Bile duct tube stent

Abstract

To provide a tube stent for a bile duct in which a kink is hard to be generated even in use in a bent state.SOLUTION: Provided is a tube stent for a bile duct formed of a resin material. The tube stent includes a groove along a circumferential direction in at least a part of an outer surface thereof. The depth of the groove is 1.3 to 5.5% with respect to the thickness of the tube stent.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a tube stent for a bile duct formed of a resin material.

Background Art

[0002] Stents are generally known as medical devices that are placed in a stenotic or occluded lesion of a biological lumen such as a blood vessel or a digestive tract such as a bile duct or a pancreatic duct to treat various diseases caused by stenosis or occlusion of the lumen, expand the lesion from the inside, and maintain the lumen inner diameter. For example, by placing a bile duct stent to maintain the bile duct inner diameter at the lesion, the lesion at the stenotic or occluded site can be expanded from the inside, enabling bile to be discharged from the bile duct to the duodenal side, and various diseases such as biliary obstruction, jaundice, and bile duct cancer caused by stenosis or occlusion of the bile duct can be treated.

[0003] Such bile duct stents include those formed of a metal material and those formed of a resin material. A bile duct stent formed of a metal material has a large diameter and is difficult to occlude, but has the demerit of being difficult to remove or replace. On the other hand, a tube stent for a bile duct formed of a resin material has a small diameter and is easily occluded, but can be easily removed or replaced.

[0004] In addition to being used in a straight state, stents are also used in a bent state, so flexible bendability is required, and it is required that no kink occurs even in a bent state. A medical tubular body having kink resistance is described in Patent Document 1. This medical tubular body is a tubular body including at least a two-layer structure of an inner layer and an outer layer, the outer layer is composed of a material harder than the inner layer, and has a groove forming a spiral or a ring on the outer periphery of the tubular body at a depth reaching from the outer layer to the inner layer but not penetrating the inner layer, and the dynamic compliance defined by ISO 7198 satisfies 1% / 100 mmHg or more.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2003-275228 [Overview of the project] [Problems that the invention aims to solve]

[0006] The aforementioned Patent Document 1 did not focus on the depth of the grooves formed on the surface of the medical tubular body, leaving room for further improvement in kink resistance.

[0007] This invention was made in view of the circumstances described above, and its purpose is to provide a bile duct tube stent that does not kink even when used in a bent state. [Means for solving the problem]

[0008] The present invention is as follows: [1] A bile duct tube stent formed of a resin material, wherein the tube stent has grooves along the circumferential direction on at least a portion of its outer surface, and the depth of the grooves is 1.3 to 5.5% of the wall thickness of the tube stent. [2] The groove is spiral or annular in shape, the bile duct tube stent as described in [1]. [3] The tube stent for the bile duct according to [1] or [2], wherein the side of the tube stent positioned toward the duodenum is designated as the proximal side and the opposite side as the distal side, the tube stent has locking flaps in the distal and proximal portions, and the groove is formed in a region proximal to the region where the locking flap is present in the distal portion and distal to the region where the locking flap is present in the proximal portion. [4] The tube stent for the bile duct according to any one of [1] to [3], wherein the side of the tube stent that is positioned on the duodenal side is the proximal side and the opposite side is the distal side, the tube stent has locking flaps in the distal and proximal portions, and does not have the groove distal to the area where the locking flap is present in the distal portion, and proximal to the area where the locking flap is present in the proximal portion. [5] The bile duct tube stent according to [3] or [4], wherein the locking flap has the groove on its surface. [6] The bile duct tube stent according to any one of [1] to [5], wherein the grooves are 10 to 30 per centimeter of the longitudinal length of the tube stent. [7] The tube stent has through holes that penetrate the outer surface and inner surface of the tube stent, and the through holes are in contact with two or more grooves, as described in any of [1] to [6]. [Effects of the Invention]

[0009] The bile duct tube stent of the present invention has grooves formed along the circumferential direction on at least a portion of the outer surface of the tube stent, and the depth of these grooves is appropriately controlled, so that kinking can be suppressed even when used in a bent state. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a plan view showing one embodiment of the tube stent according to the present invention. [Figure 2] Figure 2 is a plan view showing one example configuration of a delivery system for delivering a tube stent according to the present invention to a lesion. [Figure 3] Figure 3 is a photograph used as a substitute for a drawing, showing the appearance of the test specimen prepared in the example. [Figure 4] Figure 4 is a photograph used as a substitute for a drawing, showing an example of measuring the groove width and pitch of a test specimen prepared in the example. [Figure 5] Figure 5 is a photograph used as a substitute for a drawing, showing the appearance of the raw material tube and test specimen when they are bent. [Modes for carrying out the invention]

