JP2005287568A - Stent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stent having excellent characteristics of flexibility in the axial direction and radial support power and also having excellent biocompatibility. <P>SOLUTION: The stent 1 comprises a stent body 2 having an almost cylindrical overall shape and a membrane 10 covering almost all of the outer surface of the stent body 2, and is inserted into and indwelled in the inner lumen part of a luminal organ of a living body. The stent body 2 has a mesh-like structure with a plurality of openings 20. Each of the openings 20 has a polygonal shape surrounded by a plurality of straight lines 21 connected with each other at angles smaller than 180°. Recesses 22a that are recessed in the direction of or in the opposite direction of the central axis of the stent body 2 are formed on intersection points and/or in the middle of at least a part of the straight lines 21. Each of the recesses 22a are arranged along a spiral centering the central axis of the stent body 2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a medical stent, and more particularly to a stent used by being inserted and placed in a tubular organ such as a blood vessel.

  2. Description of the Related Art Conventionally, stents are known that are inserted and placed in the lumen of biological tubular organs (for example, blood vessels, trachea, esophagus, bile ducts, etc.) and support the tubular organ from the inside.

  The stent is generally cylindrical as a whole, and is introduced into the lumen of the tubular organ in a reduced diameter state. After the lumen is moved, the stent is fixed by being expanded in the target site for placement. (Installed).

  For this reason, the stent needs to have a certain degree of flexibility in the radial direction and also needs to have an axial flexibility (that is, flexibility) so that it can easily pass through the bent portion of the tubular organ. . Also, when the narrowed portion (target site) of the tubular organ is bent, flexibility in the axial direction is also required.

  As a stent having such flexibility, for example, a stent having a configuration described in Patent Document 1, that is, a configuration in which cylindrical elements are connected to each other by an interconnecting member has been proposed.

  Among them, the interconnecting member is provided for the purpose of increasing the fixing force at the lumen of the tubular organ by increasing the strength of the stent and increasing the contact area with the inner wall of the tubular organ. .

JP-A-11-104246

  However, in this type of stent, there is a problem in that the axial flexibility of the stent is impaired when the size of the interconnection member is increased. On the other hand, if importance is attached to the flexibility in the axial direction and the dimensions of the interconnecting members are reduced, the force (radiation support force) for maintaining the shape of the tubular organ in the expanded state is reduced.

  Therefore, the present invention solves the above-described problems, and an object of the present invention is to provide a stent having excellent characteristics in both axial flexibility and radiation supporting force.

  In order to solve the above-mentioned problems, the stent of the present invention is a stent having a stent body which is used by being inserted and placed in a lumen portion of a living tubular organ and has a substantially cylindrical shape as a whole. The stent body has a network structure having a plurality of openings, and each of the openings has a polygonal shape by being surrounded by a plurality of straight portions connected to each other at an angle of less than 180 °, and at least a part of the stent body is formed. The straight portion is formed with a recessed portion that is recessed toward the center axis side or the opposite side of the central axis of the stent body at the intersection and / or in the middle thereof. The stent body is arranged along a spiral centered on the central axis of the stent body. According to the present invention, both the axial flexibility and the radiation supporting force are excellent.

  In the present invention, it is desirable that each of the recessed portions is recessed toward the same side. According to the present invention, it is possible to prevent the directionality from occurring in the axial flexibility and the radiation supporting force.

  In the present invention, it is desirable that the spiral pitch and the intersection pitch are different. According to the present invention, high flexibility in the axial direction and high radiation supporting force can be ensured while preventing the overall rigidity and strength from decreasing.

In the present invention, when the spiral pitch is P ₁ and the intersection pitch is P ₂ , P ₁ / P ₂ is preferably in a range of less than 1. According to the present invention, high flexibility in the axial direction and high radiation support force can be more reliably ensured while more reliably preventing the overall rigidity and strength from being lowered.

  In the present invention, it is desirable that the pitch of the spiral is substantially constant. According to the present invention, axial flexibility can be made substantially uniform along the axial direction.

  In the present invention, the recessed portion is preferably formed over substantially the entire stent body. According to the present invention, axial flexibility can be imparted over substantially the entire length.

