Synthetic resin stent

A stent can ensure storability in thin tubular members such as delivery systems and is insusceptible to positional displacement after placement of the stent in an affected part of a bodily conduit. This synthetic resin comprises a tubular first braid component comprising a plurality of fibers that are braided into a net-like form, and a second braid component comprising a plurality of fibers that are disposed braided into the first braid component to form an annular shape. The first braid component includes a plurality of first fibers, a plurality of second fibers, and a plurality of first intersections. The second braid component includes a plurality of wave-like third fibers disposed separated in an axial direction and a plurality of wave-like fourth fibers disposed separated in the axial direction. At least one of the first intersections is disposed in an intersection region surrounded by the third fiber and the fourth fiber.

TECHNICAL FIELD

The present invention relates to a synthetic resin stent such as a biodegradable stent.

BACKGROUND ART

Stenotic diseases (such as tumors and inflammations) in natural tracts such as blood vessels and gastrointestinal tracts are heretofore treated by placing a stent at a stenotic site and dilating the stenotic site. Stents made of metal or synthetic resin are known, for example. Among these, when a metal stent is removed from the body, a surgical intervention is needed and imposes a significant burden on the patient. Therefore, use of a metal stent is limited to cases such as malignant tumors for which semi-permanent placement or surgical procedures are planned. Against such a background, a biodegradable stent as a synthetic resin stent has been proposed as a stent for use in cases where a metal stent cannot be used (see, for example, Patent Document 1).

A synthetic resin stent is inferior to a metal stent, in self-expandability, restorability, adherence to the gastrointestinal tract such as the intestinal tract, and trackability to peristaltic movement of the gastrointestinal tract; therefore, required performance may not be achieved when a synthetic resin stent is manufactured in the same shape as a metal stent.Patent Document 1: Japanese Unexamined Patent Application, Publication No. 2009-160079

DISCLOSURE OF THE INVENTION

Problems to be Solved by the Invention

Achieving an anchoring effect may be conceivable by forming the ends of the stent into a flare shape, i.e., making the diameter of the ends of the stent larger than the diameter of the central portion. However, even if the ends are formed into a flare shape, a biodegradable stent is inferior in strength to a metal stent; therefore, when pressure is applied to the flare-shaped portion from outside in the radial direction, it is difficult to maintain the shape and sufficiently achieve an anchoring effect.

Enhancing the resistance of the biodegradable stent to pressure from outside in the radial direction may be conceivable by thickening the fiber composing the biodegradable stent. However, when the fiber composing the biodegradable stent is thickened, it becomes difficult to load the stent into a fine tubular member such as a delivery system to be used when the stent is placed at a stenotic site.

Accordingly, it is an object of the present invention to provide a synthetic resin stent that is unlikely to cause migration after placing the stent at an affected site inside a natural tract, while ensuring loadability into a fine tubular member such as a delivery system.

Means for Solving the Problems

The invention relates to a synthetic resin stent, including a first woven component portion being tubular and composed of a plurality of fibers woven into a mesh, and a second woven component portion composed of a plurality of fibers arranged so as to be woven into the first woven component portion and configured into an annular shape; the first woven component portion preferably includes a plurality of first fibers extending so as to be inclined at a predetermined angle with respect to the axial direction, a plurality of second fibers extending so as to intersect with the first fibers, and a plurality of first intersecting points configured with intersections of the plurality of first fibers and the plurality of second fibers; the second woven component portion preferably includes a plurality of wave-shaped third fibers arranged so as to be spaced apart in the axial direction, and a plurality of wave-shaped fourth fibers arranged so as to be spaced apart in the axial direction; and at least one first intersecting point of the plurality of first intersecting points is preferably arranged in intersecting regions surrounded by the third fibers and the fourth fibers.

The plurality of intersecting regions are preferably formed side by side in the circumferential direction of the first woven component portion; and the plurality of first intersecting points are preferably arranged side by side in the circumferential direction of the first woven component portion and arranged in the plurality of intersecting regions, respectively.

In a configuration in which the first intersecting points are arranged in the intersecting regions, respectively, the third fibers are preferably arranged in a state of being hookable by one or more of the first fibers, the second fibers and the fourth fibers, in relation to movement in a direction in which an overlapping portion of the third fibers and the fourth fibers shrinks in size; and the fourth fibers is preferably arranged in a state of being hookable by one or more of the first fibers, the second fibers and the third fibers, in relation to movement in a direction in which the overlapping portion of the third fibers and the fourth fibers shrinks in size.

A plurality of configurations are provided in which the first intersecting point is arranged in the intersecting region, in which the synthetic resin stent is preferably configured to partly include a configuration, in which the third fibers and the fourth fibers are arranged in a state of being mutually hookable, in relation to movement in a direction in which the overlapping portion of the third fibers and the fourth fibers shrinks in size, and arranged in a state of not being hookable by the first fibers and the second fibers when the third fibers and the fourth fibers move.

A loop having a loop shape is preferably formed at the top of the peaks of the wave-shaped third fibers and/or the wave-shaped fourth fibers, the loop arranged so as to surround any one or more of the first fibers, the second fibers, the third fibers and the fourth fibers.

The second woven component portion is preferably formed of synthetic resin fiber having an expansion force higher than the first woven component portion.

The present invention relates to a synthetic resin stent, including a first woven component portion being tubular and composed of one more fibers configured into a mesh, and a second woven component portion arranged so as to be woven into the first woven component portion and composed of one or more fibers configured into an annular shape; the first woven component portion preferably includes a plurality of first fibers repeatedly bent so as to be inclined at a predetermined angle with respect to the axial direction and extending in the axial direction, a plurality of second fibers arranged to include a portion intersecting with the first fibers and repeatedly bent so as to be inclined at a predetermined angle with respect to the axial direction and extending in the axial direction, and a plurality of first intersecting regions configured with intersections of the plurality of first fibers and the plurality of second fibers; the second woven component portion preferably includes a plurality of third fibers repeatedly bent so as to be inclined at a predetermined angle with respect to the axial direction and extending in the circumferential direction, a plurality of fourth fibers arranged to include a portion intersecting with the third fibers and repeatedly bent so as to be inclined at a predetermined angle with respect to the axial direction and extending in the axial direction, and a plurality of second intersecting regions configured with intersections of the plurality of third fibers and the plurality of fourth fibers; and the first intersecting regions and the second intersecting regions are preferably arranged to at least partly overlap with each other.

