Stents

Abstract

To provide a stent capable of suppressing going out from an indwelling part caused by a motion in the axial direction of a biological lumen.SOLUTION: A stent 1 indwelt in a biological lumen comprises a skeleton part 2 formed tubularly by braiding a wire 3. The skeleton part 2 has a first elastic part 4 which is provided on the upstream side in the flowing direction of a fluid flowing inside the biological lumen and which has higher elasticity in an axial direction than the other parts.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a stent. [Background technology]

[0002] Stents have been known that are placed in narrowed or blocked areas in biological lumens, such as the digestive system lumens including the esophagus, stomach, duodenum, small intestine, large intestine, and bile duct (hereinafter referred to as the "digestive tract"), to expand the diameter of the diseased area and maintain the patency of the biological lumen (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4651943 Summary of the Invention [Problem to be solved by the invention]

[0004] However, although a stent placed in a biological lumen as in Patent Document 1 above is unlikely to shift out of its position from the placement site due to its radial expansion force, the axial movement of the biological lumen itself (e.g., the passage of stool or peristaltic movement of the digestive tract) can cause the stent to deviate from the placement site.

[0005] The present invention has been made in consideration of such problems, and has an object to provide a stent that can be prevented from escaping from the placement site due to axial movement of the biological lumen. [Means for solving the problem]

[0006] One aspect of the present invention is a stent to be placed in a biological lumen, comprising: Braiding the wire circle A cylindrically formed skeleton is provided, the wire is folded back in a zigzag pattern so that peaks protruding on one side in an axial direction of the skeleton and valleys protruding on the other side in the axial direction are alternately formed, and the peaks and valleys opposed in the axial direction are interwoven so as to mesh with each other to form a diamond lattice; The skeleton portion is a first stretchable portion that is provided upstream in the flow direction of the fluid flowing through the biological lumen and has higher stretchability in the axial direction than other portions; and, A body portion provided downstream of the first stretchable portion in the flow direction and having lower axial stretchability than the first stretchable portion; Have death, The lattice of the wire material constituting the first stretchable portion is woven to form a diamond shape that is longer in the circumferential direction than the lattice of the wire material constituting the body portion. .

[0007] Another aspect of the present invention is a stent to be placed in a lumen of a living body, comprising: Braiding the wire circle A cylindrically formed skeleton is provided, the wire is folded back in a zigzag pattern so that peaks protruding on one side in an axial direction of the skeleton and valleys protruding on the other side in the axial direction are alternately formed, and the peaks and valleys opposed in the axial direction are interwoven so as to mesh with each other to form a diamond lattice; The skeleton portion is a second stretchable portion that is provided downstream in the flow direction of the fluid flowing through the biological lumen and has lower stretchability in the axial direction than other portions; and, A body portion that is provided upstream of the second stretchable portion in the flow direction and has higher axial stretchability than the second stretchable portion; Have death, The second stretchable portion The lattice of the wires constituting the body portion is woven to form a diamond shape that is longer in the axial direction than the lattice of the wires constituting the body portion. . Effect of the Invention

[0008] According to the present invention, it is possible to suppress deviation from the placement site caused by axial movement of the biological lumen. [Brief description of the drawings]

[0009] [Figure 1] FIG. 2 is a perspective view showing an example of the configuration of a stent according to the present embodiment. [Diagram 2] FIG. 2(a) is a side view of FIG. 1, and FIG. 2(b) is a schematic diagram showing the state in which the stent is placed at a lesion site in the digestive tract. [Diagram 3] FIG. 2 is a plan view showing a part of a circumferential direction of a skeleton portion. [Figure 4] FIG. 1 shows a first modified example of a stent. [Diagram 5] FIG. 13 shows a second modified example of a stent. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing a configuration example of a stent 1 according to one embodiment of the present invention. Fig. 2(a) is a side view of Fig. 1. In the drawing, the axial direction Ax of the stent 1 is indicated by an arrow. Also, a direction substantially perpendicular to the axial direction Ax is defined as a radial direction. Also, in the drawing, one side of the stent 1 is indicated by the symbol F, and the other side of the stent 1 is indicated by the symbol B.

[0011] The stent 1 is placed at a lesion such as a stenosed site or an obstructed site in a living lumen, and is used to expand the lesion. The stent 1 of this embodiment is introduced, for example, into the digestive tract.

