JP2007325952A - Stent for vascular channel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stent for a vascular channel which is inserted into the vascular channel without producing a stress concentration zone in the vascular channel. <P>SOLUTION: A stent for a vascular channel 31 which is inserted into the vascular channel of a living body and holds the inserted vascular channel from its inside has a tubular member 33 which constitutes a passageway from one end to other end side. In the tubular member 33, low rigidity parts 35, 36 which are lower in rigidity than the central main body part are formed in one on a metallic thin wire 32 or a central main body part 34 which twists a polymer thread in a net-like shape, and on the both ends side of the central main body part 34. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a vascular stained that is inserted into a blood vessel, a lymphatic vessel, a bile duct, a ureter, or the like, and this vascular stent has a vascular shape when inserted into a living vessel. Used to keep a certain state.

  Conventionally, when a stenosis occurs in a blood vessel of a living body, in particular, a blood vessel such as an artery, the balloon stenosis is formed by inserting a balloon forming part attached near the distal end of the catheter into the stenosis to form a balloon. Percutaneous angioplasty (PTA), which is a surgery to expand blood flow and improve blood flow, has been performed.

  By the way, it is known that even when percutaneous angioplasty is performed, restenosis is generated at a high probability in a portion where stenosis has occurred.

  In order to prevent such restenosis, a tubular stent is inserted into a portion where percutaneous angioplasty has been performed. As shown in FIG. 11, the stent 1 is embedded in the blood vessel 2 in an expanded state, thereby supporting the blood vessel 2 from the inside thereof and trying to prevent restenosis from occurring in the blood vessel 2. It is.

  According to a clinical case in which a stent formed by weaving a stainless steel wire in a mesh shape used in the past was inserted into the percutaneous angioplasty site, restenosis occurred in about 15%. It has been reported.

In order to prevent such restenosis, a stent formed of a polymer fiber containing a drug for preventing the occurrence of stenosis has been proposed in Japanese translation of PCT publication No. 5-502179 (WO91 / 01097) (Patent Document 1). ing. Further, there is one described in Japanese Patent Application Laid-Open No. 10-505527 (Patent Document 2) as one that is inserted into a blood vessel to maintain blood circulation.
Japanese Patent Publication No. 5-502179 Japanese National Patent Publication No. 10-505527

  By the way, it is known that the restenosis of the blood vessel after the stent is inserted frequently occurs at the end of the stent or from the end.

A stent used by being inserted into a blood vessel is formed to have a sufficiently large rigidity as compared with a blood vessel in order to keep the blood vessel in an expanded state. For example, the Young's modulus of a blood vessel is approximately 3 × 10 ⁷ Pascals, whereas the Young's modulus of stainless steel, which is the main stent material used to hold the blood vessel in an expanded state, is approximately 3 × 10 ¹¹ Pascals. .

  The stent 1 expanded and inserted into the blood vessel 2 holds the blood vessel 2 in an expanded state as shown in FIG. At this time, the blood vessel 2 is reduced in diameter at a position corresponding to each end 1a, 1b of the stent 1 that is no longer supported by the stent 1. At this time, the portions of the blood vessel 1 supported by the end portions 1a and 1b of the stent 1 become stress concentration portions.

  The blood vessel 1, particularly the artery, constantly pulsates because blood flows. Therefore, a load based on pulsation is repeatedly applied to the stress concentration portion of the blood vessel 2 supported by the end portions 1 a and 1 b of the stent 1. As a result, the inner wall of the blood vessel 2 may be damaged by the end portions 1 a and 1 b of the stent 1. Since a load is applied to the stress concentration portion supported by the inner wall of the blood vessel 2, a wound is generated from the inner membrane of the blood vessel 2 and further from the inner membrane to the outer membrane of the blood vessel 2. When the blood vessel 2 is damaged, it repairs the damage as a biological reaction. When repairing damage, the blood vessel 2 may overgrow the intima and cause restenosis.

  An object of the present invention is to provide a novel vascular stent that can solve the problems of conventional vascular stents.

  Another object of the present invention is to provide a vascular stent that can reliably prevent damage to the blood vessel while reliably maintaining the expanded state of the blood vessel such as a blood vessel.

  Still another object of the present invention is to provide a vascular stent that can be inserted into a vascular vessel without generating a stress concentration portion in the vascular vessel.

