JP2026009330A - stents - Google Patents

Abstract

A stent is provided that has high conformability to the body lumen at the end portions of the stent and can be appropriately placed even in a body lumen with a complex shape.
[Solution] The duodenal stent (1) is a cylindrical stent to be placed in the duodenum (D) (biological lumen), and is formed to be expandable and contractable in a radial direction substantially perpendicular to the axial direction (AX), and a portion distal to the central portion in the axial direction (AX) has a first circumferential surface portion (20A) formed so that at least one portion can be displaced relative to the other portions in at least one of the axial, radial, and circumferential directions. The first circumferential surface portion has a plurality of skeletal portions spaced apart in the circumferential direction, and the circumferential lengths of the plurality of skeletal portions increase toward the distal end, opposite the second circumferential surface portion.
[Selected Figure] Figure 1

Description

The present invention relates to a stent.

Stents are known that are placed in narrowed or obstructed areas in biological lumens, such as blood vessels, the esophagus, the bile duct, the trachea, and the ureter, to expand the diameter of the affected area and maintain the patency of the biological lumen (see, for example, Patent Document 1).

Patent No. 4651943

However, when a biological lumen has a complex shape, such as being curved or flattened or having protrusions, stress is likely to be placed on the biological lumen during stent placement. While the flexibility of the biological lumen corrects the lumen shape and reduces stress to some extent, localized stress concentration can potentially damage the biological lumen. In particular, stents that are formed in a straight cylindrical shape along their entire length, such as the stent disclosed in Patent Document 1, have difficulty conforming to a curved biological lumen. Because axial force (straightening force) strongly presses a portion of the circumferential surface at the ends of the stent against the lumen wall, the risk of perforation increases during long-term placement. Furthermore, if the ends of the stent are expanded in diameter to prevent deviation due to pulsatile flow or lumen movement, for example, the expansion force is greater than when the entire stent is formed in a straight cylindrical shape, and the load on the biological lumen is also greater.

The object of the present invention is to provide a stent that has high conformability to the biological lumen at the end portion of the stent and can be appropriately placed even in biological lumens with complex shapes.

The stent according to the present invention comprises:
A cylindrical stent to be placed in a biological lumen,
a cylindrical first stent portion that is expandable and contractable in a radial direction substantially perpendicular to the axial direction;
a second stent portion that is different from the first stent portion in at least one of the shape and the radial expansion force,
each of the first stent section and the second stent section is formed by weaving a wire rod that extends spirally while being folded back in a zigzag shape into a diamond-shaped wire mesh shape such that a convex peak portion on one end side in the axial direction and a convex valley portion on the other end side in the axial direction intermesh with each other;
the second stent section has a first circumferential surface section that is disposed distally of a central section in the axial direction and is formed so as not to be continuous in the circumferential direction, a second circumferential surface section that is provided closer to the first stent section than the first circumferential surface section and is formed so as to be connected in the circumferential direction, and a movable section that is formed by the first circumferential surface section and at least one portion of which is formed so as to be displaceable relative to the other portions in at least one direction among the axial direction, the radial direction, and the circumferential direction,
The first circumferential surface portion has a plurality of skeletal portions arranged circumferentially apart, and the circumferential length of the plurality of skeletal portions increases toward the tip side, which is opposite the second circumferential surface portion.

The present invention improves the ability of the end portion of the stent to conform to the biological lumen, allowing the stent to be placed appropriately even in biological lumens with complex shapes.

FIG. 1 is a diagram showing the appearance of a duodenal stent according to a first embodiment. FIG. 2 is a diagram showing an example of an indwelling mode of the duodenal stent according to the first embodiment. FIG. 3 is a schematic diagram of the second stent portion of the duodenal stent according to the first embodiment. FIG. 4 is a schematic diagram showing a modified example of the second stent section. FIG. 5 is a diagram showing the appearance of a duodenal stent according to the second embodiment. FIG. 6 is a diagram showing an example of an indwelling mode of the duodenal stent according to the second embodiment. 7A and 7B are schematic diagrams showing an example of a constricted portion in a duodenal stent according to the second embodiment.

Embodiments of the present invention will be described in detail below with reference to the drawings. In this embodiment, as an example of the present invention, duodenal stents 1 and 2 will be described that are placed in the duodenum D to treat obstruction (stenosis) by radially expanding a lesion in the duodenum D outward.

