JP5691184B2 - Covered stent - Google Patents

Description

  The present invention relates to a covered stent, and more particularly, to a covered stent that can suppress the occurrence of migration when placed in a digestive system or blood vessel.

  Various stents (bare stents) are used for the purpose of securing the body lumen when the digestive system body lumen and blood vessels such as the bile duct, esophagus, duodenum, and large intestine are narrowed or occluded by cancer cells. ing. However, in the case of a stent placed in the body, when the cancer cell grows (infiltrates) beyond the peripheral wall of the stent, the lumen secured by the stent may be narrowed or blocked again. There is.

  Thus, as a conventional technique for preventing this, a covered stent in which a bare stent is covered with a resin film has been proposed (see, for example, Patent Document 1). In the covered stent, the resin film covering the bare stent can suppress the narrowing of the body lumen due to the growth of cancer cells. A covered stent in which a bare stent is covered with a resin film in which a large number of holes are formed has also been proposed (see, for example, Patent Documents 2 and 3).

JP 2001-327609 A JP 2005-152527 A JP 2009-108163 A

  However, in the conventional covered stent, since the outer periphery of the bare stent is covered with a resin film, the outer peripheral surface is smoother than that of the bare stent, and thus the covered stent moves from the place where it is placed. It was found that the problem (migration) is likely to occur.

  This invention is made | formed in view of such a subject, The objective is to provide the covered stent which can suppress generation | occurrence | production of migration, when indwelling in a digestive organ system, a blood vessel, etc.

In order to solve the above problem, a covered stent according to the present invention is a covered stent including a cylindrical bare stent and a covering film covering an outer periphery of the bare stent,
The bare stent is provided between the both ends of the bare stent, with a protruding portion in which a part of the cylindrical main body protrudes in the outer diameter direction,
While being configured by the protruding portion, a convex shape protruding radially outward from the outer circumferential surface of the covered stent possess an outer shape that includes at least one,
The protrusions have a ring shape that continues along the circumferential direction of the bare stent, and two are formed on the main body,
These two protrusions are arranged at a position that is separated from the center position by an equal distance from the center position toward the both end sides with respect to the center position of the main body,
The bare stent further includes a flare portion provided at at least one end of the both ends,
The flare portion is formed in a tapered shape having an outer diameter that increases from the main body side toward the end side of the flare portion .

  In the covered stent according to the present invention, since the bare stent is covered with the covering film, cancer cells and the like can be prevented from growing in the bare stent beyond the peripheral wall of the covering film. It is possible to extend the period until the blockage. Furthermore, since the covered stent according to the present invention has an outer shape including a convex shape protruding in the outer diameter direction from the outer peripheral surface of the stent, when the stent is placed in the body lumen, the convex shape is formed in the body lumen. The effect of contact and anchoring can be achieved, thereby suppressing the migration described above. Moreover, when the protrusion part of a bare stent comprises convex shape, when a diameter is reduced, a covered stent can be in a more compact state.

Further, the protrusions Ru ring-shaped der which is continuous in the circumferential direction of the bare stent. According to such a configuration, it is possible to more closely adhere to the body lumen, so that the occurrence of migration can be further suppressed.

Further, the prior SL projections, the are formed two in the body, these two projections, based on the center position of the body, apart evenly distance toward the both ends from the central position It is disposed at a position. Since such a covered stent has two convex shapes constituted by two second portions, the effect of suppressing migration is large, and the convex shape is arranged at an equal position from the center of the stent. There is an effect that it is easy to use because it does not matter the direction of time.

The front Symbol bare stents, the includes both end portions of the further flared portion provided with at least one end, said flared portion has a larger outer diameter toward the main body side terminal of said flared portion It is formed in a tapered shape.

  The flare portion of the bare stent constitutes a flare shape portion that is an outer shape for anchoring the covered stent to the body lumen, similarly to the projection portion, so that migration can be suppressed. For example, when such a covered stent is placed in the bile duct, in the state immediately after placement in the bile duct, the convex shape is caught on the wall surface of the bile duct in the vicinity of the stenosis center, and migration is further suppressed. When bile ducts that have been swelled with bile accumulated in the bile ducts after the passage of time and bile duct contraction due to bile drainage by the covered stent, the flare shape part constituted by the flare part in addition to the convex shape is also the wall surface of the bile duct Therefore, migration can be more effectively suppressed.

  Further, for example, the covering film includes an inner peripheral layer including an inner surface facing the inner diameter direction of the bare stent, and an outer surface facing the outer diameter direction of the bare stent, and a plurality of pores opening in the outer surface. And an outer peripheral layer regularly arranged along the outer surface.

  Since the inner peripheral layer in which no pores are formed is harder to break than the outer peripheral layer in which pores are formed, such a covering film is less likely to be damaged even when the covered stent is repeatedly deformed. Moreover, such a covered stent can ensure the flexibility of the covered stent and suppress migration by appropriately setting the thickness of the inner peripheral layer and the like.

  The covered stent according to the present invention is suitably used for digestive organs including the bile duct, duodenum, large intestine and the like, but is particularly preferably used as a biliary stent used for the bile duct.

