JP6750255B2 - Stent - Google Patents

Description

The present invention relates to stents such as biodegradable stents.

BACKGROUND ART Conventionally, in a stenotic disease (tumor, inflammation, etc.) of a biological duct such as a blood vessel or a digestive tract, a treatment has been performed in which a stent is placed in the stenotic portion to expand the stenotic portion. Known stents include, for example, metal stents and biodegradable stents made of biodegradable synthetic resin fibers or the like. Among these, a metal stent requires a surgical operation when it is removed from the body, and thus a great burden is placed on the patient. Therefore, the use of the metal stent is limited when it is used for a case such as a malignant tumor for which semi-permanent placement or surgery is planned. From such a background, a biodegradable stent has been proposed as a stent to be used for a case where a metal stent cannot be used.

The biodegradable stent is formed into a cylindrical shape by knitting biodegradable fibers, and is decomposed in a blood vessel or a digestive tract with the passage of time. Therefore, it is not necessary to remove the stent from the body. Biodegradable stents are expected to reduce the burden on patients, especially when used for benign stenotic diseases.

By the way, in general, a stent pushes a narrowed portion by expanding the diameter after approaching the narrowed portion in a reduced diameter state. For example, a method of using an endoscope is known as a method of bringing a biodegradable stent close to a stenosis. In this method, a reduced-diameter stent is housed in a thin tubular member called a delivery system, and this delivery system is inserted from the forceps port into the endoscope to approach the stenosis.

As described above, the stent is expanded in diameter after being brought close to the narrowed portion in a reduced diameter state. On the other hand, the stent may be reduced in diameter by the pressure from the outside in the radial direction when the digestive tract or the like is restenosis when placed in the stenosis portion. In particular, biodegradable stents made of biodegradable fibers have lower strength than metal stents, and are sufficient to withstand clinical use against the pressure applied from the radial outside in the expanded state. It is difficult to obtain good tolerance.

With respect to such a problem, a technique is disclosed in which a reinforcing crosspiece extending in the axial direction is arranged in the cylindrical portion of the biodegradable stent to impart resistance to pressure from the radially outer side of the biodegradable stent. (For example, see Patent Document 1).

In addition, after the stent is placed in the stenosis portion of the body duct using an endoscope, the stent is required to maintain the stenosis portion in a patent state without moving from the placement position. In the case of a metal stent such as a self-expanding stent made of a shape memory alloy, the stent can dig into the affected area by the self-expanding force, and the displacement is unlikely to occur. On the other hand, a biodegradable stent made of a synthetic resin or the like has a weaker expansion force than a metal stent, and thus it can be said that a positional shift after placement is likely to occur.

JP, 2009-160079, A

Therefore, it is considered that the end effect of the stent is flared, that is, the diameter of the end of the stent is made larger than the diameter of the center of the stent to provide an anchor effect. However, since the biodegradable stent has weaker strength than the metal stent even if the end portion is flared, it is possible to maintain the shape when pressure is applied to the flared portion from the outside in the radial direction. It is difficult to make full use of the anchor effect.

It is also conceivable to thicken the fibers constituting the biodegradable stent in order to increase the resistance of the biodegradable stent to pressure from the outside in the radial direction. However, if the fibers constituting the biodegradable stent are made thick, it becomes difficult to store the stent in a thin tubular member such as a delivery system used when the stent is placed in a stenosis.

Therefore, it is an object of the present invention to provide a stent that can be stored in a thin tubular member such as a delivery system and is less likely to be displaced after the stent is placed in an affected area in a living body duct. ..

The present invention relates to a stent main body portion formed by braiding a fiber material into a cylindrical shape and capable of deforming from a reduced diameter state to an expanded diameter state, and connecting the stent main body portion and reducing the diameter of the stent main body portion. And a diameter-expanding mechanism for deforming the stent main body to an expanded diameter and maintaining the expanded diameter of the stent main body, wherein the stent main body is arranged at least in a central portion in the axial direction. A first pitch portion, and a second pitch portion that is arranged on one end side and/or the other end side of the first pitch portion and is braided more coarsely than the first pitch portion. Regarding

Further, the diameter-expanding mechanism is formed on the string-shaped member, one end of which is connected to one end side of the stent main body in the axial direction and which extends to the other end side of the stent main body in the axial direction. An engaging portion, and an annular portion which is formed in an annular shape on the other end side of the stent main body portion and through which the string-like member is inserted, and the string in a state where the stent main body portion has a reduced diameter. By pulling the ring-shaped member toward the other end side, the member is contracted in the axial direction and expanded in diameter, and the locking portion and the annular portion move in a direction in which the locking portion and the annular portion come close to each other, and It is preferable to engage with each other to maintain the diameter of the main stent body.

Further, the diameter expansion mechanism, an annular member attached to one end side in the axial direction of the stent main body portion, and one end is connected to the other end side in the axial direction of the stent main body portion and is inserted into the annular member, A string-shaped member whose other end extends to the other end of the stent main body, and a connection portion between the string-shaped member and the stent main body, or in the vicinity of the connection portion, which can lock the annular member. An engaging portion, and in a state where the diameter of the stent main body portion is reduced, by pulling the string-shaped member toward the other end side, the diameter is reduced by axially contracting, and the annular member and the It is preferable that the annular member and the engaging portion are engaged with each other while the engaging portion moves in a direction in which they approach each other, and the diameter of the stent main body portion is maintained.

Further, it is preferable that the second pitch portion is arranged at an end portion on the one end side in the axial direction of the stent main body portion.

Further, the diameter expansion mechanism further includes a restricting mechanism that restricts excessive shrinkage of the second pitch portion in the axial direction of the main stent body portion, and the restricting mechanism is provided on the string-shaped member. A regulating member and a second regulating member provided in the vicinity of a boundary between the first pitch portion and the second pitch portion in the main stent body, and the string-like member on the other end side. When pulled toward, it is preferable that the second restricting member interferes with the first restricting member and restricts excessive contraction of the second pitch portion in the axial direction.