In a configuration in which the first intersecting region is arranged to overlap with the second intersecting region, the first fibers are preferably arranged in a state of being hookable by one or more of the third fibers and the fourth fibers, in relation to movement in a direction in which an overlapping portion of the first fibers and the second fibers shrinks in size; and the second fibers are preferably arranged in a state of being hookable by one or more of the third fibers and the fourth fibers, in relation to movement in a direction in which an overlapping portion of the first fibers and the second fibers shrinks in size.

Effects of the Invention

The present invention can provide a synthetic resin stent that is unlikely to cause migration after placing the stent at an affected site inside the natural tract, while ensuring loadability into a fine tubular member such as a delivery system.

PREFERRED MODE FOR CARRYING OUT THE INVENTION

Hereinafter, each embodiment of a synthetic resin stent of the present invention will be described with reference to the drawings.

First Embodiment

With reference toFIGS.1and2, a biodegradable stent1according to the first embodiment will be described.FIG.1is a perspective view illustrating the biodegradable stent1according to the first embodiment of the present invention.FIG.2is an enlarged view of the biodegradable stent1illustrated inFIG.1.

The synthetic resin stent of the present embodiment is the biodegradable stent1composed of biodegradable fiber, and includes a meshed tubular portion2(first woven component portion) and a wavily woven portion3(second woven component portion) arranged so as to be woven in the meshed tubular portion2, as illustrated inFIGS.1and2.

The meshed tubular portion2is woven into a mesh of a plurality of fibers20and configured into a tubular structure, and includes a multitude of argyle voids formed of the fibers20on the outer periphery and arranged in an orderly fashion. The mesh of the meshed tubular portion2becomes sparse in the axial direction when the biodegradable stent1is in the reduced diameter state, and becomes dense in the axial direction when the biodegradable stent1is in the expanded diameter state.

In the present embodiment, as illustrated inFIG.2, the plurality of fibers20configuring the meshed tubular portion2includes a plurality of first fibers21and a plurality of second fibers22. As viewed from the side, the meshed tubular portion2includes a multitude of argyle voids formed of the first fibers21and the second fibers22, and includes a plurality of first intersecting points23configured by intersections of the plurality of first fibers21and the plurality of second fibers22.

The plurality of first fibers21are formed of synthetic resin fiber extending so as to be inclined at a predetermined angle with respect to the axial direction. In the present embodiment, as illustrated inFIG.2, the plurality of first fibers21are arranged so as to be inclined and extending from the upper right side to the lower left side.

The plurality of second fibers22are formed of synthetic resin fiber extending so as to intersect with the plurality of first fibers21. In the present embodiment, as illustrated inFIG.2, the plurality of second fibers22are arranged so as to be inclined and extending from the upper left side to the lower right side.

The material of the first fibers21and the second fiber22is not limited; however, a material having a high degree of rigidity is preferable. Examples of the biodegradable resin may include homopolymer, copolymer, or blend polymer composed of L-lactic acid, D-lactic acid, DL-lactic acid, glycolic acid, ε-caprolactone, or para-dioxanone. Non-biodegradable resin may also be used as long as the material has a high degree of rigidity. In particular, for example, polylactic acid (PLA) or poly-L-lactic acid (PLLA) is preferably used as the material of the fiber configuring the first fibers21and the second fiber22. In the present embodiment, the first fibers21and the second fiber22are formed from polylactic acid (PLA), for example.

In the case of using biodegradable fiber as the fiber20, the diameter thereof is preferably 0.1 mm to 0.4 mm. When the diameter of the biodegradable fiber20is less than 0.1 mm, the strength of the biodegradable stent1tends to decrease. When the diameter of the biodegradable fiber20exceeds 0.4 mm, the diameter increases in the reduced diameter state, so that it tends to be difficult to load the biodegradable stent1into a fine tubular member such as a delivery system. The upper limit of the diameter of the biodegradable fiber20is further preferably 0.3 mm, from a perspective of loading into a delivery system having a small inner diameter. The lower limit of the diameter of the biodegradable fiber20is more preferably 0.2 mm, from a perspective of maintaining high strength. In the present embodiment, biodegradable fiber having a diameter of 0.2 mm and biodegradable fiber having a diameter of 0.3 mm are used as the fibers20.

As illustrated inFIG.1, the plurality of annularly formed wave-shaped fibers30of the wavily woven portion3are arranged so as to be woven in the meshed tubular portion2. In the present embodiment, the plurality of fibers30configuring the wavily woven portion3include: a plurality of third fibers31arranged so as to be spaced apart in the axial direction; and a plurality of fourth fibers32arranged so as to be spaced apart in the axial direction. The wavily woven portion3includes a plurality of second intersecting points33formed by intersections of the plurality of third fibers31and the plurality of fourth fibers32.

As illustrated inFIG.2, the third fibers31and the fourth fibers32are formed into a wave shape extending in the circumferential direction of the meshed tubular portion2, in which peaks and valleys consecutively alternate. The third fibers31and the fourth fibers32are arranged such that the mutual convex portions face each other and the facing convex portions partly overlap with each other.

More specifically, the third fibers31and the fourth fibers32are formed into a wave shape having peaks convex toward the first direction D1side and peaks convex toward the second direction D2side, in which mutual peaks partly overlap with each other and intersect at two second intersecting points33, as viewed from the side. The wavily woven portion3includes an intersecting region34as viewed from the side. The intersecting region34is a region surrounded by the third fiber31and the fourth fiber32between the two adjacent second intersecting points33among the plurality of second intersecting points33, where the mutual convex portions of the third fiber31and the fourth fiber32overlap with each other. The plurality of intersecting regions34are formed side by side in the circumferential direction of the meshed tubular portion2being tubular.