FIG. 1 is a schematic view of a covered stent according to the first embodiment of the present invention. FIG. 2 is a partial plan view showing a part of a bare stent included in the covered stent shown in FIG. FIG. 3 is a conceptual diagram illustrating dimensions of each part in the covered stent shown in FIG. 4 is a cross-sectional view of the covered stent shown in FIG. FIG. 5 is an enlarged cross-sectional view in which a part of FIG. 4 is enlarged. FIG. 6 is a sketch of a second polymer film included in the covered stent shown in FIG. FIG. 7 is an enlarged cross-sectional view showing a cross-sectional shape of the second polymer film shown in FIG. FIG. 8 is a diagram schematically showing a state where the covered stent 10 shown in FIG. 1 is placed in the bile duct.

  FIG. 1 is a schematic view of a covered stent 10 according to an embodiment of the present invention. As shown in FIG. 1, the covered stent 10 according to the present embodiment includes a cylindrical bare stent 16 formed by a frame 17 and a covering film portion 50 that covers the outer periphery of the bare stent 16.

  FIG. 2 is a plan view showing a part of the bare stent 16 included in the covered stent 10 shown in FIG. The bare stent 16 includes a cylindrical bare stent main body portion 160 and bare stent flare portions 16 c provided at both ends of the bare stent 16. The bare stent main body 160 is formed with a bare stent protrusion 16a in which a part of the bare stent main body 160 protrudes in the outer diameter direction. That is, the bare stent main body 160 includes a bare stent tube portion 16b having a predetermined outer diameter and a bare stent protrusion portion 16a protruding from the bare stent tube portion 16b in the outer diameter direction. The bare stent protrusion 16 a has a ring shape that continues along the circumferential direction of the bare stent 16. Two bare stent projecting portions 16a are formed on the bare stent main body portion 160, and these two bare stent projecting portions 16a are located at both ends of the bare stent 16 from the central position with reference to the central position of the bare stent main body portion 160a. It is arrange | positioned in the position equidistant away toward the part.

  The bare stent flare portion 16c is formed in a tapered shape whose outer diameter increases from the bare stent main body portion 160 side toward the end side of the bare stent flare portion 16c. Specifically, the bare stent flare portion 16c is formed from the connection portion between the bare stent end portion 16e having a diameter larger than that of the bare stent tube portion 16b located at both ends of the covered stent body portion 100 and the bare stent body portion 160. A strut 10 b is provided with a bare stent inclined portion 16 d that is inclined with respect to the axial direction of the bare stent 16 toward the distal end portion 16. The axial length of the bare stent end portion 16e is not particularly limited, and the length may be 0 mm (the end of the bare stent inclined portion 16d is the bare stent end portion 16e). As shown in FIG. 2, by providing the bare stent end portion 16e having a constant diameter along the axial direction, the covered stent 10 exhibits a stable bile duct anchoring effect and a high migration suppressing effect. Play.

  The bare stent 16 is formed by a frame 17 that is a metal linear member. Here, the bare stent may be a type formed by braiding or a laser cut type in which a pipe is formed by laser cutting, but it is more preferable if it is a laser cut type in which the length in the major axis direction is difficult to expand and contract. The cross-sectional shape of the frame 17 can be a square shape or a circular shape. The bare stent 16 includes a plurality of struts 170a formed in an annular shape by the frame 17, and a bridge 170b that connects adjacent struts. The struts 170a are formed in an annular shape that is folded in a zigzag manner along the axial direction of the bare stent and continues in a triangular wave shape along the circumferential direction of the bare stent 16. The bridge 170b is formed in an S shape and connects a part of the apex portion 17a that is the apex of the triangular wave in the adjacent struts 170a in the axial direction. The cylindrical bare stent 16 is configured by connecting the plurality of struts 170a in this manner. Here, two adjacent struts 170a are connected by a plurality of bridges 170b. The number of bridges 170b connecting two adjacent struts 170a is the same between any struts 170a, but the positions of the bridges 170b connecting two adjacent struts 170a are formed side by side in the axial direction. Not in the circumferential direction.

  Since the bare stent projecting portion 16a and the bare stent flare portion 16c are swelled from the bare stent tubular portion 16b, the bare stent tubular portion 16b has a frame 17 compared to the bare stent projecting portion 16a and the bare stent flare portion 16c. Closely arranged. The struts 170a of the bare stent projecting portion 16a and the bare stent flare portion 16c have a lower density than the struts 170a of the bare stent tube portion 16b.

  As shown in FIG. 1, the covering film portion 50 covers the bare stent 16 while following the peripheral wall shape of the bare stent 16 as shown in FIG. 2. Therefore, the covered stent 10 has an outer shape corresponding to the peripheral wall shape of the bare stent 16. Specifically, the covered stent 10 has an outer shape including a flared shape portion 38 provided at both ends of the covered stent 10 and a covered stent main body portion 100 provided between both ends of the covered stent 10.

  The covered stent body 100 is constituted by a bare stent projection 16a (FIG. 2), two convex portions 34 projecting from the outer peripheral surface 12 of the stent in the outer diameter direction, and a bare stent cylinder 16b (FIG. 2). The cylindrical shape part 36 comprised by these is provided. The convex portion 34 has a ring shape that continues along the circumferential direction of the covered stent 10. The two convex portions 34 are arranged at positions that are equidistant from the center position toward both ends of the covered stent 10 with respect to the center position of the covered stent body 100. The convex portion 34 can be caught in the body lumen when it is indwelled, and the covered stent 10 can be prevented from moving in the axial direction from the indwelling position.