According to the stent of the present invention, the storability in the thin tubular member is ensured, and the shape of the end portion of the stent has an anchoring effect, so that displacement after placement is unlikely to occur.

It is a perspective view of the stent which concerns on 1st Embodiment. It is a side view of the stent concerning a 1st embodiment. It is a perspective view of the stent concerning a 1st embodiment, and is a figure showing the state where the diameter of the stent was expanded. It is a side view of the stent concerning a 1st embodiment, and is a figure showing the state where the diameter of the stent was expanded. It is a schematic diagram for demonstrating the method of leaving the stent which concerns on 1st Embodiment in a stenosis part. It is a schematic diagram for demonstrating the method of leaving the stent which concerns on 1st Embodiment in a stenosis part. It is a schematic diagram for demonstrating the method of leaving the stent which concerns on 1st Embodiment in a stenosis part. It is a schematic diagram for demonstrating the method of leaving the stent which concerns on 1st Embodiment in a stenosis part. It is a schematic diagram for demonstrating the state which left the stent which concerns on the modification of 1st Embodiment in the stenosis part. It is a perspective view of the stent concerning a 2nd embodiment. It is a side view of the stent concerning a 2nd embodiment. It is a side view which shows the state which the stent which concerns on 2nd Embodiment expanded. It is a perspective view of the stent concerning a 3rd embodiment. It is a side view of the stent concerning a 3rd embodiment. It is a partially expanded view of FIG. 5B. It is a schematic diagram for demonstrating the method of indwelling the stent which concerns on 3rd Embodiment in a stenosis part, and is a figure which shows the state in which the diameter of the main stent part was reduced. FIG. 6B is a diagram showing a state in which the string-shaped member is pulled from the state shown in FIG. 6A to expand the diameter of the main stent body. It is a figure which shows the state which pulls a string-like member further from the state shown to FIG. 6B, and makes a locking part lock an annular member. It is a figure which shows the state which pulled the string-shaped member further from the state shown to FIG. 6C, and made the annular member lock the locking part.

Hereinafter, preferred embodiments of the stent of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1A is a perspective view of the stent 1 according to the first embodiment of the present invention, and FIG. 1B is a side view of the stent 1.
As shown in FIGS. 1A and 1B, the stent 1 includes a main stent body portion 2 and a diameter expansion mechanism 3.

The stent body 2 is formed of the fiber material 20 in a cylindrical shape. More specifically, the main stent body portion 2 is woven in a mesh shape with a plurality of fiber materials 20, and has a large number of diamond-shaped holes formed on the outer periphery of the fiber material 20 and arranged regularly.
The stent main body portion 2 has coarser stitches than at least the first pitch portion 21 arranged at the central portion in the axial direction and the first pitch portion 21 arranged at one end portion and/or the other end portion in the axial direction. A second pitch portion 22. In the present embodiment, the second pitch portion 22 is arranged on the end side in the X direction of the stent main body 2. The second pitch portion 22 may be arranged on the Y-direction end side of the stent main body 2, and the second pitch portion 22 may be arranged on the X-direction end side of the stent main body 2 and the Y direction. It may be arranged on the end side in the direction.

In this specification, the pitch is defined as follows. The pitch means the length in the axial direction when one fiber material 20 makes one round in the circumferential direction. That is, as shown in FIG. 1B, when an external force is not applied to the stent main body 2, the pitch L1 of the first pitch portion 21 where the stitches are relatively dense is relatively coarse. The pitch is smaller than the pitch L2 of the second pitch portion 22. When the diameter of the main stent body 2 is reduced, the pitches of both the first pitch portion 21 and the second pitch portion 22 increase, and when the diameter of the stent main body portion 2 increases, both pitches decrease.

Examples of the fiber material 20 include biodegradable fibers, and examples of the material include L-lactic acid, D-lactic acid, DL-lactic acid, ε-caprolactone, γ-butyrolactone, δ-valerolactone, glycolic acid, trimethylene carbonate. , Homopolymers and copolymers synthesized from monomers such as paradioxanone, and blend polymers thereof. In particular, it is preferable to use fibers made of poly-L-lactic acid (hereinafter sometimes referred to as PLLA), lactic acid-caprolactone copolymer (hereinafter sometimes referred to as P(LA/CL)), or a blend polymer thereof. preferable.

The fiber material 20 may be a monofilament yarn or a multifilament yarn. Further, the fiber material 20 may or may not be twisted. From the viewpoint of strengthening the repulsive force against the pressure applied from the outside of the stent main body 2 in the radial direction, the fiber material 20 is preferably a monofilament thread.

The fiber material 20 preferably has a diameter of 0.05 mm to 0.7 mm. If the diameter of the fiber material 20 is less than 0.05 mm, the strength of the stent 1 tends to decrease. If the diameter of the fiber material 20 exceeds 0.7 mm, it tends to be difficult to store the stent 1 in a thin tubular member such as a delivery system to be inserted into the endoscope described in detail later. The upper limit of the diameter of the fiber material 20 is more preferably 0.4 mm, and further preferably 0.3 mm, from the viewpoint of being housed in a delivery system having a smaller inner diameter. The lower limit of the diameter of the fiber material 20 is more preferably 0.2 mm from the viewpoint of maintaining high strength.

The diameter expansion mechanism 3 deforms the stent main body 2 from a reduced diameter to an expanded diameter and maintains the stent main body 2 in an expanded diameter. As shown in FIGS. 1A and 1B, the diameter expansion mechanism 3 includes a cord-shaped member 30, a locking portion 31, and an annular portion 32. Here, the state in which the diameter is expanded refers to a state in which the diameter is expanded to a desired diameter when the stent is placed in the body. Therefore, the state in which the diameter is reduced means a state in which the diameter is smaller than the desired diameter.