The material of the synthetic resin fiber configuring the third fiber31and the fourth fiber32is not limited in particular; however, a material having a high degree of restorability is preferable. Examples of the biodegradable resin may include homopolymer, copolymer, or blend polymer composed of L-lactic acid, D-lactic acid, DL-lactic acid, glycolic acid, ε-caprolactone, or para-dioxanone. Non-biodegradable resin may also be used as long as the material has a high degree of restorability. For example, polydioxanone (PDO) is preferably used as the material of the third fiber31and the fourth fiber32.

In the case of using biodegradable fiber as the fiber30, the diameter thereof is preferably 0.1 mm to 0.4 mm. In the present embodiment, the biodegradable fiber having a diameter of 0.15 mm to 0.22 mm is used as the fiber30.

The first intersecting points23of the meshed tubular portion2are arranged in the plurality of intersecting regions34of the wavily woven portion3, respectively, as the meshed tubular portion2is viewed from the side. The plurality of first intersecting points23are arranged in the plurality of intersecting regions34, respectively, and arranged side by side in the circumferential direction of the meshed tubular portion2being tubular. The portion where the first intersecting point23of the meshed tubular portion2is arranged in the intersecting region34of the wavily woven portion3configures a first hooking portion41. The biodegradable stent1of the present embodiment includes the plurality of first hooking portions41, in which a row of the plurality of first hooking portions41arranged side by side in the circumferential direction is formed throughout the axial direction.

In the first hooking portion41, the third fiber31is arranged in the state of being hookable by one or more of the first fibers21, the second fibers22, and the fourth fibers32, in relation to movement in a direction in which the mutually overlapping convex portion of the third fiber31and the fourth fiber32shrinks in size. The fourth fiber32is arranged in the state of being hookable by one or more of the first fibers21, the second fibers22, and the third fibers31, in relation to movement in a direction in which the mutually overlapping convex portion of the third fiber31and the fourth fiber32shrinks in size.

In the present embodiment, the third fiber31and the fourth fiber32configuring the wavily woven portion3are formed of synthetic resin fiber having an expansion force higher than the first fibers21and the second fiber22configuring the meshed tubular portion2; therefore, the bent portion thereof has a property of returning to a straight line. At least part of the third fiber31and the fourth fiber32is arranged so as to be woven in the meshed tubular portion2, can apply a force to increase the diameter of the biodegradable stent1, and can deform the meshed tubular portion2from the reduced diameter state to the expanded diameter state.

The configuration of the first hooking portion41will be described.FIG.2is a view, in which the radial direction of the tubular biodegradable stent1inFIG.1is rearranged along the direction perpendicular to the paper (direction penetrating the paper) ofFIG.2. Therefore, the inside of the biodegradable stent1in the radial direction is the backside in the vertical direction of the paper ofFIG.2; and the outer side of the biodegradable stent1in the radial direction is the frontside in the vertical direction of the paper ofFIG.2.

As illustrated inFIG.2, the first fibers21and the second fibers22of the meshed tubular portion2decussate at the first intersecting point23in the first hooking portion41.

The third fiber31is arranged on the frontside or backside inFIG.2with respect to the fourth fiber32(outer side or inner side of the biodegradable stent1in the radial direction) at both of the two second intersecting points33. As a result, the third fiber31and the fourth fiber32of the biodegradable stent1are arranged in the state of not being mutually hookable, in relation to mutual movement toward the first direction D1or the second direction D2.

The first intersecting point23of the first fiber21and the second fiber22is arranged in the intersecting region34surrounded by the third fiber31and the fourth fiber32, in the overlapping convex portion between the third fiber31and the fourth fiber32of the wavily woven portion3.

As illustrated inFIG.2, the first fiber21is arranged so as to be inclined and extending from the upper right side to the lower left side in the intersecting region34. From the upper right side toward the lower left side, the first fiber21passes the frontside of one of the third fiber31and the fourth fiber32, intersects with the second fiber22at the first intersecting point23, and passes the backside of the other one of the third fiber31and the fourth fiber32. As illustrated inFIG.2, the second fiber22is arranged so as to be inclined and extending from the upper left side to the lower right side in the intersecting region34. The second fiber22passes the frontside of one of the third fiber31and the fourth fiber32, intersects with the first fiber21at the first intersecting point23, and passes the backside of the other one of the third fiber31and the fourth fiber32.

The first fiber21, the second fiber22, the third fiber31, and the fourth fiber32are arranged as described above, whereby, in the first hooking portion41, one of the third fiber31and the fourth fiber32having a peak convex toward the first direction D1is arranged in the state of being hookable by the first fiber21and the second fiber22, in relation to movement in a direction in which the mutually overlapping convex portion of the third fiber31and the fourth fiber32shrinks in size; and the other one of the third fiber31and the fourth fiber32having a peak convex toward the second direction D2opposite to the first direction D1is arranged in the state of being hookable by the first fiber21and the second fiber22, in relation to movement in a direction in which the mutually overlapping convex portion of the third fiber31and the fourth fiber32shrinks in size.

The biodegradable stent1as described above may be manufactured by weaving the wavily woven portion3and then weaving the meshed tubular portion2, or conversely, by weaving the meshed tubular portion2and then weaving the wavily woven portion3. In the case of manufacturing the biodegradable stent1, for example, a tubular tool with a plurality of pins standing on a circumferential surface at a predetermined interval may be used, the fiber is hooked by the plurality of pins to weave the wavily woven portion3, and then the fiber of the meshed tubular portion2passes through the intersecting region of the wavily woven portion3, whereby the biodegradable stent1can be manufactured.

