Biliary tract woven stent and biliary tract woven stent conveying system with same

Abstract

The utility model relates to a biliary tract woven stent, which comprises a woven stent formed by weaving one or a plurality of woven filaments, the woven filaments are wound along the axis in a positive and negative spiral line mode and interwoven with one another, and the mutually staggered woven filaments form a lap joint buckle structure capable of freely sliding or a hooking buckle structure limited in sliding at nodes. According to the technical scheme, the structure is reasonable, the stent can be degraded automatically while the radial supporting force of the stent is improved, and the stent taking-out operation is omitted.

Description

Technical Field

[0001] The utility model relates to a medical device, in particular to a degradable biliary tract braided stent. Background Art

[0002] Biliary obstruction is a common digestive system disease in clinical practice, which can be divided into benign obstruction and malignant obstruction. Most cases are benign obstruction, which is generally caused by bile duct damage or repeated attacks of cholangitis, scar stenosis, and malignant obstruction is mainly caused by malignant tumors such as liver cancer, pancreatic cancer, and bile duct cancer. Biliary obstruction can lead to bile stasis. Long-term bile duct obstruction can lead to complications such as deterioration of liver function, gastrointestinal bleeding, and renal failure. Severe cases are life-threatening, so timely treatment is necessary. Releasing a biliary stent in the obstructed bile duct is currently the most common treatment method. As shown in the attached Figure 1 and attached Figure 2 As shown, traditional biliary stents include plastic biliary stents and self-expanding metal stents. Regardless of the type of stent, the most typical problem is stent restenosis. Due to the limitation of the bile duct, the maximum inner diameter of the plastic biliary stent is only 3 mm, which is easily blocked by bile duct stones, biofilms, and bile sludge. Generally, another surgery is required every three months to replace the plastic stent. The complications of this type of surgery are cholangitis and pancreatitis, which greatly increase the patient's pain and economic burden. Self-expanding metal biliary stents are mostly woven with metal wires, which will cause excessive proliferation of endothelial inflammation and lead to restenosis. In addition, the stent mesh cannot be removed after being covered by the proliferative tissue. Therefore, metal biliary stents are rarely used to treat benign obstruction. In theory, degradable biliary stents can solve the above problems.

[0003] Degradable materials are mainly divided into two categories: polymers and metals. Among them, although polymer materials have good biosafety, their mechanical properties are weak and the degradation time is too long. Degradable metals mainly include iron, magnesium, zinc, and molybdenum. The poor biocompatibility of iron and zinc and the non-degradability of corrosion products are fatal flaws. Magnesium alloys have very good biocompatibility, but the problem of magnesium alloys is that they degrade too quickly (too fast degradation causes the product to lose mechanical support prematurely) and have poor mechanical properties. Summary of the Invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a biliary braided stent, which includes one or more braided wires woven together to form a braided stent. The braided wires are wound in positive and negative spiral lines along the axis and interwoven with each other. The interlaced braided wires form a freely sliding overlap buckle structure or a restricted sliding hook buckle structure at the nodes.

[0005] Preferably, the diameter of the braided wire is 50-500 μm, the spacing between two braided wires is 1-2 mm, and the mesh size in the middle of the braided stent is smaller than or equal to the mesh size at both ends of the middle section of the braided stent.

[0006] Preferably, the cross-sectional shape of the braided wire includes but is not limited to one or more combinations of circular, elliptical, and rectangular.

[0007] Preferably, the braided wire includes but is not limited to one or more combinations of degradable molybdenum wire, magnesium alloy wire, iron alloy wire and degradable polymer wire.

[0008] Preferably, the diameter of the braided stent after release is 5 to 15 mm, and the length of the braided stent after release is 20 to 150 mm.

[0009] Preferably, the outer peripheral surface of the braided stent is partially or completely coated with a polymer film layer, and the polymer film layer is made of one or more degradable polymer materials, including but not limited to polyglycolide, polylactic acid, polyglycolide-lactide, and polycaprolactone.

[0010] Preferably, the surfaces of the braided stent and the polymer film layer can be loaded with therapeutic drugs.

[0011] A biliary braided stent delivery system includes an inner tube and an outer tube that are nested inside and outside. A accommodating cavity for compressing the biliary braided stent is defined between the inner tube and the outer tube. A handle is provided at the proximal end of the inner tube, and a soft head extending out of the accommodating cavity is provided at the distal end. A stent recovery ring is also provided at the distal end of the inner tube. The outer tube is connected to an external traction mechanism through its proximal end.