[0011] The present invention will be described more specifically below based on embodiments, but the present invention is not limited by the embodiments described below, and it is of course possible to implement modifications within the scope that is consistent with the spirit described above and below, and all such modifications are included within the technical scope of the present invention. In addition, hatching and component reference numerals may be omitted in the drawings for convenience, in which case please refer to the specification or other drawings. Furthermore, the dimensions of various components in the drawings may differ from the actual dimensions, as priority is given to helping to understand the features of the present invention.

[0012] The bile duct tube stent according to the present invention is made of a resin material, and the tube stent has a groove along the circumferential direction on at least a portion of its outer surface, the depth of which is 1.3 to 5.5% of the wall thickness of the tube stent. When forming a groove along the circumferential direction on at least a portion of the outer surface of the tube stent, kink resistance can be improved by controlling the depth of the groove to an appropriate range with respect to the wall thickness of the tube stent.

[0013] As the resin material for forming the tube stent, known resins can be used, such as polyamide resins such as nylon; polyether polyamide resins; polyimide resins; polyester resins such as polyethylene terephthalate (PET); polyurethane resins; polyolefin resins such as polyethylene and polypropylene; fluororesins such as polytetrafluoroethylene (PTFE), perfluoroalkoxyalkanes (PFA), and ethylene tetrafluoroethylene copolymer (ETFE); polyvinyl chloride resins; silicone resins; and natural rubber. These may be used individually or in combination of two or more. Among these, polyamide resins, polyurethane resins, polyolefin resins, and fluororesins are preferably used as the resin material for forming the tube stent. By containing at least one of the polyamide resin, polyurethane resin, polyolefin resin, and fluororesin in the tube stent, both biocompatibility and flexibility can be achieved.

[0014] The tube stent may have a single-layer structure or a multi-layer structure, and a single-layer structure is preferred. By adopting a single-layer structure, it can be easily manufactured.

[0015] When the tube stent has a multi-layer structure, the resin materials forming each layer may be the same or different.

[0016] The tube stent may be a single tube from the proximal end to the distal end, or may be formed by joining a plurality of tubes. By being composed of a plurality of tubes, the bending rigidity in the longitudinal direction of the tube stent can be changed. For example, by making the hardness of the material of the tube constituting the distal side lower than the hardness of the material of the tube constituting the proximal side, the distal side can have a low bending rigidity and the proximal side can have a high bending rigidity, so that a tube stent can be obtained. Since the bending rigidity of the distal side of the tube stent is low, the passability of the curved portion of the bile duct can be improved. Also, since the bending rigidity of the proximal side of the tube stent is high, the pushability can be improved.

[0017] The tube stent has a groove along the circumferential direction of the outer surface. The groove only needs to be formed on at least a part of the outer surface of the tube stent, and may be formed on the entire outer surface.

[0018] The depth of the groove formed on the outer surface of the tube stent is 1.3 to 5.5% with respect to the wall thickness of the tube stent. If the depth of the groove is less than 1.3%, the kink resistance cannot be improved. Therefore, the depth of the groove is 1.3% or more, preferably 1.4% or more, more preferably 1.5% or more. However, if the depth of the groove exceeds 5.5%, the rigidity of the tube stent becomes low and it is likely to kink. Therefore, the depth of the groove is 5.5% or less, preferably 5.4% or less, more preferably 5.3% or less.

[0019] The depth of the groove can be determined by measuring the thickness (maximum outer diameter) D1 of the thickest part of the tube stent, measuring the thickness (minimum outer diameter) D2 of the thinnest part of the tube stent in the groove closest to the position where the maximum outer diameter D1 is measured, and subtracting the minimum outer diameter D2 from the maximum outer diameter D1.

[0020] The cross-sectional shape of the groove is not particularly limited, and examples include a rectangle, trapezoid, U-shape, V-shape, semi-circle, wave shape, etc. Among them, a rectangle, trapezoid, or U-shape is preferable.

