JP5419569B2 - Stent - Google Patents

Description

  The present invention relates to a stent used to improve a stenosis or occlusion occurring in a living body.

  A stent is used as a medical device for inserting a stenosis or blockage of a lumen or body cavity (hereinafter referred to as a lumen or the like) of a blood vessel, urethra, or other organ in a living body to secure a space inside the lumen or the like. Are known. Balloon expandable stents are known as such stents.

  The balloon-expandable stent is inserted into the body, for example, in a state of being tightly fixed to the outside of the balloon, and the balloon is expanded in the body. This balloon expansion force deforms the balloon expandable stent to a substantially normal tube diameter at the target site. Thereby, the balloon expandable stent is tightly fixed inside the lumen of the body and expands the inside of the lumen (for example, see Patent Document 1).

  An example of a conventional balloon expandable stent will be described with reference to FIG. The stent 40 shown in FIG. 4 has a cylindrical shape, and a plurality of bases 41 formed in an annular shape by linear elements are arranged side by side in the axial direction, and are connected by being curved by the linear elements. The adjacent base portions 41 are connected by 42. The base 41 provides a rigid function for maintaining the stenosis and occlusion in an expanded state after placement in the living body, and the base 42 provides a flexible function required for placement in the living body. Fulfilled.

JP 2000-342893 A

  Here, in order to satisfactorily treat a stenosis part or an obstruction part, it is preferable that the stent is expanded more favorably. However, in order to improve the extensibility, if a configuration other than the configuration having the base portion and the connection portion is to be adopted, there is a risk that a great amount of cost and time may be required for the design. In addition, there is a concern that the effects of having the connection portion may be lost.

  This invention is made | formed in view of the said situation, and it aims at providing the stent which can perform the transition from a contracted state to an expanded state favorably.

  Hereinafter, means and the like effective for solving the above-described problems will be described while showing functions and effects as necessary.

  The stent according to the present invention includes a plurality of base portions arranged in the axial direction so as to be capable of transitioning from a contracted state to an expanded state when a force spreading from the central axis side to the outside is applied, and further integrating these base portions. In this way, a connecting portion for connecting a part of adjacent base portions is provided. And at least one part of the location where the said connection part is connected in each said base is formed thinly compared with the surrounding area | region where the base of the said connection part exists in the said area | region.

  According to this configuration, when the base portion transitions from the contracted state to the expanded state, the concentration of stress on the connection portion of the base portion to which the connecting portion is connected is suppressed. For example, a part of the base portion is orthogonal to the axial direction. The occurrence of inconveniences such as standing up in the direction of movement is suppressed. In addition, for example, in the base portion, the region where the connecting portion is connected and the region where the connecting portion is not connected can have the same degree of spread upon transition to the expanded state, and the base portion can be easily expanded uniformly. Thereby, in the stent including the base portion and the connection portion, it is possible to satisfactorily perform the transition from the contracted state to the expanded state.

  The region where the base of the connection portion exists may be formed so that the dimension in the direction in which the connection portion extends from the base is narrower than the surrounding region. As a result, it is expected that the concentration of stress at the location where the connection portion is connected in the transition to the expanded state can be suppressed by local deformation of the connection location in the range along the outer peripheral surface of the stent. Is done. Therefore, the possibility that a part of the base portion stands in a direction orthogonal to the axial direction is reduced.

  Each of the bases is formed by a linear element, and a first return part that returns the linear element toward the other end side at one end side in the axial direction, and the other in the axial direction. Second return portions returning toward the one end side on the end side are alternately arranged around the axis, and the connection portion is provided at one base portion between the adjacent end portions of the adjacent base portions. In the configuration formed to connect the outer periphery side of the first return portion and the outer periphery side of the second return portion in the other base portion, at least the return portion to which the connection portion is connected Some include a concave portion that is recessed toward the root side on the inner edge, and a region where the root of the connection portion exists is formed narrower than the surrounding region due to the presence of the concave portion. It is good to be.