[0012] By means of the above solution, the present invention has at least the following advantages:

[0013] 1. The braided stent will not deform when passing through a tortuous path;

[0014] 2. Using braided wires with strong mechanical properties as part of the braided wire can improve the radial support force of the stent;

[0015] 3. The self-expanding metal cavity is large and not easy to be blocked;

[0016] 4. After 12 to 24 months of stent implantation, all braided wires degrade, eliminating the need for stent removal surgery.

[0017] 5. The surface of the woven stent and the polymer film layer can be loaded with therapeutic drugs, such as antibiotics or anti-inflammatory drugs, to facilitate treatment.

[0018] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and to implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate a certain embodiment of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0020] Figure 1 This is a schematic diagram of the usage status of a traditional plastic biliary stent;

[0021] Figure 2 This is a schematic diagram of the usage status of a traditional metal biliary stent;

[0022] Figure 3 This is a schematic diagram of surgical instruments entering the bile duct through a digestive endoscope;

[0023] Figure 4 Schematic diagram of the biliary stent structure shown in Example 1 of the present application;

[0024] Figure 5 Schematic diagram of the bile duct stent structure shown in Example 2 of the present application;

[0025] Figure 6 This is a state diagram of the radial support force tester performing compression testing on the biliary stent;

[0026] Figure 7 This is a summary diagram of the radial support force of the bile duct stents in Example 1, Example 2, and Example 3 of the present application after compression testing;

[0027] Figure 8 This is a schematic diagram of the structural relationship between the braided stent and the polymer film layer of the present application;

[0028] Figure 9 It is a schematic diagram of the structural relationship of the inner tube of this application;

[0029] Figure 10 It is a schematic diagram of the structural relationship between the inner tube and the outer tube of this application.

[0030] In the figure: 1 braided wire, 2 braided stent, 3 polymer film layer, 4 inner tube, 5 outer tube, 6 accommodating cavity, 7 soft head, 8 stent recovery ring. DETAILED DESCRIPTION

[0031] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0032] Example 1:

[0033] like Figure 4As shown, the biliary stent of this embodiment is made of 32 braided wires by a braiding machine. The two interlaced braided wires are hook structures with limited sliding at the nodes. The diameter of each braided wire is 100 μm. The biliary stent made of the above structure has a very small shortening rate after release, which is convenient for accurate positioning and release of the stent, and the radial support force of the stent is large. After the stent is fully released, the stent diameter is 10 mm and the stent length range is 20 to 150 mm.

[0034] The processing method of the stent in this embodiment is as follows: a stainless steel tube with an outer diameter of 9.9 mm, an inner diameter of 9 mm and a length of 1 m is taken as a braiding core shaft, the braiding core shaft is fixed on a braiding machine, 32 spools filled with braiding wire (with a diameter of 100 μm) are taken and fixed on the braiding machine head, and a braided mesh tube with a length of 80 to 90 cm is prepared according to a mesh count of 75 to 100 per inch and a rotation speed of 70 to 180 r / min. After the braided mesh tube is wound and fixed with stainless steel wire, the braiding core shaft with the braided mesh tube is removed and placed in a heat treatment furnace for heat setting. After heat setting, a cutter is used to cut the braided mesh tube into a specific length. The length range of the mesh tube is 20 to 150 mm. Finally, the braided mesh tube of a specific length is fixed on a LaserStar laser welding fixture, and the wires scattered at both ends of the mesh tube are welded together in pairs to obtain the following. Figure 4 The biliary stent shown in FIG. 1 ; wherein, when the stent is in a natural state (i.e., a fully released state), the spacing between two adjacent braided wires is 1.2 mm, and the diameter of the stent is 10 mm. Because the braided wires have strong mechanical properties, the radial supporting force of the stent of this embodiment meets clinical requirements.

[0035] Example 2:

[0036] like Figure 5 As shown, the stent of this embodiment is made of 32 braided wires using a braiding machine. The braided wires are wound in positive and negative spiral lines along an axis and interwoven with each other. The two interwoven braided wires form a freely sliding overlapping structure at the node.

[0037] The processing method of the stent in this embodiment is as follows: a stainless steel tube with an outer diameter of 9.9 mm, an inner diameter of 9 mm and a length of 1 m is taken as a braiding core shaft, the braiding core shaft is fixed on a braiding machine, 32 spools filled with braiding wire (with a diameter of 100 μm) are taken and fixed on the braiding machine head, and a braided mesh tube with a length of 80 to 90 cm is prepared according to a mesh count of 75 to 100 per inch and a rotation speed of 70 to 180 r / min. After the braided mesh tube is wound and fixed with stainless steel wire, the braiding core shaft with the braided mesh tube is removed and placed in a heat treatment furnace for heat setting. After heat setting, a cutter is used to cut the braided mesh tube into a specific length. The length range of the mesh tube is 20 to 150 mm. Finally, the braided mesh tube of a specific length is fixed on a LaserStar laser welding fixture, and the wires scattered at both ends of the mesh tube are welded together in pairs to obtain the following. Figure 5 The biliary stent shown in FIG. 1 ; wherein, when the stent is in a natural state (i.e., a fully released state), the spacing between two adjacent braided wires is 1.2 mm, and the diameter of the stent is 10 mm. Because the braided wires have strong mechanical properties, the radial supporting force of the stent of this embodiment meets clinical requirements.