  In the present invention, it is desirable that the cross-sectional area of the straight portion is substantially constant over substantially the entire stent body. According to this invention, it is possible to prevent the strength from being extremely lowered in the portion where the recessed portion is formed. As a result, it can be prevented that it becomes easy to extend in the axial direction, and it becomes easy to bend in a direction perpendicular to the axial direction. That is, higher stretch resistance and buckling resistance are exhibited.

In the present invention, the average cross-sectional area of said straight portions is desirably in the range of 1 × 10 ^-5 mm ² or more 0.1 mm ² or less. According to this invention, high rigidity and axial flexibility can be ensured.

  In the present invention, it is desirable that the cross-sectional shape of the straight portion is substantially constant over substantially the entire stent body. According to the present invention, it is possible to prevent the axial flexibility from being uneven in each part.

  In the present invention, it is desirable that the edge of the straight portion is rounded. According to the present invention, it is possible to prevent the inner wall of the tubular organ from being inadvertently damaged during or after the stent placement operation. In addition, when applied to an indwelling stent, it contributes to a reduction in the incidence of thrombus after placement.

  In the present invention, the main stent body is preferably composed of Au, Pt, Ta, Rh, Ru, Pd, Nb, Os, Ir, Ag, or an alloy containing these as a main material. According to the present invention, it can be suitably applied to a balloon-expandable stent, and is excellent in biotissue compatibility after placement, and can minimize degradation and degradation of properties in vivo.

  In the present invention, the stent body is preferably composed of a Ni / Ti alloy as a main material. According to the present invention, it can be suitably applied to a self-expanding stent, has excellent compatibility with living tissue after placement, and can minimize deterioration and degradation of characteristics in vivo.

  In the present invention, it is desirable that the stent main body is formed by integrally forming the linear portion. According to this invention, the strength as a whole is further improved.

  In the present invention, it is desirable to have a membrane covering at least a part of the outer surface and / or inner surface of the stent body. According to this invention, for example, by impregnating a membrane with various drugs, the effect according to the drug can be exerted, and a safer treatment can be performed.

  ADVANTAGE OF THE INVENTION According to this invention, the softness | flexibility of an axial direction can be improved, preventing the fall of radiation | emission supporting force by providing the recessed part in the linear part which comprises a stent main body. That is, both the axial flexibility and the radiation supporting force are excellent.

  As a result, the lumen of the tubular organ that is curved, bent, or branched in a complicated manner can be easily and reliably transferred to the target site where the stent is to be placed. In addition, even when the target portion has a bent shape, it can be reliably placed (fixed).

  Moreover, since the concave and convex portions are formed on the outer surface side of the stent, it is possible to prevent the stent from being displaced in the axial direction after being placed at the target site.

  In addition, by setting the relationship between the pitch of the spiral and the pitch of the intersection of the linear portions, the axial flexibility and the radiation support force are further improved.

  Further, by making the cross-sectional area of the straight portion almost constant over the entire stent body, higher stretch resistance and buckling resistance are exhibited.

Next, embodiments of the stent according to the present invention will be described in detail with reference to the accompanying drawings.
In FIG. 1, a stent 1 is used by being inserted and placed in a lumen of a living tubular organ, and a stent body 2 having a substantially cylindrical shape as a whole, and an outer surface of the stent body 2. And a film 10 covering the whole.

  The stent 1 is transported (conveyed) to a target site in the lumen of the tubular organ in a state where the outer diameter of the stent body 2 is contracted (reduced diameter) (hereinafter referred to as a “reduced diameter state”). . And, at this target site, by applying the restoring force of the stent body 2 itself or by applying an external force, the outer diameter of the stent body 2 is expanded (expanded) to be larger than the outer diameter of the reduced diameter state, In this state (hereinafter referred to as “expanded diameter state”), it is fixed (attached) to the target site.

  The stent body 2 has a network structure formed by connecting a plurality of flat plate-like straight portions 21 together. An opening 20 is formed in a portion surrounded by a plurality of straight portions (struts) 21.

  The straight portions 21 are connected to each other at an angle of less than 180 °, whereby each opening 20 has a polygonal shape (in this embodiment, a diamond shape by being surrounded by four straight portions 21). . With this configuration, the stent 1 (stent body 2) has excellent radial flexibility while ensuring sufficient rigidity and strength. In addition, since sufficient rigidity and strength can be ensured, the stent 1 has excellent radiation support.

