JP2023121577A - Tube stent for bile duct - Google Patents

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 The present invention relates to a bile duct tube stent made of a resin material.

Stents are generally used to treat various diseases caused by stenosis or occlusion of blood vessels or biological lumens such as bile ducts and pancreatic ducts. , is known as a medical device placed therein to maintain lumen caliber. For example, by placing a biliary stent to maintain the bile duct caliber in the lesion, the lesion at the site of stenosis or obstruction can be expanded from the inside, allowing bile to drain from the bile duct to the duodenum. It can treat various diseases such as biliary obstruction, jaundice, and biliary tract cancer caused by narrowing or obstruction of the biliary tract.

Such bile duct stents include those made of a metal material and those made of a resin material. A biliary stent made of a metal material has a large diameter and is difficult to block, but has the disadvantage of being difficult to remove or replace. On the other hand, a biliary tube stent made of a resin material has a small diameter and is easily obstructed, but can be easily removed or replaced.

Stents are used not only in a straight state but also in a bent state, so they are required to have flexible bendability and not to cause kink even in a bent state. A medical tubular body having kink resistance is described in Patent Document 1, and this medical tubular body is a tubular body including a two-layer structure of at least an inner layer and an outer layer, wherein the outer layer is thicker than the inner layer. is made of a hard material, and has grooves forming a spiral or annular shape around the outer periphery of the tubular body at a depth that reaches from the outer layer to the inner layer but does not penetrate the inner layer, and has dynamic compliance as defined in ISO 7198. , 1%/100 mmHg or more.

Japanese Patent Application Laid-Open No. 2003-275228

In Patent Document 1, attention is not paid to the depth of the grooves formed in the surface layer of the medical tubular body, and there is room for further improvement in kink resistance.

The present invention has been made in view of the circumstances as described above, and an object of the present invention is to provide a bile duct tube stent that does not cause kinking even when used in a bent state.

The present invention is as follows.
[1] A tube stent for bile ducts made of a resin material, wherein the tube stent has grooves along the circumferential direction on at least a part of the outer surface thereof, and the depth of the grooves is equal to the depth of the tube. A biliary tube stent having a wall thickness of 1.3 to 5.5% of the stent.
[2] The biliary tube stent according to [1], wherein the groove is helical or annular.
[3] The tube stent has locking flaps at the distal and proximal portions, where the side of the tube stent placed on the duodenum side is the proximal side and the opposite side is the distal side. , the groove is formed in a region proximal to the locking flap existing region in the distal portion and distal to the locking flap existing region in the proximal portion [1] or [2] A biliary tube stent as described.
[4] The tube stent has locking flaps at the distal and proximal portions, where the side of the tube stent placed on the duodenum side is the proximal side and the opposite side is the distal side. , the groove is not provided on the distal side of the region where the locking flap exists in the distal portion and on the proximal side of the region where the locking flap exists in the proximal portion [1] to [3]. bile duct tube stent.
[5] The biliary tube stent according to [3] or [4], wherein the locking flap has the groove on its surface.
[6] The tube stent for bile duct according to any one of [1] to [5], wherein the number of grooves is 10 to 30 per 1 cm of longitudinal length of the tube stent.
[7] The tube stent has a through hole penetrating the outer surface and the inner surface of the tube stent, and the through hole is in contact with two or more grooves [1] to [6]. ] The tube stent for bile ducts according to any one of

The biliary tube stent of the present invention has grooves along the circumferential direction formed on at least a part of the outer surface of the tube stent, and the depth of the grooves is appropriately controlled, so that it can be used in a bent state. It is possible to suppress the occurrence of kinks.

FIG. 1 is a plan view showing one embodiment of a tube stent according to the present invention. FIG. 2 is a plan view showing one configuration example of a delivery system for delivering the tube stent according to the present invention to a lesion site. FIG. 3 is a drawing-substituting photograph of the appearance of the test piece produced in the example. FIG. 4 is a drawing-substituting photograph showing an example of measuring the groove width and pitch of the test piece produced in the example. FIG. 5 is a drawing-substituting photograph of the appearance when the raw material tube and the test piece are bent.