[0012] As shown in FIG. 1 and FIG. 2(a), the stent 1 includes a framework 2 formed in a cylindrical shape, one side of which communicates with the other side in the axial direction Ax. In the following description, as an example of stent 1, a bare stent configuration example having no coating on the peripheral surface of the skeleton 2 is shown, but at least one of the inner and outer circumferences of the skeleton 2 may have a tubular coating (not shown) formed of, for example, a fluororesin, polyester resin, or the like attached thereto.

[0013] 2(b) is a schematic diagram showing a state in which the stent 1 of this embodiment is placed in a lesion site 11 of the digestive tract 10. When the stent 1 is placed, the inner surface of the placement site (lesion site 11 in the digestive tract 10) is pressed radially outward by the outer circumferential surface of the framework 2, and the lesion site 11, which has narrowed inward so as to block the digestive tract 10, is pushed radially outward.

[0014] The framework 2 is a so-called self-expanding structure that memorizes the shape of the expanded state, and can expand and contract from a contracted state contracted radially inward to an expanded state expanded radially outward. The stent 1 of this embodiment is introduced into the digestive tract 10 in a radially inward contracted state (not shown) using a catheter not shown. The stent 1 released from the catheter may be expanded radially outward by compressing it from inside with a balloon (not shown).

[0015] When the stent 1 is placed in the digestive tract 10 with one side facing the upstream side (colon side) of the digestive tract 10, the internal space of the skeleton 2 forms a flow path through which fluid flowing through the digestive tract 10 can pass from one side to the other side in the axial direction Ax. The fluid flowing through the digestive tract 10 may be in any state of matter, including, for example, food immediately after ingestion that has not been digested at all, food that has been broken down as it passes through the digestive tract, and food that has passed through the digestive tract but not been digested (e.g., feces, etc.).

[0016] The skeleton 2 is formed by weaving wires 3 made of metal wires in a lattice pattern. Examples of materials for the wires 3 of the skeleton 2 include known metals or metal alloys such as Ni-Ti alloy, stainless steel, and titanium alloy. The wires 3 of the skeleton 2 may be made of an alloy material having X-ray contrast, or a marker piece (not shown) made of an alloy material having X-ray contrast may be appropriately attached to the wires 3. In these cases, the position of the stent 1 can be confirmed from outside the body.

[0017] When a Ni-Ti alloy is used as the material forming the skeleton 2, after the skeleton 2 is adjusted to a shape in the expanded state, the skeleton 2 can be made to memorize that shape by carrying out a specified heat treatment.

[0018] 3 is a plan view showing a part of the circumferential direction of the skeleton 2. The up-down direction in FIG.

[0019] The wire rods 3 constituting the skeleton 2 are folded back in a zigzag pattern so that peaks 3a and valleys 3b are alternately formed at a predetermined pitch. In addition, between adjacent stages on one side and the other side in the axial direction, a bent portion (valley portion 3b) protruding to the other side in the stage on one side of the wire rod 3 faces a bent portion (peak portion 3a) protruding to one side in the stage on the other side of the wire rod 3. In adjacent stages in the axial direction, the wire rods 3 are woven in a fence shape so that the opposing bent portions (peak portion 3a, valley portion 3b) mesh with each other, forming a diamond lattice.

[0020] As described above, the skeleton 2 is formed by weaving the wires 3 into a fence shape. Therefore, in each stage of the skeleton 2, intersections 3c are provided where the wires 3 cross each other without being weaved, in order to move the wires 3 to the adjacent stage in the axial direction. As shown in Fig. 3, the circumferential positions at which the intersections 3c are provided are shifted from each other in each stage of the skeleton 2. Note that the circumferential positions of the intersections 3c may be regularly shifted in the axial direction or irregularly shifted.

[0021] Since the wires 3 are not woven at the intersections 3c, the flexibility at the intersections 3c is lower than that at the other sections where the wires 3 are woven. On the other hand, the circumferential positions of the intersections 3c at each stage of the skeleton 2 are shifted from each other, so that the intersections 3c are not arranged overlapping each other along the axial direction. Therefore, the occurrence of an event in which the intersections 3c are stiff and the skeleton 2 is difficult to bend is unlikely to occur, and the axial force of the skeleton 2 is prevented from increasing due to the presence of the intersections 3c. In other words, the flexibility is easily ensured even in the stent 1 of the skeleton 2 in which the wires 3 are woven in a fence shape, so that the stent can be easily placed at the lesion site 11 of the curved digestive tract 10.

