JP2006296559A - Medical stent formed of composite material comprising metal and bioabsorbable material, its manufacturing method and knitting machine used therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an improved stent capable of retaining original expansive force of a stent, being extracted from the living body at an arbitrary timing, and thereby avoiding as much as possible a possibility of creating problems such as inflammation and excessive thickening causing the vascular restenosis. <P>SOLUTION: This medical stent having a contractible hollow tube structure comprises a spiral-structure metal wire for retaining the expansive force in the outer direction of the tube, and a bioabsorbable resin fiber interlaced with the metal wire; and the bioabsorbable resin fiber provides the metal wire with the evulsion property from the living body by its degradation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a medical stent, a method for producing the same, and a stent knitting machine for the production thereof.

  A stent that is inserted into a blood vessel (esophagus, bile duct, ureter, blood vessel, etc.) and retains the shape of the tube, and placement in the vessel are known (for example, see Non-Patent Documents 1-8, etc.) . In particular, airway lesions that may cause suffocation, respiratory failure, biliary stricture lesions that may cause obstructive jaundice, vascular stenosis lesions that may cause tissue necrosis, lumens that may cause dysfunction Stenosis and occlusion of organs occur due to various causes such as compression of neoplastic diseases and trauma. The stenosis and occlusion of these luminal organs leads to stagnation of the contents, and causes complications such as organ dysfunction, perforation, and infection. More specifically, for example, airway damage due to trauma and subsequent granulation proliferation, and airway stenosis and obstruction caused by malignant disease trachea, intrabronchial proliferation are fatal due to respiratory failure and asphyxia if left untreated There is a possibility of incurring progress. Therefore, in these pathological conditions, it is necessary to quickly release stenosis and occlusion of the lumen. Conventionally, in order to release the stenosis and occlusion of the lumen, an indwelling operation to the lumen of a hollow tube (stent) having a self-expanding force has been performed.

  Most of the medical stents used in this stent placement are hollow silicon tubes, or mesh-like cylindrical / tubular bodies formed by crossing metal meridians and latitude wires made of stainless steel or the like. Or it is a cylindrical knitted fabric formed by braiding metal wires (see the above non-patent documents and patent documents 1-4).

  However, the silicon hollow tube stent needs to be thicker in order to ensure practically sufficient strength. For this reason, the inner / outer diameter ratio is reduced to ensure the required lumen cross-sectional area. There are difficulties that are difficult to do. Furthermore, the position of this stent is likely to shift after placement, and in the case of an airway stent, it is difficult to discharge sputum.

  Metal stents are currently used for intravascular placement because they do not have the disadvantages found in the silicon hollow tube. However, this metal stent is usually difficult to remove after indwelling in the body, and has a fatal defect that it remains semi-permanently as a foreign substance in the living body. It is not preferable for a living body to leave a stent that is a foreign body for such a living body in itself, but the remaining part is particularly hard in a metal stent. It has the disadvantage of stressing and causing problems such as inflammation and excessive thickening that cause vascular restenosis. In addition, there is a drawback that the stent breakage due to metal fatigue occurring in long-term use causes organ damage.

  That is, a medical stent is removed from a living body as quickly as possible when, for example, complications due to stent placement occur, or when the patency of the lumen is restored by the completion of lesion treatment. Although desirable, conventional medical metal stents have the fatal drawback that they cannot be easily removed at such necessary times.

  In recent years, as a medical stent that has improved the disadvantage that it cannot be easily removed after being placed in the living body, which is a serious drawback found in the above-mentioned metal stent, polylactic acid (PLA), polyglycolic acid (PGA), etc. Stents produced by knitting bioabsorbable resin fibers have been proposed (see Patent Documents 5-8, etc.).

  In these stents, resin fibers are decomposed in a certain period after being placed in the living body and absorbed by the living body, and thus the stent does not remain in the living body as a foreign substance.

However, the proposed stent cannot artificially control the degradation rate of the bioabsorbable resin constituting the stent after in-vivo placement, and the degradation rate depends on the environmental conditions in the body. Therefore, there is a drawback that the expansion force of the stent is reduced at an unexpected time. The decrease in expansion force during use of the stent causes the negative effect that the stent cannot maintain its own strength and the vessel is occluded. In addition, for example, when the resin does not rapidly decompose after healing of the lesion, there is a possibility that problems such as inflammation and excessive thickening may occur as in the case of the metal stent described above.
Advanced Medical Series 20, Cancer The latest medical treatment of lung cancer, Terada International Office Co., Ltd. / Advanced Medical Technology Research Institute, April 2003, first edition, first edition, supervised by Keiichi Suehiro, P189 -195 Seiichi Nobeyama et al., The Journal of the Japan Society for Broncholgy, Vol.26, No. 2, March 2004, p.132-137 Masayuki Tanahashi et al., The Journal of the Japan Society for Broncholgy, Vol. 26, No. 1, Jan 2004, p. 33-38 Keisuke Miwa et al., The Journal of the Japan Society for Broncholgy, Vol.25, No. 7, Nov 2003, p. 497-502 Takagi Keigo et al., The Journal of the Japan Society for Broncholgy, Vol. 26, No. 2, Mar 2004, p. 138-144 Shinya Ito et al., The Journal of the Japan Society for Broncholgy, Vol. 26, No. 2, Mar 2004, p. 145-148 Jun Araki et al., The Journal of the Japan Society for Broncholgy, Vol.25, No. 8, Dec 2003, p. 622-631 Igaki Keiji et al., Transactions of the Japan Society of Mechanical Engineers (Part A), Vol. 65, No. 639 (1999-11), pp. 187-192 Japanese Patent No. 2842943 JP 2002-95756 A JP 2003-334255 A JP-T 8-502428 Japanese Patent No. 2961287 Japanese Patent Laid-Open No. 9-308693 Japanese Patent Laid-Open No. 11-137694 JP 2004-166807 A