  Here, in the present specification, “radial flexibility” refers to flexibility in the direction of the arrow in FIG. 2, that is, the direction from the central axis toward the outside. “Radiation support force” refers to a force that maintains the shape of the tubular organ in the expanded state.

  Each linear portion 21 is formed with a recessed portion 22a that is recessed toward the central axis side of the stent body 2 at the intersection 211 and / or in the middle thereof. Each of the recessed portions 22a is arranged along a spiral with the central axis of the stent body 2 as the center. Thereby, high flexibility in the axial direction can be imparted to the stent 1.

  Here, in this specification, “axial flexibility” refers to flexibility in the direction of the arrow in FIG. 1 (ease of bending, that is, flexibility).

  Further, by providing the recessed portion 22a, irregularities are formed on the outer surface side of the stent 1, so that slipping with respect to the inner surface of the tubular organ is prevented, and the stent 1 can be more securely fixed in the lumen portion of the tubular organ.

Further, the spirals are arranged such that the pitch P ₁ is substantially constant and is different from the pitch P _{2 at} the intersection 211 of the straight line portion 21. By making the helical pitch substantially constant, the flexibility of the stent 1 in the axial direction can be made substantially uniform along the axial direction. Further, by making the spiral pitch P ₁ different from the pitch P _{2 of the} intersection 211, the concave portion 22 a randomly appears that overlaps the intersection 211 and does not overlap the intersection 211. With this configuration, high flexibility in the axial direction can be ensured while preventing a decrease in rigidity and strength of the entire stent 1.

In this case, the pitch P _{1 of} the spiral and the pitch P _{2 of the} intersection 211 are preferably in the range where P ₁ / P ₂ is less than 1, more preferably in the range of 0.5 or less, and in the range of 0.01 to 0.1 More desirably, it is in the range. As a result, high flexibility in the axial direction can be ensured more reliably while preventing the rigidity and strength of the entire stent 1 from decreasing more reliably.

  In this embodiment, the recessed portion 22a has a shape such that the linear portion 21 is deformed in the thickness direction, as shown in FIGS. That is, the cross-sectional area of the straight part 21 is substantially constant over the entire stent body 2. Thereby, it is possible to prevent the strength of the stent body 2 from being extremely reduced in the portion where the recessed portion 22a is formed. As a result, it is possible to prevent the stent 1 from easily extending in the axial direction and from being easily bent in the direction perpendicular to the axial direction.

The average cross-sectional area of the straight portion 21 varies slightly depending on the constituent material of the stent main body 2 is preferably in the range of 1 × 10 ^-5 mm ² or more 0.1 mm ² or less, 1 × 10 ^-4 mm ² or more A range of 0.01 mm ² or less is more desirable. If the cross-sectional area of the straight portion 21 is too small (the straight portion 21 is too thin), the rigidity of the stent 1 may be reduced. If the cross-sectional area of the straight portion 21 is too large (the straight portion 21 is too thick), the stent The axial flexibility (flexibility) of 1 may be reduced.

  Further, the cross-sectional shape of the straight portion 21 may be different in each portion of the stent body 2, but it is desirable that the straight portion 21 is substantially constant over almost the entire stent body 2, as shown in FIG. Thereby, it is possible to prevent the axial flexibility of the stent 1 from becoming uneven in each part.

  Note that the cross-sectional shape of the straight line portion 21 may be, for example, a polygon such as a circle, an ellipse, a square, a rhombus, a triangle, a pentagon, and a hexagon in addition to a quadrangle (rectangular shape) as shown in FIG.

  Moreover, the longitudinal cross-sectional shape (shape in side view) of the recessed part 22a is not limited to a U-shaped thing as shown in FIG.1 and FIG.3, For example, V shape and U shape may be sufficient.

  Although not shown, it is desirable that the edge of the stent body 2 (the straight portion 21) is rounded. Thereby, it is possible to prevent the inner wall of the tubular organ from being inadvertently damaged at the time of or after the placement of the stent 1. Further, when the stent 1 is applied to an intravascular stent, it is useful for preventing thrombus formation.