The string-shaped member 30 has one end connected to one end side (X direction) in the axial direction of the stent main body 2 and extends to the other end side (Y direction) in the axial direction of the stent main body 2. More specifically, the string-shaped member 30 is connected to the end of the stent body 2 on the side where the second pitch portion 22 is arranged (X direction), and is arranged inside the stent body 2. The string-shaped member 30 may be made of a biodegradable fiber similar to the fiber material 20, or may be made of a material that is not biodegradable.

The locking portion 31 is formed on the string-shaped member 30. The locking portion 31 is arranged inside the main stent body portion 2 as shown in FIGS. 1A and 1B.
The locking portion 31 is formed in a shape having a diameter larger than the diameter of the string-shaped member 30. The locking portion 31 may be a knot of the string-shaped member 30 or may be a triangular return member formed on the string-shaped member 30. Further, the locking portion 31 may be formed by forming a part of the string-shaped member 30 into a ring shape. The string-shaped member 30 and the locking portion 31 may be made of a biodegradable material, or may be made of a non-biodegradable material.
When the locking portion 31 is formed of a triangular return member, the locking portion 31 is preferably formed so as to project radially inward of the main stent body 2. This prevents the locking portion 31 from being caught in the mesh of the stent body 2.

The annular portion 32 is connected to the Y-direction side of the stent main body 2 and is formed in an annular shape so that the string-like member 30 is inserted therein. More specifically, the annular portion 32 is connected to the end of the main stent body 2 on the Y direction side so as to extend inward.

Next, an example of a method for manufacturing the stent 1 of this embodiment will be described.
First, a method for manufacturing the stent body 2 will be described.
As the fiber material 20, a poly-L-lactic acid monofilament yarn having a fiber diameter of 0.25 mm was prepared, and 16 fiber materials 20 were braided into a core rod having a constant diameter in the axial direction to form a stent body. A cylinder was prepared.
The center portion of the cylinder was braided at a relatively small pitch, and the ends were braided at a relatively large pitch. Braiding so that the pitch ratio at the time of braiding the cylinder, that is, the pitch ratio at the time of manufacturing the stent main body 2 is the pitch L1 of the first pitch portion: the pitch L2 of the second pitch portion = 1:3 did. The axial length of the second pitch portion may be a length sufficient to obtain the anchor effect when contracted and expanded in diameter, and the axial length of the second pitch portion becomes longer. It is possible to increase the compressive strength from the outside in the radial direction when expanding the diameter.

Since the core rod having a constant diameter in the axial direction is used in this manner, the diameter when expanding the diameter can be changed in the axial direction simply by changing the pitch when braiding. Alternatively, the cylinder may be manufactured by repeating braiding at a predetermined pitch, and then cut into a length corresponding to one main stent body.

After braiding, after removing the cylinder from the core rod, annealing treatment was performed at 50 to 80° C. for 30 to 60 minutes to obtain a stent body 2.

Incidentally, the cylinder after being removed from the core rod in a state where no external force is applied is slightly contracted in the axial direction and expanded in diameter as compared with before being removed. In this unloaded state, the second pitch portion 22 contracts more than the first pitch portion 21, so that the pitch ratio at the time of manufacturing and the pitch ratio after manufacturing are slightly different.

In the present invention, the pitch ratio L1:L2 at the time of manufacture (that is, the state where the first pitch portion 21 and the second pitch portion 22 have the same diameter) is preferably 1:1.1 to 1:7. , 1:2 to 1:4 are more preferable. When the pitch ratio L1:L2 is smaller than 1:1.1, it is difficult to obtain a sufficient anchor effect by the second pitch portion 22, and when the pitch ratio L1:L2 is larger than 1:7, the delivery system is formed. When the diameter of the main stent body portion 2 is reduced in order to store it in the above, the second pitch portion 22 becomes too long, which makes it difficult to expand and indwell the stent 1.

The size of the main stent body 2 is not particularly limited, but in the expanded state, for example, the diameter is 5 mm to 40 mm and the length is 30 mm to 250 mm.

The stent 1 is manufactured by attaching the string-shaped member 30 having the locking portion 31 and the annular portion 32 to the stent main body 2 manufactured as described above.

Next, the operation of the stent 1 will be described with reference to FIGS. 2A and 2B. FIG. 2A is a diagram (perspective view) showing a state where the diameter of the stent 1 is expanded, and FIG. 2B is a diagram (side view) showing a state where the diameter of the stent 1 is expanded.
By pulling the string-shaped member 30 in the Y direction, the stent body 2 is contracted in the axial direction and expanded in diameter as shown in FIGS. 2A and 2B.

The locking portion 31 of the diameter expansion mechanism 3 passes the annular portion 32 from the X direction side to the Y direction side by pulling the string-shaped member 30 toward the Y direction. The locking portion 31 that has passed through the annular portion 32 is locked by the annular portion 32 and cannot pass through the annular portion 32 from the Y direction side to the X direction side.
As described above, the diameter expansion mechanism 3 contracts the stent main body 2 in the axial direction to expand the diameter by pulling the string-like member 30 in the Y direction, and the locking portion 31 and the annular portion 32 come close to each other. By moving both in the direction and engaging with each other, it is possible to prevent the stent main body 2 from expanding from a diameter-expanded state, and maintain the stent main body 2 in an expanded diameter state.