  It is an object of the present invention to provide an improved medical stent that overcomes the disadvantages found in known medical stents. More specifically, the object of the present invention is to maintain the inherent expansion force of the stent after placement of the stent, and can be removed from the living body at any time, thus causing inflammation that causes vascular restenosis. It is an object of the present invention to provide an improved stent that avoids the possibility of causing problems such as excessive thickening.

As a result of intensive research, the present inventors have conducted, for example, an operation such as using a metal wire and a bioabsorbable resin fiber to form a spiral structure by knitting both into a stepped pattern. When the spiral and the bioabsorbable resin fiber are entangled, the spiral structure of the metal wire retains the expansion force, and the bioabsorbable resin fiber that is entangled with this by knit bonding is decomposed after the obtained stent is placed in vivo. Then, it was found that the metal wire can be easily removed by the disappearance after being absorbed by the living body. The present invention has been completed as a result of further research based on this knowledge.
The present invention provides the inventions described in Items 1 to 11 below.

  Item 1. A medical stent having a hollow tube structure that can be reduced in diameter, a metal wire having a spiral structure for holding an expansion force in an external direction of the tube, and a living body entangled with the metal wire A medical stent comprising an absorbent resin fiber, and the bioabsorbable resin fiber imparts a removal property from a living body to a metal wire by its decomposition.

  Item 2. The metal wire has a spiral structure (coiled) that can extend in the length direction of the tube, and the bioabsorbable resin fiber controls the extension of the metal wire spiral structure in the length direction of the tube. Item 2. The stent according to Item 1, wherein the stent is entangled to

  Item 3. The stent according to Item 1 or 2, wherein the spiral structure of the metal wire has a knit stitch, and the stitch portion is knitted by a bioabsorbable resin fiber.

  Item 4. Any one of Items 1 to 3, wherein a spiral structure of a metal wire having a knit stitch and a spiral structure of a bioabsorbable resin fiber having a knit stitch are knitted in a step pattern (alternately) by both knit stitches. The stent according to crab.

  Item 5. The stent according to Item 4, wherein at least the knit stitch of the metal wire has a needle loop and a sinker loop having a larger course direction length than the needle loop.

  Item 6. The stent according to any one of Items 1 to 5, wherein the metal wire is made of stainless steel (SUS) or nickel titanium alloy (NiTi).

  Item 7. The stent according to any one of Items 1 to 6, wherein the bioabsorbable resin fiber is polylactic acid (PLA) monofilament, PLA multifilament, polyglycolic acid (PGA) monofilament or PGA multifilament.

  Item 8. The medical stent according to any one of Items 1 to 7, wherein at least one of the metal wire and the bioabsorbable resin fiber further holds a medical drug.

  Item 9. Any one of Items 1 to 8 for vascular selection from the group consisting of esophagus, bile duct, ureter, prostate urethra, urethra, colon, bronchial / tracheal lumen, gastrointestinal lumen, blood vessel, pancreatic duct, small intestine and large intestine The stent according to crab.

  Item 10. The method for producing a stent according to Item 4, wherein the stent is provided with at least one yarn feeder for supplying a metal wire and at least one yarn feeder for supplying a bioabsorbable resin fiber. A method comprising a step of knitting a metal wire and a bioabsorbable resin fiber into a stepped pattern using a knitting machine.

  Item 11. A stent knitting machine for the method of manufacturing a stent according to Item 4, wherein at least one yarn feeder for supplying a metal wire and at least one feeder for supplying a bioabsorbable resin fiber. A stent knitting machine provided with a thread end.

  Furthermore, the present invention provides a method for retaining the form of the vascular vessel by placing the stent according to the above-mentioned items 1-9 in a vascular vessel that requires treatment, particularly in a stenotic part in the vascular vessel. It also provides a method of expanding this and thus preventing its blockage and the like.

  The stent of the present invention has the following advantages based on the above configuration.

  That is, the stent according to the present invention is based on the above-described configuration, and the bioabsorbable resin fiber constituting the stent is decomposed and disappeared after in-vivo placement, and a spiral structure (hollow spiral structure) constituted by a metal wire. Only will be placed in the lumen. However, since the intimal cells of the luminal organ line the stent in a relatively rapid manner after the placement of the stent, the stent of the present invention has collapsed the helical structure of the metal wire even after the bioabsorbable resin fiber is decomposed. There is no misalignment, and sufficient expansion force can be maintained. On the other hand, when complications occur due to placement of the stent, or when the patency of the lumen is restored by treatment of the lesion, removal of the stent is desired. In the stent of the present invention, the spiral structure of the metal wire is no longer entangled with the bioabsorbable resin fiber and can be freely extended in the length direction thereof. In addition, it can be easily removed from the body as a single metal wire simply by pulling one end of the spiral structure.