[0021] The width of the groove is preferably, for example, 0.04 mm or more, more preferably 0.045 mm or more, still more preferably 0.050 mm or more, and preferably 0.2 mm or less, more preferably 0.15 mm or less, still more preferably 0.10 mm or less. The width of the groove may be the average value of the widths of the grooves measured by observing the longitudinal side surface of the tube stent.

[0022] The pitch is preferably, for example, 0.40 mm or more, more preferably 0.50 mm or more, still more preferably 0.60 mm or more, and preferably 1.0 mm or less, more preferably 0.90 mm or less, still more preferably 0.80 mm or less. The pitch may be the average value of the distances between the positions of the peaks of adjacent convex portions (i.e., the positions of the vertices of the thick-walled portions of the tube stent) observed on the longitudinal side surface of the tube stent.

[0023] It is preferable that no groove is formed on the inner surface of the tube stent. Since no groove is formed on the inner surface, it is difficult for a liquid pool such as bile to form in the lumen of the tube stent, and even if tissue of a lesion such as cancer cells enters, it is difficult for it to accumulate in the lumen of the tube stent, so that blockage or stenosis of the lumen of the tube stent can be suppressed.

[0024] The form of the groove formed along the circumferential direction of the outer surface of the tube stent is not particularly limited, and for example, a spiral shape or an annular shape is preferable, and an annular shape is more preferable.

[0025] The tube stent of the present invention is positioned in the bile duct, and when the side of the tube stent facing the duodenum is considered the proximal end and the opposite side (gallbladder side or liver side) is considered the distal end, the distal end of the tube stent may be positioned on the gallbladder side or the liver side. If positioned on the liver side, a portion of the distal end of the tube stent may be positioned in the hepatic duct.

[0026] In the tube stent of the present invention, when the side positioned towards the duodenum is considered the proximal side and the opposite side (towards the gallbladder or liver) is considered the distal side, it is preferable that the tube stent has locking flaps at both the distal and proximal portions.

[0027] A locking flap is a component that prevents displacement of a tube stent placed in the bile duct. The locking flap located at the distal end of the tube stent extends from the distal end towards the proximal end and radially outward. By placing a locking flap at the distal end of the tube stent, it is possible to prevent the tube stent placed in the bile duct from falling out into the duodenum. The locking flap located at the proximal end of the tube stent extends axially from the proximal end towards the distal end and radially outward. By placing a locking flap at the proximal end of the tube stent, it is possible to prevent the tube stent from entering the gallbladder.

[0028] The locking flap may be formed, for example, by making a cut on the surface of the end of the tube, causing a portion of the tube to protrude diagonally outward from the tube body. Alternatively, it may be formed by providing locking flap members, which are separate components from the tube, at the proximal and distal ends of the tube. When the locking flap is formed by joining the locking flap members to the outer surface of the tube, the locking flap members may be made of the same material as the tube or different material. Methods for joining the tube and the locking flap members include heat welding, ultrasonic welding, and adhesive bonding, but heat welding is preferred. By joining the tube and the locking flap members by heat welding, the joint strength between the tube and the locking flap members can be increased.

[0029] The locking flap is preferably formed by making a notch on the outer surface of the tube. Forming it by making a notch on the outer surface of the tube makes it easier to prevent the locking flap from falling off than if a separate member were to be fixed in place.

[0030] The locking flaps located at the distal and proximal ends of the tube stent may be formed in the same way or in different ways.

[0031] The number of locking flaps positioned at the distal and proximal ends of the tube stent may be one or more, for example, two or more, three or more, or five or less.

[0032] When multiple locking flaps are arranged on the distal or proximal portion of a tube stent, it is preferable that each locking flap is arranged at equal intervals in the circumferential direction of the tube stent. This enhances the effect of preventing the tube stent from becoming misplaced when using locking flaps on the proximal portion of the tube stent. When using locking flaps on the distal portion of the tube stent, it enhances the effect of preventing the tube stent from falling off.

[0033] When multiple locking flaps are arranged on the distal or proximal portion of a tube stent, the length from the base to the free end of each locking flap, as well as the width and thickness of each locking flap, may be the same or different. For example, if the length, width, and thickness of each locking flap are the same, manufacturing becomes easier. Also, by varying the length, width, and thickness of each locking flap, the strength of each locking flap can be changed. Specific examples include increasing the strength of locking flaps in areas prone to stress and fracture, and decreasing the strength of locking flaps in areas where flexibility is required.