  The length of the connection portion is established by connecting the outer periphery side of the first return portion in one base portion and the outer periphery side of the second return portion in the other base portion between the adjacent base portions of the adjacent base portions by the connection portion. It is possible to shorten the size. However, the return portion is a location that becomes a reference for deformation when the base portion transitions from the contracted state to the expanded state, and if a connecting portion is connected to the corresponding portion, stress concentration occurs during the transition to the expanded state. It becomes easy. On the other hand, at least a part of the return portion to which the connection portion is connected has a concave portion that is recessed toward the root side at the inner edge portion, so that the transition portion is in an expanded state. It is expected that the stress concentration at the location where the connection portion is connected can be suppressed by local deformation of the connection location in a range along the outer peripheral surface of the stent. Moreover, the recessed part is formed not in the root side of a connection part but in the inner periphery side of the return part. Thereby, stress concentration can be suitably suppressed as described above while firmly connecting the base portion and the connection portion.

  A recessed portion different from the recessed portion is formed at the inner edge of the return portion where the recessed portion is formed. Of these recessed portions, the recessed portion recessed toward the root side is the another recessed portion. The dent amount is preferably set larger than that of As a result, the concentration of stress on the return portion when transitioning to the expanded state is suppressed not only in the region where the root of the connection portion exists, but also in a different region, making stress concentration more suitable. Can be suppressed. Furthermore, among the two concave portions formed on the same return portion, the concave portion recessed toward the root side is set to have a larger concave amount than that of the other concave portion. Compared to the configuration in which the concave portion is set to the same degree as the former concave portion, the concentration of stress on the side where the root of the connecting portion exists is more emphasized while suppressing the strength of the return portion from being extremely reduced. be able to.

  The concave portion may be formed at a position biased toward an intermediate portion for connecting the adjacent return portions around the axis in the same base portion with respect to the vertex of the return portion to be formed. Thereby, a recessed part can be provided, suppressing the influence on the deformation | transformation of the base part on the basis of the vertex of a return part.

  The connecting portion is formed such that the root exists on the outer periphery side of the position biased to the intermediate portion side for connecting the returning portions adjacent to each other around the axis in the same base portion from the vertex of the returning portion to be connected. And at least a part of the return part to which the connection part is connected is based on the vertex of the return part so that the area where the root of the connection part exists is thinner than the area on the opposite side. A recess may be formed. Thereby, it is possible to make the extent of spread at the time of transition to the expanded state of the stent comparable in the region where the root of the connection portion exists in the return portion to which the connection portion is connected and in the region on the opposite side.

  At least a part of the intermediate portion for connecting the return portions adjacent to each other around the axis in the same base portion is formed so that the surface constituting the outer peripheral portion of the stent becomes wider toward the center side between the two return portions. Good. Thereby, it is possible to ensure a wide contact surface with the tube wall of the treatment target portion, and it is possible to suppress the occurrence of prolapse in which the tube wall of the treatment target portion enters between the linear elements. In addition, the entire intermediate part is not formed wide, but is formed so as to widen toward the center side between the two turning parts, while suppressing the influence on deformation based on the turning part. , Generation of prolapse can be suppressed.

  By the way, although it is different from the above purpose, when focusing on the effect that it is possible to suppress the occurrence of prolapse, as described above, “the middle for connecting the return portions adjacent to each other around the axis in the same base portion” At least a part of the site is formed so that the surface constituting the outer peripheral portion of the stent is widened toward the center between the two return portions ”, and“ the region where the root of the connecting portion exists is the region. It is also possible to apply to stents that do not have a “thinner configuration” or “recessed” configuration, and to self-expanding stents. It is also possible to do.

  The connection portion is formed by bending, and the connection portions adjacent to each other in the axial direction with the base portion interposed therebetween may have a reverse bending direction. The bending of the connecting part enhances the flexibility of the connecting part, and even if the axial dimension of the base is shortened when the stent transitions to the expanded state, The connecting portion is extended, and it is possible to suppress fluctuations in the overall length of the stent. Further, in the configuration in which the connection part is formed in such a manner, when the connection part is deformed during the transition to the expanded state of the stent, the shaft is connected to the pair of base parts connected by the connection part. A force to rotate around is applied from the connection portion. In this case, if it is assumed that the bends of all the connection portions are in the same direction, there is a concern that all the base portions rotate in the same direction and the stent is twisted. On the other hand, the connecting portions adjacent to each other in the axial direction are considered to have an opposite relationship in the direction of the rotational force applied to each base because the direction of the bending is opposite. . Thereby, it is suppressed that each base part rotates all in the same direction, and generation | occurrence | production of the twist at the time of expansion of a stent can be suppressed in connection with it.