[0022] In the skeleton portion 2, a first stretchable portion 4, a body portion 5, and a second stretchable portion 6, each of which has a different braiding pattern of the wires 3, are formed in this order from one side to the other side in the axial direction Ax.

[0023] The body section 5 is provided between the first stretchable section 4 and the second stretchable section 6. The body section 5 has an expansion force capable of pushing open the narrowed lesion site 11, and by pushing open the lesion site 11 with its outer circumferential surface, it has the function of securing a flow path through which fluid flowing through the digestive tract 10 can pass. The lattice of the body section 5 is shorter in the circumferential direction than the lattice of the first stretchable section 4, and is rhombus-shaped and shorter in the axial direction than the lattice of the second stretchable section 6.

[0024] The first elastic section 4 is disposed on one side of the body section 5, and faces the colon side, which is the upstream side of the digestive tract 10, when the stent 1 is placed. Similar to the body section 5, the first elastic section 4 has the function of ensuring a flow path through which fluid flowing through the digestive tract 10 can pass.

[0025] The lattice of the first stretchable portion 4 is shaped like a diamond that is longer in the circumferential direction than the lattices of the body portion 5 and the second stretchable portion 6, and is woven into a shape that is easy to stretch and contract in the axial direction. With the above-mentioned configuration, the first stretchable portion 4 has higher axial stretchability than the body portion 5 and the second stretchable portion 6. Therefore, the first stretchable portion 4 has a small repulsive force against axial forces from the upstream side to the downstream side of the digestive tract 10 caused by the passage of stool and peristaltic movement of the digestive tract.

[0026] Therefore, the first stretchable portion 4 is more easily movable in the axial direction than other portions of the skeletal portion 2. In addition, the first stretchable portion 4 can function to contract downstream with the passage of stool and the peristaltic movement of the digestive tract 10, and be applied to the narrowed portion of the digestive tract 10.

[0027] The second stretchable part 6 is disposed on the other side of the body part 5, and faces the anus side, which is the downstream side of the digestive tract 10, when the stent 1 is placed. Similar to the body part 5, the second stretchable part 6 has the function of ensuring a flow path through which fluid flowing through the digestive tract 10 can pass.

[0028] The lattice of the second stretchable portion 6 is shaped like a diamond that is longer in the axial direction than the lattices of the body portion 5 and the first stretchable portion 4, and is woven in a shape that is less prone to stretching and contracting in the axial direction. Due to the above-mentioned configuration, the second stretchable portion 6 has lower axial stretchability than the body portion 5 and the first stretchable portion 4. Therefore, the second stretchable portion 6 has a large repulsive force against the axial force from the upstream side to the downstream side of the digestive tract 10 described above.

[0029] Therefore, the second elastic part 6 is less likely to move in the axial direction compared to other parts of the framework part 2. In addition, the second elastic part 6 has the function of suppressing migration (displacement) of the stent 1 induced by the axial force from the upstream side to the downstream side of the digestive tract 10 described above.

[0030] Comparing the ease of stretching in the axial direction in the skeleton 2, the first stretchable section 4 is the most axially stretchable, followed by the body section 5 and the second stretchable section 6. In other words, the second stretchable section 6 is the least axially stretchable. Note that the first stretchable section 4, body section 5, and second stretchable section 6 may be manufactured separately, for example, and the skeleton 2 may be constructed by connecting these sections.

[0031] In addition, a flare portion whose diameter increases toward the end is provided at each end in the axial direction Ax of the framework portion 2. The flare portion serves to suppress the positional displacement of the stent 1 by generating friction with the inner wall of the digestive tract 10.

[0032] In this embodiment, a first flare section 7 is formed on one side of the first expandable section 4, and a second flare section 8 is formed on the other side of the second expandable section 6. The first flare section 7 is an example of an upstream side expanded diameter section, and the second flare section 8 is an example of a downstream side expanded diameter section. Both the first flare section 7 and the second flare section 8 are formed by braiding wires.