  The flare-shaped portion 38 is configured by the bare stent flare portion 16c (FIG. 2), and is formed in a tapered shape whose outer diameter increases from the covered stent main body portion 100 side toward the distal end side of the flare-shaped portion 38. . The flare shape portion 38 includes an inclined shape portion 42 constituted by the bare stent inclined portion 16d and a bare stent end portion 40 constituted by the bare stent end portion 16e. The flare-shaped portion 38 can also be caught in the body lumen when placed, and the covered stent 10 can be prevented from moving in the axial direction from the placement position.

  FIG. 3 is a conceptual diagram illustrating dimensions of each part in the covered stent 10 shown in FIG. The total length H of the covered stent 10 is determined according to the size of the body lumen in which the covered stent 10 is placed and the size of the stenosis, but may be 30 mm to 200 mm, and may be 40 mm to 120 mm. preferable. Further, the diameter D of the cylindrical portion 36 in the covered stent 10 is also determined according to the size of the body lumen in which the covered stent 10 is placed and the size of the stenosis, but can be set to φ2 mm to φ20 mm. The diameter is preferably 4 mm to 15 mm, and more preferably 6 mm to 10 mm.

  The diameter E of the convex portion 34 is preferably 1.1 to 2.1 times the diameter D of the cylindrical portion 36 (E / D = 1.1 to 2.1), preferably 1.2 to More preferably, it is 1.6 times (E / D = 1.2 to 1.6). By appropriately setting the ratio of the diameter E of the convex portion 34 and the diameter D of the cylindrical portion 36, the movement of the covered stent 10 from the indwelling position can be suppressed while appropriately securing the body lumen. . Further, the axial length F of the convex portion 34 is 0.2 to 2.1 times the diameter D of the cylindrical portion 36 (F / D = 0.2 to 2.1). Preferably, it is 0.4 to 1.6 times (F / D = 0.4 to 1.6). By appropriately setting the ratio of the length F of the convex portion 34 and the diameter D of the cylindrical portion 36, the convex portion 34 is appropriately set against the wall of the body lumen when the covered stent 10 is placed. It is possible to obtain a suitable anchoring effect.

  Furthermore, the distance A from the end portion of the covered stent 10 to the central portion of the convex portion 34 is 0.1 to 0.4 times the total length H of the covered stent 10 (A / H = 0.1 to 0). .4), preferably 0.3 to 0.4 times (A / H = 0.3 to 0.4). By appropriately setting the ratio between the distance A and the total length H, when the covered stent 10 is indwelled, the convex portion 34 is located near the center of the stenosis or near the end of the covered stent 10. It can arrange | position and the convex-shaped part 34 can show | play the suitable anchoring effect. In addition, it is preferable that two convex-shaped parts 34 are arrange | positioned in the equivalent position from the stent center 10b which is the axial center position in the covered stent 10. FIG. Covered stents generally aim to expand the entire stenosis by expanding the stenosis in the vicinity of the center of the covered stent by placing it in the center with respect to the bile duct stenosis. The convex portions are easily positioned before and after the bile duct stenosis and are easily anchored in the bile duct, thereby providing a high migration suppressing effect.

  The diameter C of the end shape portion 40 in the flare shape portion 38 is preferably 1.1 to 2.1 times the diameter D of the cylindrical shape portion 36 (C / D = 1.1 to 2.1). 1.2-1.6 times (C / D = 1.2-1.6) is more preferable. By appropriately setting the ratio of the diameter C of the distal shape portion 40 and the diameter D of the tubular shape portion 36, the movement of the covered stent 10 from the indwelling position can be suppressed while appropriately securing the body lumen. . The length G of the flare-shaped portion 38 is preferably 0.1 to 0.4 times (G / H = 0.1 to 0.4) with respect to the total length H of the covered stent 10. It is more preferable to set it to -0.3 times (G / H = 0.1-0.3). This is because the flare-shaped portion 38 has a suitable anchoring effect, and the convex-shaped portion 34 can be appropriately disposed in the remaining portion of the covered stent 10 (covered stent main body portion 100).

  The diameter E of the convex portion 34 and the diameter C of the end shape portion 40 are preferably the same (E = C). By making the diameter E of the convex portion 34 and the diameter C of the end shape portion 40 the same, the covered stent 10 maximizes the steps in the outer diameters of the small straight body outer diameter D, outer diameter E, and outer diameter C. Thus, while exhibiting the anchoring effect, the effect of expanding the bile duct stenosis as evenly as possible by suppressing the variation in the expansion force (radial force) between the end portion and the intermediate portion. Furthermore, it is preferable that the two convex portions 34 disposed on both sides of the stent central portion 10b have the same shape as each other, and two flare shapes disposed on both sides of the covered stent central portion 10b. It is preferable that the portions 38 have the same shape.

  The bare stent 16 shown in FIG. 2 may be usable not only as a covered stent covered with the covering film portion 50 but also as a bare stent not covered with a film or the like. The wire diameter of the frame 17 constituting the bare stent 16 is preferably 0.05 to 1 mm. Moreover, when the cross section of the frame 17 is rectangular, the length in the long side direction in the cross section of the frame 17 is preferably 1 to 10 mm, and the length in the short side direction is preferably 0.05 to 5 mm. .

  The outer diameter dimension of the bare stent 16 is substantially the same as the dimension of the covered stent 10 described above. However, the diameters of the bare stent 16 and the covered stent 10 are reduced to about a fraction of the above-mentioned value, which is the dimension when the covered stent 10 is transported to the indwelling position. It may be diameter.