The meshed tubular portion2of the biodegradable stent1configured as described above is woven into a tubular structure with the first fiber21and the second fiber22inclined with respect to the axial direction, whereby the shape of the stent is maintained in the tubular structure. The wave-shaped wavily woven portion3is woven into the meshed tubular portion2, and the wavily woven portion3(third fiber31and fourth fiber32) is formed of synthetic resin fiber having an expansion force higher than the meshed tubular portion2(first fiber21and second fiber22), and the bent portion thereof has a property of returning to a straight line. Therefore, the wavily woven portion3is woven into a wave shape so as to circle the meshed tubular portion2in the circumferential direction, whereby the wavily woven portion3can apply a force to increase the diameter of the biodegradable stent1, and can enhance the expansion force. Thus, the expansion force of the biodegradable stent1in the radial direction can be strengthened to achieve self-expandability. Adherence to the wall of the gastrointestinal tract can be increased, and trackability to gastrointestinal motility can be achieved.

According to the biodegradable stent1of the first embodiment described above, the following effects can be achieved.

(1) The biodegradable stent1is configured to include the meshed tubular portion2being tubular and composed of the plurality of fibers21and22woven into a mesh, and the wavily woven portion3composed of the plurality of fibers31and32annularly formed and woven into the meshed tubular portion2; the meshed tubular portion2is configured to include the plurality of first fibers21extending so as to be inclined at a predetermined angle with respect to the axial direction, the plurality of second fibers22extending so as to intersect with the first fibers21, and the plurality of first intersecting points23formed at intersections of the plurality of first fibers21and the plurality of second fibers22; the wavily woven portion3is configured to include the plurality of wave-shaped third fibers31arranged so as to be spaced apart in the axial direction, and the plurality of wave-shaped fourth fibers32arranged so as to be spaced apart in the axial direction; and the at least one of the first intersecting points23is arranged in the intersecting region34surrounded by the third fibers31and the fourth fibers32.

As a result, the meshed tubular portion2of the biodegradable stent1is woven into a tubular structure with the first fibers21and the second fibers22inclined with respect to the axial direction, whereby the shape of the stent is maintained in the tubular structure. The wave-shaped wavily woven portion3is woven into the meshed tubular portion2, and the first intersecting point23of the meshed tubular portion2is arranged in the intersecting region34of the wavily woven portion3, whereby the wavily woven portion3can apply a force to increase the diameter and can enhance the expansion force in the radial direction. Thus, the expansion force of the biodegradable stent1in the radial direction can be strengthened to achieve self-expandability. Adherence to the wall of the gastrointestinal tract can be increased, and trackability to gastrointestinal motility can be achieved. Therefore, the stent can ensure loadability into a fine tubular member such as a delivery system, in which migration of the stent is unlikely to occur after placement at the affected site of the natural tracts.

(2) The plurality of intersecting regions34are formed side by side in the circumferential direction of the meshed tubular portion2being tubular; and the plurality of first intersecting points23are formed side by side in the circumferential direction of the meshed tubular portion2being tubular, and arranged in the plurality of intersecting regions34, respectively. As a result, the wavily woven portion3can be woven along the circumferential direction, whereby the expansion force of the biodegradable stent1in the radial direction can be further strengthened.

(3) When the first intersecting point23of the meshed tubular portion2is configured so as to be arranged in the intersecting region34of the wavily woven portion3, the third fiber31is arranged in the state of being hookable by one or more of the first fiber21, the second fiber22, and the fourth fiber32, in relation to movement in a direction in which the overlapping portion of the third fiber31and the fourth fiber32shrinks in size; and the fourth fiber32is arranged in the state of being hookable by one or more of the first fiber21, the second fiber22, and the third fiber31, in relation to movement in a direction in which the overlapping portion of the third fiber31and the fourth fiber32shrinks in size. As a result, any of these fibers is hooked by the third fiber31and the fourth fiber32of the wavily woven portion3, whereby displacement of the first intersecting point23can be prevented.

(4) The wavily woven portion3(third fiber31and fourth fiber32) is formed of synthetic resin fiber having an expansion force higher than the meshed tubular portion2(first fiber21and second fiber22). As a result, the meshed tubular portion2being tubular is formed of the first fiber21and the second fiber22, and the third fiber31and fourth fiber32can expand the first fiber21and the second fiber22in the radial direction; therefore, the expansion force in the radial direction can be further enhanced.

Second Embodiment

A biodegradable stent1A of a second embodiment will be described.FIG.3is a view illustrating the biodegradable stent1A according to the second embodiment. As illustrated inFIG.3, the biodegradable stent1A of the second embodiment is configured to include a first hooking portion41(left side inFIG.3) and a second hooking portion42(right side inFIG.3). The plurality of first hooking portions41and the plurality of second hooking portions42are spirally and alternately arranged in the circumferential direction in the biodegradable stent1A.

Since the configuration of the first hooking portion41illustrated inFIG.3is similar to that of the first hooking portion41described in the first embodiment, description thereof is omitted.

The configuration of the second hooking portion42will be described. As illustrated inFIG.3, the first fiber21and the second fiber22of the meshed tubular portion2decussate at the first intersecting point23in the second hooking portion42as well, similar to the first hooking portion41of the first embodiment.

In the second hooking portion42, the third fiber31is arranged frontside of the fourth fiber32at one of the two second intersecting points33(left side inFIG.3) and arranged backside of the fourth fiber32at the other one of the second intersecting points33(right side inFIG.3). As a result, the third fiber31and the fourth fiber32are arranged in the state of being mutually hookable, in relation to movement in a direction in which the mutually overlapping convex portion of the third fiber31and the fourth fiber32shrinks in size.

The first intersecting point23of the first fiber21and the second fiber22is arranged in the intersecting region34surrounded by the third fiber31and the fourth fiber32of the wavily woven portion3.

As illustrated inFIG.3, the first fiber21is arranged so as to be inclined and extending from the upper right side to the lower left side in the intersecting region34, and passes the backside of the fourth fiber32, intersects with the second fiber22at the first intersecting point23, and passes the backside of the third fiber31, from the upper right side to the lower left side. As illustrated inFIG.3, the second fiber22is arranged so as to be inclined and extending from the upper left side to the lower right side in the intersecting region34, passes the backside of the fourth fiber32, intersects with the first fiber21at the first intersecting point23, and passes the backside of the third fiber31, from the upper left side to the lower right side. In other words, in the second hooking portion42, the first fiber21and the second fiber22in their entirety are arranged backside of the third fiber31and the fourth fiber32, whereby the third fiber31and the fourth fiber32in their entirety are arranged frontside of the first fiber21and the second fiber22.