  In such a stent body 2, the straight portions 21 are integrally formed by a method as described later. Thereby, the strength of the stent 1 as a whole is further improved.

  As the constituent material of the stent body 2, the following materials are desirably used according to the type of the stent 1.

  When the stent 1 is applied to a balloon expandable stent, the stent body 2 needs not to be deformed by the compressive stress received from the tubular organ in the expanded state. For this reason, it is desirable to use a material that is work-hardened by plastic deformation due to expansion and that has relatively high rigidity after expansion as the constituent material of the stent body 2. In addition, it is desirable to use a material with high biotissue compatibility and high chemical stability.

  As such a material, Au, Pt, Ta, Rh, Ru, Pd, Nb, Os, Ir, Ag or an alloy containing them, high-density polyolefin, or the like can be used.

  Among these, in particular, Au, Pt, Ta, Rh, Ru, Pd, Nb, Os, Ir, Ag or an alloy containing these is desirable, Au, Pt, Rh, Ru, Ir or these It is more preferable to use an alloy containing mainly. These are particularly excellent in the property of being work-hardened by plastic deformation due to expansion (work-hardening property), and are also excellent in biological tissue compatibility and X-ray contrast properties. In the case of an alloy, there is an advantage that work hardening can be easily controlled by the composition ratio.

  Therefore, by forming the stent body 2 with these materials, for example, when the stent 1 is applied to an intravascular stent, thrombus formation can be effectively prevented. In addition, since the operation of placing the stent 1 in the lumen of the tubular organ can be performed under fluoroscopy, the placement operation can be performed more smoothly and accurately.

  On the other hand, when the stent 1 is applied to a self-expanding stent, the stent body 2 needs to be able to spontaneously restore its shape. For this reason, it is desirable to use a superelastic alloy, a shape memory alloy, or a material with relatively high elasticity as the constituent material of the stent body 2.

  Examples of such materials include Ni / Ti alloys, Cu / Zn alloys, Ni / Al alloys, Cu / Cd alloys, Au / Cd / Ag alloys, Ti / Al / V alloys, and the like.

  Among these, those mainly composed of Ni / Ti alloy are particularly desirable. This is because the material exhibits particularly high elasticity and also has excellent shape memory characteristics.

  In addition, these materials are excellent in biological tissue compatibility and excellent in X-ray contrast properties. Therefore, by forming the stent body 2 with these materials, for example, when the stent 1 is applied to an intravascular stent, thrombus formation can be effectively prevented. In addition, since the operation of placing the stent 1 in the lumen of the tubular organ can be performed under fluoroscopy, the placement operation can be performed more smoothly and accurately.

  The stent 1 of the present embodiment has a membrane 10 that covers almost the entire outer surface of the stent body 2. For example, by impregnating the membrane 10 with various drugs, an effect corresponding to the drug can be exhibited, and a safer treatment can be performed.

  For the membrane 10, for example, woven fabrics, nonwoven fabrics, sheets and the like composed of various polymers can be used, and in particular, those composed of biodegradable and bioabsorbable polymers should be used. Is desirable. Thereby, when the membrane 10 is impregnated with the drug, it is easy to impart a good drug sustained release function of the drug to the membrane 10.

  As such a polymer, for example, one or more of polycaprolactone, poly DL lactic acid, poly L lactic acid, lactide, polyorthoester, polyimino carbonate, aliphatic polycarbonate, polyphosphazene and the like can be used.

  Note that the film 10 may have a single-layer structure, and has a laminated structure of two or more layers formed of the above-described materials, a layer formed of the above-described materials, and a layer formed of other materials. A laminated structure of more than one layer may be used.

  Further, the membrane 10 is not limited to covering the entire outer surface of the stent body 2, but is provided so as to cover almost the entire inner surface, and is provided so as to cover both the outer surface and the entire inner surface. It may be a thing and provided so that at least one part of an outer surface and / or an inner surface might be covered. Further, the film 10 may be omitted as necessary.

  When the membrane 10 is impregnated with a drug, the drug is selected according to the type of tubular organ in which the stent 1 is placed, and for example, an antithrombotic agent, an analgesic / sedative agent, an antiproliferative agent, and the like can be used. .