[0038] Example 3:

[0039] Based on the biliary stent of the present invention, the stent of this embodiment is composed of 32 magnesium alloy wires. The braided wires are wound in positive and negative spiral lines along an axis and interwoven with each other. The two intertwined wires are a lap structure that can slide freely at the node. The diameter of the braided wire is 100 μm. After the stent is fully released, the diameter of the stent is 10 mm, and the stent length range is 20 to 150 mm. Because the mechanical properties of magnesium alloy are weak, the radial support force of the stent of this embodiment is relatively small.

[0040] like Figure 6 As shown, the radial support force test method of the stent is to use a stent radial force tester to measure the force (N) required to compress the stent diameter by half. Five stent samples of each of Examples 1, 2, and 3 of the present invention are taken. Each stent is gradually compressed from a diameter of 10 mm to 5 mm. The compression force value (N) is measured every 0.25 mm of compression.

[0041] According to the above steps, each stent sample is tested three times to obtain the summary data of the radial support force of each stent sample, such as Figure 7 As shown in the figure, the three areas from top to bottom are the radial support force data of the stents of Examples 1, 2 and 3 respectively. It is obvious that, for the same 32 braided wires with a diameter of 100 μm, the radial support force of the stent with restricted sliding of the interlaced wires is slightly greater than the radial force of the stent with free sliding of the interlaced wires, while the radial support force of the stent in Example 3 of magnesium alloy wire is significantly smaller than that of the stents of the other two designs.

[0042] In summary, as attached Figure 8 、 9 As shown in 10, when the technical solution of the present application is in use, the inner tube 4 is generally 1.8 to 2 meters long: the handle is outside the patient's body and is controlled by the doctor; and the soft head 7 is farthest from the handle. In the patient's bile duct, when the traction mechanism drives the outer tube 5 to move toward the handle, the mesh-shaped braided stent gradually exposes the accommodating cavity 6 and is released, and the inner diameter of the braided stent after release is greater than the outer diameter of the outer tube 5.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and modifications without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A biliary tract braided stent, characterized by: The invention comprises one or more braided wires (1) which are braided to form a braided support (2), wherein the braided wires (1) are wound in positive and negative spiral lines along an axis and interwoven with each other, and the interwoven braided wires (1) form a freely sliding overlap buckle structure or a restricted sliding hook buckle structure at the nodes.

2. The biliary braided stent according to claim 1, characterized in that: The diameter of the braided wire (1) is 50-500 μm, the spacing between two braided wires (1) is 1-2 mm, and the mesh size of the middle portion of the braided stent (2) is smaller than or equal to the mesh size at both ends of the middle portion of the braided stent (2).

3. The biliary tract braided stent according to claim 1, characterized in that: The cross-sectional shape of the braided wire (1) includes but is not limited to one or a combination of circular, elliptical, and rectangular.

4. The biliary tract braided stent according to claim 1, characterized in that: The braided wire (1) includes but is not limited to one or more combinations of degradable molybdenum wire, magnesium alloy wire, iron alloy wire and degradable polymer wire.

5. The biliary tract braided stent according to claim 1, characterized in that: The diameter of the braided stent (2) after release is 5 to 15 mm, and the length of the braided stent (2) after release is 20 to 150 mm.

6. The biliary tract braided stent according to claim 5, characterized in that: The outer peripheral surface of the braided stent (2) is partially or completely coated with a polymer film layer (3), and the polymer film layer (3) is made of one or more degradable polymer materials, including but not limited to polyglycolide, polylactic acid, polyglycolide lactide, and polycaprolactone.

7. The biliary tract braided stent according to claim 5, characterized in that: The surfaces of the braided stent (2) and the polymer film layer (3) can be loaded with therapeutic drugs.

8. A biliary tract braided stent delivery system, comprising the biliary tract braided stent according to any one of claims 1 to 7, characterized in that: The invention comprises an inner tube (4) and an outer tube (5) which are nested together. A receiving cavity (6) for compressing a biliary braided stent is defined between the inner tube (4) and the outer tube (5). A handle is provided at the proximal end of the inner tube (4), and a soft head (7) extending out of the receiving cavity (6) is provided at the distal end. A stent recovery ring (8) is also provided at the distal end of the inner tube (4). The outer tube (5) is connected to an external traction mechanism through its proximal end.

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