Hereinafter, the present invention will be described in more detail based on the embodiments, but the present invention is not limited by the following embodiments, and can be implemented with modifications within the scope that can conform to the spirit of the above and below. Of course, it is also possible, and all of them are included in the technical scope of the present invention. In each drawing, for the sake of convenience, hatching, member symbols, etc. may be omitted, but in such cases, the specification and other drawings shall be referred to. In addition, the dimensions of various members in the drawings may differ from the actual dimensions, since priority is given to helping to understand the features of the present invention.

A tube stent for bile ducts according to the present invention is made of a resin material, and has grooves extending along the circumferential direction on at least a part of the outer surface of the tube stent. It is 1.3 to 5.5% of the wall thickness of the tube stent. When forming grooves along the circumferential direction of the tube stent on at least a part of the outer surface of the tube stent, the depth of the grooves is controlled within an appropriate range for the wall thickness of the tube stent, Can improve kink resistance.

As the resin material for forming the tube stent, known resins can be used, for example, polyamide resins such as nylon; polyether polyamide resins; polyimide resins; polyester resins such as polyethylene terephthalate (PET); Polyurethane-based resins; Polyolefin-based resins such as polyethylene and polypropylene; Fluorine-based resins such as polytetrafluoroethylene (PTFE), perfluoroalkoxyalkane (PFA), and ethylenetetrafluoroethylene copolymer (ETFE); Polyvinyl chloride-based resins; Silicone system resin; includes natural rubber and the like. These may use only 1 type and may use 2 or more types together. Polyamide-based resins, polyurethane-based resins, polyolefin-based resins, and fluorine-based resins are preferably used as the resin material for forming the tube stent. Since the tube stent contains at least one of polyamide-based resin, polyurethane-based resin, polyolefin-based resin, and fluorine-based resin, both biocompatibility and flexibility of the tube stent can be achieved.

The tube stent may have a single-layer structure or a multi-layer structure, preferably a single-layer structure. The single-layer structure facilitates production.

When the tube stent has a multilayer structure, the resin material forming each layer may be the same or different.

A tube stent may be a single tube extending from the proximal end to the distal end, or may be a plurality of tubes joined together. Since it is composed of a plurality of tubes, the bending stiffness can be changed in the longitudinal direction of the tube stent. 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 has low bending rigidity and the proximal side has high bending rigidity. It can be a tube stent. Due to the lower bending stiffness of the distal side of the tube stent, the ability to pass through bends in the bile duct can be enhanced. In addition, since the tube stent has a high bending rigidity on the proximal side, the pushability can be enhanced.

The tube stent has circumferential grooves on its outer surface. The groove may be formed on at least part of the outer surface of the tube stent, or may be formed on the entire outer surface.

The depth of the grooves formed on the outer surface of the tube stent is 1.3-5.5% of the wall thickness of the tube stent. If the groove depth is less than 1.3%, 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 stiffness of the tube stent becomes low, and kinking is likely to occur. Therefore, the depth of the groove is 5.5% or less, preferably 5.4% or less, more preferably 5.3% or less.

The depth of the groove is determined by measuring the thickness (maximum outer diameter) D1 of the tube stent at its thinnest part and measuring the thickness (minimum outer diameter) D2, and subtract the minimum outer diameter D2 from the maximum outer diameter D1.

The cross-sectional shape of the groove is not particularly limited, but may be, for example, rectangular, trapezoidal, U-shaped, V-shaped, semi-circular, wavy, etc. Among them, rectangular, trapezoidal or U-shaped is preferable.

The width of the groove is, for example, preferably 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 groove widths measured by observing the longitudinal side of the tube stent.