Antithrombotic agents include, for example, heparin sodium, heparin calcium, low molecular weight heparin, heparin-like substance (low molecular dextran), hirudin, recombinant hirudin, argatroban, forskolin, bapiprost, prostaglandin E ₁ , prostacyclin, prostacyclin Homologues such as aspirin, sulpyrine, dipyridamole, antithrombin III, streptokinase, urokinase, tissue plasminogen activator, prourokinase and the like can be used.

  As the analgesic / sedative, for example, pentazocine, buprenorphine hydrochloride, butorphanol tartrate, tramadol hydrochloride, opium alkaloid hydrochloride, morphine hydrochloride, pethidine hydrochloride, pethidine levalorphan, fentanyl citrate, fentanyl dropperidol and the like can be used.

  Examples of the antiproliferative agent include somatostatin or a homologue thereof, nitroprusside, colchicine, fish oil (ω3 fatty acid), steroid agent, serotonin antagonist, calcium groove blocking antibody, hestamine antagonist, enzyme inhibitor (eg, angiotensin) Converting enzyme inhibitor, prostaglandin synthase inhibitor, HMG-CoA reductase inhibitor, phosphodiesterase inhibitor, thiol protease inhibitor, methotrexate), growth factor antagonist (eg, fibroblast growth factor antagonist, platelet derived) Growth factor antagonists), nitric oxide, and the like can be used.

  Next, a method of using the stent 1 will be described by taking a case where a balloon expandable stent is applied to a stenosis of a blood vessel as an example.

  (I) First, a guide catheter is percutaneously inserted into a blood vessel (a lumen of a tubular organ) by a well-known Seldinger method, and the distal end thereof reaches the vicinity of the stenosis (target site).

  (II) Then, the stent 1 is mounted on the outer periphery of the balloon at the distal end of the balloon-attached catheter in a reduced diameter state, and the balloon-attached catheter is guided into the blood vessel through the guide catheter.

  (III) Next, using the guide wire inserted into the catheter with balloon as a guide, the catheter with balloon is further pushed forward, and the stent 1 attached to the distal end thereof is transferred to the stenosis and arranged.

  At this time, since the stent 1 is provided with the recessed portion 22a, the stent 1 is given high flexibility in the axial direction. Therefore, the stent 1 is narrowed along the complicatedly bent, curved, or branched blood vessel. Can be transported easily and reliably.

  (IV) In this state, a liquid such as physiological saline is injected into the balloon through the balloon catheter and the balloon is inflated. As a result, the outer diameter of the stent 1 gradually increases.

  (V) Further, when the balloon is inflated and expanded, the outer diameter of the stent 1 is further expanded (becomes the expanded diameter state), abuts against the inner wall of the blood vessel, and presses the inner wall.

  (VI) After sufficiently expanding the diameter of the stent 1, the liquid in the balloon is extracted to deflate the balloon, and the balloon catheter is extracted from the inner periphery of the stent 1. As a result, the stent 1 can be placed in the blood vessel.

  At this time, since the unevenness is formed on the outer surface side of the stent 1 by the recessed portion 22a, the stent 1 can be reliably fixed by the narrowed portion.

  Further, since the recessed portion 22a is arranged in a spiral shape, the stent 1 is slightly expanded in position in the blood vessel by rotating the stent 1 in a predetermined direction around the central axis after the stent 1 is in a diameter-expanded state. Back and forth.

  As described above, the narrowed portion of the blood vessel can be expanded by the stent 1 to prevent or treat myocardial infarction or cerebral infarction.

Next, a method for manufacturing the stent 1 will be described.
(A) First, as shown in FIG. 4A, a substantially cylindrical or pipe-shaped core material 3 is prepared.

  Desirably, the core material 3 is relatively hard and can be removed relatively easily in the step (E) described later.

  The constituent material of the core material 3 is selected according to the constituent material of the stent body 2, and for example, polyolefin (for example, PE, PP, etc.), polyvinyl chloride, polyamide, polyphenylene sulfide, polycarbonate, polymethyl Compared to resin materials such as methacrylate and polyether, and other metal materials that constitute the stent body 2 such as Ni and Ni alloys, Cu and Cu alloys, Fe and Fe alloys, the base electrode is a base metal in terms of natural electrode potential Materials can be used.

