direction of the tube stent, and the distal end refers to the opposite side of the proximal side (i.e., the direction toward the treatment target side). In addition, the direction from the proximal end side to the distal end side of the tube stent is called the longitudinal direction.

[0018] <Overall structure of tube stent> As shown in Fig. 1, the tube stent 1 of the present invention is a tube having a distal end 10a and a proximal end 10b, and having a first section 21, a second section 22, and a third section 23 in that order from the distal end 10a. The distal end 10a is an end portion disposed on the distal side of a delivery system, and the proximal end 10b is disposed on the proximal side. In a living body, the distal end 10a is disposed deep inside the body.

[0019] The tube stent 1 is formed of a resin material. Examples of the resin material include polyamide resin, polyester resin, polyurethane resin, polyolefin resin, fluorine resin, vinyl chloride resin, silicone resin, and natural rubber. These may be used alone or in combination of two or more. As the resin material for forming the tube stent 1, polyamide resin, polyurethane resin, polyolefin resin, and fluorine resin are preferably used. Since the tube stent 1 has at least one of polyamide resin, polyurethane resin, polyolefin resin, and fluorine resin, the tube stent 1 can have both biocompatibility and flexibility.

[0020] The length of the tube stent 1 in the longitudinal direction is not particularly limited, but is preferably 3 cm or more and 18 cm or less. Of the total length of the tube stent 1 in the longitudinal direction, the first section 21 is preferably 10 mm to 20 mm, the second section 22 is preferably 1 mm to 5 mm, and the third section 23 is preferably the remaining section. Although not shown, flaps may be provided in the first section 21 and the third section 23, and the length of the flaps is preferably 5 mm to 15 mm. The second section 22 may be provided multiple times. If the second section 22 is too long, kinking is likely to occur, so it is desirable that the second section 22 is shorter in length than the first section 21 and the third section 23.

[0021] The first edge 11 is located at the proximal end of the first portion 21, and the second edge 12 is located at the proximal end of the second portion 22. The first edge 11 is an edge of the first portion 21 formed by making the wall thickness of the proximal end of the first portion 21 thicker than the wall thickness of the distal end of the second portion 22. The second edge 12 is an edge of the second portion 22 formed by making the wall thickness of the proximal end of the second portion 22 thicker than the wall thickness of the distal end of the third portion 23. The first edge 11 may be formed over the entire outer circumference of the tube stent 1, or may be formed on a part of the outer circumference of the tube stent 1. When the first edge 11 is formed over the entire outer circumference of the tube stent 1, the entire wall thickness of the proximal end of the first portion 21 is thicker than the entire wall thickness of the distal end of the second portion 22. When the first edge 11 is not formed over the entire circumference of the tube stent 1, that is, when the first edge 11 is formed on a part of the circumference of the tube stent 1, at least a part of the wall thickness of the proximal end of the first part 21 is thicker than at least a part of the wall thickness of the distal end of the second part 22. That is, a part or all of the wall thickness of the proximal end of the first part 21 is thicker than a part or all of the wall thickness of the distal end of the second part 22. The same is true for the second edge 12, where a part or all of the wall thickness of the proximal end of the second part 22 is thicker than a part or all of the wall thickness of the distal end of the third part 23. In other words, the wall thickness of the distal end of the third part 23 is thinner than the wall thickness of the proximal end of the second part 22.

[0022] In the present invention, by providing the tube stent 1 with multiple edges such as the first edge 11 and the second edge 12, these edges can effectively catch on the narrowed portion, preventing the tube stent 1 from moving and becoming displaced. Furthermore, if the edges catch on the lumen in the body during delivery of the tube stent 1, it becomes difficult to deliver the tube stent 1 to the target site, but the first edge 11 and the second edge 12 of the present invention are shaped so that the thickness of the tube stent 1 is first thinned and then thickened at the edge portions, and therefore the first edge 11 and the second edge 12 are shaped so that they are unlikely to catch on the lumen in the body during delivery of the tube stent 1.

