Gastrointestinal stents

Abstract

Provided is a gastrointestinal stent that can be placed accurately at a placement target site of the gastrointestinal tract. The gastrointestinal stent (1) is equipped with: cylindrical skeleton (20) that is capable of expanding and contracting in the radial direction, which is substantially orthogonal to the axial direction; and conversion means (31, 32) capable of keeping axial-direction portions (21, 22) of the skeleton in a contracted state and converting portions from a contracted state to an expanded state with the skeleton released from a sheath (110). A plurality of portions are provided to allow axial-direction positions of the skeleton to be different from each other, and a plurality of conversion means are provided in a manner corresponding to the plurality of portions.

Description

[Technical Field]

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

[0002] Conventionally, digestive tract stents have been known that are placed in narrowed or obstructed areas in digestive tract lumens such as the esophagus, stomach, small intestine, large intestine, and bile duct (hereinafter referred to as the "digestive tract") to expand the diameter of the lesion area and maintain the patency of the digestive tract (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] A gastrointestinal stent is delivered to a target site by a stent placement system, but is housed in the sheath of the stent placement system in a radially contracted and axially extended state. This makes it difficult to smoothly release the gastrointestinal stent from the sheath. Furthermore, the skeleton of the gastrointestinal stent shortens axially when released from the sheath and expands, making it difficult to accurately place the gastrointestinal stent at the target site in the gastrointestinal tract. In particular, gastrointestinal stents with a skeleton made of spirally wound wires have a large shortening rate, making the above-mentioned problem more pronounced.

[0005] An object of the present invention is to provide a gastrointestinal stent that can be placed accurately at a target placement site in the gastrointestinal tract. [Means for solving the problem]

[0006] The gastrointestinal stent according to the present invention comprises: A gastrointestinal stent to be placed in the gastrointestinal tract, a cylindrical skeleton that is expandable and contractable in a radial direction substantially perpendicular to the axial direction; a conversion means for maintaining a specific portion of the skeleton in an axial direction in a contracted state when the skeleton is released from the sheath, and for converting the specific portion from the contracted state to an expanded state; the specific portion includes a plurality of skeleton portions provided at different positions in the axial direction of the skeleton, The conversion means is provided in plurality corresponding to the plurality of skeletal parts, and is configured to be operable independently of each other to maintain the contracted state of each skeletal part and to convert the contracted state to an expanded state. 、 The plurality of conversion means are a string-like member that is used in common for the plurality of skeletal portions, that is wound around the outer circumferential surfaces of the plurality of skeletal portions, and that maintains the plurality of skeletal portions in a contracted state in the wound state; a plurality of retaining members that are engaged with corresponding portions of the restraining member at the plurality of skeletal portions, and that maintain the wound state of the restraining member in the engaged state; the plurality of holding members are thin metal wires extending along the axial direction on the outer circumferential surface, The plurality of holding members can be individually pulled out to individually release engagement with the corresponding portions of the restraining members in each of the plurality of skeletal portions. . [Effects of the Invention]

[0007] According to the present invention, a gastrointestinal stent can be placed at a target placement site in the gastrointestinal tract with high accuracy. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram schematically showing a colonic stent according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing an example of the first conversion means and the second conversion means. [Figure 3] 3A and 3B are diagrams showing the configuration of a stent placement system. [Figure 4] 4A to 4D are diagrams showing an example of changes in state during placement of a colonic stent. [Figure 5] 5A to 5D are diagrams showing another example of changes in state during placement of a colonic stent. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In this embodiment, as an example of the present invention, a colonic stent 1 that is placed in the large intestine to treat an obstruction (stricture) by radially expanding a lesion in the large intestine (for example, an obstructed or strictured portion of the large intestine) outward will be described.

[0010] Fig. 1 is a schematic diagram of a colonic stent 1 according to an embodiment. As shown in Fig. 1, the colonic stent 1 has a cylindrical shape that defines a tubular flow path through which digestive matter flows. The colonic stent 1 is a bare stent of the one-side flare type that is composed only of a framework 20.