The pitch is, for example, preferably 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 0.60 mm or more. 80 mm or less. The pitch may be obtained by observing the longitudinal side of the tube stent and taking the average value of the distances between the positions of adjacent crests of the convex portions (that is, the positions of the vertices of the thick portion of the tube stent).

Preferably, the inner surface of the tube stent is free of grooves. Since no grooves are formed on the inner surface, it is difficult for liquids such as bile to accumulate in the lumen of the tube stent, and even if tissue from a lesion such as cancer cells enters, it is difficult for it to accumulate in the lumen of the tube stent. Therefore, it is possible to prevent the lumen of the tube stent from being clogged or narrowed.

Although the shape of the groove formed along the circumferential direction of the outer surface of the tube stent is not particularly limited, for example, it is preferably helical or annular, and more preferably annular.

The tube stent of the present invention is placed in the bile duct, and when the side of the tube stent placed on the duodenum side is the proximal side and the opposite side (gallbladder side or liver side) is the distal side, the tube stent is placed distally. The end may be placed on the gallbladder side or the liver side. When placed on the hepatic side, a distal portion of the tube stent may be placed in the hepatic duct.

The tube stent of the present invention is anchored to the distal and proximal portions of the tube stent, with the side placed on the duodenum side being the proximal side and the opposite side (gallbladder side or liver side) being the distal side. It preferably has flaps.

A locking flap is a member that prevents displacement of a tube stent placed in a bile duct. A locking flap disposed at the distal portion of the tube stent extends radially outward in a distal-to-proximal direction. By arranging the locking flap at the distal portion of the tube stent, it is possible to prevent the tube stent placed in the bile duct from dropping out of the bile duct toward the duodenum. Locking flaps disposed on the proximal portion of the tube stent extend axially and radially outward from the proximal side to the distal side. By arranging the locking flap at the proximal portion of the tube stent, it is possible to prevent the tube stent from entering the gallbladder side.

The locking flap may be formed, for example, by making a cut in the surface of the end of the tube and projecting a part of the tube obliquely outward from the tube body. Moreover, as a member different from the tube, it may be formed by providing locking flap members constituting locking flaps at the proximal and distal portions of the tube. When the locking flap member is bonded to the outer surface of the tube to form the locking flap, the locking flap member may be the same or different material from which the tube is constructed. A method for joining the tube and the locking flap member includes heat welding, ultrasonic welding, adhesion with an adhesive, and the like, but joining by heat welding is preferable. By joining the tube and the locking flap member by heat welding, the joint strength between the tube and the locking flap member can be increased.

The locking flaps are preferably cut into the outer surface of the tube. By forming cuts in the outer surface of the tube, it is possible to prevent the locking flap from coming off, rather than fixing a separate member.

The distal and proximal locking flaps of the tube stent may be formed in the same manner or may be formed in different manners.

The number of locking flaps disposed on the distal and proximal portions of the tube stent may be one or more, for example, two or more, three or more, or five or less. be.

When a plurality of locking flaps are arranged on the distal portion or the proximal portion of the tube stent, it is preferable that the locking flaps are arranged at regular intervals in the circumferential direction of the tube stent. As a result, in the locking flap arranged at the proximal portion of the tube stent, the effect of preventing the tube stent from being misplaced can be enhanced. The locking flap disposed at the distal portion of the tube stent can enhance the drop-off prevention effect of the tube stent.

When multiple locking flaps are arranged at the distal or proximal part of the tube stent, even if the length from the base of the locking flap to the free end and the width and thickness of the locking flap are all the same. may be different. For example, if each locking flap has the same length, width and thickness, manufacturing is facilitated. In addition, the strength of each locking flap can be varied by varying the length, width, and thickness of each locking flap. As a specific example, the strength of the locking flap may be increased at locations where stress is likely to be applied and may break, and the strength of the locking flap may be decreased at locations where flexibility is required.

One embodiment of a tube stent according to the present invention is shown in FIG. A tube stent 1 shown in FIG. 1 is a bile duct tube stent made of a resin material and extends in the longitudinal direction x. In FIG. 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 .