[0034] Figure 1 shows one embodiment of the tube stent according to the present invention. The tube stent 1 shown in Figure 1 is a bile duct tube stent made of a resin material and extends in the longitudinal direction x. In Figure 1, the left side of the figure is the distal side of the tube stent 1, and the right side of the figure is the proximal side of the tube stent 1.

[0035] The tube stent 1 has locking flaps at its distal and proximal ends. The distal locking flap 2a is formed by making an incision on the distal outer surface of the tube stent 1, and the proximal locking flap 2b is formed by making an incision on the proximal outer surface of the tube stent 1. Hereinafter, the region where the distal locking flap 2a is formed and the region where the proximal locking flap 2b is formed may be referred to as the locking flap region y.

[0036] In the tube stent 1 shown in Figure 1, radiopaque marker 3a is positioned distal to the area where the locking flap is located at the distal end of the tube stent 1, and radiopaque marker 3b is positioned proximal to the area where the locking flap is located at the distal end of the tube stent 1. Furthermore, radiopaque marker 3c is positioned distal to the area where the locking flap is located at the proximal end of the tube stent 1, and radiopaque marker 3d is positioned proximal to the area where the locking flap is located at the distal end of the tube stent 1.

[0037] If the tube stent has locking flaps at the distal and proximal portions, it is preferable that the groove be formed in a region proximal to the region where the locking flap is located at the distal portion, and distal to the region where the locking flap is located at the proximal portion.

[0038] Grooves may be formed distal to the locking flap region in the distal part and / or proximal to the locking flap region in the proximal part, or they may not be formed distal to the locking flap region in the distal part and proximal to the locking flap region in the proximal part, and it is preferable that they are not formed distal to the locking flap region in the distal part and proximal to the locking flap region in the proximal part. This is because kinking is less likely to occur distal to the locking flap region in the distal part and proximal to the locking flap region in the proximal part.

[0039] The locking flap may or may not have the groove on its surface. If the locking flap does not have a groove on its surface, its rigidity is not reduced, thus further preventing displacement of the tube stent. On the other hand, if a groove is formed on the surface of the locking flap, the friction between the locking flap and the bile duct increases, thus further preventing displacement of the tube stent.

[0040] The number of grooves formed in the tube stent is not particularly limited, but for example, 10 to 30 grooves per centimeter in the longitudinal direction of the tube stent is preferred. This improves kink resistance. More preferably, there are 12 or more grooves per centimeter in the longitudinal direction of the tube stent, even more preferably 14 or more grooves, and more preferably 25 or fewer grooves per centimeter in the longitudinal direction of the tube stent, and even more preferably 20 or fewer grooves.

[0041] The number of grooves formed in the tube stent can be determined by drawing a 1 cm long straight line along the longitudinal direction of the tube stent and measuring the number of grooves that intersect this line.

[0042] The tube stent of the present invention may have through-holes that penetrate the outer and inner surfaces of the tube stent. Having through-holes allows bile to be taken into the lumen of the tube stent from sources other than the distal end opening, thereby promoting drainage. Preferably, the through-holes are in contact with two or more grooves. Contact with grooves means that the grooves are divided by the through-holes, and the divided surfaces of the grooves are in contact with the through-holes. Drainage can be promoted by forming through-holes with openings large enough to contact two or more grooves.

[0043] The number of grooves in contact with the through hole is more preferably three or more, and even more preferably four or more. The upper limit of the number of grooves in contact with the through hole is preferably eight or fewer, more preferably seven or fewer, and even more preferably six or fewer.

[0044] The size of the through-hole is not particularly limited as long as it is large enough to contact two or more grooves, but for example, it is preferably 0.01 mm or larger, more preferably 0.02 mm or larger, even more preferably 0.03 mm or larger, preferably 0.1 mm or smaller, more preferably 0.09 mm or smaller, and even more preferably 0.08 mm or smaller.

[0045] The number of through holes is not particularly limited; it may be one or two or more. However, if the number of through holes is too large, the rigidity of the tube stent will decrease, so the upper limit is preferably 20 or less, more preferably 18 or less, and even more preferably 15 or less.

[0046] The shape of the through-hole is not particularly limited, but examples include circular, elliptical, and rectangular (e.g., triangular, quadrilateral, etc.). A circular or elliptical through-hole is preferred as it facilitates machining.