[0033] The first flared portion 7 has a longer axial dimension than the second flared portion 8. Therefore, when placing the stent 1, the first flared portion 7 can be easily made to follow the curved portion of the digestive tract 10. On the other hand, the second flared portion 8 has a shorter axial dimension than the first flared portion 7. Therefore, in the procedure for placing the stent 1, it is also easy to position the second flared portion 8 in accordance with the placement position of the stent 1 (the narrowed portion of the digestive tract 10).

[0034] In addition, in order to prevent the tip of the flared portion from perforating the digestive tract 10, the wire forming the first flared portion 7 and the second flared portion 8 may be thinner in diameter than the wire forming the first telescopic portion 4, the body portion 5, and the second telescopic portion 6.

[0035] The effects of the stent of this embodiment will be described below. The stent 1 of this embodiment includes a skeletal section 2 formed into a tubular shape by braiding wires 3. The skeletal section 2 is provided on the upstream side (one side) of the flow direction of a fluid flowing inside a biological lumen (digestive tract 10), and includes a first stretchable section 4 that has higher axial stretchability than other sections. When one side of the stent 1 is placed facing the upstream side of the digestive tract 10, the first elastic section 4 located on the upstream side of the digestive tract 10 is more likely to move in the axial direction than other parts of the skeleton section 2. Even if an axial force is applied from the upstream side of the digestive tract 10 to the downstream side, the elasticity of the first elastic section 4 allows displacement in the axial direction on the upstream side of the skeleton section 2. Therefore, the elasticity of the first elastic section 4 allows the stent 1 to respond to the axial movement of the digestive tract 10. In other words, other parts of the skeleton 2 located downstream of the first stretchable section 4 (for example, the body section 5 and the second stretchable section 6) have lower axial stretchability and are less likely to move in the axial direction compared to the first stretchable section 4. Therefore, the part downstream of the first stretchable section 4 functions to resist the axial force from the upstream side to the downstream side of the digestive tract 10 and to keep the stent 1 at the placement site. As described above, in this embodiment, a portion that allows axial displacement is provided upstream of the skeleton 2, while the downstream portion of the skeleton 2 functions to retain the stent 1 at the placement site, thereby preventing the stent 1 from escaping from the placement site due to axial movement of the digestive tract 10.

[0036] Furthermore, when the first elastic part 4 contracts downstream due to the passage of stool or the like, the first elastic part 4 located upstream is applied to the narrowed part of the digestive tract 10. Therefore, the position of the stent 1 can be adjusted by utilizing the axial movement of the digestive tract 10, and the stent 1 can be appropriately placed at the placement site. This can greatly reduce the burden on the practitioner when placing the stent 1.

[0037] Next, a modified example of the stent of the above embodiment will be described. In the description of the modified example, the same elements as those in the above embodiment will be given the same reference numerals, and the duplicated description will be omitted.

[0038] FIG. 4 is a diagram showing an example of the configuration of a stent 1a according to a first modified example. The stent 1a in Fig. 4 has a structure in which the second elastic portion 6 is omitted from the framework 2. In the stent 1a in Fig. 4, a first elastic portion 4 and a body portion 5 are formed from one side to the other side in the axial direction Ax. And, a second flare 8 portion is formed on the other side of the body portion 5. As in the first modified example, the presence or absence of the second expansion section 6 can be appropriately adjusted depending on, for example, the type of biological lumen in which it is placed, the type and strength of axial movement, the dimensions of the lesion, etc., to obtain the same effect as in the above embodiment.

[0039] FIG. 5 is a diagram showing an example of the configuration of a stent 1b according to the second modified example. A stent 1b in FIG. 5 has a structure in which the body section 5 is omitted from the framework section 2, and one side of a second stretchable section 6 is connected to the other side of the first stretchable section 4. As in the second modified example, the presence or absence of the body portion 5 can be appropriately adjusted depending on, for example, the type of biological lumen in which it is placed, the type and strength of axial movement, the dimensions of the lesion, etc., to obtain the same effect as in the above embodiment.

[0040] The present invention is not limited to the above-described embodiment, and various improvements and design changes may be made without departing from the spirit of the present invention.