  A vascular stent according to the present invention proposed to achieve the above-described object is a vascular stent that is inserted into a vascular vessel of a living body and holds the inserted vascular vessel from the inside thereof. It has a tubular body that constitutes one flow path from one end to the other end, and this tubular body has a central main body knitted in a mesh shape with fine metal wires, and both ends of the central main body. The low-rigidity parts having lower rigidity than the central main part are integrally formed.

  In the tubular body constituting the vascular stent according to the present invention, a low-rigidity portion is formed on both ends of the central main body portion having a predetermined stitch density by making the stitch density smaller than that of the central main body portion. What was made can be used.

  In addition, the tubular body may be formed by laminating a polymer material on the central main body to form low-rigidity portions on both ends of the central main body.

  Further, the low rigidity portion is made of a polymer material.

  Furthermore, the tubular body is composed of a central main body knitted in a mesh shape of fine metal wires, and a low-rigidity portion formed by continuously knitting polymer fibers in a tubular shape at both ends of the central main body. Is used.

  Furthermore, the tubular body constituting the vascular stent according to the present invention includes a central main body knitted with a polymer yarn in a tubular shape, and a low-rigidity portion lower in rigidity than the central main body on each side of the central main body. What was formed in is used.

  By forming a tubular body using a bioabsorbable polymer thread, the stent retains its shape for several weeks to several months after insertion in the vessel, but the biological tissue is around several months after insertion. Can be absorbed and disappear.

  In addition, when the tubular body is formed of metal fine wires or polymer yarns, in the case where the yarn is knitted or woven, the central main body of the linear body constituting both ends By using a flexible linear body having a strength smaller than that of the linear body constituting the portion, low-rigidity portions are formed at both ends of the tubular body.

  Since the vascular stent according to the present invention is composed of a tubular body integrally formed with low-rigidity portions having low rigidity at both ends of the central main portion, the vascular stent according to the present invention can be expanded. It is possible to reliably hold it in a state in which the stress concentration portion is generated in the vascular vessel. Therefore, the vascular stent according to the present invention can prevent vascular inflammation, excessive thickening, and the like, and can prevent restenosis.

  Hereinafter, a vascular stent to which the present invention is applied will be described in detail with reference to the drawings.

  First, a vascular stent which is intended to solve a technical problem common to the technical problem to be solved by the present invention will be described with reference to the drawings. As shown in FIG. 1, the vascular stent 11 is used by being inserted into a blood vessel such as a coronary artery of a living body, and forms a single flow path from one end side to the other end side. A body 12 is provided. The tubular body 12 is formed using stainless steel having excellent corrosion resistance and biocompatibility.

In addition, as a metal which comprises the tubular body 12, nickel-titanium alloy, platinum, a tantalum, and platinum other than stainless steel can be used.

  And the tubular body 12 has the center main-body part 13 which has rigidity sufficient to hold | maintain a blood vessel in an expanded state, when inserted in the blood vessel. Low-rigidity portions 14 and 15 having lower rigidity than the central main body portion 13 are integrally formed on both ends of the central main body portion 13. These low-rigidity portions 14 and 15 are formed by making both end portions of the tubular body 12 thinner than the thickness of the central main body portion 13.

  The thin rigid portions 14 and 15 are formed by cutting both ends of the tubular body 12 or forging. At this time, as shown in FIG. 2, the low-rigidity parts 14 and 15 are preferably formed so that the thickness gradually decreases from the thick central main body 13 toward the end of the tubular body 12. . That is, the tubular body 12 is formed with low-rigidity portions 14 and 15 whose rigidity gradually decreases from the central main body 13 side toward both end portions.

At this time, the central main body 13 is formed to have a Young's modulus sufficiently larger than the Young's modulus of the blood vessel so that the blood vessel into which the stent 11 is inserted can be held in an expanded state. Since the Young's modulus of the blood vessel into which the stent 11 is inserted is approximately 3 × 10 ⁷ pascals, the central main body 13 is formed to have a Young's modulus of approximately approximately 3 × 10 ¹¹ pascals. The low rigidity portions 14 and 15 are formed so as to have a Young's modulus substantially equal to or slightly larger than the Young's modulus of the blood vessel.

  As described above, when the stent 11 using the tubular body 12 in which the low-rigidity portions 14 and 15 are formed at both ends of the central main portion 13 having high rigidity is inserted into the blood vessel 16 as shown in FIG. The blood vessel 16 can be held in an expanded state by the central main body portion 13 having high rigidity.