  (B) Next, as shown in FIG. 4 (b), a groove 31 having a shape corresponding to the shape of the recessed portion 22 a is formed in a spiral shape on the peripheral surface of the core material 3. At this time, the spiral pitch is formed to be substantially constant.

  As a method for forming the groove 31, for example, cold / hot forging, die casting, injection molding, laser processing, cutting processing, engraving processing, rolling processing, and the like can be used.

  (C) Next, as shown in FIG. 4C, the body material layer 4 is formed on the peripheral surface of the core material 3 using the constituent material (body material) of the stent body 2 as described above.

  The method of forming the main body material layer 4 is appropriately selected according to the constituent material (main body material) of the stent main body 2. For example, physical vapor deposition methods such as vacuum deposition and sputtering, One or two of a phase film formation method, a plating method such as electrolytic plating and electroless plating, and a liquid film formation method such as a method by applying (applying) a liquid material (solution or dispersion) including a main body material More than species can be used.

(D) Next, as shown in FIG. 4D, a part of the main body material layer 4 is removed to form an opening 20.
As a method of forming the opening 20 (a method of removing the main body material layer 4), for example, one of a dry etching method, a wet etching method, laser processing, machining by a machining center, engraving by an engraving machine, etc. Two or more types can be used.

  (E) Next, the core material 3 is removed. Thereby, as shown in FIG.4 (e), the stent main body 2 is obtained.

  The method for removing the core material 3 is appropriately selected depending on the constituent material of the core material 3 and the like. For example, the core material 3 is a method in which the core material 3 is burned off by heating (a method of burning off), or the stent body 2 is not dissolved or swollen. A method of dissolving the core material 3 in a solvent that can be selectively dissolved, a method of selectively eluting the core material 3 by chemical etching, or an electrochemical method can be used.

  (F) Next, if necessary, a process for rounding the edge of the stent body 2 (straight line portion 21) is performed.

  As this processing method, for example, polishing, barrel polishing, electrolytic polishing, chemical polishing, honing, electromagnetic barrel polishing and the like can be used.

  (G) Next, as shown in FIG. 4 (f), the membrane 10 as described above is coated so as to cover almost the entire outer surface of the stent body 2.

The stent 1 is obtained as described above.
Although omitted in the above description, it is desirable to provide a cleaning step after the previous step before moving to each step. This prevents unnecessary substances (impurities) from being brought into the next step, and the quality of the stent 1 is improved.

Next, another configuration example of the recessed portion will be described.
The recessed portion 22b shown in FIG. 5 is configured by a recessed portion (thin wall portion) shaped such that a part of the linear portion 21 is removed from the outer surface toward the central axis of the stent body 2.

  Such a recessed portion 22b may be formed by processing the body material layer 4 when the opening 20 is formed in the step (D) by omitting the step (B).

  The recessed portion 22c shown in FIG. 6 is formed so as to be recessed toward the side opposite to the central axis of the stent body 2 contrary to the recessed portion 22a.

  The recessed portion 22d shown in FIG. 7 is formed so as to be recessed toward the opposite side to the central axis of the stent body 2 contrary to the recessed portion 22b.

  In the step (B), the concave portions 22c and 22d are spirally formed with protrusions having shapes corresponding to the shapes of the concave portions 22c and 22d on the peripheral surface of the core material 3 instead of the grooves 31. It is obtained by forming it into

  By forming such recessed portions 22b, 22c, and 22d in the stent body 2, the same effect as in the case of forming the recessed portions 22a in the stent body 2 can be obtained.

  The recessed portions 22a, 22b, 22c, and 22d as described above may be formed in one stent body 2 by combining two or more of them, but the recessed portions are all on the same side. It is desirable that it is depressed toward the top, and it is more desirable that it is the same shape. Thereby, it is possible to prevent the directionality of the axial flexibility and the radiation supporting force of the stent 1 from occurring.