The first fiber21, the second fiber22, the third fiber31, and the fourth fiber32are arranged as above, whereby, in the second hooking portion42, the third fiber31and the fourth fiber32are arranged in the state of being mutually hookable, in relation to movement in a direction in which the mutually overlapping convex portion of the third fiber31and the fourth fiber32shrinks in size; the third fiber31and the fourth fiber32in their entirety are arranged frontside of the first fiber21and the second fiber22; and the third fiber31and the fourth fiber32are arranged in the state of not being hookable by the first fiber21and the second fiber22, in relation to movement of the third fiber31and the fourth fiber32in the first direction D1or the second direction D2direction.

According to the biodegradable stent1A of the second embodiment described above, in addition to the effects (1) to (4) described above, the following effects can be achieved. (5) The plurality of configurations are provided, in which the first intersecting point23of the meshed tubular portion2is arranged in the intersecting region34of the wavily woven portion3; and the third fiber31and fourth fiber32are arranged in the state of being mutually hookable, in relation to movement in a direction in which the overlapping portion of the third fiber31and fourth fiber32shrinks in size, and also arranged in the state of not being hookable by the first fiber21and the second fiber22when the third fiber31and fourth fiber32move. As a result, the third fiber31and/or the fourth fiber32are/is arranged in the state of not being hookable by the first fiber21and the second fiber22, whereby the length in the axial direction is unlikely to be restricted when the biodegradable stent1A is extended; therefore, loadability into a delivery system can be improved.

Third Embodiment

A biodegradable stent1B of a third will be described.FIG.4is a view illustrating the biodegradable stent1B according to the third embodiment. As compared with the biodegradable stent1of the first embodiment, in the case of the biodegradable stent1B of the third embodiment, the rows of the plurality of first hooking portions41arranged in the circumferential direction are arranged so as to be spaced one row apart from each other, instead of being packed in the axial direction of the biodegradable stent1A, in the wave-shaped wavily woven portion3(second woven component portion) woven into the meshed tubular portion2(first woven component portion).

As illustrated inFIG.4, the wavily woven portion3is configured to include a row in which the plurality of first hooking portion41are arranged side by side in the circumferential direction, and a row without the first hooking portions41, in the axial direction of the meshed tubular portion2having the plurality of first intersecting points23. The first intersecting point23is arranged in the intersecting region34of the wavily woven portion3in the first hooking portion41, in the row in which the plurality of first hooking portions41are arranged side by side in the circumferential direction. The plurality of first intersecting points23are arranged side by side in the circumferential direction, in the row without the first hooking portions41.

According to the biodegradable stent1B of the third embodiment described above, in addition to the effects (1) to (5) described above, the following effects can be achieved.

(6) The rows of the plurality of first hooking portions41arranged in the circumferential direction are arranged so as to be spaced one row apart from each other in the axial direction. As a result, the rows without the first hooking portions41are provided, instead of packing the first hooking portions41in the axial direction of the biodegradable stent1B, whereby the length in the axial direction is unlikely to be restricted by the third fiber31and the fourth fiber32when the biodegradable stent1B is extended; therefore, loadability into a delivery system can be improved.

Fourth Embodiment

A biodegradable stent1C of a fourth embodiment will be described.FIG.5is a view illustrating the biodegradable stent1C according to the fourth embodiment.

As illustrated inFIG.5, the biodegradable stent1C of the fourth embodiment includes a plurality of loops35formed at the top of the peaks of the wave-shaped fourth fiber32. The loop35is formed into a loop shape surrounding the first fiber21, the second fiber22, the third fiber31, and the fourth fiber32, in which the first intersecting point23of the meshed tubular portion2is arranged in the intersecting region34of the wavily woven portion3.

The plurality of loops35may be consecutively provided at the top of the peaks of the wave-shaped fourth fiber32, or may be intermittently provided at the top of the plurality of peaks of the wave-shaped fourth fiber32. The loops35may not be configured to surround all of the first fiber21, the second fiber22, the third fiber31, and the fourth fiber32, or may be configured to surround only part of the first fiber21, the second fiber22, the third fiber31, and the fourth fiber32.

According to the biodegradable stent1C of the fourth embodiment described above, in addition to the effects (1) to (6) described above, the following effects can be achieved.

(7) The loops35are provided at the top of the peaks of the wave-shaped third fiber31and/or the wave-shaped fourth fiber32. Here, for example, in the case without the loops35at the top of the peaks of the wavily woven portion3, only an expansion force in the radial direction is applied to the wave-shaped third fiber31and the wave-shaped fourth fiber32of the wavily woven portion3; therefore, it is difficult to control the diametrical size of the biodegradable stent1C. In contrast, in the present invention, the loops35can apply a contraction force in the radial direction; therefore, the diametrical size of the biodegradable stent1C can be controlled.

Fifth Embodiment

Referring toFIGS.6and7, a biodegradable stent110according to fifth embodiment will be described.FIG.6is a perspective view illustrating the biodegradable stent110according to the fifth embodiment of the present invention.FIG.7is an enlarged view of the biodegradable stent110illustrated inFIG.6. In the biodegradable stent110illustrated inFIG.7, one side in the axial direction is referred to as a first direction D1, and the other side in the axial direction is referred to as a second direction D2. In the biodegradable stent110, one side in the circumferential direction is referred to as a third direction D3(left side ofFIG.7), and the other side in the circumferential direction is referred to as a fourth direction D4(right side ofFIG.7).

As illustrated inFIGS.6and7, the synthetic resin stent of the present embodiment is the biodegradable stent110composed of biodegradable fiber, and includes a first bent woven portion200(first woven component portion) and a second bent woven portion300(second woven component portion) arranged so as to be woven in the first bent woven portion200.

The first bent woven portion200is formed into a mesh, in which a plurality of fibers220repeatedly bent so as to extend in the axial direction are arranged in the circumferential direction and formed into a tubular structure. In the present embodiment, as illustrated inFIG.7, the fiber220configuring the first bent woven portion200is configured with a plurality of first fibers221and a plurality of second fibers222.