  By the way, although it is different from the above purpose, when focusing on the effect that it is possible to suppress the occurrence of twisting at the time of expansion of the stent, as described above, `` the connection part is formed by bending, The configuration in which the connecting portions adjacent to each other in the axial direction across the base portion are in a reverse relationship of the bending direction is referred to as “the region where the root of the connecting portion exists is narrower than the surrounding region continuous with the region” It can be applied to a stent that does not have a “formed” configuration or a “recessed” configuration, and can also be applied to a self-expanding stent.

  Each of the bases is formed by a linear element, and a first return part that returns the linear element toward the other end side at one end side in the axial direction, and the other in the axial direction. Second return portions returning toward the one end side on the end side are alternately arranged around the axis, and the connection portion is provided at one base portion between the adjacent end portions of the adjacent base portions. In the structure formed to connect the outer periphery side of the first return portion and the outer periphery side of the second return portion in the other base portion, the return portion to which the connection portion is connected in each base portion. As a return part of the same kind adjacent to the part and the axis, the connection part is not connected, and the amount of protrusion outward in the axial direction is set smaller than that of the return part to which the connection part is connected It is good to have a return part. Thereby, even when the connection portion is deformed when the stent is in a contracted state, the possibility that the connection portion interferes with other return portions is reduced. Therefore, the transition to the contracted state of the stent can be performed well.

  By the way, although it is different from the above purpose, when attention is paid to the effect that the transition to the contracted state of the stent can be performed satisfactorily, as described above, “the non-returning return portion is provided. The configuration is applied to a stent that does not have a configuration in which the region where the base of the connection portion exists is formed thinner than the surrounding region that is continuous with the region or a configuration in which the concave portion is not provided. It is also possible to apply to a self-expanding stent.

(A) is the expanded view at the time of manufacture of the stent in 1st Embodiment, (b), (c) is the elements on larger scale of Fig.1 (a). (A) is the expanded view at the time of manufacture of the stent in 2nd Embodiment, (b) is the elements on larger scale of Fig.2 (a). It is the elements on larger scale at the time of manufacture of the stent in 3rd Embodiment. It is explanatory drawing for demonstrating the structure of the conventional stent.

(First embodiment)
Hereinafter, a first embodiment when the present invention is applied to a stent that transitions from a contracted state to an expanded state when an external force is applied from the central axis side by a balloon or the like will be described with reference to the drawings. FIG. 1A is a development view of the stent 10 according to the first embodiment at the time of manufacturing, and FIGS. 1B and 1C are partially enlarged views of FIG.

  The stent 10 is made of a metal material such as stainless steel or cobalt chrome alloy, and is manufactured by laser cutting a tube formed of the metal material. The stent 10 that has been subjected to the laser cutting has a tubular shape (or a tubular shape) as a whole and a mesh shape by linear elements. In addition, in the stent 10 of a non-deployment state, the both ends of the vertical direction of Fig.1 (a) will be in the continuous state. In the following description, the horizontal direction in FIG. 1A is referred to as the axial direction, and the vertical direction is referred to as the direction around the axis.

  As shown in FIG. 1 (a), the stent 10 includes a plurality of annular portions 11 that are continuous around an axis, and more specifically, an annular portion 11 that forms an annular shape, and the annular portions 11 are integrated. A plurality of connecting portions 12 for connecting a part of the adjacent annular portions 11 to each other are provided. The annular part 11 corresponds to a base part in the stent 10, and the annular parts 11 are arranged on the same axis.