  As a material of the bare stent 16, a synthetic resin or a metal is used. As the synthetic resin used for the bare stent 16, a resin having appropriate hardness and elasticity can be used, and a biocompatible resin is preferable. Examples of the synthetic resin used as the material for the bare stent 16 include polyolefin, polyester, and fluororesin. Specific examples of polyolefin include polyethylene terephthalate and polybutylene terephthalate. Specific examples of the fluororesin include polytetrafluoroethylene (PTFE) and ethylene / tetrafluoroethylene copolymer (ETFE).

  Examples of the metal used for the bare stent 16 include nickel titanium (Ni—Ti) alloy, stainless steel, tantalum, titanium, cobalt chromium alloy, magnesium alloy, and the like. preferable. A specific example of the superelastic alloy used for the bare stent 16 is a Ti-Ni alloy of 49 to 58 atomic% Ni. Moreover, Ti-Ni-X alloy (X = Co, Fe, Mn, Cr, V, Al, Nb, etc.) in which 0.01% to 10.0% of atoms in the Ti-Ni alloy are substituted with other atoms. W, B, etc.), Ti—Ni—X alloys (X = Cu, Pb, Zr) in which 0.01 to 30.0% of atoms in the Ti—Ni alloy are replaced with other atoms are also bare It is suitable as a material for the stent 16. The mechanical properties of these superelastic alloys are adjusted by selecting the cooling rate and / or final heat treatment conditions.

  The bare stent 16 can be formed by processing a tube-shaped or pipe-shaped base material by, for example, laser processing using a YAG laser or the like, electric discharge processing, chemical etching, cutting processing, or the like. The bare stent projecting portion 16a and bare stent flare portion 16c as shown in FIG. 2 are not particularly limited as a method for forming the bare stent 16, but for example, a straight barrel (cylindrical) bare stent after laser processing. The method of heat-treating the bare stent 16 after inserting the core material which has the processus | protrusion corresponding to the bare stent protrusion part 16a etc. to 16 is mentioned.

  The bare stent 16 is preferably provided with a single or a plurality of X-ray markers. The X-ray marker is made of, for example, an X-ray contrast material (X-ray opaque material). When the covered stent 10 is placed in the body lumen, the placement position of the covered stent 10 can be grasped by confirming the position of the X-ray marker under X-ray contrast.

  4 is a cross-sectional view of the covered stent 10 shown in FIG. However, FIG. 4 shows a state in which the diameter is reduced to one half from the state shown in FIG. As shown in FIG. 4, the surface of the bare stent 16 is covered with a coating film 26, and the coating film 26 spreads so as to fill the space between the adjacent frames 17, so that the outer peripheral surface of the bare stent 16 is covered. It is covered. The outer periphery of the bare stent 16 covered with the coating film 26 is covered with a covering film portion 50 including the first polymer film 30 and the second polymer film 14.

  By covering the bare stent 16 with the coating film 26, the stent inner peripheral surface 10a which is the inner peripheral surface of the covered stent 10 can be made smooth. By smoothing the stent inner peripheral surface 10a, when the covered stent 10 is placed in the digestive tract, waste materials are less likely to be deposited on the stent inner peripheral surface 10a, and infection is prevented. It is possible to prevent stenosis or occlusion again.

  As a material for the coating film 26, a polymer such as a resin is used. Among them, a material that dissolves in an organic solvent and has low toxicity is preferable. As the polymer that can be used for the coating film 26, for example, a non-biodegradable resin or a biodegradable resin can be used, but it is preferable to use a non-biodegradable resin that is not easily decomposed in a living body. Among the resins, it is particularly preferable to use polyurethane. In addition, you may mix | blend additives, such as chemical | medical agents, such as an anticancer agent and an antithrombotic agent, and anti-aging agent, with resin which comprises the coating film 26 as needed.

  A method for forming the coating film 26 on the surface of the bare stent 16 is not particularly limited. For example, the bare stent 16 having an enlarged diameter is externally fitted to a rotatable shaft member, and the shaft is rotated. A method in which a resin solution is dropped onto the bare stent 16 and the resin is attached to the bare stent 16 is exemplified. At this time, the solvent used in the resin solution is preferably highly volatile. For example, when the coating film 26 is made of polyurethane, tetrohydrofuran or tetrohydrofuran and 1,4-dioxane are used. A mixed solvent can be used.

  As shown in FIG. 1, the stent outer peripheral surface 12, which is the outer peripheral surface of the covered stent 10, is constituted by a covering film portion 50. As shown in FIG. 4, the covering film portion 50 covering the outer periphery of the bare stent 16 includes a first polymer film 30 and a second polymer film 14. The first polymer film 30 is disposed between the bare stent 16 and the second polymer film 14 and covers the outer periphery of the bare stent 16.

  The thickness of the first polymer film 30 is preferably 4 to 20 μm in view of the average value of the entire first polymer film 30. If the first polymer film 30 is too thick, the flexibility of the covered stent 10 may be insufficient. Further, if the first polymer film 30 is too thin, the second polymer film 14 may not be protected from perforation or the like by the bare stent 16.