The plurality of first fibers221are formed of synthetic resin fiber repeatedly bent so as to be inclined at a predetermined angle with respect to the axial direction and extending in the axial direction. The plurality of first fibers221are repeatedly bent and extend in the axial direction so as to shuttle in a predetermined range of width in the circumferential direction of the first bent woven portion200.

The plurality of second fibers222are arranged to include a portion intersecting with the plurality of first fibers221, and formed of synthetic resin fiber repeatedly bent so as to shuttle and extending in the axial direction. The plurality of second fibers222are repeatedly bent and extend in the axial direction so as to shuttle in a predetermined range of width in the circumferential direction of the first bent woven portion200.

In the present embodiment, the plurality of first fibers221and the plurality of second fibers222are composed of a single fiber, folding back at the upper and lower ends of the first bent woven portion200in the axial direction. The plurality of first fibers221and the plurality of second fibers222are part of a single fiber. In other words, the first fiber221and the second fiber222are alternately arranged in the circumferential direction of the first bent woven portion200. The first bent woven portion200may be configured with a plurality of fibers.

More specifically, as illustrated inFIG.7, the first fiber221and the second fiber222both include a plurality of bent portions including peaks convex toward the third direction D3side and peaks convex toward the fourth direction D4side. As viewed from the side, the first fiber221and the second fiber222are arranged to have bent portions overlapping with each other and intersect in the first intersecting region223. The first fiber221and the second fiber222are formed such that the region surrounded by the first fiber221and the second fiber222is an opening having a substantially diamond shape in the first intersecting region223.

In the first intersecting region223, the first fiber221and the second fiber222may be arranged so as to overlap with each other as viewed from the side, and may be hooked by each other or may not be hooked by each other. In the present embodiment, the bent portions of the first fiber221and the second fiber222are hooked by each other in the upper end portion and the lower end portion of the biodegradable stent110in the axial direction, and are not hooked by each other in portions excluding the upper end portion and the lower end portion of the biodegradable stent110in the axial direction. The first intersecting regions223are arranged side by side in both the axial direction and the circumferential direction of the first bent woven portion200.

The first intersecting region223is formed such that the region surrounded by the first fiber221and the second fiber222is an opening. However, the size of the opening of the first intersecting region223is not limited. In the first intersecting region223, the first fiber221and the second fiber222may pull each other in the overlapping portion in a direction to shrink in size, so that the first fiber221and the second fiber222may be hooked by each other, whereby the region surrounded by the first221and the second fiber222may not be an opening.

The material of the first fiber221and the second fiber222is not limited in particular; however, a material having a high degree of rigidity is preferable. Examples of the biodegradable resin may include homopolymer, copolymer, or blend polymer composed of L-lactic acid, D-lactic acid, DL-lactic acid, glycolic acid, ε-caprolactone, or para-dioxanone. Non-biodegradable resin may also be used as long as the material has a high degree of rigidity. In particular, for example, polylactic acid (PLA) or poly-L-lactic acid (PLLA) is preferably used as the material of the fiber composing the first fiber221and the second fiber222. In the present embodiment, the first fibers221and the second fiber222are formed from polylactic acid (PLA), for example.

In the case of using biodegradable fiber as the fiber220, the diameter thereof is preferably 0.1 mm to 0.4 mm. When the diameter of the biodegradable fiber220is less than 0.1 mm, the strength of the biodegradable stent110tends to decrease. When the diameter of the biodegradable fiber20exceeds 0.4 mm, the diameter in the reduced diameter state increases, so that it tends to be difficult to load the biodegradable stent110into a fine tubular member such as a delivery system. The upper limit of the diameter of the biodegradable fiber20is further preferably 0.3 mm, from a perspective of loading into a delivery system having a small inner diameter. The lower limit of the diameter of the biodegradable fiber220is more preferably 0.2 mm, from a perspective of maintaining high strength. In the present embodiment, biodegradable fiber having a diameter of 0.2 mm and biodegradable fiber having a diameter of 0.3 mm are used as the fibers220.

As illustrated inFIGS.6and7, the second bent woven portion300is arranged so as to be woven into the first bent woven portion200, in which a plurality of circularly configured fibers230repeatedly bent so as to extend in the circumferential direction are arranged side by side in the axial direction. In the present embodiment, as illustrated inFIG.7, the fiber230configuring the second bent woven portion300is configured with a plurality of third fibers231and a plurality of fourth fibers232.

The plurality of third fibers231are formed of synthetic resin fiber repeatedly bent so as to be inclined at a predetermined angle with respect to the axial direction and extending in the circumferential direction. The plurality of third fibers231are repeatedly bent and extend in the circumferential direction so as to shuttle in a predetermined range of width in the axial direction of the second bent woven portion300.

The plurality of fourth fibers232are arranged to include a portion intersecting with the plurality of third fibers231, and formed of synthetic resin fiber repeatedly bent so as to extend in the circumferential direction. The plurality of fourth fibers232are repeatedly bent and extend in the circumferential direction so as to shuttle in a predetermined range of width in the axial direction of the second bent woven portion300.

More specifically, the third fiber231and the fourth fiber232both include a plurality of bent portions including peaks convex toward the first direction D1side and peaks convex toward the second direction D2side. As viewed from the side, the third fiber231and the fourth fiber232are arranged to have bent portions overlapping with each other and intersect in the second intersecting region233. In the second intersecting region233, the third fiber231and the fourth fiber232may be arranged so as to overlap with each other as viewed from the side, and may be hooked by each other or may not be hooked by each other. In the present embodiment, the bent portions of the third fiber231and the fourth fiber232are hooked by each other in the second intersecting region233, and the region surrounded by the third fiber231and the fourth fiber232is not an opening. The second intersecting regions233are arranged side by side in the axial direction and the circumferential direction of the second bent woven portion300.