[0011] The colonic stent 1 has a constrained portion 11 that remains contracted when released from a sheath 110 (see FIG. 3A), and an unconstrained portion 12 that expands upon release from the sheath 110. The colonic stent 1 is placed at a lesion site in the large intestine so that the constrained portion 11 is located upstream (mouth side) in the direction of digestive flow, and the unconstrained portion 12 is located downstream (anus side) in the direction of digestive flow. In the following explanation, the left side in FIG. 1 (the end side of the constrained portion 11) is referred to as the distal side S1, and the right side (the end side of the unconstrained portion 12) is referred to as the proximal side S2. The colonic stent 1 may have an extension restricting portion for restricting expansion and contraction in the axial direction.

[0012] The framework 20 is a reinforcing member for maintaining the expanded state of the colonic stent 1. The framework 20 is formed to be self-expandable in the radial direction, which is approximately perpendicular to the axial direction, from a contracted state in which it contracts inward to an expanded state in which it expands outward.

[0013] The framework 20 is formed, for example, by weaving wire material into a tubular shape. The framework 20 is formed, for example, by weaving two wire materials that extend spirally while being folded back in a zigzag (Z-shape) at a predetermined pitch into a diamond-shaped wire mesh (fence-like) shape so that the bent portions (the peaks on one side (the convex portion on one axial end) and the valleys on the other side (the convex portion on the other axial end)) interlock with each other. In this case, when tension is applied to the colonic stent 1 in the axial direction, the bent portions of the wire material that form the mesh intersect closely, restricting axial extension. As a result, the axial length of the colonic stent 1 does not fluctuate significantly during placement, allowing the colonic stent 1 to be placed appropriately at the desired placement site.

[0014] The skeleton 20 is not limited to the above-described skeleton structure, and may be configured as a spiral skeleton in which, for example, a single metal wire is spirally wound while being bent in a zigzag (Z-shape) so that peaks (bends at the leading end) and valleys (bends at the trailing end) are alternately formed. The skeleton 20 may also be formed by laser processing a cylindrical metal member. Furthermore, the skeleton 20 may be formed of a plurality of wires.

[0015] Examples of materials for forming the framework 20 include known metals or metal alloys such as stainless steel, nickel-titanium alloy (nitinol), and titanium alloy. Also, alloy materials that are radiopaque may be used. In this case, the position of the colonic stent 1 can be confirmed from outside the body. The skeleton 20 may be made of a material other than a metal material (for example, ceramic, resin, etc.).

[0016] Furthermore, the framework 20 is configured to be deformable in response to an external force applied from the outer surface side. As a result, even if an external force is applied to the colonic stent 1 from the outer surface side, the framework 20 deforms, so that the colonic stent 1 can remain in the placement site without kinking and continue to expand the affected area of ​​the colon.

[0017] The material of the wire forming the skeleton 20, the type of wire (for example, circular wire such as wire, or angular wire made by laser cutting), cross-sectional area (corresponding to the wire diameter in the case of round wire), the number of bends in the circumferential direction and the shape of the bends (the number of ridges and the shape of the ridges), and the wire spacing in the axial direction (amount of skeleton per unit length) are appropriately selected based on criteria such as the ability to be stored in a sheath, the ability to be released from the sheath, the ability to be placed (to withstand expansion force), and the flexibility (ease of bending) required of the colonic stent 1 depending on the placement site.

[0018] The skeleton 20 has a first skeleton portion 21 and a second skeleton portion 22 that are disposed in the constrained portion 11, and a third skeleton portion 23 that is disposed in the non-constrained portion 12. The first skeleton portion 21 and the second skeleton portion 22 are formed to have a straight shape, and the third skeleton portion 23 is formed to have a flared shape. In FIG. 1, the boundary between the first skeletal portion 21 and the second skeletal portion 22 is indicated by a broken line.

[0019] The first skeletal portion 21 is constrained by the first conversion means 31 (see Figure 2) so as to maintain a contracted state, and the second skeletal portion 22 is constrained by the second conversion means 32 (see Figure 2) so as to maintain a contracted state. On the other hand, the third skeletal portion 23 is not constrained and expands as it is released from the sheath 110.