[First embodiment]
Fig. 1 is a diagram showing the appearance of a duodenal stent 1 according to a first embodiment. Fig. 2 is a diagram showing the deployed state of the duodenal stent 1. Fig. 3 is a schematic diagram of a second stent portion 20.

The duodenal stent 1 is placed in the duodenum D to expand the lumen and define a flow path for digestive matter (fluid) (see FIG. 2). The duodenal stent 1 is placed, for example, across the boundary between the duodenal bulb D1 and the descending duodenum D2.
As shown in Fig. 1, the duodenal stent 1 is a so-called bare stent, which is composed only of a framework. The duodenal stent 1 has a first stent section 10 and a second stent section 20 connected to the first stent section 10. In Fig. 1, the boundary between the first stent section 10 and the second stent section 20 is indicated by a dashed line.
In the following description, the second stent section 20 side in the axial direction AX will be referred to as the "one end side" and the opposite side as the "other end side."

The duodenal stent 1 includes a movable section 2 at one end portion closer to the tip than the central portion in the axial direction AX, the movable section 2 being formed so that one portion can be displaced relative to the other portion in at least one direction among the axial direction AX, the radial direction perpendicular to the axial direction AX, and the circumferential direction about the axis. In other words, the movable section 2 has a structure that easily follows the shape of the duodenum D. In this embodiment, the movable section 2 is provided in the second stent section 20.
Here, the "portion closer to the distal end than the central portion" is the portion that is strongly pressed against the biological lumen wall by the axial force (straightening force) of the duodenal stent 1.

The first stent section 10 has a cylindrical shape extending straight along the axial direction AX and is radially expandable and contractible. The first stent section 10 is disposed, for example, in the descending duodenum D2 downstream of the duodenal bulb D1 in the flow direction of digestive matter, and is formed long so that the other end is located downstream of the papilla of Vater VP. The first stent section 10 is composed of a cylindrical framework 11 formed by braiding wire material so that elongation in the axial direction AX is restricted, for example.

The second stent section 20 is, for example, bent relative to the descending duodenum D2 and placed in the duodenal bulb D1, which has a different shape from the descending duodenum D2. The second stent section 20 is connected to one end of the first stent section 10 and has an overall flared shape that slopes so that its diameter expands toward the tip in the axial direction AX. In other words, the second stent section 20 has a different shape and radial expansion force from the first stent section 10.

The second stent section 20 is located closer to the end than the center in the axial direction AX. The second stent section 20 has a first circumferential surface section 20A and a second circumferential surface section 20B, with the first circumferential surface section 20A functioning as the movable section 2 that easily conforms to the biological lumen.

The second circumferential surface portion 20B is continuous with one end of the first stent section 10. The second circumferential surface portion 20B is a portion consisting of a single crown-shaped skeleton 25 (hereinafter referred to as the "crown skeleton 25"). In other words, the second circumferential surface portion 20B is formed continuously in the circumferential direction.
Furthermore, the first circumferential surface portion 20A is connected to the end (tip) of the second circumferential surface portion 20B opposite to the first stent portion 10.

The first peripheral surface portion 20A is a portion in which four petal-shaped skeletons 21-24 (hereinafter referred to as "petal skeletons 21-24") are arranged circumferentially at intervals to form a flared shape. In other words, the first peripheral surface portion 20A is formed so that they are not continuous in the circumferential direction. Gaps are provided between adjacent petal skeletons 21-24.

It should be noted that the number of petal skeletons 21 to 24 may be more than one and is not limited to four. Increasing the number of petal skeletons 21 to 24 increases the degree of freedom of the first circumferential surface portion 20A, making it easier to follow the biological lumen, but it also reduces the expandability and shape stability when returning from a contracted state to an expanded state, which may make it easier for the duodenal stent 1 to slip out of the duodenum D. Therefore, the number of petal skeletons 21 to 24 is set appropriately taking these factors into consideration.
Furthermore, it is preferable that the size of the gap between adjacent petal skeletons 21 to 24 be set in consideration of the magnitude of the displacement of the petal skeletons 21 to 24 in the circumferential direction.

The first circumferential surface portion 20A is formed from separate petal skeletons 21-24, which reduces its expansive force and shape stability compared to when it is formed in a tubular, connected configuration. In this embodiment, the second circumferential surface portion 20B is provided at the end of the first stent portion 10 side of the first circumferential surface portion 20A, and by forming one end portion circumferentially connected, the reduction in expansive force and shape stability of the first circumferential surface portion 20A is suppressed.