  Each annular portion 11 has a shape in which a plurality of linear elements are folded back at both ends in the axial direction, and has a wavy shape continuous as a whole around the axis. Specifically, each annular portion 11 has a first return portion 13 that returns (or turns) toward the other end side at one end side in the axial direction, and toward the one end side at the other end side in the axial direction. The return (or folded back) second return portions 14 are alternately arranged around the axis.

  In the single annular portion 11, the vertex of each first return portion 13 is set so that the position in the axial direction is the same or substantially the same, and the vertex of each second return portion 14 is also in the axial direction. The positions are set to be the same or substantially the same. Moreover, each 1st return part 13 and each 2nd return part 14 are U-shaped, and the internal angle is less than 180 degree | times, even if any of an expanded state, a contracted state, and the state at the time of manufacture. More specifically, the angle is less than 90 degrees. In addition, the interior angle is set to be the same between the return portions 13 and 14 at least in the manufacturing state, and is also the same or substantially the same in the contracted state and the expanded state. Further, the pitch between the vertices of each first return portion 13 is the same or substantially the same, and the pitch between the vertices of each second return portion 14 is also the same or substantially the same. The pitch according to the first return portion 13 and the pitch according to each second return portion 14 are also the same or substantially the same. That is, the wavy line shape of each annular part 11 is set so that the period and amplitude are constant or substantially constant.

  In the state at the time of manufacture, the size is set between the expanded state and the contracted state, but the present invention is not limited to this, and the state at the time of manufacture may be the same size as the expanded state. It is also possible to adopt a configuration in which the state at the time of manufacture is a size expanded from the expanded state. The annular portions 11 have substantially the same shape. Further, the number of the annular portions 11 arranged in the axial direction is not limited to the number shown in FIG. 1A, and the function can be satisfactorily exhibited according to the purpose of use of the stent 10. For example, the specific number is arbitrary.

  Since each annular portion 11 is formed in a wavy line shape by a linear element, the radial direction of each annular portion 11 is adjusted through the adjustment of the wavy pitch by deformation based on each return portion 13, 14, particularly its apex. Can be contracted and expanded. Thereby, when attaching to the balloon catheter which is a medical instrument for conveyance, the transition (namely, deformation | transformation) from the state at the time of manufacture to a contracted state can be performed favorably. In addition, the transition from the contracted state to the expanded state (that is, deformation) can be favorably performed after transporting to the treatment target location.

  A plurality of connection portions 12 are provided between adjacent annular portions 11. In the present stent 10, the number of connecting portions 12 between adjacent annular portions 11 is two, but is not limited thereto, and may be three or more, and the function of the stent 10 is exhibited well. If it is, it may be one. In addition, each connecting portion 12 is arranged so that connecting portions 12 adjacent in the axial direction do not line up in the axial direction across one annular portion 11, and the interval between them is the axis of both connecting portions 12. The surrounding positions are set to be different from each other by at least one set of return portions 13 and 14.

  Each connection part 12 is provided so as to connect between end parts close to each other in adjacent annular parts 11. Specifically, among the adjacent annular portions 11, one end is connected (integrated) to the outer periphery side of the first return portion 13 in one annular portion 11, and the first in the other annular portion 11. The other end is connected (integrated) to the outer periphery side of the second return portion 14 located closest to the return portion 13. By connecting the connection portion 12 in this way, the length dimension of the connection portion 12 can be kept short. In addition, the connection location of the connection portion 12 is a position deviated from the apex of the return portions 13 and 14 in order to suppress the influence on the deformation of the annular portion 11 with respect to the return portions 13 and 14.

  Each connecting portion 12 is formed in a curved shape between both end portions. Specifically, as shown in FIG. 1B and FIG. 1C, it is formed in an S shape so that a plurality of curved portions 15 and 16 are generated at intermediate positions between both ends. As already described, each annular portion 11 is radially contracted and expanded when the stent 10 is used, and the axial length of each annular portion 11 varies during this transition. On the other hand, since the connecting portion 12 is formed in a curved shape as described above, the bending portions 15 and 16 can absorb the variation in the axial length of each annular portion 11, Variations in the overall length of the stent 10 can be suppressed.