    The first polymer film 30 is wound around the bare stent 16 so that the outer circumference of the bare stent 16 circulates one or more times and less than one and a half times. By setting the number of windings of the first polymer film 30 to 1 to 1 and a half, it is possible to protect the second polymer film 14 from perforation by the bare stent 16 and the flexibility of the covered stent 10 is insufficient. Can be prevented.

  As the material of the first polymer film 30, polymers such as rubber and resin are used, and among them, a material that dissolves in an organic solvent and has little toxicity is preferable. Further, in order to protect the second polymer film 14 from perforation by the bare stent 16, the material of the first polymer film 30 has higher strength than the resin used for the second polymer film 14. It is preferable to use a resin. For example, it is preferable that the first polymer film 30 is made of polyurethane and the second polymer film 14 is made of polybutadiene.

  As shown in FIG. 4, the second polymer film 14 is disposed on the outer diameter direction side of the bare stent 16 with respect to the first polymer film 30. The second polymer film 14 covers the bare stent 16 covered with the first polymer film 30 from above the first polymer film 30.

  When the second polymer film 14 is wound around the outer periphery of the bare stent 16 two or more times, the portion located on the outermost peripheral surface of the covered stent 10 can be protected from perforation due to the protrusion of the bare stent 16 or the like. Further, if the number of rounds of the second polymer film 14 is too large, the covered stent 10 may not be flexible enough to cause migration.

  FIG. 5 is an enlarged cross-sectional view in which a part of FIG. 4 is enlarged. The second polymer film 14 includes an inner peripheral layer 18 including an inner surface 18 a facing the inner diameter direction of the bare stent 16 and an outer peripheral layer 20 including an outer surface 20 a facing the outer diameter direction of the bare stent 16. A plurality of holes 22 are formed in the outer peripheral layer 20. The second polymer film 14 has a two-layer structure in which an inner peripheral layer 18 and an outer peripheral layer 20 are laminated along the thickness direction of the second polymer film 14. The second polymer film 14 forms a stent outer peripheral surface 12 that is an outer peripheral surface of the covered stent 10 having a tubular outer shape, and the thickness direction of the second polymer film 14 is the radial direction of the covered stent 10. Is approximately the same.

  FIG. 7 is a partially enlarged cross-sectional view of the second polymer film 14. The total thickness L of the second polymer film 14 including the inner peripheral layer 18 and the outer peripheral layer 20 is preferably 2 to 50 μm in view of the average value of the entire second polymer film 14.

  The plurality of holes 22 formed in the outer peripheral layer 20 open on the outer surface 20 a of the second polymer film 14. As shown in FIG. 7, since the inner peripheral layer 18 in which the hole 22 is not formed exists in the inner diameter direction with respect to the hole 22, the hole 22 is not opened on the inner surface 18a side. .

  The plurality of holes 22 are regularly arranged along the outer surface 20 a of the second polymer film 14. FIG. 6 is a sketch of a laser micrograph of the second polymer film 14 included in the covered stent 10 shown in FIG. 1 observed from the outer surface 20a side (the outer peripheral side of the covered stent 10). As shown in FIG. 6, the plurality of holes 22 formed in the outer peripheral layer 20 have substantially the same shape. Thus, the outer peripheral layer 20 has a honeycomb-like structure in which a plurality of pores 22 having substantially the same shape are arranged. It is preferable that the average value of the hole diameter K (refer FIG. 7) of the void | hole 22 shall be 0.1-10 micrometers.

  As shown in FIG. 7, the hole diameter K of the hole 22 refers to the diameter of the maximum inscribed circle with respect to the opening shape of the hole 22. Therefore, the hole diameter K of the hole 22 indicates the diameter of the circle when the opening shape of the hole 22 is substantially circular, and indicates the minor axis of the ellipse when the opening shape is substantially elliptical. When it is substantially square, it indicates the length of the side of the square, and when it is substantially rectangular, it indicates the length of the short side of the rectangle. The measurement of the hole diameter K of the air holes 22 can be performed using, for example, a scanning electron microscope (SEM), a laser microscope, or the like.

  As shown in FIG. 7, the thickness J of the outer peripheral layer 20 is preferably 1.0 to 19.5 μm, considering the average value of the entire second polymer film 14. On the other hand, the thickness I of the inner peripheral layer 18 is preferably 0.5 to 3.0 μm in view of an average value in the entire second polymer film 14.

  In the covered stent 10, the outer peripheral layer 20 and the inner peripheral layer 18 in the second polymer film 14 constitute a single continuous film. That is, the outer peripheral layer 20 and the inner peripheral layer 18 have substantially the same composition, there is no compositional change between the outer peripheral layer 20 and the inner peripheral layer 18, and there is no joined portion or the like.

  As the material constituting the second polymer film 14, polymers such as rubber and resin are used. For example, non-biodegradable resins and biodegradable resins can be used. From the viewpoint of maintaining the cell growth inhibitory action in the living body for a long period of time, those formed from non-biodegradable resins that are not easily decomposed in the living body are preferable.