Also, as shown in Figure 4, the petal skeletons 21-24 that form the first circumferential surface portion 20A may be connected in the circumferential direction using a connecting member 26, such as a crimping member, to the extent that tracking is not impaired. Furthermore, the second stent portion 20 may be formed only with the first circumferential surface portion 20A without providing the second circumferential surface portion 20B, and the first circumferential surface portion 20A may be directly connected to the first stent portion 10.

The petal skeletons 21-24 of the first peripheral surface portion 20A and the crown skeleton 25 of the second peripheral surface portion 20B are formed, for example, by weaving wire material, similar to the tubular skeleton 11 of the first stent portion 10.

The tubular skeleton 11 of the first stent section 10, and the petal skeletons 21-24 and cap skeleton 25 of the second stent section 20 are formed by weaving four spirally extending wire rods that are folded back in a zigzag (Z-shape) pattern 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 addition, the tubular skeleton 11, petal skeletons 21-24, and crown skeleton 25 may not be diamond-shaped wire mesh, but may be constructed by winding one or more wire rods in a spiral pattern in the axial direction while bending them to form alternating peaks and valleys.

The tubular skeleton 11, petal skeletons 21-24, and cap skeleton 25 have self-expanding properties, meaning that they retain their expanded shape, and expand radially outward upon release from the sheath (not shown). In other words, the first stent section 10 and the second stent section 20 are configured to be deformable from a contracted state in which they are folded radially inward to an expanded state in which they expand radially outward to define a tubular flow path.

The wire materials forming the tubular skeleton 11, petal skeletons 21-24, and cap skeleton 25 may be well-known metals or metal alloys, such as stainless steel, Ni-Ti alloy (nitinol), and titanium alloy. An alloy material with X-ray contrast properties may also be used. In this case, the position of the duodenal stent 1 can be confirmed from outside the body. The tubular skeleton 11, petal skeletons 21-24, and cap skeleton 25 may also be formed from materials other than metals (e.g., ceramic, resin, etc.).

The material, wire diameter (cross-sectional area), number of circumferential folds and fold shape (number and shape of bends), and mesh size (amount of skeletal structure per unit length) of the wire forming the tubular skeleton 11, petal skeletons 21-24, and cap skeleton 25 are appropriately selected based on the expansive force and flexibility of the first stent section 10 and second stent section 20 required for the biological lumen in which they are to be placed. Here, flexibility refers to the ease with which the first stent section 10 and second stent section 20 bend, and is determined particularly by their axial bending rigidity. In other words, the first stent section 10 and second stent section 20 have high flexibility when their axial bending rigidity is appropriately low and they have the ability to conform to the shape of the biological lumen or sheath without kinking within the biological lumen or sheath.

As shown in Figure 3, in the second stent section 20, the petal skeletons 21-24 each have a generally fan-shaped configuration in the unfolded state, with the circumferential length increasing toward the tip. The petal skeletons 21-24 are connected to the end (tip) of the cap skeleton 25 opposite the first stent section 10 so that they are adjacent to each other in a curved state. This forms the second stent section 20 in a flared shape. The petal skeletons 21-24 and the cap skeleton 25 may each be formed from separate wire rods and then connected using a crimping member or the like, or they may be formed integrally from the same wire rod.

Unlike a typical flare shape, the second stent section 20 has petal skeletons 21 to 24 arranged separately in the circumferential direction, and therefore each can be independently displaced radially and in the axial direction AX, with the connection to the crown skeleton 25 as the fixed end.
Furthermore, since there are gaps between adjacent petal skeletons 21 to 24, each can be displaced independently in the circumferential direction.
In this way, one petal skeleton (e.g., petal skeleton 21) is formed as one part, and another petal skeleton (e.g., petal skeleton 22) is formed as another part, so that one petal skeleton can be displaced in the axial direction AX, the longitudinal direction, and the circumferential direction relative to the other petal skeletons. As a result, the first circumferential surface portion 20A made up of petal skeletons 21 to 24 functions as a movable portion 2 that can easily follow the biological lumen.

When the second stent section 20 is released from the sheath, the petal skeletons 21-24 attempt to return to their expanded state. At this time, the petal skeletons 21-24 can independently displace in the axial, radial, and circumferential directions, and even if the placement site is curved or bulging, they will conform to the shape of the site and adhere appropriately.