[0023] The thickness of the second portion 22 increases from the distal end side toward the proximal end side. By forming the second edge 12 by tapering the protrusion and providing the second edge 12 on the second portion 22, the second edge 12 is less likely to get caught on the stenosis when the tube stent 1 is transported (when breaking through the stenosis). The thickness of the distal end of the third portion 23 is thinner than the thickness of the proximal end of the second portion 22. As a result, the second edge 12 is formed at the proximal end of the second portion 22.

[0024] In the present invention, by providing multiple edges on the main body of the tube stent 1, it is possible to prevent the tube stent 1 from moving relative to the stenosis and becoming displaced. If protrusions or the like are directly provided on the tube stent body to prevent the tube stent from being displaced as in the past, the protrusions protrude from the surface of the tube stent, and the outer diameter of the part where the protrusions are provided becomes large. Therefore, the conventional tube stents have a problem in that they are difficult to deliver to the desired placement site. On the other hand, in the present invention, by providing the first edge 11 and the second edge 12, it is possible to prevent the tube stent 1 from moving without increasing the outer diameter of the main body of the tube stent 1 too much.

[0025] It is preferable that there are a plurality of second edges 12. Having a plurality of second edges 12 means that a plurality of tapered structures such as the second portion 22 are provided in the longitudinal axis direction. In other words, by providing a plurality of second portions 22, it is possible to provide a plurality of second edges 12. By having a plurality of second edges 12, when the tube stent 1 is placed at an arbitrary position, the plurality of second edges 12 can prevent the tube stent 1 from moving even in a lesion having a plurality of stenosis portions or a lesion such as a neointima having a soft and slippery surface.

[0026] The first edge 11 and the second edge 12 may be provided on the entire circumference of the outer surface of the tube stent 1. By providing the first edge 11 and the second edge 12 on the entire circumference of the outer surface of the tube stent 1, the tube stent 1 can be prevented from moving by the first edge 11 and the second edge 12 present on the entire circumference of the outer surface of the tube stent 1, regardless of the position of the lesion in the radial direction of the lumen in the living body. The first edge 11 and the second edge 12 may be provided on a part of the outer circumference of the tube stent 1. In this case, the first edges 11 and the second edges 12 may be arranged in a row on the outer circumference of the tube stent 1, and the first edges 11 and the second edges 12 may be striped in the longitudinal direction.

[0027] By providing a difference in thickness between the first edge 11 and the distal end of the second portion 22, and also between the second edge 12 and the distal end of the third portion 23, the first edge 11 and the second edge 12 are more likely to catch on the lesion, enhancing the effect of preventing movement of the tube stent 1. Note that it is desirable for the difference in thickness between the first edge 11 and the distal end of the second portion 22, and the difference in thickness between the second edge 12 and the distal end of the third portion 23 to be large.

[0028] The first edge 11 is formed by making the wall thickness of the proximal end of the first portion 21 thicker than the wall thickness of the distal end of the second portion 22. The wall thickness of the second portion 22 is made thicker from the distal end side toward the proximal end side, and the second edge 12 is tapered, so that the second edge 12 is less likely to get caught in the stenosis when the tube stent 1 is transported (when breaking through the stenosis). The wall thickness of the distal end of the third portion 23 is made thinner than the wall thickness of the proximal end of the second portion 22 to form the second edge 12, and the effect of preventing the tube stent 1 from moving is enhanced by increasing the difference in outer diameter between the second edge 12 and the distal end of the third portion 23.

[0029] The difference between the maximum outer diameter and the minimum outer diameter of the tube stent 1 is preferably 30% or less. By making the difference between the maximum outer diameter and the minimum outer diameter of the tube stent 1 30% or less, the difference in outer diameter between the distal ends of the first edge 11 and the second part 22 and the difference in outer diameter between the distal ends of the second edge 12 and the third part 23 can be increased, and the effect of preventing the tube stent 1 from moving can be improved. It is preferable that the difference between the maximum outer diameter and the minimum outer diameter of the tube stent 1 is large, but if the difference in outer diameter exceeds 30%, kinks are likely to occur between the distal ends of the first edge 11 and the second part 22, or between the distal ends of the second edge 12 and the third part 23, so it is preferable that the difference is 30% or less. The lower limit of the difference between the maximum outer diameter and the minimum outer diameter of the tube stent 1 is preferably 10% or more, more preferably 13% or more, and even more preferably 15% or more.