  When the stent 10 is used, first, the stent 10 is arranged outside the balloon in a deflated state in the balloon catheter, and the stent 10 is shifted to the deflated state in that state, so that the stent 10 is in relation to the balloon. To fix. In this state, a balloon catheter is inserted into the living body from the distal end side, and the balloon is inflated at a treatment target site such as a stenosis or occlusion in the living body. The stent 10 is expanded to a substantially normal tube diameter at the treatment target site by the expansion force of the balloon. Thereby, the stent 10 is tightly fixed inside the lumen or the like in the body, and is held in an expanded state of the inside of the lumen or the like. In this case, the function of rigidity for expanding the treatment target portion and maintaining the expanded state is performed in each annular portion 11, and further, with respect to the axial direction required for performing placement in the treatment target portion. A flexible function in the intersecting direction is performed at the connection portion 12.

  Next, a configuration that can prevent the stent 10 from being twisted when transitioned from the contracted state to the expanded state will be described.

  Each connecting portion 12 is formed in a curved shape as described above. However, as shown in FIG. 1A, when compared with connecting portions 12 that are adjacent in the axial direction with one annular portion 11 interposed therebetween, The connection part 12 has a mirror image relationship. Specifically, in the connection portion 12a whose axial position is a predetermined position, the first bending portion 15a disposed on one end side, and the bending direction is opposite to that of the first bending portion 15a. Whereas the relationship with the second bending portion 16a is the relationship shown in FIG. 1B, the one end side of the connection portion 12b adjacent to the connection portion 12a with the annular portion 11 interposed therebetween. The relationship between the first bending portion 15b disposed on the second bending portion 16b and the second bending portion 16b disposed on the other end side in the reverse direction is the relationship shown in FIG. ing. When both are compared, the first bending portions 15a and 15b disposed on the one end side have opposite bending directions, and the second bending portions disposed on the other end side. The portions 16a and 16b are also reversely curved.

  In the transition from the contracted state to the expanded state, when each connecting portion 12 disposed at each position in the axial direction is deformed, a force for rotating the pair of annular portions 11 around the axis is generated. It is given from the connection unit 12. In this case, assuming that the curves of all the connecting portions 12 are in the same direction, there is a concern that the annular portions 11 are all rotated in the same direction and the stent 10 is twisted. On the other hand, when the connection parts 12 adjacent to each other in the axial direction have a mirror image relationship, it is considered that the direction of the rotational force applied to each annular part 11 is opposite for each adjacent annular part 11. Thereby, it can suppress that each cyclic | annular part 11 rotates all in the same direction, and generation | occurrence | production of the twist at the time of expansion of the stent 10 can be suppressed in connection with it.

  Next, a configuration capable of suppressing the occurrence of prolapse will be described.

  As shown in FIGS. 1B and 1C, the straight portion 17 between the first return portion 13 and the second return portion 14 in each annular portion 11 has both return portions 13 and 14. Both edges in the direction around the axis of the stent 10, that is, both edges sandwiching the contact surface to the tube wall of the treatment target site are tapered outward so that the width increases from the side toward the center in the linear direction. ing. Thereby, it is possible to ensure a wide contact surface with the tube wall of the treatment target portion, and it is possible to suppress the occurrence of prolapse in which the tube wall of the treatment target portion enters between the linear elements. In addition, the said width | variety means that the dimension of the direction orthogonal or substantially orthogonal to a radial direction becomes large.

  Moreover, the width dimension of each return part 13 and 14 can be made somewhat small by making it wide toward the center side of a linear direction instead of making the whole linear part 17 wide. Thereby, at the time of the transition between the expanded state and the contracted state, the wavy line pitch is well adjusted by the deformation with reference to the return portions 13 and 14.

  Note that the wide configuration as described above does not have to be applied to all of the straight portions 17, and is applied only to a portion of the straight portions 17 corresponding to places where the occurrence of prolapse is a concern. May be.

  Next, the structure which can suppress the stress concentration to the connection part of the connection part 12 and the annular part 11 is demonstrated.