The stent main body 2 is provided with coarse and dense stitches, that is, a first pitch portion 21 and a second pitch portion 22 having different pitches, so that the diameter is reduced by the diameter expansion mechanism 3 (see FIGS. 1A and 1B). Therefore, when the main stent body portion 2 is contracted in the axial direction and expanded in diameter (see FIGS. 2A and 2B), the first pitch portion 21 and the second pitch portion 22 are expanded to have different diameters.
Specifically, in the first pitch portion 21 and the second pitch portion 22, the second pitch portion 22 has a larger pitch before being contracted in the axial direction, but when contracted in the axial direction, both The pitch becomes almost equal. As a result, the diameter of the second pitch portion 22 after the diameter expansion is larger than the diameter of the first pitch portion 21 after the diameter expansion, and as shown in FIGS. 2A and 2B, in the diameter expanded state. The end portion (second pitch portion 22) has a dumbbell shape having an anchor effect.

In addition, in the present embodiment, one end of the string-shaped member 30 is attached to the end portion (X direction side) of the second pitch portion 22 in the main stent body 2. Therefore, when the stent 1 is placed in the body, the second pitch portion 22 having the anchor effect is arranged on the distal end side (X direction side) of the delivery system, and on the proximal end side (Y direction side) of the delivery system. By pulling the extending string-shaped member 30, the diameter of the main stent body 2 can be expanded and the stent 1 can be left indwelling, so that the operability can be improved.

Next, a method of indwelling the stent 1 in a stenosis such as in the digestive tract of a patient using the delivery system including the endoscope 100 and the thin tubular member 110 will be described. 3A to 3D are schematic views for explaining a method of placing the biodegradable stent 1 in a stenosis. In FIGS. 3A to 3D, two string-shaped members 30, locking portions 31, and annular portions 32 are arranged at equal intervals in the circumferential direction of the stent main body 2.

As shown in FIG. 3A, the stent 1 is housed in a thin tubular member 110. In this state, the distal end portion of the endoscope 100 is brought close to the narrowed portion N. The thin tubular member 110 accommodating the stent 1 is inserted into a forceps port (not shown) of the endoscope 100, and carries the stent 1 to the distal end portion of the endoscope 100.

Subsequently, as shown in FIG. 3B, the stent 1 is extruded from the thin tubular member 110 and placed at a position surrounded by the narrowed portion N. The stent body 2 of the biodegradable stent 1 discharged from the thin tubular member 110 slightly expands in diameter.

Subsequently, as shown in FIG. 3C, the cord body 30 is pulled in the Y direction, whereby the diameter of the main stent body portion 2 is further expanded, and the narrowed portion N is expanded. Then, at this time, the locking portion 31 passes through the annular portion 32.

Finally, as shown in FIG. 3D, the thin tubular member 110 and the endoscope 100 are taken out of the patient's body, and the biodegradable stent 1 is placed in the stenosis N. At this time, the length of the string-shaped member 30 can be adjusted by cutting the string-shaped member 30 with scissors as needed.
In this way, the locking portion 31 is locked to the annular portion 32, and the diameter of the main stent body portion 2 is maintained. Therefore, the narrowed portion N is maintained in the expanded state by the diameter-enlarged first pitch portion 21 forming the central portion of the main stent body 2. Further, the diameter-enlarged second pitch portion 22 forming the end portion of the main stent body portion 2 is maintained in a state of having a larger diameter than the first pitch portion 21.

The stent 1 according to the first embodiment has the following effects.
(1) In the first embodiment, in the stent 1, the stent body portion 2 formed by braiding the fiber material 20 into a cylindrical shape and the stent body portion 2 are expanded from a contracted state to a desired diameter. The diametrical expansion mechanism 3 that deforms and maintains the state is provided.
As a result, even if pressure is applied from the outside in the radial direction in the expanded state of the stent main body 2, the stitches that form the stent main body 2 become dense and the strength increases and it is difficult for the diameter to decrease. Therefore, even if the diameter of the fiber material 20 is made thin or the biodegradable fiber having weak strength is used, the stent 1 is resistant to the pressure applied from the outside in the radial direction in the expanded state. Have.

(2) In the first embodiment, the stent main body 2 having the portions (the first pitch portion 21 and the second pitch portion 22) in which the density of the stitches is different in the axial direction is made to have a desired diameter by the diameter expansion mechanism 3. The diameter expansion mechanism 3 is provided to deform and maintain the expanded diameter.
Thereby, only by varying the density of the stitches in the axial direction of the stent main body 2, the stent main body 2 can obtain a portion having a different diameter in the axial direction after the diameter expansion.

(3) In the first embodiment, the main stent body portion 2 has the first pitch portion 21 in which the stitches are relatively dense in the central portion in the axial direction and the coarse stitches in the end portions in the axial direction. It has a certain second pitch portion 22, and is expanded and maintained to a desired diameter by the diameter expansion mechanism 3.
As a result, in the expanded diameter state, the main stent body portion 2 is maintained in a state in which the diameter of the end portion is larger than the diameter of the central portion arranged in the narrowed portion N. Therefore, there is a possibility that the stent 1 may deviate from the indwelling position by the end portion (second pitch portion 22) of the stent 1 being caught by the narrowed portion after the stent 1 is placed in the narrowed portion such as the digestive tract. It can be reduced (see FIG. 3D).

(4) In the first embodiment, the diameter-expanding mechanism 3 is formed on the string-shaped member 30 and the string-shaped member 30 having one end connected to the axial direction X of the stent body 2 and extending in the Y-direction. The stopper portion 31 and the annular portion 32 which is formed in an annular shape on the other end side of the main stent body portion 2 and through which the string member 30 is inserted are configured.
As a result, the stent main body 2 is expanded in diameter only by pulling the string-shaped member 30 in the Y direction, and the locking portion 31 and the annular portion 32 are engaged with each other, so that the stent main body 2 is expanded in diameter. Can be maintained. Therefore, it is possible to easily expand the diameter of the stent 1 (stent main body portion 2) that has approached the narrowed portion N, and improve the operability.

(5) In the first embodiment, the main stent body 2 is provided with the second pitch portion 22 at the end in the X direction of the axial direction.
Accordingly, when the stent 1 is placed, the second pitch portion 22 (dumbbell-shaped portion) can be arranged on the distal end side of the delivery system, so that the operability when the diameter is increased and the stent 1 is placed is good.