[0020] The first conversion means 31 is configured to maintain the first skeletal portion 21 in a contracted state when the skeleton 20 is released from the sheath, and to be able to convert the first skeletal portion 21 from the contracted state to an expanded state in response to a predetermined operation. The second conversion means 32 is configured to maintain the second skeletal portion 22 in a contracted state when the skeleton 20 is released from the sheath, and to be able to convert the second skeletal portion 22 from the contracted state to an expanded state in response to a predetermined operation. The first conversion means 31 and the second conversion means 32 are configured to be operable independently so that the timing of expanding the first skeletal portion 21 and the second skeletal portion 22 can be flexibly controlled while checking the placement state, etc.

[0021] Next, the first conversion means 31 and the second conversion means 32 will be described in detail with reference to FIG. Fig. 2 is a schematic diagram showing a specific example of the first conversion means 31 and the second conversion means 32. Note that the configuration shown in Fig. 2 is an example of the first conversion means 31 and the second conversion means 32, and other configurations may also be applied.

[0022] 2, the first conversion means 31 and the second conversion means 32 are composed of, for example, restraining members 31A and 32A wound around the outer circumferential surfaces of the first skeletal section 21 and the second skeletal section 22, and holding members 31B and 32B that engage with the restraining members 31A and 32A, respectively. The first conversion means 31 and the second conversion means 32 are attached, for example, by mounting the colonic stent 1 on the inner rod 120 and in a radially contracted state.

[0023] In the example shown in FIG. 2 , the restraining members 31A and 32A are wound circumferentially around the outer peripheral surfaces of the first skeletal portion 21 and the second skeletal portion 22, bending and winding in the opposite direction with each rotation. Meanwhile, the retaining members 31B and 32B are arranged along the axial direction of the first skeletal portion 21 and the second skeletal portion 22 and engage with the bent portions B formed on the restraining members 31A and 32A. That is, the restraining members 31A and 32A are wound in such a manner that they cannot maintain their wound state by themselves, but are held in place by engaging with the retaining members 31B and 32B. Therefore, when the engagement between the restraining members 31A and 32A and the retaining members 31B and 32B is released, the restraining members 31A and 32A naturally fall off the first skeletal portion 21 and the second skeletal portion 22. As a result, the first skeletal portion 21 and the second skeletal portion 22 are released from the contracted state and transition to the expanded state.

[0024] One end of restraining members 31A and 32A is pulled out, for example, from branch port 112a provided in hub 112 (see FIG. 3B, etc.). One end of holding members 31B and 32B is pulled out, for example, from an opening provided separately from branch port 112a (not shown), and can be pulled out while making fine adjustments by rotating a dial, etc.

[0025] The restraint members 31A, 32A and the holding members 31B, 32B are formed, for example, from a material having a predetermined strength and rigidity, and examples of such materials include suture threads such as nylon fibers or fluorine fibers, thin metal wires made of nickel-titanium alloy or stainless steel, and string-like members made of resin. It is preferable that the restraining members 31A and 32A and the holding members 31B and 32B are made of different materials in order to improve the sliding properties when they are pulled out.

[0026] 3A and 3B are diagrams showing the configuration of stent placement system 100. FIG. 3A shows stent placement system 100 in a disassembled state, and FIG. 3B shows stent placement system 100 in an assembled state. Note that in FIGS. 3A and 3B, the size (length, diameter, etc.) and shape of each member constituting stent placement system 100 are schematically shown to facilitate understanding of the invention. Also, FIGS. 3A and 3B show the case where the configuration shown in FIG. 2 is applied to first conversion means 31 and second conversion means 32.

[0027] The stent placement system 100 is used by inserting it into the forceps hole of an endoscope, for example, when placing a colonic stent 1 in the colon. As shown in Figures 3A and 3B, the stent placement system 100 includes a tubular sheath 110 and an inner rod 120 that is disposed inside the sheath 110 and is configured to be able to advance and retreat within the sheath 110 along the axial direction (longitudinal direction) of the sheath 110.