  Of course, the stent of the present invention can be easily placed in various vasculature based on the inherent properties of the stent, that is, based on the fact that it has a medium space structure that can be reduced in diameter. It has the characteristics of expansion and form retention.

The above advantages and other main advantages of the stent of the present invention are listed as follows.
(1) No operation such as heat setting is required to stabilize the diameter at the time of diameter reduction before being placed in the vessel.
(2) Can be easily applied to any biological lumen of various diameters,
(3) It is easy to bend in the length direction of the tube and can be applied to bent vessels.
(4) Excellent flexibility and form retention,
(5) The stress applied to the inner wall of the living vessel where it is placed can be minimized.
(6) By appropriately changing the type of metal wire and bioabsorbable resin fiber used, the blending ratio, etc., it is possible to easily control expansion force, stretchability, bioabsorption loss period, etc.
(7) Inflammation and excessive thickening of the indwelling vessel can be avoided as much as possible to prevent restenosis and can be removed from the body at any time
(8) A therapeutic drug such as an anticancer drug can be retained on the surface of the metal wire by a coating, or can be contained in a bioabsorbable resin fiber, whereby the therapeutic drug can be selectively released to the lesion. ,
(9) The treatment with the therapeutic drug shown in (8) above can be performed repeatedly because the stent can be removed. That is, this therapy can be used as a drug delivery system.

  Hereinafter, the medical stent of the present invention will be described in detail.

(1) Metal Wire As the metal wire, any of various metal wires that have been conventionally used for constructing this kind of stent can be used. Specific examples thereof include stainless steel, tantalum, platinum or platinum alloy, gold or gold alloy, cobalt base alloy such as cobalt-chromium-nickel alloy, nickel titanium alloy, and the like. Of these, stainless steel and nickel titanium alloy are preferred. Particularly preferred stainless steels include SUS304 and SUS716. One type of these metal wires can be used alone, or two or more types can be used in combination.

  The thickness of these metal wires can be appropriately determined according to the expansion force required for the stent to be produced, and is not particularly limited. Usually, it is appropriately selected according to the type of metal wire, the form of use, that is, the size and shape of the stent produced using the metal wire, the type of bioabsorbable resin fibers to be entangled with this, the usage ratio, and the like. In general, it is usually selected from the range of about 20 to 300 μm.

  The metal wire may hold (contain) an appropriate medical drug (therapeutic drug). The medical drug can be held by coating the metal wire with the medical drug or a film containing the same according to a technique such as coating. Examples of the drug include thrombolytic agents and antithrombotic agents such as heparin, urokinase, and t-PA (tissue plasminogen activator). Furthermore, this drug includes immunosuppressive agents such as Sirolimus (trade name Rapamycin), and anti-neoplastic agents such as paclitaxel. The stent of the present invention obtained by utilizing the metal wire holding these is useful as a drug-eluting stent (DES). That is, after the stent of the present invention is placed in the vascular vessel, the drug can be gradually eluted from the stent surface according to the in vivo environment and exert its original function. The amount of each drug retained on the metal wire is an effective amount that allows these drugs to exhibit their original therapeutic effects due to their dissolution, which requires the type of drug to be used, the type of stent to be obtained, and the treatment required. It can be determined appropriately by those skilled in the art according to the vascularity and the degree of the disease.

(2) Bioabsorbable resin fiber The bioabsorbable resin fiber is a fiber of bioabsorbable or biodegradable polymer. Here, bioabsorbable and biodegradable means that it can be completely degraded into non-toxic degradation products that are converted into normal metabolites utilized in vivo. As the polymer, any of various polymers conventionally proposed as materials for this type of stent and surgical sutures can be used. This includes, for example, polylactic acid (including PLA, poly-L-lactide (PLLA) and poly-D-lactide (PDLA)), polyglycolic acid (also called PGA, polyglycolide), polyglactin (polyglycolic acid-poly Lactic acid copolymer), polydioxanone, polycaprolactin, polyglyconate (trimethylene carbonate-glycolide copolymer), polyglycolic acid or polylactic acid and ε-caprolactone copolymer, polylactic acid and polyoxyethylene oxide copolymer Examples include coalescence, modified cellulose, collagen, poly (hydroxybutyrate), polyphosphoester, poly (amino acid) and the like. Of these, PLA, particularly PLLA and PGA are preferred. These bioabsorbable resin fibers can be used singly or in combination of two or more.

  These polymer fibers may be in the form of a single filament (monofilament) formed by spinning (extruding) each polymer, or a plurality of filaments made of each polymer fiber (may be different polymer fibers). Alternatively, it may be in the form of a twisted yarn (multifilament) which is usually knitted from 10-36 pieces. Specific commercial products include, for example, multifilament absorption, such as various polymer fibers manufactured by Birmingham Polymer (USA) and “Bikrill” (manufactured by Ethicon), which has been commercialized as a suture material for surgery. And monopolymer absorption yarns such as sex yarn, “Maxon” (manufactured by Tyco health care).

  The wire diameter of the bioabsorbable resin fiber (including both monofilaments and multifilaments, the same applies hereinafter) affects the desired stent expansion force and in vivo degradation rate. Therefore, it can be appropriately determined according to these requirements and the kind of the vessel to be treated by applying the stent. In general, it is usually selected in the range of about 0.1 mm to 1.0 mm.