(6) In the first embodiment, as a method for manufacturing the main stent body 2, a fiber material 20 is prepared, and a core rod having a constant diameter in the axial direction is used, and the central portion is braided at a relatively small pitch. Then, the end portions were braided at a relatively large pitch to obtain a cylinder to be the main stent body 2.
Since the core rod having a constant diameter in the axial direction is used in this manner, the diameter when expanding the diameter can be changed in the axial direction simply by changing the pitch when braiding. In addition, since it is possible to fabricate a cylinder by repeating braiding at a predetermined pitch, and then to fabricate the cylinder by cutting it into a length corresponding to one stent main body portion 2, the production efficiency is good.

<Modification of First Embodiment>
A modified example of the first embodiment will be described with reference to FIG. 3E. About the same structure as 1st Embodiment, in FIG. 3E, the same code|symbol as the stent 1 is attached|subjected and description is abbreviate|omitted.

The stent 1A shown in FIG. 3E is different from the first embodiment in that the diameter of both ends is larger than the diameter of the central part in the expanded state.
In the state where the diameter of the stent main body 2A is not expanded, the first pitch portion 21A having relatively dense stitches in the central portion in the axial direction and the coarse stitches relatively in both end portions in the axial direction. Second pitch portions 22a, 22b.

The diameter expansion mechanism 3A deforms the stent main body 2A from a reduced diameter to an expanded diameter, and maintains the stent main body 2A in an expanded diameter. The diameter expansion mechanism 3 has a string-shaped member 30A, a locking portion 31A, and an annular portion 32A.

One end of the string-shaped member 30A is connected to one end side (X direction) of the stent main body 2 in the axial direction and extends to the other end side (Y direction) of the stent main body 2 in the axial direction. More specifically, the string-shaped member 30 is connected to the end of the second main body 2 in the X direction of the second pitch portion 22 a and is arranged inside the main stent body 2.

The locking portion 31A is formed on the cord-shaped member 30A and has a shape having a diameter larger than the diameter of the cord-shaped member 30A.

The annular portion 32A is connected to the end of the second pitch portion 22b on the Y direction side of the stent body 2 and is formed in an annular shape, and the string-shaped member 30A is inserted therethrough.

The stent main body 2A is expanded and contracted in the axial direction as shown in FIG. 3E by pulling the string-shaped member 30A toward the Y direction side by the diameter expansion mechanism 3A, and the diameter of both ends is the central part. A dumbbell shape having an anchor effect is formed at both ends of the dumbbell shape.

According to the stent 1A of the modified example of the first embodiment, the following effects are exhibited in addition to the above effects (1) to (6).
(7) In the modified example of the first embodiment, the stent main body portion 2A has the first pitch portion 21A in which the stitches are relatively dense in the central portion in the axial direction and the stitches in the both end portions in the axial direction relatively. The second pitch portions 22a and 22b, which are rough, are provided.
As a result, in the expanded diameter state of the stent main body 2A, the diameter of both end portions is maintained larger than the diameter of the central portion arranged in the narrowed portion N, and dumbbell shapes are formed at both end portions. .. Therefore, after the stent 1A is left in a narrowed portion such as a digestive tract, both ends (second pitch portions 22a and 22b) of the stent 1A are caught in the narrowed portion N, so that the diameter of only one end is the central portion. It is possible to further reduce the possibility that the stent 1A will deviate from the indwelling position or be displaced from its position, as compared with the case where the diameter is larger than the diameter.

<Second Embodiment>
FIG. 4A is a perspective view of a stent 1B according to the second embodiment of the present invention. About the same structure as the stent 1 among the stents 1B, the same code|symbol as the stent 1 is attached in FIG. 4A, and description is abbreviate|omitted.

In the present embodiment, the stent 1B is similar to the first embodiment in that the stent main body 2 and the diameter expansion mechanism 3B are provided, but the first embodiment is that the diameter expansion mechanism 3B further includes the restriction mechanism 4. Different from

In the main stent body 2, the second pitch portion 22 is softer than the first pitch portion 21 because the stitches are coarse (the pitch is large). Therefore, the second pitch portion 22 may be excessively contracted in the axial direction when the diameter is expanded by the diameter expansion mechanism 3.

The restricting mechanism 4 restricts the excessive contraction of the second pitch portion 22 in the stent main body 2 in the axial direction when the main stent body 2 is contracted in the axial direction and expanded in diameter. The regulation mechanism 4 includes a second locking portion 41 as a first regulation member and a second annular portion 42 as a second regulation member.

The second locking portion 41 is formed at a predetermined position on the string-shaped member 30. Here, in the string-shaped member 30, the distance between the second locking portion 41 and the end portion connected to the second pitch portion 22 is an optimum width when the second pitch portion 22 is contracted in the axial direction. Can be set to.
The second locking portion 41 may be a knot of the string-shaped member 30 as long as it cannot pass through the second annular portion 42, or is a triangular return member formed on the string-shaped member 30. It may be. Further, the second locking portion 41 may be formed by forming a part of the string-shaped member 30 into a ring shape. The second locking portion 41 may be made of a biodegradable material, or may be made of a non-biodegradable material.

The second annular portion 42 is connected to the stent main body 2 and is formed in an annular shape so that the string-like member 30 is inserted therein. More specifically, the second annular portion 42 is arranged at the boundary between the first pitch portion 21 and the second pitch portion 22 or in the vicinity of the boundary in the stent main body 2, and extends inside the stent main body 2. Connected.

The operation of the stent 1B will be described with reference to FIGS. 4A and 4B. FIG. 4A is a perspective view of the stent 1B, and FIG. 4B is a side view of the stent 1B.
By pulling the string-shaped member 30 toward the Y direction side, the stent main body 2 is contracted in the axial direction and expanded in diameter as shown in FIG. 4C.