[0028] The sheath 110 has, for example, a tubular sheath main body 111 formed of a flexible material, and a hub 112 (operation part operated by the practitioner) provided on the proximal side of the sheath main body 111 (on the right side in Figures 3A and 3B) for fixing and releasing the inner rod 120 to and from the sheath main body 111.

[0029] The inner rod 120 has, for example, a rod-shaped rod main body portion 121, a holding portion 122 formed with a smaller diameter than the rod main body portion 121 and holding the colon stent 1 in a contracted state, and a tip chip 123 provided on the distal side of the inner rod 120.

[0030] Although not shown in the figures, the rod main body 121, the holding portion 122 and the distal tip 123 are provided with, for example, a guide wire lumen for passing a guide wire, a trigger wire lumen for passing a trigger wire for expanding the colon stent 1 in a contracted state at the affected area, and the like, which are formed along the axial direction of the inner rod 120. Furthermore, the rod body 121, the holding portion 122 and the distal tip 123 are formed from various materials having appropriate hardness and flexibility, such as resin or metal, but detailed description thereof will be omitted here.

[0031] The colonic stent 1 is attached to the holding portion 122 of the inner rod 120 and housed in the sheath 110 in a contracted state that allows it to expand in the radial direction. The colonic stent 1 is attached, for example, so that the unconstrained portion 12 is on the proximal side S2 (the hub 112 side). Specifically, when the colonic stent 1 is attached to the inner rod 120, it is brought into a contracted state by being folded in the radial direction while being extended in the axial direction, and then housed in the sheath 110. At this time, the first skeletal portion 21 and the second skeletal portion 22 are held in the contracted state by the first conversion means 31 and the second conversion means 32. One ends of the constraint members 31A, 32A and the holding members 31B, 32B are pulled out to the outside from openings (for example, the branch opening 112a in FIG. 3A) provided in the sheath 110.

[0032] 4A to 4D are diagrams showing changes in state during placement of the colonic stent 1. Note that in Fig. 4A to 4D, the colonic stent 1 is shown schematically, and the detailed configurations of the first converting means 31 and the second converting means 32 are not shown.

[0033] When placing the colonic stent 1 at the lesion site L (target placement site) of the colon C, the sheath 110 and inner rod 120 are inserted from the anal side along a guide wire (not shown) that has been previously introduced into the colon C, and the colonic stent 1 is positioned at the lesion site L (see Figure 4A).

[0034] Next, with the sheath 110 positioned, it is moved to the proximal side S2 (anal side), and the colonic stent 1 is released from the sheath 110 (see FIG. 4B). At this time, the first skeletal portion 21 and the second skeletal portion 22 of the colonic stent 1 are restrained by the first converting means 31 and the second converting means 32 and are maintained in a contracted state, while only the third skeletal portion 23 expands. Alternatively, the colonic stent 1 may be released from the sheath 110 by moving the inner rod 120 so as to push it toward the oral side while the position of the sheath 110 is fixed.

[0035] In conventional colonic stents, when the entire colonic stent expands upon release from the sheath, the positioning is determined by the expansion force of the colonic stent, making it difficult to adjust the placement position. Furthermore, once the colonic stent has expanded from the distal side S1 to the proximal side S2, the placement state can be confirmed endoscopically, making it difficult to adjust the placement position during placement. In contrast, in this embodiment, when the colonic stent 1 is released from the sheath 110, only the third skeletal portion 23 of the colonic stent 1 expands. Therefore, in the state shown in FIG. 4B , the placement position of the colonic stent 1 can be adjusted while endoscopically confirming the position of the proximal side S2, making it easier to place the colonic stent 1 in the appropriate position.

[0036] Next, the constraint by the first conversion means 31 is released, and the first skeleton portion 21 is released. For example, by pulling out the constraint member 31A or the holding member 31B, the constraint by the first conversion means 31 is released. As a result, only the first skeleton portion 21 transitions to the expanded state (see FIG. 4C). At this time, the second skeleton portion 22 is maintained in the contracted state by the second conversion means 32.

