Covered stent

Abstract

To provide a covered stent that can prevent a nonreturn valve function from being damaged due to the inversion of a nonreturn valve part formed of a film.SOLUTION: A covered stent 1 comprises: a stent 2 extending long; and a cylindrical film 3 mounted along the stent 2. The film 3 has a nonreturn valve part 3a exposed toward a long direction outer side from the inside of the stent 2, and preventing a flow in a second direction as an opposite direction to a flow in a first direction while permitting flow in the first direction from the stent 2 toward the long direction outer side. The nonreturn valve part 3a is provided with an inversion prevention portion (reinforcement tape 3b) extending in a revolving direction of the film 3 and enhancing rigidity.SELECTED DRAWING: Figure 1

Description

【Technical Field】 【0001】 The present invention relates to a covered stent that can be indwelling in a body cavity. 【Background Art】 【0002】 Conventionally, a technique of indwelling a covered stent to eliminate the occlusion of a body tube has been performed for the treatment of a digestive tract (esophagus, stomach and duodenum, large intestine, bile duct, etc.), blood vessel or other body tube occluded by cancer or the like. 【0003】 For example, Patent Document 1 discloses a covered stent that can not only perform an expansion treatment of a stenotic blood vessel but also simultaneously perform a tumor growth avoidance treatment such as an aneurysm. Specifically, the covered stent disclosed in Patent Document 1 is formed by a cylindrical body of a mesh-like structure using a bioabsorbable fiber, and includes a stent (described as a stent body in the same document) whose diameter can be expanded and contracted, and a film (described as a cover material in the same document) spirally wound around the inner surface of the cylindrical body of the stent. In addition, in a covered stent, it is generally known that the end of a tubular film is exposed from the stent to function as a check valve portion like a duckbill valve. 【Prior Art Documents】 【Patent Documents】 【0004】 【Patent Document 1】 Japanese Patent Application Laid-Open No. 2018-175776 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0005】 However, when the end of the film functions as a check valve portion, when a backflow occurs, the end of the film may be reversed, and the opening of the end of the film may not be blocked, and the check function may be impaired, and there is room for improvement. 【0006】 The present invention has been made in view of the above problems, and provides a covered stent that can prevent the check valve function from being impaired by the reversal of the check valve portion made of film. [Means for solving the problem] 【0007】 According to the present invention, a covered stent comprises a stent extending in a long length and a tubular film attached along the stent, wherein the film is exposed from the inside of the stent outward in the longitudinal direction and has a check valve portion that allows flow in a first direction outward in the longitudinal direction from the stent while preventing flow in a second direction which is the opposite direction of the flow in the first direction, and the check valve portion includes, The film is prevented from being reversed. An anti-reversal mechanism is provided. Furthermore, the anti-reversal portion comprises a first anti-reversal portion that extends in the circumferential direction of the film to increase rigidity, and a second anti-reversal portion that extends in the longitudinal direction of the stent to increase rigidity, wherein the first anti-reversal portion extends further outward in the longitudinal direction of the stent than the second anti-reversal portion, and imparts less rigidity to the film than the second anti-reversal portion. A covered stent characterized by the above is provided. [Effects of the Invention] 【0008】 According to the present invention, it is possible to prevent the check valve function from being impaired by the reversal of the check valve portion, which is made of film. [Brief explanation of the drawing] 【0009】 [Figure 1] This is a schematic side view of a covered stent 1 according to an embodiment of the present invention. [Figure 2] This is a schematic enlarged view showing a portion of a film equipped with reinforcing tape according to the first modified example. [Figure 3] This is a schematic enlarged view showing a plate piece relating to the second modified example and a portion of a film equipped with reinforcing tape. [Figure 4] This is a schematic enlarged view showing a plate piece relating to the third modified example and a portion of a film equipped with reinforcing tape. [Modes for carrying out the invention] 【0010】 Embodiments of the present invention will be described below with reference to the drawings. The embodiments described below are merely examples to facilitate understanding of the present invention and do not limit it. In other words, the shape, dimensions, arrangement, etc., of the components described below can be changed or improved without departing from the spirit of the present invention, and of course, equivalents thereof are included in the present invention. Furthermore, in all drawings, similar components are denoted by the same reference numerals, and redundant explanations are omitted as appropriate. Note that the dimensional ratios in each drawing have been adjusted to clearly show the differences in the characteristic configurations of each part, and therefore may differ from the actual dimensional ratios. 【0011】 <Overview> First, an overview of the covered stent 1 according to this embodiment will be described, mainly with reference to Figure 1. Figure 1 is a schematic side view of the covered stent 1 according to an embodiment of the present invention. 【0012】 The covered stent 1 according to this embodiment comprises a stent 2 that extends in a long length and a tubular film 3 attached along the stent 2. The film 3 is exposed from the inside of the stent 2 to the outside in the longitudinal direction and has a check valve portion 3a that allows flow in a first direction outward in the longitudinal direction from the stent 2 while preventing flow in a second direction which is the opposite direction to the flow in the first direction. The check valve section 3a is provided with an anti-reversal section (reinforcement tape 3b) that extends in the circumferential direction of the film 3 to increase its rigidity. 【0013】 The phrase "attached along stent 2" above can be rephrased as meaning that it is attached along a cylindrical portion of stent 2, overlapping with it. Specifically, the film 3 according to this embodiment covers at least a portion of the inner surface of a single-layer stent 2. However, the configuration is not limited to this, and the stent 2 may be composed of two layers, and the film 3 may be arranged so as to be sandwiched between the two layers of the stent 2. 