  In the present invention, the bioabsorbable resin fiber can hold various medical drugs such as antibiotics and anticancer agents as necessary. The medical drug is retained when the bioabsorbable resin is produced or when the resin is molded into a desired fiber shape, and the drug is kneaded into the resin material or fiber, or the fiber surface is coated. It can be carried out by adhering. The attachment to the fiber surface can be carried out most simply by, for example, simply immersing the fiber in a suitable solution in which a medical drug is dissolved, or spraying a similar solution onto the fiber.

  The above medical drugs include various drugs that are considered useful for the treatment (prevention) of restenosis, such as anticoagulant agents, antiplatelet agents, antimetabolite agents, anti-inflammatory agents, mitotic inhibitors, etc. Is also included. For the details thereof, for example, the description of International Patent Publication No. WO91 / 12779 is referred. More specifically, for example, tranilast (trade name Rizaben, allergic disease / keloid / hypertrophic scar treatment), dexamethasone (synthetic corticosteroid, inflammation treatment), tocopherol (vitamin E) and the like can be mentioned. The amount of each drug used is an effective amount that allows these drugs to exert their original therapeutic effects, etc. This is the type of drug used, the type of stent obtained, the vessel required for treatment and the disease. It can be appropriately determined by those skilled in the art depending on the degree.

  According to utilization of the bioabsorbable resin fiber holding a medical drug, the drug can be intensively administered to the affected area. That is, the medical drug held in the bioabsorbable resin fiber is gradually released into the body as the bioabsorbable resin fiber is decomposed from the stent after the stent of the present invention is placed in the living body, and thus the The drug's original therapeutic effect can be exerted.

(3) Stent of the Present Invention Hereinafter, the stent of the present invention will be described in more detail with reference to the accompanying drawings.

  The stent of the present invention can be produced by entanglement of the metal wire and the bioabsorbable resin fiber.

(3-1) Knitted Knitted Stent One embodiment of the stent of the present invention that is particularly preferred is shown in FIG. The stent 1 of the present invention shown in this figure has a spiral structure of a metal wire 10 having a knitted stitch and a spiral structure of a bioabsorbable resin fiber 20 having a knitted stitch in a stepped pattern (alternately by both knitted stitches). ) It has a medium space structure that can be reduced in diameter by knitting.

The knitting mode of the stent of the present invention shown in FIG. 1 is shown in FIG. 2 (enlarged view). According to (a) of FIG. 2, each of the metal wire 10 and the bioabsorbable resin fiber 20 includes a stitch formed of a needle loop 11, 11 ′ and a sinker loop 12, 12 ′. Ten sinker loops 11 are knitted intertwined with the sinker loop 11 ′ of the bioabsorbable resin fiber 20. Here, the ratio of the length in the course direction (L _N ) to the height in the wale direction (H _N ) of the needle loop 11 of the metal wire 10 is that the curvature in the plastic bending region of the metal wire is obtained. preferable. In addition, by setting the course length (L _S ) of the sinker loop 12 to be longer (longer) than the course direction length (L _N ) of the needle loop 11, a metal in the range of the length of the sinker loop 11 is obtained. The wire 10 can maintain an elastic deformation zone, and thus can maintain an expansion force in the outward direction of the tube of the stent of the present invention.

  The stent of the present invention in the knitting mode shown in FIG. 2-a is configured such that when an extension force is applied in the wale direction, that is, in the axial length direction (the length direction of the tube), the sinker loop 12 is located inside the needle loop 11. As shown in FIG. 2 (b), it is pulled in from the inside, and expands in the wale direction, and accordingly, decreases in diameter in the course direction. That is, the axial length L shown in FIG. 1 is increased and the diameter D is decreased.

  The stent of the present invention can be inserted and placed at a desired site in the vessel in such a state. After the insertion, the diameter can be increased by applying a force, for example, by inflating the balloon from the inside of the tube toward the outside. This diameter expansion is, for example, a return from the state shown in (b) of FIG. 2 to the state (knitting) shown in (a), and corresponds to the withdrawal of the sinker loop 12 to both sides of the needle loop 11. This pull-out is possible until the needle loops 11, 11 ′ are entangled, and by this pull-out and entanglement, the stent of the present invention exerts a strong expansion force toward the outside of the tube. In particular, the drawn sinker loop 12 has a shape extending substantially linearly between adjacent needle loops 11 and 11 as shown in FIG. 2 (a), which greatly contributes to the development of the expansion force. This expansion force is particularly large in the case of a metal wire, and relatively small in a bioabsorbable resin fiber, but in the case of a bioabsorbable resin fiber capable of plastic bending, for example, increasing the fiber diameter, etc. Can be made substantially the same as a metal wire.

  Further, in the above, the stent of the present invention can be self-expanded by itself by changing the combination of the wire length of the metal wire and the length of the bioabsorbable resin fiber. That is, the stent of the present invention can be prepared as a self-expandable stent or a balloon expandable stent by appropriately changing the combination of the metal wire and the bioabsorbable resin fiber constituting the stent. There are advantages. Therefore, the stent of the present invention can be effectively used as both a balloon expandable type and a self-expandable type as a stent suitable for a preferred placement method depending on the characteristics of the luminal organ to which the stent is applied.