[0037] Next, the restraint by the second conversion means 32 is released, and the second skeletal portion 22 is released. For example, by withdrawing the restraining member 32A or the holding member 32B, the restraint by the second conversion means 32 is released. As a result, the second skeletal portion 22 also transitions to an expanded state, the colonic stent 1 enters a completely expanded state, and the colonic C is kept patent (see FIG. 4D). Thereafter, although not shown, the colonic stent 1 is disengaged from the inner rod 120, and the inner rod 120 is withdrawn, thereby placing the colonic stent 1 at the lesion site L.

[0038] 4A to 4D, the central portion (second skeletal portion 22) of the colonic stent 1 is expanded while the proximal side S2 (third skeletal portion 23) and distal side S1 (first skeletal portion 21) of the colonic stent 1 are fixed to the colon C, thereby preventing displacement due to shortening or jumping of the colonic stent 1. This allows the colonic stent 1 to be placed appropriately even in diseased areas (particularly near the rectum) where strict positional adjustment of the stent ends is required.

[0039] As described above, the colonic stent 1 according to this embodiment is a digestive tract stent to be placed in the large intestine C (digestive tract), and includes a cylindrical skeleton 20 that is expandable and contractable in a radial direction substantially perpendicular to the axial direction, and first conversion means 31 and second conversion means 32 (conversion means) that maintain the first skeleton portion 21 and the second skeleton portion 22 (parts of the axial direction of the skeleton) in a contracted state when the skeleton 20 is released from the sheath 120 and can convert the first skeleton portion 21 and the second skeleton portion 22 from the contracted state to an expanded state. The first skeleton portion 21 and the second skeleton portion 22 are provided at different axial positions of the skeleton 20, and the first conversion means 31 and the second conversion means 32 are provided corresponding to the first skeleton portion 21 and the second skeleton portion 22, respectively.

[0040] This allows the colon stent 1 to be partially expanded in the axial direction in various ways depending on the introduction direction and placement site of the stent placement system 100, and the colon stent 1 can be placed accurately at the target placement site in the colon C.

[0041] Furthermore, in the colonic stent 1, the skeleton 20 further has a third skeleton 23 (other portion) whose axial position is different from that of the first skeleton 21 and the second skeleton 22 (part), and after release from the sheath 110, the third skeleton 23 expands while the first skeleton 21 and the second skeleton 22 are contracted. This allows the placement position of the colonic stent 1 to be adjusted in a temporary placement state by expanding the third skeleton 23, and then the first skeleton 21 and the second skeleton 22 can be expanded to perform actual placement, so that the colonic stent 1 can be placed accurately at the target placement site in the colon C.

[0042] Furthermore, in the colonic stent 1, the first conversion means 31 and the second conversion means 32 (multiple conversion means) are configured to be independently operable. This allows the timing of expanding the first skeletal portion 21 and the second skeletal portion 22 to be flexibly controlled while checking the placement state, etc., and the colonic stent 1 can be placed in the appropriate position. Furthermore, a stable procedure can be achieved regardless of the practitioner's experience or skill.

[0043] Furthermore, in the colonic stent 1, the framework 20 is formed by weaving wires into a fence shape, which prevents the axial length of the colonic stent 1 from fluctuating significantly during placement, allowing the colonic stent 1 to be placed appropriately at the desired placement site.

[0044] The invention made by the inventor has been specifically described above based on an embodiment, but the present invention is not limited to the above embodiment and can be modified within the scope of the gist thereof.

[0045] For example, in the embodiment, a case has been described in which the third skeletal portion 23, which is the non-constrained portion 12, is expanded, and then the constrained portion 11 is expanded from the distal side S1 in the order of the first skeletal portion 21 and the second skeletal portion 22, but this is merely an example and is not intended to be limiting. For example, depending on the condition of the lesion site, the placement position in the large intestine C, etc., the constrained portion 11 may be expanded from the proximal side S2 in the order of the second skeletal portion 22 and the first skeletal portion 21, as shown in Figures 5A to 5D.