【0014】 Further, the film 3 is formed to project long outside the stent 2 only on one side in the longitudinal direction, and the projecting portion serves as a check valve portion 3a. With the check valve portion 3a formed in this way, the film 3 in the covered stent 1 allows the flow of a fluid (not shown) from the end on the side where the film 3 does not project from the stent 2 (the lower end in FIG. 1) toward the check valve portion 3a (in the upward direction in FIG. 1), and can restrict the reverse flow. 【0015】 That is, when the fluid flows from the end opposite to the check valve portion 3a toward the end on the check valve portion 3a side (that is, from bottom to top in FIG. 1), the fluid itself pushes the check valve portion 3a (the upper end of the film 3) outward from the inside to form an opening, thereby allowing the flow of the fluid. On the other hand, when the fluid attempts to flow from the end on the check valve portion 3a side toward the end opposite to the check valve portion 3a (that is, from top to bottom in FIG. 1), the fluid pushes the check valve portion 3a (the upper end of the film 3) inward from the outside to close the opening, thereby restricting the flow of the fluid. 【0016】 Here, depending on the angle of the fluid flow, even when the fluid flows from top to bottom as shown in FIG. 1, a load is applied to reverse the film 3 and widen the opening of the check valve portion 3a. Even when such a load is applied, an anti-reversal portion (reinforcement tape 3b) is provided to impart rigidity for preventing the reversal of the film 3. 【0017】 Note that the above-mentioned "anti-reversal portion" is a resin-made and adhesive reinforcement tape 3b in this embodiment, but any component can be used as long as it can impart a predetermined rigidity (a certain degree of difficulty in deformation) to the film 3 to prevent reversal, and the invention is not limited to such a configuration. For example, the "anti-reversal portion" may be formed by applying a liquid elastomer and then drying it to be fixed to the film 3, or may be a ring made of metal or resin. In addition, the "circumferential direction" shall include, in addition to the circumferential direction that circulates around the axis center, the spiral direction that obliquely circulates as described later. 【0018】 According to the above configuration, the overall rigidity of the film 3 including the reinforcing tape 3b in the film 3 is increased by the anti-reversal portion (reinforcing tape 3b), so that the check valve portion 3a formed of the film 3 is reversed, thereby preventing the check valve function from being impaired. 【0019】 [Overall Configuration] The covered stent 1 according to the present embodiment includes a cylindrical stent 2 and a cylindrical film 3 attached to the inner surface of the stent 2. 【0020】 [Stent] The stent 2 is formed of, for example, a nickel-titanium alloy or the like, and is formed into a partial lattice network shape by reciprocating a wire in the longitudinal direction of the stent 2 while being rotated in the circumferential direction, and is formed into a cylindrical shape as a whole. Note that such a method of forming the stent is an example and does not limit the forming method. A diameter-expanded portion 2a having a larger diameter than other portions is formed at the tip of the stent 2. 【0021】 [Film] The film 3 is formed of, for example, silicone rubber, is formed longer in the longitudinal direction than the stent 2, and a part thereof protrudes from the diameter-expanded portion 2a side of the stent 2, and this protruding portion constitutes the check valve portion 3a. The film 3 is attached to the inner surfaces of both ends in the longitudinal direction of the stent 2 by two attachment wires 4 extending in the circumferential direction with respect to the stent 2. 【0022】 However, it is not limited to such a configuration. For example, the film 3 may be formed so as to cover the stent 2 by dipping. And a reinforcing tape 3b as an anti-reversal portion is provided in the check valve portion 3a. 【0023】 The anti-reversal section (reinforcement tape 3b) is formed in a circular shape around the central axis of the film 3. Here, "circular" means that it is formed in a closed manner around the central axis of the film 3, and includes not only perfectly circular shapes but also irregularly deformed shapes due to the flexibility of the film 3. In Figure 1, the reinforcing tape 3b is schematically shown as a straight line, but in reality it is formed in a wavy manner along the film 3 which is made of a flexible material. 【0024】 With the above configuration, the anti-reversal portion (reinforcement tape 3b) is formed in a circular shape, which firmly prevents the film 3 from reversing in all directions perpendicular to the central axis of the film 3. As described above, it is preferable for the reinforcing tape 3b to be formed in a circular shape, but the configuration is not limited to this. For example, the reinforcing tape may be formed extending in the axial direction of the film 3 (stent 2). 【0025】 <First variation> Next, with reference to Figure 2, the film 13 (check valve portion 13a) according to the first modified example will be described. Figure 2 is a schematic enlarged view showing a part of the film 13 equipped with the reinforcing tape 13b according to the first modified example. 【0026】 The anti-reversal portion (reinforcement tape 13b) in this example is formed in a grid pattern so as to extend not only in the circumferential direction of the film 13 but also in a direction intersecting the circumferential direction of the film 13 (i.e., the axial direction). According to the above configuration, the anti-reversal section is formed in a grid pattern, which makes it possible to prevent the film from reversing over a wide range in both the longitudinal and circumferential directions. 【0027】 The anti-reversal portion may be formed in a spiral shape around the central axis of the film 13. With the above configuration, the inversion prevention portion is formed in a spiral shape, which prevents the film 13 from inverting over a wide range in both the longitudinal and circumferential directions, and makes it easier for the film 13 to expand and contract in the axial direction, thereby suppressing expansion and contraction in the radial direction. Furthermore, compared to structures formed in a circular pattern, it can suppress obstruction of the flow of bodily fluids (such as blood, gastric juice, and ingested food) in the axial direction in the forward direction (from bottom to top in Figure 1 or Figure 2). 【0028】 <Second variation> Next, with reference to Figure 3, a check valve section 23a equipped with a second anti-reversal section (plate piece 23c) according to a second modified example will be described. Figure 3 is a schematic enlarged view showing a part of the film 23 equipped with the plate piece 23c and reinforcing tape 3b according to the second modified example. 【0029】 The anti-reversal section is a first anti-reversal section (reinforcement tape 3b), and the check valve section 23a includes a second anti-reversal section (plate piece 23c) that extends in the longitudinal direction of the stent 2 to increase its rigidity. The reinforcing tape 3b extends further outward in the longitudinal direction of the stent than the plate piece 23c, and therefore imparts less rigidity to the film 23 than the plate piece 23c. 