More specifically, when the string-shaped member 30 is pulled toward the Y direction side, the second annular portion 42 interferes with the movement of the second locking portion 41 in the Y direction, and the second pitch portion 22 moves. Controls excessive axial shrinkage. That is, since the second locking portion 41 cannot pass through the second annular portion 42 from the X direction side to the Y direction side, the second pitch portion 22 is more than necessary when operating the diameter expansion mechanism 3B. The contraction in the axial direction can be restricted.
From this state, by further pulling the string-shaped member 30 toward the Y direction side, from the position where the second annular portion 42 and the second locking portion 41 are engaged in the regulation mechanism 4, the first pitch portion 21 Contracts in the axial direction and expands in diameter. The locking portion 31 that has passed through the annular portion 32 is locked by the annular portion 32 and cannot pass through the annular portion 32 from the Y direction side to the X direction side.

As described above, in the diameter expansion mechanism 3B including the restriction mechanism 4, the second pitch portion 22 of the stent main body portion 2 is axially moved only by a desired width by pulling the string-shaped member 30 toward the Y direction side. The first pitch portion 21 contracts in the axial direction and expands and maintains the diameter.

According to the stent 1B of the second embodiment described above, the following effects are exhibited in addition to the above effects (1) to (6).
(8) In the second embodiment, the diameter expansion mechanism 3B includes the first restricting member (second locking portion 41) formed on the string-shaped member 30, the first pitch portion 21, and the second pitch portion. The restriction mechanism 4 having a second restriction member (second annular portion 42) formed at or near the boundary with the boundary 22 is further provided.
Thereby, when the diameter expansion mechanism 3B is operated, it is possible to regulate the excessive contraction in the axial direction of the second pitch portion 22 in the main stent body 2, and the shape having the desired strength in the axial direction and the anchor effect. It can be set as the stent 1B.

<Third Embodiment>
FIG. 5A is a perspective view of a stent 1C according to the third embodiment of the present invention. The same configurations as the stent 1 of the stent 1C are denoted by the same reference numerals as those of the stent 1 in FIG. 5A, and description thereof will be omitted. The stent 1C of the third embodiment differs from that of the first embodiment mainly in that the main stent body 2C includes an extension portion 23 and in the configuration of the diameter expansion mechanism 3C.

In the present embodiment, the stent main body portion 2C has the first pitch portion 21 having relatively dense stitches arranged in the central portion in the axial direction and the relatively stitches arranged in one end portion in the axial direction. The second pitch portion 22 that is sparse and the extension portion 23 arranged at the other end portion in the axial direction are provided.

The extending portion 23 is formed by extending a plurality of fiber materials 20 from the other end side of the first pitch portion 21 toward the outer side in the axial direction of the first pitch portion 21. Specifically, the extending portion 23 is configured such that the other end sides of the plurality of fiber materials 20 forming the first pitch portion 21 extend to the axially outer side of the stent main body portion 2C while being slightly separated from the axis. It is formed.

The tip of the extending portion 23 is formed in a loop shape by connecting the ends of the two fiber materials 20. More specifically, the loop-shaped tip portion is formed by the curved portion of the fiber material 20 at one end of the stent 1C. The “two fiber materials 20 ”here means two fiber materials 20 when only the extending portion 23 is focused, and in the present embodiment, “two fiber materials 20 ”is 1 It is derived from the fiber material 20 of the book.
In the present embodiment, the extension part 23 includes a first extension part 231 having a short extension length, and a second extension part 232 having an extension length longer than the first extension part 231. .. And the 1st extension part 231 and the 2nd extension part 232 are arranged by turns at predetermined intervals, and are arranged by turns, respectively. Further, in the present embodiment, the extending portion 23 is arranged only on the one end side of the first pitch portion 21.

The number of the fiber materials 20 forming the main stent body portion 2C is 16 in this embodiment, but is not particularly limited. The number of fiber materials 20 is preferably 16 to 24. The size of the main stent body 2C is not particularly limited, but for example, in the expanded state, the diameter is 5 to 40 mm and the length is 30 to 250 mm.
The extension length of the first extension portion 231 is preferably 2 mm to 7 mm, and the extension length of the second extension portion 232 is preferably 7 mm to 30 mm.

The diameter expansion mechanism 3C deforms the stent main body 2C from the diameter-reduced state to the diameter-expanded state, and maintains the diameter of the stent body 2C. As shown in FIG. 5C, the diameter expansion mechanism 3C includes an annular member 32C, a cord-shaped member 30C, and a locking portion 31C.

The annular member 32C is attached to one end side (X direction side) of the main stent body 2C. More specifically, the annular member 32C is attached to the end portion of the second pitch portion 22 on the X direction side where the extending portion 23 is not arranged in the main stent body portion 2C. The annular member 32C is made of synthetic resin fiber or biodegradable fiber, and is formed in an annular shape by connecting both ends of the synthetic resin fiber or biodegradable fiber to the fibers constituting the main stent body 2C. The mounting position of the annular member 32C to the main stent body 2C is preferably a position close to the tip of the main stent body 2C from the viewpoint of appropriately expanding the diameter of the main stent body 2C.

The string-shaped member 30C has one end connected to the other end side (Y direction side) of the stent main body 2C and is inserted through the annular member 32C, and the other end side extends to the other side (Y direction side) of the stent main body 2C. ..
More specifically, in the present embodiment, one end of the string-shaped member 30C is tied and connected to the tip end portion of the first extending portion 231 as shown in FIG. 5C. Then, the cord-shaped member 30C passes through the outside of the stent main body 2C from the connecting portion with the first extending portion 231 and, in the vicinity of the first extending portion 231, passes through the mesh of the stent main body 2C and the stent main body. It enters the inside of the portion 2C (see the portion A in FIG. 5C).