In this way, the duodenal stent 1 is a tubular stent that is placed in the duodenum D (biological lumen) and is formed to be expandable and contractable in a radial direction that is approximately perpendicular to the axial direction AX, and the portion distal to the center in the axial direction AX has a movable portion 2 formed so that at least one portion can be displaced relative to the other portions in at least one of the axial direction AX, the radial direction, and the circumferential direction.
Specifically, the duodenal stent 1 comprises a cylindrical first stent section 10 that is radially expandable and contractible, and a second stent section 20 that differs from the first stent section 10 in at least one of shape and radial expansion force. Of the first stent section 10 and the second stent section 20, the second stent section 20 that is positioned distally of the center in the axial direction AX has a movable section 2.
According to the duodenal stent 1, the movable portion 2 is formed to be displaceable in the axial direction AX, the radial direction, and the circumferential direction, and the portion distal to the central portion in the axial direction AX can be configured with a high degree of freedom, making it easier to follow the shape of the duodenum D having the duodenal bulb D1. This improves adhesion to the duodenal wall when the duodenal stent 1 is placed, allowing the duodenal stent 1 to be placed appropriately even in the duodenum D having a complex shape, and preventing displacement of the duodenal stent 1. Furthermore, the portion distal to the central portion in the axial direction AX of the duodenal stent 1 is no longer pressed strongly against the duodenal wall, thereby reducing the load on the duodenum D.

Furthermore, in the duodenal stent 1, the second stent section 20 of the first stent section 10 and the second stent section 20 is positioned closer to the tip than the center in the axial direction AX, and the movable section 2 is formed by the first circumferential surface section 20A of the circumferential surface sections 20A, 20B of the second stent section 20, which is formed so as not to be continuous in the circumferential direction.
This allows the first circumferential surface portion 20A, that is, the petal skeletons 21 to 24 arranged at intervals in the circumferential direction, to be displaced independently, thereby improving adhesion to the duodenal wall.

The second stent section 20 has a circumferential surface section 20B formed on the circumferential surface section thereof and connected in the circumferential direction.
As a result, the reduction in the expansive force caused by the first circumferential surface portion 20A being separated in the circumferential direction can be compensated for by the second circumferential surface portion 20B.

The second stent section 20 is provided on the distal end side in the axial direction AX and has a flared shape that is inclined so that the outer diameter expands toward the distal end side in the axial direction AX.
As a result, even if the second stent portion 20 is configured to have a flared shape in order to increase the expansion force, by forming the first circumferential surface portion 20A so that it is not continuous in the circumferential direction, the load on the duodenum D can be reduced, and the risk of perforation when the duodenal stent 1 is left in place for a long period of time can be reduced.

Second Embodiment
Fig. 5 is a diagram showing the appearance of a duodenal stent 1A according to the second embodiment. Fig. 6 is a diagram showing the duodenal stent 1A in an indwelling state. In the duodenal stent 1A, components that are the same as or correspond to those of the duodenal stent 1 according to the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

The duodenal stent 1A is placed, for example, so as to straddle the pylorus P, which is the boundary between the stomach S and the duodenal bulb D1 (see Figure 6). Specifically, the constricted portion 3 formed at the boundary between the first stent portion 10 and the second stent portion 20 is placed so as to be positioned at the pylorus P.

In the second embodiment, the first stent section 10 has a straight section 10A extending straight along the axial direction AX, and a tapered section 10B connected to the straight section 10A and tapering toward the second stent section 20. The tapered section 10B is inclined so that its outer diameter increases toward the base end in the axial direction AX. The first stent section 10 is positioned, for example, from the duodenal bulb D1 to the descending duodenum D2 in the flow direction of digestive matter. In particular, the tapered section 10B is positioned near the pylorus P within the duodenal bulb D1.

The second stent section 20 is connected to the distal end of the tapered section 10B in the axial direction AX, and has a flared shape that slopes so that the outer diameter increases toward the distal end. The second stent section 20 is disposed, for example, near the pylorus P in the stomach S, which has a shape different from that of the duodenal bulb D1. In the second embodiment, the second stent section 20 is formed only by a first circumferential surface section 20A consisting of petal skeletons 21-24, and the first circumferential surface section 20A is connected to the tapered section 10B of the first stent section 10.
The tapered portion 10B of the first stent portion 10 and the flared first circumferential surface portion 20A of the second stent portion 20 form the constricted portion 3. The shape of the constricted portion 3, i.e., the inclination angle of the tapered portion 10B and the first circumferential surface portion 20A, is set according to the shape of the pylorus P.