[0041] In the above embodiment, the elasticity of the skeletal section 2 may be changed by changing the shape of the braid, the dimensions and material of the wire, etc. For example, in the skeletal section 2 of the above embodiment, the diameter of the wire of the first elastic section 4 may be made smaller than the wire of the second elastic section 6. In this case, the elasticity in the axial direction of the first elastic section 4 is greater than when the wires of the first elastic section 4 and the second elastic section 6 have the same diameter.

[0042] Furthermore, the first stretchable section 4 may be positioned upstream of the second stretchable section 6 in the fluid flow direction, and for example, the skeleton section 2 may be configured in such a way that the first stretchable sections 4 and the second stretchable sections 6 are alternately positioned in the axial direction (not shown). In addition, the stent 1 may have a structure (not shown) in which the skeleton 2 is formed of a body 5, a first flared portion 7 is formed on one side of the body 5 using a wire having a smaller diameter than the body 5, and a second flared portion 8 is formed on the other side of the body 5 using a wire having a smaller diameter than the body 5.

[0043] In the above embodiment, the passage of feces and the peristaltic movement of the digestive tract 10 have been described as examples of the axial movement of the digestive tract 10. However, the axial movement of the digestive tract 10 is not limited to the above, and may occur when the digestive tract 10 performs segmental movement or pendulum movement other than peristalsis.

[0044] The stent 1 of the present invention can be applied not only to the digestive tract 10 which moves in the axial direction, but also to, for example, a pulsating artery, etc. Furthermore, the stent 1 of the present invention can be applied to other biological lumens in which axial movement may occur due to the flow of a fluid in the biological lumen.

[0045] In addition, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0046] Reference Signs List 1, 1a, 1b... stent, 2... framework, 3... wire, 4... first stretchable section, 5... body section, 6... second stretchable section, 7... first flared section (upstream expanded section), 8... second flared section (downstream expanded section), 10... digestive tract (biological lumen), 11... lesion site

Claims

1. A stent to be placed in a biological lumen, The wire rod is braided to form a cylindrical skeleton. the wire is folded back in a zigzag pattern so that peaks protruding on one side in an axial direction of the skeleton and valleys protruding on the other side in the axial direction are alternately formed, and the peaks and valleys opposed in the axial direction are interwoven so as to mesh with each other to form a diamond lattice; The skeleton portion is A first stretchable portion is provided upstream in a flow direction of a fluid flowing through the biological lumen and has higher stretchability in an axial direction than other portions; A body portion is provided downstream of the first stretchable portion in the flow direction and has lower axial stretchability than the first stretchable portion, The lattice of the wire material constituting the first stretchable portion is woven to form a diamond shape that is longer in the circumferential direction than the lattice of the wire material constituting the body portion. Stent.

2. The skeleton portion is The downstream expansion section is provided downstream in the flow direction and has a larger diameter than the first expansion section.

2. The stent of claim 1.

3. The skeleton portion is The upstream expansion section is provided upstream of the first expansion section in the flow direction and has a larger diameter than the first expansion section. The downstream expanded diameter portion has a smaller dimension in the axial direction than the upstream expanded diameter portion. The stent of claim 2.

4. The skeleton portion is Further comprising a second stretchable section provided downstream of the first stretchable section in the flow direction and having lower axial stretchability than the body section, The lattice of the wire material constituting the second stretchable portion is woven to form a diamond shape that is longer in the axial direction than the lattice of the wire material constituting the first stretchable portion and the body portion. A stent according to any one of claims 1 to 3.

5. A stent to be placed in a biological lumen, The wire rod is braided to form a cylindrical skeleton. the wire is folded back in a zigzag pattern so that peaks protruding on one side in an axial direction of the skeleton and valleys protruding on the other side in the axial direction are alternately formed, and the peaks and valleys opposed in the axial direction are interwoven so as to mesh with each other to form a diamond lattice; The skeleton portion is A second stretchable portion is provided downstream in the flow direction of the fluid flowing through the biological lumen and has lower stretchability in the axial direction than other portions; A body portion is provided upstream of the second stretchable portion in the flow direction and has higher axial stretchability than the second stretchable portion, The lattice of the wire material constituting the second stretchable portion is woven to form a diamond shape that is longer in the axial direction than the lattice of the wire material constituting the body portion. Stent.

Images