Next, the string-shaped member 30C extends inside the stent main body 2C toward the X direction side, is inserted into the annular member 32C, and is then folded back (see portion B in FIG. 5C). Next, the string-shaped member 30C extends inside the stent main body 2C toward the Y direction side of the main stent body 2C, and in the vicinity of the first extending portion 231, the mesh of the main stent body 2C (the aforementioned main stent body 2C). 2C to the outside of the main stent body portion 2C through the same mesh as the mesh that entered from the outside to the inside of 2C (see C part in FIG. 5C). The other end of the string-shaped member 30C extends in the Y direction of the main stent body 2C.

That is, in the present embodiment, the cord-like member 30C is a portion that extends inside the stent main body 2C on the side of the annular member 32C and a portion that inserts the stent main body 2C in the vicinity of the connecting portion with the first extending portion 231. And a portion extending outside the stent main body portion 2C on the first extending portion 231 side with respect to the portion through which the stent main body portion 2C is inserted. Further, one end of the string-shaped member 30C is tied to the first extending portion 231, so that the first extending portion 231 is movably connected.

31 C of locking parts are arrange|positioned in the vicinity of the connection part of 30 C of string-shaped members, and 2 C of main stent parts. The locking portion 31C is configured to lock the annular member 32C by operating the string-shaped member 30C described later. In the present embodiment, the locking portion 31C is configured by the first extending portion 231 in which the fiber material 20 forming the main stent body portion 2C is formed in a loop shape. In addition, the string-shaped member 30C is tied and connected to the tip portion of the locking portion 31C (first extending portion 231).

In addition, the base end portion of the first extending portion 231 (locking portion 31C) to which the string-shaped member 30C is connected is such that one end of the linked string-shaped member 30C does not move to the side of the main stent body 2C. It is preferable to fix the intersecting portion of the fiber material 20.

A plurality of the diameter expansion mechanisms 3C described above are arranged at equal intervals in the circumferential direction of the main stent body 2C. In this embodiment, as shown in FIG. 5A, two diameter expansion mechanisms 3C are arranged.

According to the above-described diameter expansion mechanism 3C, the annular member 32C and the locking portion 31C are brought close to each other by pulling the string-like member 30C toward the Y direction side of the stent body 2C in the state where the diameter of the stent body 2C is reduced. The annular member 32C and the locking portion 31C are engaged with each other and the diameter of the main stent body portion 2C is maintained in an expanded state.

Next, the operation of the diameter expansion mechanism 3C will be described with reference to FIGS. 6A to 6D. 6A to 6D, the operation of the stent 1C will be described by omitting the delivery system.

First, the stent 1C is inserted into a forceps port (not shown) of an endoscope while being housed in a thin tubular member (not shown) such as a delivery system, and is carried to the distal end portion of the endoscope. .. In the present embodiment, the stent 1C is housed in the delivery system so that the side (X direction) on which the annular member 32C is arranged faces the tip.

Next, as shown in FIG. 6A, the distal end side (X direction) of the stent 1C is extruded from the thin tubular member and placed at a position surrounded by the narrowed portion N. The stent main body 2C of the stent 1C discharged from the thin tubular member expands to some extent. Although not shown, in this state, the other end side (Y direction side) of the stent 1 is maintained inside the thin tubular member, whereby the other end of the stent 1C is maintained. The sides are supported by the delivery system.

Next, as shown in FIG. 6B, the other end side of the cord-shaped member 30C (the side opposite to the one end connected to the locking portion 31C) is pulled to the proximal end side (Y direction side) of the main stent body portion 2C. Then, the annular member 32C, through which the string-shaped member 30C is inserted, is pulled toward the proximal end side of the stent main body 2C by the string-shaped member 30C and moved to the locking part 31C side, whereby the stent main body 2C expands. It is arranged in the narrowed portion N in a state where the diameter is increased and the diameter is expanded. As a result, the narrowed portion N is prevented from being restenosis at the central portion (first pitch portion 21) of the main stent body portion 2C, and the end portion (second pitch portion 22) has a dumbbell shape, which provides an anchor effect. This prevents the positional deviation and deviation from the narrowed portion N.

Further, as shown in FIG. 6C, the cord-shaped member 30C passes through the outside of the stent main body 2C from the connection portion with the locking portion 31C (first extending portion 231), and in the vicinity of the locking portion 31C, It enters the inside of the main stent body 2C through the mesh of the main stent body 2C and extends inside the main stent body 2C toward the distal end side (Y direction side). Then, after being inserted into the annular member 32C, it is folded back and extends inside the stent main body 2C toward the base end side (X direction side) of the stent main body 2C, and the string-like member 30C enters from the outside. It goes out of the main stent body 2C through the same mesh as the mesh. As a result, as shown in FIG. 6B, the annular member 32C pulled by the string-shaped member 30C comes out from the inside of the main stent body 2C through the mesh in the vicinity of the locking portion 31C.

Next, when the locking portion 31C is further pulled toward the proximal end side (Y direction) of the main stent body portion 2C, as shown in FIG. 6C, the annular member 32C causes the locking portion 31C formed in a loop shape to move from the outside to the inside. Get over. The annular member 32C that has passed over the locking portion 31C is pulled toward the distal end side (X direction) by the restoring force (the force that tries to extend in the axial direction) of the main stent body portion 2C and locked by the locking portion 31C. As a result, the stent main body 2C is held in the narrowed portion N while maintaining the expanded diameter state. Then, the cord-shaped member 30C is cut at a predetermined position, and the delivery system is taken out of the body.