  The blood then flows into the blood vessel 16 via the stent 11. Further, the blood vessel 16 applies a load for reducing the diameter of the stent 11 by pulsating and repeating expansion and contraction. At this time, the low-rigidity portions 14 and 15 formed at both ends of the tubular body 12 are easily elastically displaced by the pulsation of the blood vessel 16 as shown in FIG. That is, the low-rigidity portions 14 and 15 are elastically displaced so that the diameter gradually decreases from the central main body portion 13 toward each end portion of the tubular body 12, thereby generating a portion where stress is concentrated on the blood vessel 16. Can be prevented.

  Since the stent 11 configured as described above can suppress the generation of a portion where stress is concentrated when inserted into the blood vessel 16, damage to the blood vessel 16 can be prevented, and restenosis based on the repair function of the blood vessel 16 can be prevented. Can be suppressed.

  Further, as shown in FIG. 5, a plurality of minute through holes 16 are formed on each end portion side of the tubular body 12 having an equal thickness, and the density of each end portion is made higher than the density of the central main body portion 13. By reducing the size, low rigidity portions 14 and 15 having lower rigidity than the central main body portion 13 are formed at each end portion of the tubular body 12. At this time, it is desirable that the micro holes 16 constituting the low-rigidity portions 14 and 15 are drilled so that the number gradually increases from the central main body portion 13 toward each end portion. By forming the micro holes 16 in this way, the rigidity of the low-rigidity portions 14 and 15 gradually decreases from the central main body portion 13 toward each end portion.

  Further, the plurality of micro holes 16 are formed so that the diameter of the holes gradually increases from the central main body portion 13 toward the respective end portions, whereby the rigidity of the low rigidity portions 14 and 15 is increased from the central main body portion 13 side. It can be gradually reduced toward each end.

  And as shown in FIG. 6, the low-rigidity parts 14 and 15 formed at each end of the tubular body 12 may be formed so that the diameter gradually decreases from the central main body 13 side toward the end. desirable. By forming the tubular body 12 in this way, when the stent 11 is inserted into the blood vessel 16, the diameter of the blood vessel expanded by the central main body portion 13 is gradually reduced to follow the low rigidity portions 14 and 15. As a result, the occurrence of stress-concentrated portions can be more reliably suppressed.

  The above-described stent 11 is made of a metal such as stainless steel, but may be made of a polymer material.

  As shown in FIG. 7, the stent 21 using the polymer material is formed by forming the polymer material into a tubular shape by using an injection molding method, an extrusion molding method, or the like, or forming a sheet body made of the polymer material into a tubular shape. It has a body 22.

  As the polymer material constituting the tubular body 22, a biocompatible material is selected, and in particular, a bioabsorbable material is selected. As bioabsorbable materials, polylactic acid (PLA), polyglycolic acid (PGA), polyglactin (polyglycolic acid, polylactic acid copolymer), polydioxanone, polyglyconate (trimethylene carbonate, glycolide copolymer), Polyglycolic acid or polylactic acid and ε-caprolactone copolymer can be used. The stent 11 formed of such a bioabsorbable polymer material retains its shape for several weeks to several months after insertion into the blood vessel, but is absorbed into the living tissue around several months after insertion. Can be eliminated.

  As shown in FIG. 7, the tubular body 22 constituting the stent 21 also has a central main body portion 23 having sufficient rigidity to hold the blood vessel in an expanded state when inserted into the blood vessel. Low-rigidity parts 24 and 25 having lower rigidity than the central main body part 23 are integrally formed on both ends of the central main body part 23. These low rigidity portions 24 and 25 are formed by making both end portions of the tubular body 22 thinner than the thickness of the central main body portion 13.

  Such thin low-rigidity portions 24 and 25 are formed by extending both end portions of the tubular body 12.

  The stent 21 using the polymer material may be the one in which the low-rigidity portions 24 and 25 are formed by drilling micro holes in each end portion of the tubular body 22 as in the case of using the metal described above. Good. Further, it is desirable that the low rigidity 24, 25 is formed so as to gradually reduce the diameter from the central main body 23 side toward the end.

  The vascular stent according to the present invention realizes the same effect as the vascular stent described above by knitting a metal fine wire or a polymer yarn.

  Next, a vascular stent according to the present invention using metal fine wires will be described with reference to the drawings.