As in the first embodiment, the second stent section 20 has a second circumferential surface section 20B consisting of a cap skeleton 25 connected to the first circumferential surface section 20A (petal skeletons 21-24), and the second circumferential surface section 20B may be connected to the tapered section 10B of the first stent section 10. In this case, the tapered section 10B and the second circumferential surface section 20B form the constricted section 3.

In the duodenal stent 1A, a tapered portion 10B is provided in the first stent portion 10. Compared to the duodenal stent 1 according to the first embodiment, the boundary between the first stent portion 10 and the second stent portion 20 is more constricted, and the diameter of the constricted portion 3 is smaller. For example, an appropriate tapered shape can be formed by changing the mesh size or number of meshes in the tubular framework 11 of the tapered portion 10B.

The pylorus P, which is the connecting portion between the duodenum D and stomach S, has a smaller diameter than the tubular diameter on the stomach S side near the pylorus P and the tubular diameter on the duodenum D side, has a sharply curved, hand-shaped shape, and is normally closed. Furthermore, the pylorus P can also be said to have a steep, approximately hyperbolic shape in a cross section along the flow direction of digested matter.

The first stent section 10 is provided with a tapered portion 10B, and the constricted portion 3 located at the pylorus P is formed sharply, allowing for a strong grip at the pylorus P. In other words, the engagement of the second stent section 20 with the pylorus P prevents the duodenal stent 1A from shifting toward the duodenum D. Furthermore, the engagement of the tapered portion 10B of the first stent section 10 with the pylorus P also prevents the duodenal stent 1A from shifting toward the stomach S. In addition, the flared petal skeletons 21-24 open more easily, making them more likely to come into contact with the stomach wall near the pylorus P. The engagement of the petal skeletons 21-24 effectively prevents the duodenal stent 1A from shifting.

Furthermore, the radial expansion force of the tapered portion 10B is preferably smaller than the expansion force of the straight portion 10A. Similarly, the radial expansion force of the second stent portion 20 near the constricted portion 3 is preferably smaller than the expansion force at the distal end portion away from the constricted portion 3. The tapered portion 10B and the second stent portion 20 may be configured, for example, so that their radial expansion force gradually decreases as they approach the constricted portion 3. In this case, the constricted portion 3 can easily expand and contract, making it easier to follow the opening and closing of the pylorus P and reducing the load on the pylorus P. The expansion force of the tapered portion 10B and the second stent portion 20 can be appropriately adjusted, for example, by changing the mesh size and number of the tubular skeleton 11 and the petal skeletons 21-24. Note that, to reduce the load on the pylorus P, it is sufficient to control the expansion force of at least one of the tapered portion 10B and the second stent portion 20 as described above.

7A and 7B are schematic diagrams showing an example of the constricted portion 3 of the duodenal stent 1A.
7A, a constricted portion 3 is formed at the connection portion (the engagement portion between the bent portions) between the tubular skeleton 11 of the first stent portion 10 (tapered portion 10B) and the petal skeletons 21 to 24 of the second stent portion 20. In this case, the constricted portion 3 is easily deformed, which makes it easier to reduce the load on the pylorus portion P.

On the other hand, in Figure 7B, a constricted portion 3 is formed in the straight portion of the petal skeleton 21-24 of the second stent section 20. In this case, the constricted portion 3 is less likely to deform, making it easier to prevent displacement in the pylorus section P.

As described above, the duodenal stent 1A has the following characteristic structure in addition to the structure of the duodenal stent 1 according to the first embodiment.
That is, in the duodenal stent 1A, the first stent section 10 has a tapered section 10B that is inclined so that the outer diameter increases toward the base end in the axial direction AX, and the second stent section 20 is positioned closer to the tip side than the axial center, and the base end side of the second stent section 20 is connected to the tip side in the axial direction AX of the tapered section 10B, and has a flared shape that is inclined so that the outer diameter increases toward the tip side.
As a result, when the duodenal stent 1A is placed in a small-diameter portion such as the pylorus P, the constricted portion 3, which is the boundary between the tapered portion 10B and the second stent portion 20, catches on and physically locks onto the duct wall near the pylorus P, and the movable portion 2 makes it easier for the second stent portion 20 to follow the shape of the periphery of the pylorus P, improving adhesion to the stomach wall. As a result, the placement of the duodenal stent 1A is significantly improved.