The bent portions of the third fiber231and the fourth fiber232are hooked by each other, and the region surrounded by the third231and the fourth fiber232is not an opening in the second intersecting region233, which is not limited, however. The region surrounded by the third231and the fourth fiber232may be an opening in the second intersecting region233, and the size of the opening in the second intersecting region233is not limited.

Of the plurality of third fibers231and the plurality of fourth fibers232, the third fiber231or the fourth fiber232arranged at the upper end or the lower end of the biodegradable stent110is arranged so as to be wound around the first fiber221or the second fiber222of the first bent woven portion200.

The material of the synthetic resin fiber configuring the third fiber231and the fourth fiber232is not limited in particular; however, a material having a high degree of restorability is preferable. Examples of the biodegradable resin may include homopolymer, copolymer, or blend polymer composed of L-lactic acid, D-lactic acid, DL-lactic acid, glycolic acid, ε-caprolactone, or para-dioxanone. Non-biodegradable resin may also be used as long as the material has a high degree of restorability. For example, polydioxanone (PDO) is preferably used as the material of the third fiber231and the fourth fiber232.

In the case of using biodegradable fiber as the fiber230, the diameter thereof is preferably 0.1 mm to 0.4 mm. In the present embodiment, the biodegradable fiber having a diameter of 0.15 mm to 0.22 mm is used as the fiber230.

The first intersecting region223of the first bent woven portion200and the second intersecting region233of the second bent woven portion300are arranged so as to be at least partially overlapping with each other, as the biodegradable stent110is viewed from the side. The at least partially overlapping portion of the second intersecting region233of the second bent woven portion300and the second intersecting region233of the first bent woven portion200configures a hooking portion241. The biodegradable stent110of the present embodiment includes a plurality of hooking portions241, in which a row of the hooking portions241arranged in the circumferential direction is formed throughout the axial direction.

The configuration of the hooking portion241will be described.FIG.7is a view, in which the radial direction of the tubular biodegradable stent110inFIG.6is rearranged along the direction perpendicular to the paper (direction penetrating the paper) ofFIG.7. Therefore, the inside of the biodegradable stent110in the radial direction is the backside in the vertical direction of the paper ofFIG.7; and the outer side of the biodegradable stent110in the radial direction is the frontside in the vertical direction of the paper ofFIG.7. Some parts of the upper and lower ends of the biodegradable stent110in the axial direction are woven to prevent the fibers from coming apart. Here, the hooking portion241in the present embodiment will be described for the portions excluding the upper and lower ends of the biodegradable stent110in the axial direction.

As illustrated inFIG.7, the second intersecting region233of the third fiber231and the fourth fiber232is arranged in the first intersecting region223surrounded by the first fiber221and the second fiber222, in the hooking portion241.

The first fiber221and the second fiber222of the first bent woven portion200are arranged to include an opening in the first intersecting region223in the hooking portion241, in which a bent portion convex toward the third-direction D3side and a bent portion convex toward the fourth-direction D4side overlap with each other.

The third fiber231and the fourth fiber232of the second bent woven portion300are arranged in the state in which a bent portion convex toward the first direction D1side and a bent portion convex toward the second direction D2side are hooked by each other, in the second intersecting region233in the hooking portion241.

As illustrated inFIG.7, the bent portion convex toward the third direction D3side in the first fiber221and the second fiber222of the first bent woven portion200passes the backside of the third fiber231and the fourth fiber232on the apex side of the convex portion (third direction D3side), and passes the frontside of the third fiber231and the fourth fiber232on the opening side of the convex portion (fourth direction D4side), in the hooking portion241. The bent portion convex toward the fourth direction D4side in the first fiber221and the second fiber222passes the frontside of the third fiber231and the fourth fiber232on the apex side of the convex portion (fourth direction D4side), and passes the frontside of the third fiber231and the fourth fiber232on the opening side of the convex portion (third direction D3side). The bent portion convex toward the third direction D3side in the first fiber221and the second fiber222passes the frontside of the bent portion convex toward the fourth direction D4side.

The first fiber221, the second fiber222, the third fiber231, and the fourth fiber232are arranged as above, whereby, in the hooking portion241, the first fiber221is arranged in the state of being hookable by the third fiber231and the fourth fiber232, in relation to movement in a direction in which the mutually overlapping convex portion of the first fiber221and the second fiber222shrinks in size; and the second fiber222is arranged in the state of being hookable by the third fiber231and the fourth fiber232, in relation to movement in a direction in which the mutually overlapping convex portion of the first fiber221and the second fiber222shrinks in size.

The biodegradable stent110as described above may be manufactured by forming the second bent woven portion300and then forming the first bent woven portion200, or conversely, by forming the first bent woven portion200and then forming the second bent woven portion300.

The biodegradable stent110configured as described above is formed into a tubular structure with the first fiber221and the second fiber222repeatedly bent so as to be inclined with respect to the axial direction and extending in the axial direction in the first bent woven portion200, whereby the shape of the stent is maintained in the tubular structure. The second bent woven portion300is woven into the first bent woven portion200, the second bent woven portion300(third fiber231and fourth fiber232) is formed of synthetic resin fiber having a higher expansion force than the first bent woven portion200(first fiber221and second fiber222), and the bent portion thereof has a property of returning to a straight line. Therefore, the second bent woven portion300is woven and repeatedly bent so as to circle the first bent woven portion200in the circumferential direction, whereby the second300can apply a force to increase the diameter of the biodegradable stent110, and can enhance the expansion force. Thus, the expansion force of the biodegradable stent110in the radial direction can be strengthened to achieve self-expandability. Adherence to the wall of the gastrointestinal tract can be increased, and trackability to gastrointestinal motility can be achieved.

According to the biodegradable stent110of the fifth embodiment described above, the following effects can be achieved.