  As shown in FIG. 8, the stent 31 has a tubular body 33 formed by knitting a fine wire 32 made of biocompatible stainless steel, nickel-titanium alloy, platinum, tantalum, platinum or the like. The tubular body 33 is formed into a stitch shape by knitting one metal thin wire 32, that is, by knitting the thin wire 33 so as to form a loop.

  The tubular body 33 includes a central main body 34 having sufficient rigidity to hold the blood vessel in an expanded state when inserted into the blood vessel. Low-rigidity portions 35 and 36 having lower rigidity than the central main body portion 34 are integrally formed on both ends of the central main body portion 34. These low rigidity portions 35 and 36 are formed by making the density of the stitches coarser than that of the central main body portion 34 having a predetermined stitch density. At this time, the low-rigidity portions 35 and 36 are desirably knitted so that the density of the stitches gradually decreases from the central main body portion 34 toward the end portion of the tubular body 33.

  The central main body 34 has a stitch having a density sufficient to obtain a Young's modulus sufficiently larger than the Young's modulus of the blood vessel so that the blood vessel can be held in an expanded state when the stent 31 is inserted into the blood vessel. Thus, the low-rigidity portions 35 and 36 are knitted so as to have stitches with a density sufficient to obtain a Young's modulus substantially equal to or slightly larger than the Young's modulus of the blood vessel.

  In order to form the stent 31 having the low rigidity portions 35 and 36 having lower rigidity than the central main body portion 34 on the end side of the tubular body 33, the entire tubular body 33 is substantially equal to the Young's modulus of the blood vessel or slightly. The metal thin wires 32 are knitted with a density of stitches having a large Young's modulus. Then, as shown in FIG. 9, a reinforcing portion 37 in which polymer materials are laminated is provided on the central main body portion 34 of the tubular body 33 so as to increase the rigidity. At this time, the polymer material constituting the reinforcing portion 37 is laminated so that the central main body portion 34 has sufficient rigidity to hold the blood vessel in an expanded state.

  The reinforcing portion 37 is formed by outsert-molding a polymer material on a tubular body 33 formed by knitting metal thin wires 32. That is, the reinforcement part 37 is formed by injection-molding a polymer material on the tubular body 33 arranged in the molding die.

  Further, in order to increase the rigidity of the central main body 34 of the tubular body 33, a metal fine wire 32 may be further knitted into the central main body 34.

  The stent 31 knitted as shown in FIG. 8 may be formed using a polymer yarn. This yarn is formed by spinning a polymer fiber.

  At this time, the stent 31 constituted by the tubular body 33 knitted with a bioabsorbable polymer fiber yarn retains its shape for several weeks to several months after insertion in the blood vessel, but around several months after insertion. Can be absorbed into the living tissue and disappear.

  Here, the bioabsorbable polymer includes polylactic acid (PLA), polyglycolic acid (PGA), polyglactin (polyglycolic acid, polylactic acid copolymer), polydioxanone, polyglyconate (trimethylene carbonate, glycolide copolymer). Polyglycolic acid or polylactic acid and ε-caprolactone copolymer can be used.

  Various chemicals can be mixed in the polymer fiber yarn. Therefore, by mixing an X-ray impermeable agent at the time of spinning the fiber, the state of the vascular stent inserted into the blood vessel can be observed by X-ray, and thrombolysis such as heparin, urokinase and t-PA is possible. It is also effective to mix agents and antithrombotic agents.

  The above-described stent 31 is basically formed by knitting a single fine metal wire or polymer yarn having a substantially uniform thickness, but by changing the thickness of the fine wire or yarn, the rigidity can be increased. It can be constituted by a tubular body 33 having low-rigidity portions 35 and 36 having low rigidity as compared with the central main portion 34 having a high height. That is, the central main body portion 34 of the tubular body 33 is formed of a thick and highly rigid thin wire or thread, and each end portion of the tubular body 33 is thinner than the thin wire or thread constituting the central main body portion 34 and has a low rigidity. The low-rigidity portions 35 and 36 are formed at the end portions of the tubular body 33 by knitting.