  Examples of the material constituting the second polymer film 14 include polybutadiene (1,2-polybutadiene, 1,4-polybutadiene), polyisoprene, styrene-butadiene copolymer, styrene-isoprene copolymer, acrylonitrile-butadiene-styrene. Conjugated diene polymers such as copolymers; polyε-caprolactone; polyurethane; cellulose polymers such as cellulose acetate, celluloid, cellulose nitrate, acetylcellulose, cellophane; polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 12, polyamide polymers such as polyamide 46; fluorine polymers such as polytetrafluoroethylene, polytrifluoroethylene, perfluoroethylene-propylene copolymer; polystyrene, styrene-ethylene -Propylene copolymer, styrene-ethylene-butylene copolymer, chlorinated polyethylene-acrylonitrile-styrene copolymer, methacrylate-styrene copolymer, styrene-acrylonitrile copolymer, styrene-maleic anhydride copolymer Styrene polymers such as polymers, acrylate-acrylonitrile-styrene copolymers; polyethylene, chlorinated polyethylene, ethylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, ethylene-vinyl chloride copolymers, Olefin polymers such as ethylene-vinyl acetate copolymer, polypropylene, olefin-vinyl alcohol copolymer, polymethylpentene; formaldehyde polymers such as phenol resin, amino resin, urea resin, melamine resin, benzoguanamine resin; Polyester polymers such as ribylene terephthalate, polyethylene terephthalate, polyethylene naphthalate; epoxy resin; (meth) such as poly (meth) acrylate, poly-2-hydroxyethyl acrylate, methacrylate-vinyl acetate copolymer Examples thereof include acrylic polymers; norbornene resins; silicon resins; polymers of hydroxycarboxylic acids such as polylactic acid, polyhydroxybutyric acid, and polyglycolic acid. These can be used alone or in combination of two or more.

  Among these, in order to obtain a film having a highly regular pore size, the use of a conjugated diene polymer, a styrene polymer or polyurethane is more preferable, and the use of 1,2-polybutadiene is particularly preferable. The second polymer film 14 is preferably made of a resin that is less susceptible to hydrolysis than the first polymer film 30 from the viewpoint of indwelling the covered stent 10 in the body lumen for a long period of time. This is because the second polymer film 14 covers the first polymer film 30 and thus is more easily exposed to body fluids than the first polymer film 30. For example, it is preferable that the first polymer film 30 is made of polyurethane and the second polymer film 14 is made of polybutadiene.

  Further, an amphiphilic substance may be added to the resin constituting the second polymer film 14. The amphiphilic substance to be added is a polyethylene glycol-polypropylene glycol block copolymer; an amphiphilic resin having an acrylamide polymer as a main chain skeleton and a dodecyl group as a hydrophobic side chain and a lactose group or a carboxyl group as a hydrophilic side chain. An ion complex of an anionic polymer such as heparin, dextran sulfate, and nucleic acid (DNA or RNA) and a long-chain alkylammonium salt; an amphiphilic resin having a water-soluble protein such as gelatin, collagen or albumin as a hydrophilic group; And amphiphilic resins such as a polylactic acid-polyethylene glycol block copolymer, a polyε-caprolactone-polyethylene glycol block copolymer, and a polymalic acid-polymalic acid alkyl ester block copolymer.

  A method for producing the second polymer film 14 is not particularly limited. For example, an organic solvent solution of a resin is cast on a substrate, and humidified air is sprayed on the cast organic solvent solution to evaporate the organic solvent. In addition, there is a method in which water droplets are condensed on the surface of the organic solvent liquid cast together, and further, minute water droplets generated by the condensation are evaporated. That is, the second polymer film 14 can be produced by a method in which condensation occurs on the liquid surface of the organic solvent solution of the resin and minute water droplets generated by the condensation are used as a mold. According to such a production method, it is possible to produce the second polymer film 14 in which the holes 22 that open only on one surface are regularly arranged along the surface direction. Moreover, according to such a method, the 2nd polymer film 14 which has a honeycomb-like structure with the high uniformity of the hole diameter K can be produced.

  In the method described above, an organic solvent solution of resin is used. The organic solvent used for the organic solvent solution of the resin is preferably water-insoluble in order to form fine water droplets on the surface of the casting solution. Examples of the organic solvent used in the organic solvent solution of the resin include halogenated hydrocarbon solvents such as chloroform and methylene chloride; saturated hydrocarbon solvents such as n-pentane, n-hexane and n-heptane; cyclopentane and cyclohexane. Alicyclic hydrocarbon solvents; aromatic hydrocarbon solvents such as benzene, toluene and xylene; ester solvents such as ethyl acetate and butyl acetate; ketone solvents such as diethyl ketone and methyl isobutyl ketone; carbon disulfide; Is mentioned. These organic solvents can be used alone or as a mixed solvent composed of two or more of these.

  In the organic solvent solution, the concentration of the resin dissolved in the organic solvent is preferably 0.01 to 10% by weight, more preferably 0.05 to 5% by weight. If the resin concentration is lower than 0.01% by weight, the resulting film has insufficient mechanical strength, which is not desirable. If the resin concentration is 10% by weight or more, a desired porous structure (honeycomb-like structure) may not be obtained.

  When the second polymer film 14 is produced by the first method or the second method described above, it is preferable to add the above-mentioned amphiphilic substance to the resin. By adding an amphiphilic substance to the resin, the fusion of minute water droplets caused by condensation is suppressed and the shape of the minute water droplets is stabilized, so that the pore diameter K of the pores 22 formed in the second polymer film 14 is It is made uniform.

  The hole diameter K of the holes 22 in the second polymer film 14, the thickness L of the second polymer film 14, the thickness J of the outer peripheral layer 20, the thickness I of the inner peripheral layer 18, etc. (see FIG. 7) It is controlled by adjusting the production conditions of the second polymer film 14. The production conditions of the second polymer film 14 include the amount of the organic solvent solution to be cast, the resin concentration in the organic solvent solution, the atmosphere around the cast solution, the temperature and humidity of the humidified air, and the flow rate of the humidified air. Examples thereof include solvent evaporation speed and dew condensation speed in an organic solvent solution.