【0030】 In other words, the anti-reversal section is composed of reinforcing tape 3b and plate piece 23c. Furthermore, regarding the statement that "the reinforcing tape 3b imparts less rigidity to the film 23 than the plate piece 23c," in other words, the overall rigidity of the film 23, including the reinforcing tape 3b but without the plate piece 23c, is lower than the overall rigidity of the film 23, including the plate piece 23c but without the reinforcing tape 3b. 【0031】 Specifically, the plate piece 23c in this example is made of metal, is formed to be short in the width direction (radial direction) of the stent 2, and long in the axial direction of the stent 2. The check valve section 23a may consist of one plate piece 23c, but as will be described later, multiple check valves may be provided in the circumferential direction of the film 23. Furthermore, the second inversion prevention section only needs to be able to prevent the inversion of the film 23, and is not limited to a plate piece 23c; for example, it may be formed in the shape of a wire. 【0032】 With the above configuration, the second anti-reversal section (film 23) reliably prevents the film 23 from reversing, while the reinforcing tape 3b located on the longitudinal outer side of the stent 2 provides less rigidity to the film 23 than the plate piece 23c, thereby limiting the impairment of the function of the check valve section 23a. 【0033】 <Third variation> Next, with reference to Figure 4, the second anti-reversal section (plate pieces 33c, 33d) according to the third modified example will be described. Figure 4 is a schematic enlarged view showing a part of the film equipped with plate pieces 33c, 33d and reinforcing tape 3b according to the third modified example. Figure 4 shows the plates 33c and 33d viewed from a position rotated 90 degrees relative to the orientation in which plate 23c is viewed in Figure 3. 【0034】 Multiple second anti-reversal sections (plate pieces 33c, 33d) are provided. The tip of at least one of the plate pieces 33c, 33d (plate piece 33c) that is on the longitudinal outer side of the stent 2 is positioned to overlap with the first anti-reversal section (reinforcement tape 3b). The tip of at least the other plate piece 33c, 33d (plate piece 33d) that is on the longitudinal outer side of the stent 2 is positioned offset from the reinforcement tape 3b. In this example, two plate pieces 33c and 33d are shown, but the number is arbitrary, and more than one may be provided. 【0035】 In this example, a combination of a reinforcing tape 3b formed in a circular shape around the central axis of the film 33 and plate pieces 33c and 33d of different lengths serving as second anti-reversal sections is illustrated, but the present invention is not limited to such a configuration. For example, the plate piece serving as the second anti-reversal section may be a grid-shaped reinforcing tape 13b as shown in Figure 2, or it may be formed in a spiral shape. 【0036】 The tip of at least one of the plate pieces 33c and 33d (plate piece 33c) is positioned to overlap the first anti-reversal section (reinforcement tape 3b), and the tip of the other at least one of the plate pieces 33c and 33d (plate piece 33d) is positioned offset from the reinforcement tape 3b. For this reason, especially when the first anti-reversal section (reinforcement tape) is formed in a spiral shape, the first anti-reversal section extends offset in the circumferential direction of the film 33, so the plate pieces 33c and 33d may be formed to be of equal length. 【0037】 With the above configuration, the rigidity can be continuously increased by positioning the plate piece 33c to overlap with the reinforcing tape 3b, and the displacement of the check valve portion 33a can be suitably limited. Furthermore, the positioning of the plate piece 33d to be offset from the reinforcing tape 3b can suppress interference with the function of the check valve portion 33a. 【0038】 Furthermore, the various components of the covered stent of the present invention do not need to be independent entities. It is permissible for multiple components to be formed as a single member, for one component to be formed from multiple members, for one component to be part of another component, for a part of one component to overlap with a part of another component, and so on. 【0039】 This embodiment and the present manufacturing method encompass the following technical concepts. (1) A long, extended stent, A covered stent comprising a tubular film attached along the stent, The film is exposed from the inside of the stent outward in the longitudinal direction and has a check valve portion that allows flow in a first direction outward in the longitudinal direction from the stent, while preventing flow in a second direction which is the opposite direction to the flow in the first direction. A covered stent characterized in that the check valve portion is provided with an anti-reversal portion that extends in the circumferential direction of the film to increase rigidity. (2) The inversion prevention portion is formed in a circular shape around the central axis of the film, as described in (1) of the covered stent. (3) The covered stent according to (1), wherein the anti-reversal portion is formed in a grid pattern so as to extend in a direction intersecting the circumferential direction of the film, in addition to the circumferential direction of the film. (4) The inversion prevention portion is formed spirally around the central axis of the film, as described in (1). (5) The aforementioned anti-reversal unit is a first anti-reversal unit, The check valve portion further includes a second anti-reversal portion that extends in the longitudinal direction of the stent to increase rigidity, The covered stent according to any one of (2) to (4), wherein the first anti-reversal portion extends further outward in the longitudinal direction of the stent than the second anti-reversal portion, and the rigidity imparted to the film is lower than that of the second anti-reversal portion. (6) Multiple of the aforementioned second anti-reversal units are provided. The tip of at least one of the second anti-reversal sections, located on the longitudinal outer side of the stent, is positioned to overlap the first anti-reversal section. The covered stent according to (5), wherein the tip of at least one of the second anti-reversal sections that is on the longitudinal side of the stent is positioned offset from the first anti-reversal section. [Explanation of symbols] 【0040】 1. Covered stent 2 stents 2a Expanded diameter part 3 Films 3a Check valve section 3b Reinforcement tape (anti-reversal section, first anti-reversal section) 4. Mounting wire 13 Film 13a Check valve section 13b Reinforcement tape (anti-reversal section) 23 Film 23a Check valve section 23c Plate piece (second anti-reversal part) 33 film 33a Check valve section 33c, 33d Plate pieces (second anti-reversal section)