The tube stent 1 has locking flaps at the distal and proximal portions. The distal outer surface of the tube stent 1 is cut to form the distal locking flaps 2a and the proximal outer surface of the tube stent 1 is cut to form the proximal locking flaps 2b. is formed. Hereinafter, the region in which the distal side locking flap 2a is formed and the region in which the proximal side locking flap 2b is formed may be referred to as a locking flap existing region y.

A tube stent 1 shown in FIG. An X-ray opaque marker 3b is arranged on the proximal side of the flap existing region. In addition, the X-ray opaque marker 3c is arranged on the distal side of the region where the locking flap exists in the proximal portion of the tube stent 1, and the marker 3c is arranged on the proximal side of the region where the locking flap exists in the distal portion of the tube stent 1. An X-ray opaque marker 3d is arranged.

When the tube stent has locking flaps in the distal portion and the proximal portion, the stent is positioned proximally of the region where the locking flaps exist in the distal portion and further than the region where the locking flaps exist in the proximal portion. It is preferable that the groove is formed in the position side region.

The groove may be formed on the distal side of the region where the locking flap exists in the distal portion and/or on the proximal side of the region where the locking flap exists in the proximal portion. It may not be formed on the proximal side of the region where the locking flap exists in the distal side and the proximal portion, and the region where the locking flap exists in the distal side and the proximal portion of the region where the locking flap exists in the distal portion. It is preferably not formed proximal to the region. This is because kink is less likely to occur on the distal side of the region where the locking flap exists in the distal portion and on the proximal side of the region where the locking flap exists in the proximal portion.

The locking flap may or may not have said groove on its surface. Since no grooves are formed on the surfaces of the locking flaps, the rigidity of the locking flaps does not decrease, so that displacement of the tube stent can be further prevented. On the other hand, since the grooves are formed on the surfaces of the locking flaps, the friction between the locking flaps and the bile duct increases, thereby further preventing displacement of the tube stent.

Although the number of grooves formed in the tube stent is not particularly limited, it is preferably 10 to 30 grooves per 1 cm of longitudinal length of the tube stent. This can improve kink resistance. The number of grooves per 1 cm of the tube stent in the longitudinal direction is more preferably 12 or more, more preferably 14 or more, and more preferably 25 or less per 1 cm of the length of the tube stent in the longitudinal direction, still more preferably. 20 or less.

The number of grooves formed in the tube stent can be obtained by drawing a straight line with a length of 1 cm in the longitudinal direction of the tube stent and measuring the number of grooves that intersect this straight line.

The tube stent of the present invention may have through-holes passing through the outer surface and the inner surface of the tube stent. By having the through holes, bile can be taken into the lumen of the tube stent from other than the distal end opening of the tube stent, and drainage can be promoted. Preferably, the through-hole is in contact with two or more grooves. Contacting the groove means that the groove is divided by the through hole and the divided surface of the groove is in contact with the through hole. By forming a through-hole having an opening sized to abut on two or more grooves, drainage can be facilitated.

For example, the number of grooves in contact with the through-hole is preferably 3 or more, and more preferably 4 or more. The upper limit of the number of grooves in contact with the through-hole is, for example, preferably 8 or less, more preferably 7 or less, still more preferably 6 or less.

The size of the through-hole is not particularly limited as long as the through-hole is of a size that abuts on two or more grooves. 03 mm or more, preferably 0.1 mm or less, more preferably 0.09 mm or less, and still more preferably 0.08 mm or less.

The number of through-holes is also not particularly limited, and may be one or two or more. If the number of through-holes is too large, the rigidity of the tube stent is lowered, so the upper limit is preferably 20 or less, more preferably 18 or less, and even more preferably 15 or less.

Although the shape of the through-hole is not particularly limited, examples thereof include circular, elliptical, and rectangular (eg, triangular, quadrangular, etc.). The shape of the through-hole is preferably circular or elliptical, which facilitates processing.