  The humidity of the humidified air sprayed on the cast organic solvent solution (cast liquid) is adjusted so that moisture in the humidified air is condensed on the surface of the cast liquid. The humidity of the humidified air is preferably 20 to 100% in relative humidity, and more preferably 30 to 80%. Moreover, you may use inert gas, such as nitrogen and argon containing water vapor | steam, instead of the humidified air sprayed on a casting liquid.

  The flow rate of the humidified air blown to the casting liquid is adjusted so that condensation can occur on the liquid surface of the casting liquid and the solvent contained in the casting liquid can be evaporated. The flow rate of the humidified air is adjusted according to the size of the substrate on which the organic solvent solution is cast. For example, when the second polymer film 14 is produced by casting an organic solvent solution on a glass petri dish having a diameter of 10 cm, the flow rate of humidified air is preferably 1 to 5 L / min.

  In the covered stent 10 shown in FIGS. 1 and 4, the first polymer film 30 is wound around the bare stent 16 covered with the coating film 26, and then the second polymer film 14 is further wound. Can be produced. The first polymer film 30 or the second polymer film 14 may cover the entire peripheral surface of the bare stent 16, or may cover only a part of the outer peripheral surface of the bare stent 16. .

  The attachment method for attaching the first polymer film 30 and the second polymer film 14 to the bare stent 16 is not limited to the method of winding the first and second polymer films 30 and 14, but an adhesive. For example, fixing by heating, fusion using a solvent, and fusion by heating can be used.

  As illustrated in FIG. 1, the covered stent 10 includes the covering film portion 50 that covers the outer periphery of the bare stent 16, and thus cancer cells and the like can be prevented from growing beyond the peripheral wall of the covered stent 10. Further, since the covered stent 10 has an outer shape including the convex portion 34 protruding in the outer diameter direction from the outer peripheral surface 12 of the stent, the convex portion 34 is caught on the peripheral wall of the body lumen, thereby suppressing migration. Can do.

  FIG. 8 shows a state immediately after the covered stent 10 is placed in the bile duct <(a) at the time of placement> and a state after 1 day to 3 days after placement in the bile duct <(b) a state after the placement 1 day to 3 days> Is schematically shown. As shown in <(a) indwelling> in FIG. 8, when the covered stent 10 is indwelled, pressure is accumulated in the upper part (liver side) of the stenosis center portion due to the stenosis, and the bile duct is spread. There is a case. However, since the covered stent 10 has an outer shape including the convex portion 34, the convex portion 34 is caught on the wall surface of the bile duct in the vicinity of the central portion of the stenosis, so that migration hardly occurs even in the indwelling state. That is, even when the covered stent 10 is placed so that the stenosis center portion and the axial direction center portion of the covered stent 10 are substantially coincident with each other, the convex portion 34 is caught on the wall surface of the bile duct in the vicinity of the stenosis center portion. As a result of anchoring, the phenomenon that the covered stent 10 moves from the indwelling position can be prevented.

  As shown in <(b) 1st to 3rd day after indwelling> in FIG. 8, several days after the covered stent 10 is indwelled, decompression due to drainage occurs, and the bile duct contracts. As a result, the flare-shaped portion 38 comes into contact with the wall surface of the bile duct, and the flare-shaped portion 38 can also exhibit the effect of anchoring the covered stent 10. As described above, when the covered stent 10 is disposed in a stenosis portion or the like, the covered stent 10 can prevent migration after placement and appropriately secure a body lumen. In addition, in FIG. 8, the convex shape part and flare shape part which are arrange | positioned at the duodenum side also have an effect which prevents the migration of the covered stent 10. FIG.

  As shown in FIG. 1, the covered stent 10 has a ring-shaped convex portion 34 disposed between both end portions of the covered stent 10. Therefore, the covered stent 10 has an effect of preventing the covered stent 10 from moving in any direction from the indwelling position by the ring-shaped convex portion 34.

  Further, as shown in FIG. 2, the bare stent 16 has a bare stent protrusion 16 a and a bare stent terminal portion 16 e, and the convex shape portion 34 and the flare shape portion 38 of the covered stent 10 are formed by a covering film portion 50. Is formed by following the peripheral wall of the bare stent 16. Here, when the diameter of the bare stent 16 is reduced, the protruding amount of the bare stent protruding portion 16a and the bare stent distal end portion 16e with respect to the bare stent cylindrical portion 16b decreases substantially in proportion to the diameter of the bare stent 16. Accordingly, when the covered stent 10 is reduced in diameter and transported to the indwelling position, the outer shape of the covered stent 10 is not included in the delivery catheter or the like, although the convex shape portion 34 and the flare shape portion 38 are included. It can be stored compactly.

  Moreover, as shown in FIG. 1, since the bare stent 16 is covered with the coating | coated film part 50, the covered stent 10 can prevent the sharp part in the bare stent 16 from damaging a body lumen. For example, even when the covered stent 10 is removed after being placed in the body lumen for a certain period of time, it is possible to prevent the body lumen near the placement position from being damaged during the removal.