  The entanglement between the metal wire and the bioabsorbable resin fiber in the stent of the present invention in the knit knitted form described above is shown in FIG. 1 as an embodiment in which one yarn is alternately knitted. However, this entanglement is not limited to such an embodiment in which each one is alternately knit knitted, and the metal wire and the bioabsorbable resin fiber can retain the expansion force and impart the metal wire withdrawability, respectively. As long as any change is possible.

  The metal wire can be pulled out by the other bioabsorbable resin fiber constituting the stent of the present invention being decomposed and disappearing in the living body, so that the metal wire is loosened, and as a result, is easily pulled out of the body. Therefore, it is desirable that the metal wires are not knit-bonded to each other in the knitted stent of the present invention. As another aspect of such a stent of the present invention, for example, a spiral structure of two or more bioabsorbable resin fibers having a knit stitch is interposed between spiral structures of a single metal wire having a knit stitch. An embodiment, that is, an embodiment in which one metal wire and two or more bioabsorbable resins are knitted in a step pattern. Moreover, it is also possible to construct the stent of the present invention by using a plurality of metal wires and a plurality of bioabsorbable resin fibers to alternately entangle them.

  The above-described stent of the present invention may pass through various meandering vessels when it is transported to a target site for placement in a vessel, and has the advantage of being easy to carry. Yes. That is, the knitted and knitted stent of the present invention has an advantage that its expansion force, contraction force, and dimensional restoring force with respect to external force can be easily adjusted by changing the composition, composition, combination, etc. of the constituent materials. . In addition, by these adjustments, it can be arbitrarily meandered to a considerable degree, and has a degree of freedom that can be inserted into and placed in a bent portion of a blood vessel. In particular, this degree of freedom is obtained by using a multifilament obtained by twisting a plurality of filaments as a bioabsorbable resin fiber, when selecting a highly flexible fiber, or by reducing the fiber diameter, Can be higher.

(3-2) Blade (Assembly) Stent and Textile Stent FIG. 3 is a schematic view showing another embodiment of the stent of the present invention.

  The stent of the present invention shown in this figure is entangled with a plurality of metal wires in either a counterclockwise or clockwise direction and a plurality of bioabsorbable resin fibers in a spiral shape around the opposite direction. This is a cylindrical stent. This stent can be easily manufactured by a manufacturing technique such as a normal braid. More specifically, a bobbin around which the number of threads to be incorporated into a known braiding machine is set is set, and the metal wires in them are turned clockwise, for example, the bioabsorbable resin fibers are turned counterclockwise, respectively in a spiral shape. It can be manufactured by entanglement to obtain a cylinder.

  The stent is reduced in diameter by applying an extension force in the axial direction (the length direction of the tube), and can be easily placed in the vessel in that state. After indwelling in the vessel, the expansion force in the direction of the outside of the original tube of the stent is maintained by, for example, expanding the diameter using a balloon or the like. Further, depending on the combination of the metal wire and the bioabsorbable fiber, a self-expanding type may be used. This stent requires a certain period of time after placement in the living body, and the bioabsorbable resin fiber is decomposed in the living body and absorbed by the living body and disappears. As a result, the metal wires entangled with the bioabsorbable resin fiber remain in the living body as independent (unbonded) spiral structures. The remaining warp can maintain the expansion force by itself and can be pulled out of the body when necessary.

  As a stent having a structure similar to the above-described blade stent, for example, a single metal wire is used as a weft, a plurality of bioabsorbable resin fibers are used as warps, and the weft is a spring coil (spiral structure). A woven wire mesh-like cylindrical structure in which the coil is woven so as to be sewn with a plurality of warps is also included in another embodiment of the stent of the present invention. This stent can be manufactured using, for example, a cylindrical weaving machine.

  After the stent is placed in the vessel, the stent retains the expansion force in the direction of the outside of the original tube by expanding the diameter using, for example, a balloon. Moreover, after indwelling in the living body, the bioabsorbable resin fiber constituting the warp yarn is decomposed in the living body over a certain period of time and absorbed by the living body and disappears. As a result, the weft remains in the living body as an independent (uncoupled) spiral structure. This warp yarn can maintain its expansion force by itself and can be pulled out of the body when necessary.

(3-3) Zigzag Stent FIG. 4 shows another embodiment of the stent of the present invention.

  The stent shown in this figure uses a zigzag metal wire 10 having a corresponding stitch (loop) instead of the metal wire having a stitch in the knit knitted stent shown in FIG. 1 to form a spiral structure. The spiral stitches are knitted with the bioabsorbable resin fibers 20.

  The spacing of the spiral with respect to the stent axis direction can be appropriately determined according to the type of metal wire used, desired expansion force, the length of the stent to be placed, and the like, but is not particularly limited, but is generally 0.05-0.5 It is normal to select from a range of about mm. The angle (pitch) of the spiral with respect to the axial direction of the stent can also be arbitrarily selected, but can generally be selected from a range of 60 ° or more and less than 90 °. The radius of curvature of the metal wire is preferably within the elastic deformation range from the viewpoint of securing the drawability. The length of the straight portion of the metal wire 10 bent in a zigzag shape can be appropriately selected according to the wire diameter of the metal wire, the desired expansion force, the stent tube diameter, and the like. For example, in the case of a vascular stent having a relatively large diameter, such as the digestive tract and trachea, it can usually be selected from a range of about 0.2 to 1.0 mm. Further, the angle (θ) formed by the adjacent straight line portions can be appropriately selected from the range of about 10-110 °. This stent is expanded by self-expansion to obtain expansion force.