[0047] When forming multiple through holes, the through holes may be formed at regular intervals along the longitudinal direction of the tube stent, or the intervals may be partially varied.

[0048] When forming multiple through-holes, the size, number, shape, and spacing of the through-holes may be varied between the distal and proximal sides of the tube stent.

[0049] The tube stent of the present invention may have an X-ray opaque marker. Having an X-ray opaque marker allows the position of the tube stent to be confirmed under X-ray fluoroscopy.

[0050] There is no particular limit to the number of radiopaque markers; one or more are acceptable.

[0051] The radiopaque marker is preferably placed in the distal portion of the tube stent, more preferably distal to the region where the locking flap is located and / or proximal to the region where the locking flap is located in the distal portion of the tube stent, and even more preferably both distal to the region where the locking flap is located and proximal to the region where the locking flap is located in the distal portion of the tube stent. The radiopaque marker may also be placed in the proximal portion of the tube stent, more preferably distal to the region where the locking flap is located and / or proximal to the region where the locking flap is located in the proximal portion of the tube stent, and even more preferably both distal to the region where the locking flap is located and proximal to the region where the locking flap is located in the proximal portion of the tube stent.

[0052] The shape of the X-ray opaque marker is not particularly limited and can be, for example, cylindrical (e.g., cylindrical, polygonal cylindrical, etc.), a C-shaped cross-section with a notch in the cylinder, or a coil shape with a wire wound around it. Among these, the cylindrical shape is preferred.

[0053] Examples of materials for X-ray opaque markers include X-ray opaque materials such as lead, barium, iodine, tungsten, gold, platinum, iridium, stainless steel, titanium, and cobalt-chromium alloys.

[0054] The tube stent of the present invention can be delivered to the implantation site using a known delivery system. An example of the configuration of a delivery system will be explained with reference to Figure 2. In the delivery system 12, the outer catheter 14 and the tube stent 11 are arranged radially outward of the inner catheter 13.

[0055] The tube stent 11 and the outer catheter 14 are connected by a suture 15. This connection allows for the tube stent 11 to be withdrawn and its position finely adjusted within the bile duct lumen during transport to the lesion, ensuring that the tube stent 11 is placed in the appropriate location at the lesion site.

[0056] An insertion assist tube 16 is positioned radially outward of the outer catheter 14. The insertion assist tube 16 makes it less likely for the locking flap to fold back during transport of the tube stent 11, and also prevents kinking of the delivery system 12 during insertion, thereby enabling smooth transport of the tube stent 11.

[0057] The tube stent of the present invention can be formed by various methods, for example, by heating a raw material tube made of resin material and forming grooves on the outer surface of the raw material tube using a mold, or by scraping the outer surface of the raw material tube made of resin material with a cutting tool to form grooves.

[0058] When a raw material tube made of resin material is heated and grooves are formed on the outer surface of the raw material tube using a mold, the heating temperature is preferably, for example, 100°C to 250°C, and the heating time is preferably 2 seconds to 3 hours.

[0059] The maximum outer diameter of the tube stent is preferably, for example, 7 French to 10 French (approximately 2.3 mm to 3.3 mm). [Examples]

[0060] Test specimens were manufactured by forming grooves on the outer surface of raw material tubes made of resin material. The obtained test specimens were then bent to a radius of curvature R of 8 mm, and the presence or absence of kinking was evaluated.

[0061] A tube (hereinafter sometimes referred to as raw material tube A) was prepared using polyurethane (Lubrizol's "Carbothane") as the resin material, with an outer diameter of 2.81 mm and an inner diameter of 2.14 mm. After heating the prepared raw material tube A to 200°C, annular grooves were formed on the outer surface of the tube along the circumferential direction using various molds to produce test specimens a to d. The cross-sectional shape of the grooves in the longitudinal direction of test specimens a to d (tube stents) was U-shaped. Figure 3 shows photographs that serve as drawings of the appearance of the obtained test specimens a to d.