[0030] It is preferable that the outer diameter of the proximal end of the first portion 21 or the outer diameter of the proximal end of the second portion 22 is the maximum outer diameter, and the outer diameter of the distal end of the first portion 21 or the outer diameter of the distal end of the second portion 22 is the minimum outer diameter. By having the maximum outer diameter of the tube stent 1 be the outer diameter of the proximal end of the first portion 21 or the outer diameter of the proximal end of the second portion 22, and the minimum outer diameter of the tube stent 1 be the outer diameter of the distal end of the first portion 21 or the outer diameter of the distal end of the second portion 22, the overall rigidity of the tube stent 1 can be balanced.

[0031] It is also preferable that the outer diameter of any location of the third portion 23 is the maximum outer diameter, and the outer diameter of the distal end of the first portion 21 or the outer diameter of the distal end of the second portion 22 is the minimum outer diameter. By having the maximum outer diameter of the tube stent 1 be the outer diameter of any location of the third portion 23, and the minimum outer diameter of the tube stent 1 be the outer diameter of the distal end of the first portion 21 or the outer diameter of the distal end of the second portion 22, it is possible to provide a tube stent 1 with a well-balanced overall rigidity.

[0032] <Manufacturing method of tube stents> The edges of the tube stent 1 of the present invention can be formed by various methods. When a thermoplastic resin is used for the tube, the tube can be heated and shaped using a mold to provide tapers or edges on the outer surface of the tube. The tube stent 1 of the present invention can also be formed by joining together short tubes with tapers or edges.

[0033] Alternatively, tapers or edges can be provided by scraping or cutting the outer surface of the tube with a blade. Since it is preferable that the outer surface and the inner surface of the edge portion of the tube stent 1 do not communicate with each other, it is preferable to process the edge portion after passing a core material or the like through the lumen of the tube.

[0034] This application claims the benefit of priority based on Japanese Patent Application No. 2020-144582, filed on August 28, 2020. The entire contents of the specification of Japanese Patent Application No. 2020-144582, filed on August 28, 2020, are incorporated by reference into this application. [Explanation of symbols]

[0035] 1: Tube stent 10a: Distal end 10b: Proximal end 11: First edge 12: 2nd edge 21: Part 1 22: Part 2 23:Part 3 201: Tube stent 210a: Distal end 210b: Proximal end 231: Distal flap 232: Proximal flap

Claims

1. A tube is formed of a resin material, has a distal end and a proximal end, and has, in a longitudinal direction, a first portion, a second portion, and a third portion in that order from the distal end, and has a first edge at a proximal end of the first portion and a second edge at a proximal end of the second portion; a wall thickness of the proximal end of the first portion is greater than a wall thickness of the distal end of the second portion; The thickness of the second portion is tapered from the distal end to the proximal end, a wall thickness of the distal end of the third portion is less than a wall thickness of the proximal end of the second portion; A tube stent, wherein the outer diameter of the proximal end of the second portion is greater than the outer diameter of the proximal end of the first portion.

2. The tube stent according to claim 1 , wherein the second portion is provided in a plurality of portions in the longitudinal direction.

3. 3. The tube stent according to claim 1, wherein the first edge and the second edge are provided around the entire outer surface of the tube.

4. 4. A tube stent according to claim 1, wherein the difference between the maximum outer diameter and the minimum outer diameter of the tube is 30% or less.

5. A tube stent as described in any one of claims 1 to 4, wherein the outer diameter of the proximal end of the first part or the outer diameter of the proximal end of the second part is the maximum outer diameter, and the outer diameter of the distal end of the first part or the outer diameter of the distal end of the second part is the minimum outer diameter.

6. A tube stent as described in any one of claims 1 to 4, wherein the outer diameter of any point of the third portion is the maximum outer diameter, and the outer diameter of the distal end of the first portion or the outer diameter of the distal end of the second portion is the minimum outer diameter.

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