(3-4) Production of the stent of the present invention The stent of the present invention can be produced according to various techniques conventionally known in the field of textile products (woven fabric, knitted fabric, braided field).

  A specific example of the manufacture will be described in detail by taking the stent of the present invention shown in FIG. 1 as an example. The stent is a circular knitting machine (cylinder knitting machine) widely used for manufacturing panty stockings, for example. Can be used and organized. The cylindrical knitting machine includes a cylinder that rotates around a vertical axis, and a plurality of knitting needles that move up and down separately according to the rotation on the circumference of the cylinder. The basics of knitting with this knitting machine are as follows. That is, when the metal wire 10 is supplied on the circumference of the cylinder, the knitting needle that moves upward catches this, moves down, and pulls it down the sinker line. As the needles arranged on the circumference of the cylinder move up and down, the needle loop 11 formed in the retracting portion is intertwined on both sides of the sinker loop 12 on the sinker line as shown in FIG.

  An ordinary tubular knitting machine has one yarn feeder, but a composite knitting machine having two or more yarn feeders is used for manufacturing the stent of the present invention. By providing a cam crest corresponding to each yarn feeder of the knitting machine, two or more stitches are formed simultaneously. That is, for example, when two yarn feeders are provided, the metal wire 10 is supplied from one yarn feeder, and the knitting machine is driven while the bioabsorbable resin fiber 20 is supplied from the other yarn feeder. Thereby, the metal wire 10 and the bioabsorbable resin fiber 20 can be knitted in a step pattern (alternately).

  In the above, the upper cams corresponding to the respective yarn feeders are not integrated, but have a split structure, whereby the sizes of the stitches of the metal wire 10 and the bioabsorbable resin fiber 20 can be made different. . Moreover, it is possible to obtain a desired stent diameter by inserting a round bar having the same size as a desired inner diameter into a cylinder of a knitting machine and knitting a knitted fabric around the knitted fabric.

  In general, in a small-diameter tubular knitting machine, a cylinder on which a knitting needle operates is fixed, and a cam and a housing having a yarn feeder that moves the needle up and down rotate around the cylinder so that the needle moves up and down while supplying the yarn. ing. In the case of a knitting machine with a single yarn feeder, the yarn to be knitted is installed in a different place from the knitting machine, and the yarn is supplied to the yarn feeder from directly above the knitting machine. Since the composite knitting machine has two or more yarn feeders, if the yarn is supplied from directly above the knitting machine in the same manner as described above, the yarns are entangled before reaching the yarn feeder and cannot be knitted. Therefore, in the composite knitting machine, it is desirable to rotate each yarn in synchronism with the yarn feeder, thereby avoiding the above disadvantages.

  Furthermore, metal wires and bioabsorbable resin fibers (monofilaments) usually do not twist themselves, but when such a thread is unwound from a vertical bobbin in the vertical direction (released), the twist will not occur. appear. Such twisting has a disadvantage of causing twist in the knitted fabric after knitting. In order to prevent the occurrence of this twist, in the composite knitting machine used in the present invention, the bobbin wound with each yarn is installed horizontally, and the wound yarn is supplied by releasing (pulling) the yarn wound according to the rotation. Is desirable.

In the stent of the present invention, the course direction in which the sinker loop 12 of the metal wire (including the bioabsorbable resin fiber in some cases) constituting the stent is larger than the needle loop 11 as shown in FIGS. It is desirable to have a length. The course length (L _S ) of the sinker loop is determined by the interval between the knitting needles arranged in the circumferential direction of the cylinder of the composite knitting machine. Accordingly, the desired course length (LS) can be obtained by appropriately selecting the interval between the knitting needles. Usually, when knit knitting is performed using a general circular knitting machine, the course direction length (L _N ) of the needle loop 11 and the course length (L _S ) of the sinker loop 12 are substantially equal. As one preferred embodiment for making the course direction length (L _S ) of the sinker loop 12 longer than the course length (L _N ) of the needle loop 11, for example, a plurality of knitting needles of an ordinary cylindrical knitting machine are used as cylinders. There can be mentioned an embodiment in which 1 to 3 yarns are arranged in the circumferential direction and knit miss knitting is formed at a position corresponding to this portion. As another preferred embodiment, the design of the cam for moving the knitting needle up and down is changed, and 1 to 3 knitting needles arranged in the circumferential direction of the cylinder are skipped and moved up and down to a position corresponding to the knitting needle that does not move up and down. An embodiment in which a knit mistake stitch is formed can be given. Thus, the stent of the present invention can be knitted.

  The stent of the present invention according to another embodiment can be produced in the same manner as described above according to various knitting techniques, braiding techniques, and woven techniques conventionally known in the textile product field.

  In addition, the use ratio of the metal wire and the bioabsorbable resin fiber in the stent of the present invention can be arbitrarily determined according to these types and the expansion force and removal property of the obtained stent, and is particularly limited. It is not a thing.