[0062] Next, for each test specimen, the thickness of the thickest part (maximum outer diameter) D1, the thickness of the thinnest part of the specimen (minimum outer diameter) D2 in the groove closest to the position where the maximum outer diameter D1 was measured, the groove width w in the longitudinal direction, and the pitch p were measured. Figure 4 shows a photograph in lieu of a drawing illustrating an example of the measurements of D1, D2, w, and p. As shown in Figure 4, the thickness of the thickest part of the test specimen (maximum outer diameter) D1 was measured, and the thickness of the thinnest part of the specimen (minimum outer diameter) D2 in the groove closest to the position where the maximum outer diameter D1 was measured was measured. The inner diameter of the test specimen was also measured. Table 1 below shows the maximum outer diameter, minimum outer diameter, and inner diameter of each test specimen. In addition, the wall thickness of the test specimen [wall thickness = (maximum outer diameter - inner diameter) / 2] was calculated based on the maximum outer diameter and inner diameter, and the results are also shown. In addition, the groove depth of the test specimen [groove depth = (maximum outer diameter - minimum outer diameter) / 2] was calculated based on the maximum outer diameter and minimum outer diameter, and the results are also shown. Furthermore, the ratio of groove depth to wall thickness of the test specimen [ratio = 100 × groove depth / wall thickness] was calculated and the results are shown. In addition, the groove width w and pitch p in the longitudinal direction of the test specimen were measured and the results are also shown. Groove width w refers to the length of the groove formed in the test specimen in the longitudinal direction, and pitch p refers to the distance between the positions of adjacent protrusions (positions of the apex of the wall thickness portion of the tube stent) formed in the test specimen. The outer diameter, inner diameter, and wall thickness of the raw material tube A are also shown in Table 1 below.

[0063] [Table 1]

[0064] Next, the obtained test specimens a to d were bent to a radius of curvature of 8 mm. If a kink occurred in the test specimen at this time, it was determined that a kink had occurred, and the presence or absence of kink was evaluated. Figure 5 shows photographs in lieu of drawings of the appearance of test specimens a to d when bent to a radius of curvature of 8 mm. In addition, Figure 5 also shows, as reference data, a photograph in lieu of a drawing of the appearance of raw material tube A when bent to a radius of curvature of 8 mm.

[0065] From Figure 5, the following can be considered: Kinking occurred in raw material tube A and test specimens c and d, which did not satisfy the requirements defined in this invention. On the other hand, no kinking occurred in test specimens a and b, which satisfied the requirements defined in this invention, even when bent to a radius of curvature of 8 mm. [Explanation of Symbols]

[0066] 1 Tube stent 2a, 2b Locking flaps 3a-3d Radiopaque Markers 11 Tube stent 12 Delivery System 13 Inner Catheter 14. Outer catheter 15 Supercharger 16 Insertion support tube x Longitudinal direction of the tube stent y Locking flap existence region D1 Maximum outer diameter D2 Minimum outer diameter w Groove width p pitch

Claims

1. A bile duct tube stent made of resin material, The aforementioned bile duct tube stent is The maximum outer diameter is 2.3 to 3.3 mm. The outer surface has grooves along the circumferential direction on at least a portion of it. The groove is annular, The depth of the groove is 1.3 to 5.5% of the wall thickness of the bile duct tube stent. The width of the groove is 0.04 to 0.2 mm. A bile duct tube stent having grooves with a pitch of 0.40 to 1.0 mm.

2. When the side of the bile duct tube stent positioned toward the duodenum is considered the proximal side and the opposite side the distal side, the bile duct tube stent has locking flaps at both the distal and proximal portions. The bile duct tube stent according to claim 1, wherein the groove is formed in a region proximal to the region where the locking flap is present in the distal portion, and in a region distal to the region where the locking flap is present in the proximal portion.

3. When the side of the bile duct tube stent positioned toward the duodenum is considered the proximal side and the opposite side the distal side, the bile duct tube stent has locking flaps at both the distal and proximal portions. A bile duct tube stent according to claim 1 or 2, wherein the groove is not present distal to the area where the locking flap is present in the distal portion, and proximal to the area where the locking flap is present in the proximal portion.

4. The bile duct tube stent according to claim 2 or 3, wherein the locking flap has the groove on its surface.

5. The bile duct tube stent according to any one of claims 1 to 4, wherein the grooves number 10 to 30 per centimeter in the longitudinal direction of the bile duct tube stent.

6. The bile duct tube stent has through holes that penetrate the outer surface and inner surface of the bile duct tube stent. The bile duct tube stent according to any one of claims 1 to 5, wherein the through-hole is in contact with two or more grooves.

Images