[0046] In addition, in the above embodiment, the first conversion means 31 and the second conversion means 32 are provided as independent units, but this is merely an example and is not limiting, and a common restraining member or a holding member may be used. For example, the first skeleton 21 and the second skeleton 22 may be released in a predetermined order according to the amount of movement or the mode of movement by adjusting the shape, length, etc. of the restraining member or the holding member. Furthermore, the number of conversion means is merely an example and is not limited to this, and for example, three or more conversion means may be provided.

[0047] In the embodiment, a bare stent with a flare on one side has been described as an example of the colonic stent 1, but this is merely an example and is not limiting, and any appropriate modifications are possible. The present invention can also be applied to, for example, a gastrointestinal stent with a flare on both sides or a straight type. The present invention can also be applied to a covered stent in which a coating is disposed entirely or partially around the circumferential surface of the framework.

[0048] Furthermore, the present invention is not limited to the colonic stent 1 described in the embodiment, but can also be applied to digestive tract stents placed in the digestive tract, such as the esophagus or large intestine, and further to stent grafts placed in blood vessels. In this case, the fluid flowing through the digestive tract may be in any state, 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 (for example, feces).

[0049] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims.

[0050] The disclosures of the specification, drawings and abstract contained in Japanese Patent Application No. 2020-040277, filed on March 9, 2020, are incorporated herein by reference in their entirety. [Explanation of symbols]

[0051] 1. Colon stent (gastrointestinal stent) 20 Skeleton 21 First skeleton (part) 22 Second skeleton part (part) 23 Third skeleton part (other parts) 31 First conversion means (conversion means) 32 Second conversion means (conversion means) C Large intestine (digestive tract)

Claims

1. A gastrointestinal stent to be placed in the gastrointestinal tract, a cylindrical skeleton that is expandable and contractable in a radial direction substantially perpendicular to the axial direction; a conversion means for maintaining a specific portion of the skeleton in an axial direction in a contracted state when the skeleton is released from the sheath, and for converting the specific portion from the contracted state to an expanded state; the specific portion includes a plurality of skeleton portions provided at different positions in the axial direction of the skeleton, a plurality of the conversion means are provided corresponding to the plurality of skeletal parts, and are configured to be operable independently of each other to maintain the contracted state of each skeletal part and to convert the contracted state into an expanded state; The plurality of conversion means are a string-like member that is used in common for the plurality of skeletal portions, that is wound around the outer circumferential surfaces of the plurality of skeletal portions, and that maintains the plurality of skeletal portions in a contracted state in the wound state; a plurality of retaining members that are engaged with corresponding portions of the restraining member at the plurality of skeletal portions, and that maintain the wound state of the restraining member in the engaged state; the plurality of holding members are thin metal wires extending along the axial direction on the outer circumferential surface, A gastrointestinal stent, wherein the plurality of retention members can be individually pulled out to individually release engagement with corresponding portions of the restraining member on each of the plurality of skeletal portions.

2. the winding of the restraint member on the outer circumferential surface is formed by repeatedly winding the restraint member in a forward direction and a reverse direction while forming a bent portion for each rotation, The gastrointestinal stent according to claim 1 , wherein the plurality of retention members engage with a plurality of bends formed by a portion of the corresponding restraining member on each of the plurality of framework portions.

3. 3. The digestive tract stent according to claim 1, wherein the framework is formed by weaving wires that extend spirally while being folded back in a zigzag pattern, such that one peak portion that is convex on one end side in the axial direction and another valley portion that is convex on the other end side in the axial direction are interlocked with each other.

4. The skeleton further includes another portion whose axial position is different from that of the specific portion, 2. The gastrointestinal stent according to claim 1, wherein the conversion means is not provided corresponding to the other portion, and the other portion expands independently of operation of the conversion means when the framework is released from the sheath.

5. The gastrointestinal stent according to claim 4 , wherein the other portion is a flared framework portion located proximal to the specific portion and expanding in diameter toward the proximal end.

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