When a plurality of through-holes are formed, the through-holes may be formed at regular intervals in the longitudinal direction of the tube stent, or may be formed by partially changing the intervals.

When a plurality of through-holes are formed, the size, number, shape, spacing, etc. of the through-holes may be changed between the distal side and the proximal side of the tube stent.

The tube stent of the present invention may have radiopaque markers. By having radiopaque markers, the position of the tube stent can be confirmed under fluoroscopy.

The number of X-ray opaque markers is not particularly limited, and may be one or plural.

The location of the X-ray opaque marker is preferably at the distal portion of the tube stent, more preferably at the distal side of the region where the locking flap exists at the distal portion of the tube stent and/or at the distal portion of the tube stent. proximal to the region where the stop flap exists, more preferably both distal to the region where the locking flap exists in the distal portion of the tube stent and proximal to the region where the locking flap exists in the distal portion of the tube stent be. The radiopaque marker may also be placed on the proximal portion of the tube stent, more preferably distal to the region where the locking flap exists in the proximal portion of the tube stent and/or on the proximal portion of the tube stent. More preferably, it is proximal to the locking flap existing region in the proximal portion of the tube stent and proximal to the locking flap existing region in the proximal portion of the tube stent. Both.

The shape of the X-ray opaque marker is not particularly limited, and examples thereof include a cylindrical shape (e.g., a cylindrical shape, a polygonal cylindrical shape, etc.), a C-shaped cross section with a notch in the cylinder, a coil shape in which a wire is wound, and the like. is mentioned. Among them, a tubular shape is preferable.

Examples of radiopaque marker materials include radiopaque materials such as lead, barium, iodine, tungsten, gold, platinum, iridium, stainless steel, titanium, and cobalt-chromium alloys.

The tube stent of the present invention can be delivered to the site to be indwelled using a known delivery system. A configuration example of the delivery system will be described with reference to FIG. The delivery system 12 has an outer catheter 14 and a tube stent 11 arranged radially outward of an inner catheter 13 .

The tube stent 11 and the outer catheter 14 are connected by a suture (suture thread) 15 . By coupling the tube stent 11 and the outer catheter 14, when the tube stent 11 is delivered to the lesion site, it is possible to pull back the tube stent 11 in the lumen of the bile duct and finely adjust the position. , the tube stent 11 can be placed at an appropriate position.

An insertion auxiliary tube 16 is arranged radially outward of the outer catheter 14 . The insertion assisting tube 16 makes it difficult for the locking flap to fold back during the delivery of the tube stent 11, and prevents kinking of the delivery system 12 during insertion, thereby smoothly delivering the tube stent 11. be able to.

The tube stent of the present invention can be formed by various methods. A method of forming grooves by shaving the outer surface of the raw material tube with a cutting tool can be mentioned.

When a raw material tube made of a 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 100° C. to 250° C., and the heating time is A period of 2 seconds to 3 hours is preferable.

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).

A test piece was produced by forming grooves on the outer surface of a raw material tube made of a resin material.

A tube having an outer diameter of 2.81 mm and an inner diameter of 2.14 mm (hereinafter sometimes referred to as raw material tube A) was prepared using polyurethane ("Carbothane" manufactured by Lubrizol) as the resin material. After heating the prepared raw material tube A to 200° C., an annular groove along the circumferential direction was formed on the outer surface of the tube using various molds to produce test pieces a to d. The cross-sectional shape of the groove in the longitudinal direction of test pieces a to d (tube stents) was U-shaped. Photographs substituting for drawings of the appearances of the obtained test pieces a to d are shown in FIG.