Furthermore, in the duodenal stent 1A, the radial expansion force of at least one of the tapered portion 10B and the second stent portion 20 decreases toward the constricted portion 3, which is the boundary between the tapered portion 10B and the second stent portion 20. This makes it easier for the constricted portion 3 to follow movements of the small diameter portion, such as the opening and closing of the pylorus portion P, thereby reducing the load on the small diameter portion.

The invention made by the inventor has been specifically described above based on the embodiments, but the present invention is not limited to the above embodiments and can be modified within the scope of its gist.

For example, in the above embodiment, a configuration was illustrated in which one petal skeleton (e.g., petal skeleton 21) is formed so as to be displaceable in the axial direction AX, the longitudinal direction, and the circumferential direction relative to another petal skeleton (e.g., petal skeleton 22). However, this is merely an example and is not limiting. In other words, it is sufficient that one petal skeleton is formed so as to be displaceable in at least one direction among the axial direction AX, the longitudinal direction, and the circumferential direction relative to another petal skeleton. Furthermore, if the entire second stent section 20 is made a movable section, it is sufficient that the second stent section 20 is formed so as to be displaceable in at least one direction among the axial direction AX, the longitudinal direction, and the circumferential direction relative to another section (e.g., first stent section 10).

In addition, for example, although the second stent section 20 has a flared shape in the embodiment, it may also be formed in a straight cylindrical shape. Furthermore, in the second stent section 20, the second circumferential surface section 20B, which compensates for the expansion force of the first circumferential surface section 20A, may be provided at one end of the first circumferential surface section 20A, or may be provided so as to sandwich the first circumferential surface section 20A in the axial direction.

In the embodiment, a case has been described in which a highly compliant structure for the movable part 2 is realized by using a plurality of petal skeletons 21 to 24, but the structure of the movable part 2 is not limited to this. For example, the compliant property can be improved by changing the diameter or material of the wire material forming the movable part 2, the size of the mesh, etc.
In addition, in the embodiment, the movable portion 2 is described as being provided in the second stent portion 20, but the movable portion 2 may be provided in the first stent portion 10, or may be provided in both the first stent portion 10 and the second stent portion 20.

In addition, although not shown, in the duodenal stents 1 and 1A, the first stent section 10 and the second stent section 20 may be provided with a coating that covers each tubular skeleton 11, petal skeletons 21-24, and cap skeleton 25. By providing the coating, the narrowed portion of the duodenum D can be prevented from bulging inward of each tubular skeleton 11, petal skeletons 21-24, and cap skeleton 25, allowing the narrowed portion to be appropriately expanded.

Furthermore, the flare shape that slopes to increase in diameter toward the tip side may have any shape that slopes to increase in diameter overall, and there are no particular limitations on the detailed shape. For example, the flare shape may be an inverted cone shape that slopes linearly with a constant expansion rate, or a shape that slopes in a broken line with a changing expansion rate. Furthermore, for example, the flare shape may be a hemispherical shape like a bowl with a gradually decreasing expansion rate toward the tip side, or a trumpet shape with a gradually increasing expansion rate toward the tip side, or a shape that slopes in a curved line. Furthermore, for example, the flare shape may have a partially narrowing diameter toward the tip side, as long as it slopes to increase in diameter overall.

Examples of materials for forming the coating include silicone resin, fluororesin such as PTFE (polytetrafluoroethylene), and polyester resin such as polyethylene terephthalate.
The configuration of the coating can be changed as appropriate. For example, the coatings may be disposed on the outer and inner surfaces of the skeletons so as to sandwich the tubular skeleton 11, the petal skeletons 21 to 24, and the cap skeleton 25, or may be disposed only on the outer surfaces of the tubular skeleton 11, the petal skeletons 21 to 24, and the cap skeleton 25. Furthermore, for example, the coating may be disposed on either the first stent section 10 or the second stent section 20, or may be disposed entirely or partially on each of them.