  As shown in FIG. 5, the second polymer film 14 covering the bare stent 16 includes an inner peripheral layer 18 and an outer peripheral layer 20 in which holes 22 are arranged. As shown in FIG. 7, since the inner peripheral layer 18 in which the holes 22 are not formed is harder to break than the outer peripheral layer 20, the second polymer film 14 can be used even when the covered stent 10 is repeatedly deformed. Hard to break. Further, since the outer peripheral layer 20 in which the holes 22 are arranged is flexible, the flexibility of the covered stent 10 is ensured by setting the thickness I of the inner peripheral layer 18 to 0.5 to 3.0 μm. , Migration can be suppressed. This is because the covered stent 10 can flexibly cope with the bending of the body lumen around the placement position of the covered stent 10 after being placed in the body lumen. In addition, the covered stent 10 has an effect of suppressing complications such as inflammation and perforation in a peripheral portion that occurs with a positional shift after placement.

  Furthermore, since the covered stent 10 is doubly covered by the first polymer film 30 and the second polymer film 14, when the covered stent 10 is repeatedly deformed, the second polymer film 14 becomes bare. It can be prevented from being punctured by the protrusion of the stent 16 and being damaged.

  Further, since the covered stent 10 includes the coating film 26 that covers the bare stent 16, sludge and the like can be prevented from being deposited on the surface of the frame 17. In addition, by covering the surface of the frame 17 with the coating film 26, the first polymer film 30 and the second polymer film 14 are prevented from being pierced and damaged by protrusions or the like generated during processing of the bare stent 16. it can.

  The covered stent 10 can be suitably used as a stent placed in a digestive system body lumen such as a bile duct, esophagus, duodenum, and large intestine, but can be particularly suitably used as a biliary stent placed in a bile duct. The covered stent 10 can also be used as a stent placed in a blood vessel or the like.

Other Embodiments In the covered stent 10 according to the above-described embodiment, the bare stent projecting portion formed a convex shape portion, but as a structure for forming the convex shape portion 34 and the like on the stent outer peripheral surface 12, It is not limited to what is shown in FIG. For example, the convex portion 34 may be formed by bending the apex portion 17a of the frame 17 shown in FIG. 2 toward the outer diameter direction. Further, the convex portion 34 may be formed by providing a protrusion on a part of the covering film portion 50. The convex portion 34 included in the outer shape of the covered stent 10 is not particularly limited as long as it protrudes in the radial direction of the bare stent 16, and is a semi-ring shape or a shape that is intermittently formed in the circumferential direction. It may be.

  Moreover, in the covered stent 10 which concerns on the above-mentioned embodiment, although the flare-shaped part 38 is provided in the both ends of the covered stent 10, the outer shape of the covered stent 10 is not limited to this. The covered stent 10 may be provided with the flare-shaped portion 38 only on one end side of the covered stent main body 100, or may not include the flare-shaped portion 38, and only the covered stent main body 100. May be provided.

  Although two convex-shaped parts 34 are formed on the stent outer peripheral surface 12 of the covered stent 10 according to the above-described embodiment, the number of the convex-shaped parts 34 formed on the stent outer peripheral surface 12 is one. It may be three or more. Further, as shown in FIG. 3, the covered stent 10 may have a symmetrical shape from the stent center 10b toward both ends, but may have an asymmetric shape. For example, the bare stent flare portion 16 c may be provided only at one end portion of the bare stent 16, and the flare shape portion 38 may be formed only at one end portion of the covered stent 10.

DESCRIPTION OF SYMBOLS 10 ... Covered stent 100 ... Covered stent main-body part 12 ... Stent outer peripheral surface 14 ... 2nd polymer film 16 ... Bare stent 160 ... Bare stent main-body part 16a ... Bare stent protrusion part 16b ... Bare stent cylinder part 16c ... Bare stent flare part 16d ... Bare stent inclined part 16e ... Bare stent terminal part 17 ... Frame 170a ... Strut 170b ... Connection part 18 ... Inner peripheral layer 18a ... Inner surface 20 ... Outer peripheral layer 20a ... Outer surface 22 ... Hole 34 ... Convex shaped part 36 ... Cylindrical shape part 38 ... Flare shape part 40 ... End shape part 42 ... Inclined shape part 50 ... Covering film part

Claims (3)

A cylindrical bare stent,
A covered stent comprising a covering film covering an outer periphery of the bare stent,
The bare stent is provided between the both ends of the bare stent, with a protruding portion in which a part of the cylindrical main body protrudes in the outer diameter direction,
The outer shape including at least one convex shape protruding in the outer diameter direction from the outer peripheral surface of the covered stent while being constituted by the protruding portion,
The protrusions have a ring shape that continues along the circumferential direction of the bare stent, and two are formed on the main body,
These two protrusions are arranged at a position that is separated from the center position by an equal distance from the center position toward the both end sides with respect to the center position of the main body,
The bare stent further includes a flare portion provided at at least one end of the both ends,
The covered flare is formed in a tapered shape having an outer diameter that increases from the main body side toward the end side of the flare portion . The coating film includes an inner peripheral layer including an inner surface facing the inner diameter direction of the bare stent, and an outer surface facing the outer diameter direction of the bare stent, and a plurality of holes opening in the outer surface are formed on the outer surface. The covered stent according to claim 1, further comprising an outer circumferential layer regularly arranged along the covered stent. Covered stent of claim 1 or claim 2 which is biliary stent.

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