Next, for the test piece, the thickness of the thickest part (maximum outer diameter) D1, the thickness of the thinnest part of the test piece in the groove closest to the position where the maximum outer diameter D1 was measured (minimum outer diameter) D2, the length The groove width w and pitch p in the direction were measured. FIG. 4 shows a drawing-substituting photograph showing an example of the measurement of D1, D2, w, and p. As shown in FIG. 4, the thickness (maximum outer diameter) D1 of the thickest part of the test piece is measured, and the thickness of the thinnest part of the test piece in the groove closest to the position where the maximum outer diameter D1 is measured ( Minimum outer diameter) D2 was measured. Also, the inner diameter of the test piece was measured. Table 1 below shows the maximum outer diameter, minimum outer diameter, and inner diameter of each test piece. Also, the thickness of the test piece [thickness=(maximum outer diameter−inner diameter)/2] was calculated based on the maximum outer diameter and the inner diameter, and the results are also shown. Also, the depth of the groove of the test piece [groove depth=(maximum outer diameter−minimum outer diameter)/2] was calculated based on the maximum outer diameter and the minimum outer diameter, and the results are also shown. Also, the ratio of the groove depth to the thickness of the test piece [ratio=100×groove depth/wall thickness] was calculated, and the results are also shown. Also, the groove width w and pitch p in the longitudinal direction of the test piece were measured, and the results are also shown. The width w of the groove means the length of the groove formed in the test piece in the longitudinal direction, and the pitch p means the position of the crests of the adjacent convex portions formed in the test piece (thickness of the thick portion of the tube stent). position of the vertex). Table 1 below also shows the outer diameter, inner diameter, and wall thickness of the raw material tube A.

Next, the obtained test pieces a to d were curved with a radius of curvature of 8 mm. At this time, when the test piece broke, it was determined that a kink had occurred, and the presence or absence of the kink was evaluated. FIG. 5 is a drawing-substituting photograph of the appearance of the test pieces a to d when curved with a radius of curvature of 8 mm. FIG. 5 also shows, as reference data, a drawing substituting photograph of the appearance when the raw material tube A is bent with a radius of curvature of 8 mm.

From FIG. 5, it can be considered as follows. The raw material tube A and the test pieces c and d, which did not satisfy the requirements defined in the present invention, had kinks. On the other hand, the test pieces a and b satisfying the requirements defined by the present invention did not develop kink even when curved with a radius of curvature of 8 mm.

1 tube stent 2a, 2b locking flaps 3a to 3d radiopaque marker 11 tube stent 12 delivery system 13 inner catheter 14 outer catheter 15 suture 16 insertion aid tube x longitudinal direction of tube stent y locking flap existing area D1 maximum outer Diameter D2 Minimum outer diameter w Groove width p Pitch

Claims (7)

A biliary tube stent made of a resin material,
The tube stent has grooves along the circumferential direction on at least a portion of its outer surface,
A tube stent for bile ducts, wherein the depth of the groove is 1.3 to 5.5% of the wall thickness of the tube stent. The biliary tube stent according to claim 1, wherein the groove is helical or annular. When the side of the tube stent that is arranged on the duodenum side is the proximal side and the opposite side is the distal side, the tube stent has locking flaps at the distal and proximal portions,
3. The bile duct according to claim 1 or 2, wherein the groove is formed in a region proximal to the locking flap existing region in the distal portion and distal to the locking flap existing region in the proximal portion. tube stent. When the side of the tube stent that is arranged on the duodenum side is the proximal side and the opposite side is the distal side, the tube stent has locking flaps at the distal and proximal portions,
The bile duct according to any one of claims 1 to 3, wherein the grooves are not provided on the distal side of the region where the locking flap exists in the distal portion and on the proximal side of the region where the locking flap exists in the proximal portion. tube stent. The biliary tube stent according to claim 3 or 4, wherein the locking flap has the groove on its surface. The biliary tube stent according to any one of claims 1 to 5, wherein the number of grooves is 10 to 30 per 1 cm of longitudinal length of the tube stent. The tube stent has a through hole penetrating the outer surface and the inner surface of the tube stent,
The biliary tube stent according to any one of claims 1 to 6, wherein the through-hole is in contact with two or more grooves.

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