  Further, by changing the cross-sectional shape of the thin wire or thread constituting the central main body 34 and the thin wire or thread constituting each end of the tubular body 33, the low-rigidity portions 35 and 36 are provided at each end of the tubular body 33. You may make it form. That is, it is formed so as to reduce the rigidity by flattening the cross-sectional shape of the fine wire or thread constituting each end of the tubular body 33. Alternatively, the cross-sectional shape of the thin wire 32 or the thread 42 constituting the central main body 34 of the tubular body 33 is set to be higher than the thin wire or the thread constituting each end of the tubular body 33, for example, in FIG. As shown, it is formed to have an H-shaped cross section.

  Furthermore, when the tubular body 33 is formed by knitting with metal fine wires or polymer yarns, the number of fine wires or yarns to be knitted simultaneously is reduced from the central main body 34 to each end. Thus, the low-rigidity portions 35 and 36 may be formed at the respective end portions of the tubular body 33.

  The stent according to the present invention can be used not only for blood vessels but also for living vessels such as lymphatic vessels, bile ducts and ureters.

  The vascular stent according to the present invention is applied to percutaneous angioplasty (PTA), which is a surgery for expanding blood vessel stenosis to improve blood flow.

It is a perspective view which shows the example of the stent for vessels provided with the basic composition of the stent for vessels concerning the present invention. FIG. 2 is a cross-sectional view of the vascular stent shown in FIG. 1. It is a perspective view which shows the state which inserted the stent for blood vessels shown in FIG. 1 in the blood vessel. It is sectional drawing which shows a state when the vascular stent shown in FIG. 1 is inserted in the blood vessel, and the blood vessel beats. It is a perspective view which shows the other example of the stent for blood vessels. FIG. 9 is a cross-sectional view showing still another example of a vascular stent and showing a vascular stent in which a low-rigidity portion formed at each end of a tubular body is gradually reduced in diameter. It is sectional drawing which shows the stent for blood vessels which formed the tubular body with the polymer material. 1 is a perspective view showing a vascular stent according to the present invention formed by knitting a tubular body with metal fine wires or polymer yarns. FIG. It is a perspective view which shows the vascular stent which concerns on this invention which provided the reinforcement member in the center main-body part of the tubular body formed by knitting with the metal wire or polymer thread | yarn. It is sectional drawing which shows the metal fine wire or polymer thread | yarn which comprises the center main body part of a tubular body. It is a perspective view which shows the state which inserted the conventional vascular stent in the blood vessel.

Explanation of symbols

  31 Vascular Stent, 32 Fine Wire, 33 Tubular Body, 34 Central Main Part, 35, 36 Low Rigidity Part, 37 Reinforcement Part 2

Claims (10)

In a vascular stent that is inserted into a blood vessel of a living body and holds the inserted vessel from the inside thereof,
Comprising a tubular body constituting one flow path from one end to the other end,
The tubular body is for a vascular structure in which a central main body knitted in a mesh shape with fine metal wires and a low-rigidity portion lower in rigidity than the central main body are integrally formed on both ends of the central main body. Stent.   The tubular body is characterized in that a low-rigidity portion formed by reducing the density of the stitches compared to the central main body portion is formed on both ends of the central main body portion having a predetermined stitch density. 1. The vascular stent according to 1.   The vascular stent according to claim 1, wherein the tubular body is formed by laminating a polymer material on the central main body portion to form low-rigidity portions on both ends of the central main body portion.   The vascular stent according to claim 1, wherein the low-rigidity portion is formed of a polymer material.   The tubular body includes a central main body knitted in a mesh shape of metal thin wires, and a low-rigidity portion formed by continuously knitting polymer fibers in a tubular shape on both end sides of the central main body. The vascular stent according to claim 1, wherein In a vascular stent that is inserted into a blood vessel of a living body and holds the inserted vessel from the inside thereof,
Comprising a tubular body constituting one flow path from one end to the other end,
The tubular body is a vascular stent in which a central main body knitted from a polymer yarn in a tubular shape and a low-rigidity portion lower in rigidity than the central main body are integrally formed on both ends of the central main body.   The tubular body has low rigidity portions formed by making the density of the stitches smaller than that of the central main body portion compared to that of the central main body portion at both ends of the central main body portion having a predetermined stitch density. The vascular stent according to claim 6.   The vascular stent according to claim 6, wherein the tubular body is formed by laminating a polymer material on the central main body portion to form low-rigidity portions on both ends of the central main body portion.   The vascular stent according to claim 6, wherein the polymer yarn is made of a bioabsorbable polymer.   The vascular stent according to claim 6, wherein a drug is mixed in the polymer yarn.

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