(8) The biodegradable stent110is configured to include the tubular first bent woven portion200composed of one or more fibers formed into a mesh, and the second bent woven portion300composed of one or more fibers annularly arranged so as to be woven into the first bent woven portion200; the first bent woven portion200is configured to include the plurality of first fibers221repeatedly bent so as to be inclined at a predetermined angle with respect to the axial direction and extending in the axial direction, the plurality of second fiber222repeatedly bent so as to be inclined at a predetermined angle with respect to the axial direction and extending in the axial direction and arranged to include a portion intersecting with the first fiber221, and the plurality of first intersecting regions223configured by intersections of the plurality of first fibers221and the plurality of second fibers222; the second bent woven portion300is configured to include the plurality of third fibers231repeatedly bent so as to be inclined at a predetermined angle with respect to the axial direction and extending in the circumferential direction; the plurality of fourth fiber232repeatedly bent so as to be inclined at a predetermined angle with respect to the axial direction and extending in the axial direction and arranged to include a portion intersecting with the third fiber231, and the plurality of second intersecting regions233configured by intersections of the plurality of third fibers231and the plurality of fourth fibers232; and the first intersecting region223and the second intersecting region233are arranged so as to be at least partially overlapping with each other.

As a result, the first fiber221and the second fiber222repeatedly bent so as to be inclined at a predetermined angle with respect to the axial direction and extending in the axial direction maintains the first bent woven portion200in the tubular structure, whereby the tubular structure of the biodegradable stent110is maintained. The second bent woven portion300is woven into the first bent woven portion200, and the first intersecting region223of the first bent woven portion200and the second intersecting region233of the second bent woven portion300are arranged to at least partially overlap with each other, whereby the second bent woven portion300can apply a force to increase the diameter, and can enhance the expansion force in the radial direction. Thus, the expansion force of the biodegradable stent110in the radial direction can be strengthened to achieve self-expandability. Adherence to the wall of the gastrointestinal tract can be increased, and trackability to gastrointestinal motility can be achieved. Therefore, the stent can ensure loadability into a fine tubular member such as a delivery system, in which migration of the stent is unlikely to occur after placement at the affected site of the natural tracts.

(9) In the configuration in which the first intersecting region223of the first bent woven portion200and the second intersecting region233of the second bent woven portion300are arranged to overlap each other, the first fiber221is arranged in the state of being hookable by one or more of the third fiber231and the fourth fiber232, in relation to movement in a direction in which the overlapping portion of the first fiber221and the second fiber222shrinks in size; and the second fiber222is arranged in the state of being hookable by one or more of the third fiber231and the fourth fiber232, in relation to movement in a direction in which the overlapping portion of the first fiber221and the second fiber222shrinks in size. As a result, the first fiber221and the second fiber222of the first bent woven portion200are hooked by any one of the third fiber231and the fourth fiber232, whereby displacement of the first intersecting region223and the second intersecting region233can be prevented.

A manufacture example and an example of the biodegradable stent of the first to fourth embodiments will be briefly described. In the present manufacture example, the biodegradable stent1A of the second embodiment (seeFIG.3) and the biodegradable stent1B of the third embodiment (seeFIG.4) are manufactured by braiding six PLA fibers (three fibers having a fiber diameter of 0.2 mm, and three fibers having a fiber diameter of 0.3 mm), and using PDO fiber having a fiber diameter of 0.15 mm to 0.22 mm to manufacture a wave shape. The biodegradable stent1C of the fourth embodiment (seeFIG.5) is manufactured by braiding six PLA fibers (having a diameter of 0.2 mm) and using PDO fiber to manufacture a wave shape with a fiber diameter of 0.30 mm to 0.349 mm, and a loop shape with a fiber diameter of 0.15 mm to 0.22 mm. The biodegradable stents1A,1B and1C are formed by weaving and winding the PLA fiber around the PDO fiber having a wave shape, whereby the shape of the stents is unlikely to collapse.

The biodegradable stents1A,1B and1C are manufactured under the conditions described above, whereby a stent loadable into a delivery system for the small intestine (φ2.8 mm) can be achieved. In the case of use in other gastrointestinal tracts, the diameter of the delivery system increases and the fiber diameter can increase as well, whereby a stent having further higher strength can be expected to be manufactured. The fiber diameter as well as the stent diameter and length may be arbitrary.

The biodegradable stents1A and1C thus prepared were used to conduct the following experiment. A tool manufactured in-house to simulate peristaltic movement was used to conduct a migration test on the stents. The tool for use in the present test simulates peristaltic movement, in which the stent was placed inside a tube mimicking the intestinal tract, and the tube was squeezed 10 times with a tool having a hole-diameter of 10 mm, assuming that the intestinal tract shrinks to φ10 mm due to peristaltic movement.

In an intestinal tract model in which the diameter of the intestinal tract expands to φ17 mm and shrinks to φ10 mm during peristaltic movement, the biodegradable stent1A of the second embodiment (stent having a length of 55 mm) moved by 35 mm. In an intestinal tract model in which the diameter of the intestinal tract expands to φ12 mm and shrinks to φ10 mm during peristaltic movement, the biodegradable stent1C of the fourth embodiment (stent having a length of 36 mm) moved by 10 mm. In the same intestinal tract models, a metallic stent (stent having a length of 110 mm) moved by 40 mm, suggesting that the biodegradable stents1A and1C of the second and fourth embodiments, respectively, have trackability to the intestinal tract.

The preferred embodiments of the synthetic resin stent of the present invention have been described above; however, the present invention is not limited to the embodiments and can be modified as appropriate.

For example, the biodegradable stent composed of biodegradable fiber has been used as a synthetic resin stent in the embodiments, which are not limited. In other words, nonbiodegradable synthetic resin fiber may be used to compose a stent.

The plurality of first hooking portions41are provided to the biodegradable stent1in its entirety, in the first embodiment. The first hooking portions41and the second hooking portions42are alternately provided, in the second embodiment. The plurality of first hooking portions41are arranged side by side in the circumferential direction, in the third embodiment. However, the present invention is not limited to the embodiments, and the first hooking portions41and/or the second hooking portions42may not be provided to the biodegradable stent in its entirety, or may be provided to part of the biodegradable stent.

In the embodiments described above, the loop35is provided at the top of the peaks of the wave-shaped fourth fiber32, which is not limited, and may be provided at the top of the peaks at the wave-shaped third fiber31.

EXPLANATION OF REFERENCE NUMERALS