  In this embodiment, the recesses are arranged along one spiral, but may be arranged along two or more spirals. In the case where the recesses are arranged along two or more spirals, the spiral winding direction may be different, but the same direction is desirable. Thereby, as described above, the operation of moving the expanded stent 1 within the blood vessel (tubular organ) can be performed reliably.

  In this embodiment, the recessed portion is formed over substantially the entire stent body 2, but depending on the purpose of the stent, a part of the stent body 2 (for example, near both ends or near the center) Etc.).

Further, in this embodiment, although the pitch P ₂ of the pitch P ₁ and the point of intersection 211 of the spiral are different, it may be set substantially equal. In this case, so as not to overlap with the intersection 211 of the recessing portion 22a, for example, approximately in the middle of the straight portion 21, placed in the middle of the straight portion 21, and the pitch P ₂ of the pitch P ₁ and the point of intersection 211 of the spiral, It is desirable that they be shifted from each other by about a half pitch. Thereby, it is possible to prevent the axial flexibility of the stent 1 from being lowered.

  In this embodiment, the shape of the opening 20 has a rhombus shape, but is not limited thereto, and may be, for example, a triangle, a rectangle, a square, a pentagon, or a hexagon.

  Further, in this embodiment, the connecting portion (near the intersection 211) between the straight portions 21 is bent, but it may be curved such as an arc (U-shaped), for example.

  The stent of the present invention is not limited to the above illustrated examples, and it goes without saying that various changes can be made without departing from the spirit of the present invention.

The side view which shows embodiment of the stent which concerns on this invention. Sectional drawing in the AA line shown in FIG. The enlarged view which shows the structure of a linear part and a recessed part. The figure explaining the manufacturing method of the stent shown in FIG. The enlarged view which shows the other structural example of a recessed part. The enlarged view which shows the other structural example of a recessed part. The enlarged view which shows the other structural example of a recessed part.

Explanation of symbols

1 …… Stent
2 …… Stent body
20 …… Opening
21 …… Linear part
211 …… Intersection
22a, 22b, 22c, 22d …… Recessed part
3 …… Core
31 …… Groove
4 …… Body material layer
10 …… Membrane

Claims (14)

A stent having a stent body that is used by being inserted and placed in the lumen of a tubular organ of a living body, and whose overall shape is substantially cylindrical,
The stent body has a network structure having a plurality of openings,
Each of the openings has a polygonal shape by being surrounded by a plurality of linear portions connected to each other at an angle of less than 180 °,
At least a part of the straight part is formed with a recessed part that is recessed toward the central axis side or the opposite side of the central axis of the stent body at the intersection and / or midway thereof,
Each of the recesses is arranged along a spiral centering on the central axis of the stent body.   The stent according to claim 1, wherein each of the recessed portions is recessed toward the same side.   The stent according to claim 1 or 2, wherein a pitch of the spiral is different from a pitch of the intersection. P ₁ pitch of the helix, when the pitch of the intersection was P _2, stent according to claim 3, characterized in that P ₁ / P ₂ is in the range of less than 1.   The stent according to any one of claims 1 to 4, wherein a pitch of the spiral is substantially constant.   The stent according to any one of claims 1 to 5, wherein the recessed portion is formed over substantially the entire stent body.   The stent according to any one of claims 1 to 6, wherein a cross-sectional area of the straight portion is substantially constant over substantially the entire stent body. The average cross-sectional area of the straight portion, 1 × 10 ^-5 mm ² or more 0.1 mm ² or less of the stent according to any one of claims 1 to 7, characterized in that in the range.   The stent according to any one of claims 1 to 8, wherein a cross-sectional shape of the straight portion is substantially constant over substantially the entire stent body.   The stent according to any one of claims 1 to 9, wherein an edge of the straight portion is rounded.   The main body of the stent is composed of Au, Pt, Ta, Rh, Ru, Pd, Nb, Os, Ir, Ag, or an alloy containing them as a main material. The stent according to any one of the above.   The stent according to any one of claims 1 to 10, wherein the main stent body is composed of a Ni / Ti alloy as a main material.   The stent according to any one of claims 1 to 12, wherein the main stent body is formed by integrally forming the linear portion.   The stent according to any one of claims 1 to 13, further comprising a film covering at least a part of an outer surface and / or an inner surface of the stent body.

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