According to the stent 1C of the third embodiment described above, the following effects are exhibited in addition to the above effects (1) to (3) and (6).
(9) In the third embodiment, the diameter expansion mechanism 3C includes an annular member 32C attached to one end side (X direction) in the axial direction of the stent body 2C and the other end side (Y) in the axial direction of the stent body 2C. Direction), one end is connected and is inserted into the annular member 32C, and the other end side is a string-like member 30C extending to the other side of the stent main body 2C, and a connecting portion or a connecting portion between the string-like member 30C and the stent main body 2C. And a locking portion 31C that can be locked in the annular member 32C.
Thereby, only by pulling the string-shaped member 30C in the Y direction, the annular member 32C and the locking portion 31C move in a direction in which they approach each other, and the diameter of the stent main body portion 2C is expanded, so that the locking portion 31C and the annular member 32C. By engaging with each other, it is possible to maintain the diameter of the main stent body portion 2C. Therefore, it is possible to easily expand the diameter of the stent 1C (stent main body portion 2C) that has approached the narrowed portion, and improve the operability.

The preferred embodiment of the stent of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and can be appropriately modified.
For example, in the third embodiment, the expanding mechanism is not provided with the restricting mechanism, but like the second embodiment, the first restricting member provided on the annular member 32C of the expanding mechanism and the main stent body 2C are provided. It may be configured to include a regulation mechanism having a second regulation member provided in the.

Further, in the first to third embodiments, a biodegradable stent made of biodegradable fibers is used as the stent, but the present invention is not limited to this. That is, the stent may be formed by using synthetic resin fibers that do not have biodegradability, and can also be applied to a metal stent that is not a shape memory alloy, that is, has no self-expanding ability. is there.

The shape of the end of the main stent body 2 is not particularly limited as long as it has an anchor effect, and may be a dumbbell shape or a flare shape. Further, the second pitch portion need not have a constant pitch, and may have a gradient such as gradually increasing the pitch.

Further, in the first to third embodiments, one end or both ends of the stent main body 2 are configured by the second pitch portion 22, but the present invention is not limited to this. That is, the end portion of the second pitch portion 22 (the end portion on the side opposite to the first pitch portion 21) in the first to third embodiments is knitted more densely than the second pitch portion 22 again. You may arrange|position the assembled part (For example, the part of the same pitch as a 1st pitch part). As a result, a portion having a smaller diameter than the second pitch portion (that is, a rounded portion) can be formed at the end portion of the stent, so that when the stent is placed in the body, the end portion of the stent is less likely to damage the placed portion. it can.

1, 1A, 1B, 1C Stent 2, 2A, 2C Stent body 21 First pitch part 22 Second pitch part 3, 3A, 3B, 3C Expanding mechanism 31, 31A Locking part 31C Locking part 32, 32A annular part 32C annular member 4 restriction mechanism 41 1st restriction member (2nd locking part)
42 Second regulating member (second annular portion)

Claims (5)

A stent body that is formed by braiding in a cylindrical shape with a fiber material and is deformable from a reduced diameter state to an expanded diameter state,
A stent comprising a diameter expansion mechanism connected to the stent body and deforming the stent body from a reduced diameter state to an enlarged diameter state and maintaining the stent body portion in an expanded diameter state,
The stent body portion has a first pitch portion which is disposed in a central portion of at least the axial direction, and a second pitch portion that will be placed at one end and / or the other end of the pitch the first portion, the Prepare ,
In a state where the diameter of the stent main body is reduced, the second pitch portion has coarser stitches than the first pitch portion,
The second pitch portion has a diameter larger than that of the first pitch portion in a state where the stent main body portion is contracted in the axial direction and expanded in diameter . The diameter expansion mechanism is
One end is connected to one end side in the axial direction of the stent main body, and a string-like member extending to the other end side in the axial direction of the stent main body,
A locking portion formed on the string-shaped member,
An annular portion formed in an annular shape on the other end side of the stent main body portion and through which the string-shaped member is inserted,
In a state where the diameter of the stent main body is reduced, the cord-shaped member is contracted in the axial direction to be expanded in diameter by pulling it toward the other end side, and the locking portion and the annular portion are close to each other. The stent according to claim 1, wherein the stent is moved, and the locking portion and the annular portion are engaged with each other to maintain the diameter of the main stent body portion. A stent body that is formed by braiding in a cylindrical shape with a fiber material and is deformable from a reduced diameter state to an expanded diameter state,
A stent comprising a diameter expansion mechanism connected to the stent body and deforming the stent body from a reduced diameter state to an enlarged diameter state and maintaining the stent body portion in an expanded diameter state,
The stent main body is provided with a first pitch portion arranged at least at a central portion in the axial direction and a first pitch portion which is arranged on one end side and/or the other end side of the first pitch portion and is rougher than the first pitch portion. And a second pitch portion braided on,
The diameter expansion mechanism is
An annular member attached to one end side of the stent main body in the axial direction,
A string-shaped member having one end connected to the other end side in the axial direction of the stent main body part and being inserted into the annular member, and the other end side extending to the other end side of the stent main body part,
A connecting portion between the string-shaped member and the stent main body or a connecting portion arranged near the connecting portion and capable of locking the annular member,
In a state where the diameter of the stent main body is reduced, the cord-shaped member is contracted in the axial direction to be expanded in diameter by pulling toward the other end side, and the annular member and the locking portion are close to each other. engage and the ring shaped member and the engaging portion together with the movement, absence tent to maintain the state of being expanded the stent body portion. The stent according to claim 2 or 3, wherein the second pitch portion is arranged at an end portion on the one end side in the axial direction of the stent main body portion. The diameter expansion mechanism further includes a restriction mechanism that restricts excessive contraction in the axial direction of the second pitch portion of the stent body.
The regulation mechanism is
A first restriction member provided on the string-shaped member;
A second restricting member provided in the vicinity of a boundary between the first pitch portion and the second pitch portion in the stent main body,
When the said string-shaped member is pulled toward the said other end side, the said 2nd control member interferes with the said 1st control member, and controls the excessive contraction of the said 2nd pitch part of an axial direction. Item 4. The stent according to any one of Items 2 to 4.

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