Claims

[Claim 1] A long, extended stent, A covered stent comprising a tubular film attached along the stent, The film is exposed from the inside of the stent outward in the longitudinal direction and has a check valve portion that allows flow in a first direction outward in the longitudinal direction from the stent while preventing flow in a second direction which is the opposite direction to the flow in the first direction. The check valve section is provided with an anti-reversal section to prevent the film from reversing. The aforementioned anti-reversal unit is, The first anti-reversal portion extends in the circumferential direction of the film to increase its rigidity, The stent is further provided with a second anti-reversal portion that extends in the longitudinal direction to increase rigidity, A covered stent in which the first anti-reversal portion extends further outward in the longitudinal direction of the stent than the second anti-reversal portion, and provides less rigidity to the film than the second anti-reversal portion. [Claim 2] The covered stent according to claim 1, wherein the first anti-reversal portion is formed in a circular shape around the central axis of the film. [Claim 3] The covered stent according to claim 1, wherein the first anti-reversal portion is formed in a grid pattern so as to extend in a direction intersecting the circumferential direction of the film, in addition to the circumferential direction of the film. [Claim 4] The covered stent according to claim 1, wherein the first anti-reversal portion is formed spirally around the central axis of the film. [Claim 5] Multiple of the aforementioned second anti-reversal units are provided. The tip of at least one of the second anti-reversal sections, located on the longitudinal side of the stent, is positioned to overlap the first anti-reversal section. The covered stent according to claim 1, wherein the tip of at least one of the second anti-reversal sections that is located longitudinally outward of the stent is positioned offset from the first anti-reversal section.

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