(4) Application of the stent of the present invention The stent of the present invention is applied to various vessels such as the esophagus, bile duct, ureter, prostate urethra, urethra, colon, bronchi / tracheal lumen, gastrointestinal lumen, blood vessel, pancreatic duct, small intestine, large intestine and the like. That is, the present invention can be applied to almost all biological ducts in which stenosis can occur. In particular, the stent of the present invention can be advantageously applied to airway lesions that may cause suffocation or respiratory failure due to obstruction or stenosis, and thus can perform palliative treatment by patency of the airway.

  In addition, the stent of the present invention can be placed and applied for the purpose of temporary lumen patency against stenosis of a luminal organ due to a benign disease. In this case, by removing the stent of the present invention after healing of the disease, restenosis or the like due to the stent placement (foreign substance reaction) can be avoided.

  Furthermore, the stent of the present invention is advantageous in that it can replace the optimal stent for the pathological condition such as stenosis of a luminal organ in which a child is a patient, corresponding to the increase of the organ accompanying the growth of the patient. There is.

  When a therapeutic drug is contained in the stent, it is possible to selectively distribute the therapeutic drug at a lesion site and enhance the effect of the drug therapy. It is also possible to carry out the treatment form several times depending on the disease state.

  For example, the stent of the present invention can be applied by inserting it into the angioplasty unit through a catheter with a balloon and expanding it by expanding the balloon, or after expanding a lesion with a balloon-attached catheter. A method of insertion (detention) by self-expansion can be mentioned.

  The outer diameter at the time of expansion of the stent of the present invention suitable for these methods can be appropriately determined according to the size of the vessel to which the stent is applied. Normally, when applied to a stenosis part of a vascular vessel, it is necessary to secure the lumen lumen by expanding the stenosis part. Therefore, the outer diameter is about 5 to 20% larger than the inner diameter of the lumen to be placed. It is desirable to have. In addition, the outer diameter of the stent of the present invention at the time of contraction is not particularly limited, but it is preferably as small as possible in consideration of the patient's invasion (stress) at the time of placement. In general, the outer diameter is preferably about 1/2 to 1/5 of the expanded outer diameter.

  The length when the stent of the present invention is placed and expanded in a living body can be appropriately determined according to the type of lumen to be expanded and the length of the narrowed portion. Usually, about 20 mm to 200 mm is common.

  The stent of the present invention is preferably such that the bioabsorbable resin fiber constituting the stent is absorbed into the living tissue and disappears within a few weeks to several months after being inserted into the lumen. .

EXAMPLES Examples are given below to describe the present invention in more detail.

Example 1
Using SUS (SUS304W1, Nippon Seisen Co., Ltd., diameter 0.2 mm) as the metal wire, and PLA monofilament (520T, Chuko Kasei Co., Ltd., diameter 0.23 mm) as the bioabsorbable resin fiber, these are used. As shown in FIG. 1, the stent of the present invention was produced by alternately entanglement. This had a stent diameter of 20 mm and a stent length of 60 mm.

  That is, a composite knitting machine comprising the two yarn feeders described in the above (3-4), a cam crest corresponding to each yarn feeder, and a horizontally installed bobbin that rotates in synchronization with each yarn feeder. Utilizing the metal wire 10 and the bioabsorbable resin by driving the knitting machine while supplying the metal wire 10 from one yarn feeder and supplying the bioabsorbable resin fiber 20 from the other yarn feeder A stent sample of the present invention was produced by knitting the fibers 20 in a stepped pattern (alternately).

Example 2
In Example 1, a stent sample of the present invention was prepared in the same manner using PLA multifilament (manufactured by Chuko Kasei Co., Ltd., 150 denier) instead of PLA monofilament.

Test example 1
(1) Test Stent Sample With regard to the stent samples of the present invention obtained in Examples 1 and 2, the force (repulsive force) and the expansion force when deforming the stent, which are particularly necessary for practical use, were examined.

  There are two types of stents available for comparison: Spiral Z stent (Medico's Hirata) sample (Comparative 1) and Ultraflex stent (Boston Scientific) sample (Comparative 2) (both stent diameter 20mm, stent length 60mm) ) Was selected.

  For comparison, a stent composed of only PLA monofilament fibers (520T, manufactured by Chuko Kasei Co., Ltd., diameter 0.23 mm) in the same manner as in each example (but not using one yarn feeder of the composite knitting machine). (Control product, stent diameter 20 mm, stent length 60 mm) was prepared and used for the test.

(2) Repulsive force test The repulsive force of each sample was evaluated as a lateral compression load of the stent. The stent was sandwiched between two upper and lower metal flat plates and subjected to lateral compression deformation using an autograph. The load and displacement when the various stents were compressed in the cross-sectional direction were measured, and the load when the stent was compressed to the radius was compared. Table 1 below shows the results of the lateral compression test (repulsive force, kN).

  As is clear from the results shown in Table 1, the commercial Spiral Z stent and Ultraflex stent and the control PLA monofilament stent all showed a repulsive force value as low as 20 to 37 kN. The stent samples of the present invention obtained in Examples 1 and 2 both showed a high repulsive force value of 80 kN. These repulsive force values in the stent of the present invention correspond to about 4 times that of a commercially available product.