In addition, in the first embodiment, a configuration in which the second stent portion 20 of the duodenal stent 1 is placed in the duodenal bulb D1 has been described, but this is merely an example and is not limited to this, and the placement position (placement) of each component of the duodenal stent 1 can be changed as appropriate.
For example, the duodenal stent 1 may be positioned so that at least the first circumferential surface portion 20A of the second stent portion 20 protrudes from the pylorus of the stomach. That is, by providing the movable portion 2 in a portion of the duodenal stent 1 closer to the distal end than the axial center, even in a digestive tract with a complex internal shape extending from the stomach to the duodenum D, the movable portion 2 may be positioned in the duodenal bulb D1 or the first circumferential surface portion 20A may protrude from the pylorus of the stomach, thereby improving the flexibility of the placement position of the duodenal stent 1. Furthermore, the second circumferential surface portion 20B of the second stent portion 20 may be positioned in the pylorus, which allows the first stent portion 10 to be positioned in a substantially straight line to the descending duodenum D2 without having to be aligned along the inner wall in accordance with the shape of the duodenal bulb D1, thereby improving the flexibility of the placement position of the duodenal stent 1.

The present invention is not limited to the duodenal stent described in the embodiment, but can also be applied to stents placed in biological lumens with complex shapes, such as digestive lumens and blood vessels.

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

The disclosures of the specification, drawings, and abstract contained in Japanese Patent Application No. 2020-184540, filed November 4, 2020, are incorporated herein by reference in their entirety.

1. Duodenal stent (stent)
2 Movable portion 10 First stent portion 20 Second stent portion 20A First circumferential surface portion 20B Second circumferential surface portion

The stent according to the present invention comprises:
A cylindrical stent to be placed in a biological lumen,
a cylindrical first stent portion that is expandable and contractable in a radial direction substantially perpendicular to the axial direction;
a second stent portion that is different from the first stent portion in at least one of the shape and the radial expansion force;
a constricted portion formed at the boundary between the first stent portion and the second stent portion ,
each of the first stent section and the second stent section is formed by weaving a wire rod that extends spirally while being folded back in a zigzag shape into a diamond-shaped wire mesh shape such that a convex peak portion on one end side in the axial direction and a convex valley portion on the other end side in the axial direction intermesh with each other;
the first stent portion has a tapered portion that is inclined so that the outer diameter thereof decreases toward the second stent side,
the second stent portion is disposed distally of a central portion in the axial direction, and has a movable portion formed so that at least one portion thereof can be displaced relative to the other portions in at least one direction among the axial direction, the radial direction, and the circumferential direction, and a base end side of the second stent portion is connected to a portion on one end side of the tapered portion in the axial direction and is formed in a flared shape that is inclined so that the outer diameter increases toward the distal end side,
The constricted portion is formed by a straight portion of the wire material of the second stent portion.

Claims (4)

A cylindrical stent to be placed in a biological lumen,
a cylindrical first stent portion that is expandable and contractable in a radial direction substantially perpendicular to the axial direction;
a second stent portion that is different from the first stent portion in at least one of the shape and the radial expansion force,
each of the first stent section and the second stent section is formed by weaving a wire rod that extends spirally while being folded back in a zigzag shape into a diamond-shaped wire mesh shape such that a convex peak portion on one end side in the axial direction and a convex valley portion on the other end side in the axial direction intermesh with each other;
the second stent section has a first circumferential surface section that is disposed distally of a central section in the axial direction and is formed so as not to be continuous in the circumferential direction, a second circumferential surface section that is provided closer to the first stent section than the first circumferential surface section and is formed so as to be connected in the circumferential direction, and a movable section that is formed by the first circumferential surface section and at least one portion of which is formed so as to be displaceable relative to the other portions in at least one direction among the axial direction, the radial direction, and the circumferential direction,
The first circumferential surface portion has a plurality of skeletal portions arranged at intervals in the circumferential direction, and the circumferential length of the plurality of skeletal portions increases toward the tip side, which is opposite the second circumferential surface portion. the first stent portion has a tapered portion that is inclined so that the outer diameter increases toward the base end side in the axial direction,
2. The stent according to claim 1, wherein the second stent portion is positioned distally of the central portion in the axial direction, the base end side of the second stent portion is connected to the distal side of the tapered portion in the axial direction, and the stent has a flared shape that is inclined so that the outer diameter increases toward the distal side. The stent further includes a constricted portion formed at the boundary between the first stent portion and the second stent portion,
3. The stent according to claim 2, wherein the constricted portion is formed so as to be bent by an engagement portion between the wire material of the tapered portion of the first stent portion and the wire material of the second stent portion, or is formed by a straight portion of the wire material of the second stent portion. The stent according to claim 2 , wherein at least one of the tapered section and the second stent section has an expansion force in the radial direction that decreases toward a boundary between the tapered section and the second stent section.