(3) Expansion force test A rectangular non-woven fabric is wound into a cylindrical shape, one end of the cylinder is fixed, each stent sample is inserted into the cylinder, and the other end of the non-fixed non-woven fabric is pushed through a plastic plate. A pull gauge (Imada) was attached, a tensile load was applied, and the change in diameter of the stent sample was measured. That is, the relationship between the reduced diameter of the stent and the load associated with the reduced diameter of the nonwoven fabric cylinder by pulling the other end of the nonwoven fabric was evaluated. (See Miura, Yoshioka, Furuichi, Tanaka, Yoshikawa, Oishi, “Fundamental study on physical properties comparison of various biliary stents”, Journal of Japan Medical Association, 2003, Vol. 63, No. 5, 201-209). The obtained load measurement value (Radial Force (gf)) was evaluated as the expansion force (Radial Force (gf)) of the test stent.

  In the above test, the relationship between the amount of change in the diameter of each stent sample measured (the amount of diameter reduction, deformation, unit: mm) and the expansion force was graphed. That is, each sample when the diameter obtained as a result of the above test changes (reduces) by 0.5 mm by taking the expansion force (measured load value) of each sample as the vertical axis and the amount of change in diameter as the horizontal axis. The expansion force (measured load value) was plotted.

  The results obtained for each sample are shown in FIG.

  In the figure, line (1) is the result of the stent sample of the present invention obtained in Example 1, line (2) is the result of the stent sample of the present invention obtained in Example 2, and line (3) is the control product. Are the results of the PLA monofilament stent sample, line (4) is the result of the commercially available Ultraflex stent sample, and line (5) is the result of the commercially available Spiral Z stent sample.

  The following is clear from the results shown in FIG. That is, for the expansion force, the stent sample of the present invention (SUS + PLA monofilament) obtained in Example 1 (line (1)) showed the highest expansion force, and then the stent sample of the present invention obtained in Example 2 ( SUS + PLA multifilament) (line (2)) showed a high expansion force approximately equivalent to this. These values were even better than the commercially available Ultraflex stent sample (line (4)), which is known as one having excellent expandability. The commercial Spiral Z stent sample (line (5)) showed the lowest value. Furthermore, the PLA stent sample (line (3)) shows an expansion force almost equal to that of the stent sample of the present invention at the initial stage of deformation, but the inclination decreases with increasing load, and about 15% of the diameter (corresponding to 3 mm). It was found that the expansion force cannot be maintained due to the occurrence of kinks when a load is applied to reduce the diameter.

It is the schematic which shows one embodiment of this invention stent. FIG. 2 is an enlarged view showing a knitting mode of metal wires and bioabsorbable resin fibers in the stent of the present invention shown in FIG. It is the schematic which shows other one embodiment of this invention stent. It is the schematic which shows other one embodiment of this invention stent. 5 is a graph showing the results of (3) the expansion force test of Test Example 1 for the stent sample of the present invention obtained in Examples.

Explanation of symbols

(1) Stent of the present invention
(10) Metal wire
(11), (11 ') Needle loop
(12), (12 ') Sinker loop
(20) Bioabsorbable resin fiber

Claims (11)

A medical stent having a hollow tube structure that can be reduced in diameter, a metal wire having a spiral structure for holding an expansion force in an external direction of the tube, and a bioabsorbable resin fiber entangled with the metal wire The bioabsorbable resin fiber is a stent for medical use that imparts the ability to pull out a metal wire from a living body by decomposition. The metal wire has a spiral structure that can extend in the length direction of the tube, and the bioabsorbable resin fiber is entangled so as to control the extension of the metal wire spiral structure in the length direction of the tube, The stent according to claim 1. 3. The stent according to claim 2, wherein the spiral structure of the metal wire has a knit stitch, and the stitch portion is knitted with bioabsorbable resin fibers. 2. The stent according to claim 1, wherein a spiral structure of a metal wire having a knit stitch and a spiral structure of a bioabsorbable resin fiber having a knit stitch are knitted in a step pattern by both knit stitches. 5. The stent according to claim 4, wherein at least the knit stitch of the metal wire has a needle loop and a sinker loop having a larger course direction length than the needle loop. 2. The stent according to claim 1, wherein the metal wire is made of stainless steel (SUS) or nickel titanium alloy (NiTi). 2. The stent according to claim 1, wherein the bioabsorbable resin fiber is a polylactic acid monofilament, a polylactic acid multifilament, a polyglycolic acid (PGA) monofilament, or a PGA multifilament. 2. The medical stent according to claim 1, wherein at least one of the metal wire and the bioabsorbable resin fiber further holds a medical drug. 2. The stent according to claim 1, which is for a vascular vessel selected from the group consisting of esophagus, bile duct, ureter, prostate urethra, urethra, colon, bronchi / tracheal lumen, gastrointestinal lumen, blood vessel, pancreatic duct, small intestine and large intestine. 5. The stent manufacturing method according to claim 4, wherein the stent knitting machine includes at least one yarn feeder for supplying a metal wire and at least one yarn feeder for supplying a bioabsorbable resin fiber. A method comprising a step of knitting a metal wire and a bioabsorbable resin fiber into a stepped pattern using a wire. A stent knitting machine for the method for producing a stent according to claim 4, wherein at least one yarn feeder for supplying a metal wire, and at least one yarn feeder for supplying a bioabsorbable resin fiber; Stent knitting machine equipped with.

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