  As already described, each connection portion 12 has one end connected to the first return portion 13 in one annular portion 11 of the adjacent annular portions 11 and the second return portion in the other annular portion 11. The other end is connected to the part 14. Specifically, as shown in FIGS. 1B and 1C, the connection portion 12 has one end of the connection portion 12 at the boundary between the first return portion 13 and the one linear portion 17 rather than the apex thereof. The other end of the connecting portion 12 is a position biased toward the boundary side of the second return portion 14 with respect to the one straight line portion 17 from the apex thereof, and is connected to the connecting portion 12. It is connected to the outside of the position near the one end of the.

  The region where each of these connection points exists is formed narrower than the region adjacent to the periphery of the annular portion 11 (that is, the dimension in the direction perpendicular or substantially perpendicular to the radial direction is small). Yes. Specifically, on the inner periphery side of the return portions 13 and 14 to which the connection portion 12 is connected, the portion on the opposite side to the root portion of the connection portion 12 across the linear element, A concave portion 18 is formed that is recessed toward the base side as compared with the adjacent region around the periphery.

  On the other hand, in the return portions 13 and 14 to which the connecting portion 12 is connected, the opposite region (the other boundary side) sandwiching the apex portion with respect to the region where the connecting portion 12 is connected (one boundary side) ) Is not formed with the recess 18. Therefore, in the return parts 13 and 14 to which the connection part 12 is connected, the area where the connection part of the connection part 12 exists is narrower than the area on the opposite side.

  In the configuration in which each annular portion 11 is contracted and expanded in the radial direction by deformation based on the return portions 13 and 14, and the connection portion 12 is connected to the return portions 13 and 14, the stent 10 During the transition from the contracted state to the expanded state, it is assumed that stress concentrates on the return portions 13 and 14. And when this stress becomes large, for example, it is assumed that the linear portion 17 of the annular portion 11 rises in the radial direction at the time of transition to the expanded state. On the other hand, since the recess 18 is formed as described above, the stress concentration is suppressed by deformation in the range along the outer peripheral surface of the stent 10 where the recess 18 is formed. It is suppressed that 17 stands up toward a radial direction.

  Further, when the stress as described above is concentrated, the return portions 13 and 14 to which the connection portion 12 is connected are moved to the expanded state of the stent 10 as compared to the return portions 13 and 14 to which the connection portion 12 is not connected. It is assumed that it becomes difficult to spread during the transition. Furthermore, in the same return part 13 and 14 to which the connection part 12 is connected, the connection part 12 is connected in comparison with the region where the connection part of the connection part 12 does not exist with reference to the vertex part of the return part 13 or 14. It is assumed that the region where the location exists becomes difficult to expand when the stent 10 transitions to the expanded state. When such an event occurs, there is a concern that the stent 10 cannot be uniformly expanded. On the other hand, since the concentration of stress is suppressed by forming the recesses 18 as described above, the stent 10 can be easily expanded uniformly.

  Moreover, the recessed part 18 is formed not on the base side of the connecting part 12 but on the inner periphery side of the return parts 13 and 14 which are edges on the opposite side. Thereby, concentration of stress can be suppressed as described above while firmly connecting the annular portion 11 and the connecting portion 12.

  Here, the amount of recess in the recess 18 is 1% to 15% with respect to the width dimension of the portion where the recess 18 is not formed in the return portions 13 and 14 (specifically, the region on the opposite side across the apex). A proportion amount is preferable, and a proportion of 5% to 10% is more preferable. In this case, it is possible to satisfactorily suppress the stress concentration in the region where the connection portion 12 is connected, and the connection strength between the annular portion 11 and the connection portion 12 can be sufficient when the stent 10 is used. . In FIG. 1, the size of the recess 18 is shown slightly larger than the actual size.

  As described above, the stent 10 is contracted by forming the concave portion 18 that is recessed toward the base side of the connecting portion 12 at the inner edge of the return portions 13 and 14 to which the connecting portion 12 is connected. Concentration of stress on the return portions 13 and 14 in the transition from the state to the expanded state is suppressed. Thereby, it is suppressed that the straight line part 17 stands up in the radial direction at the time of the transition to the expanded state, and the transition from the contracted state to the expanded state can be favorably performed. Furthermore, it becomes easy to expand the stent 10 uniformly.

  In addition, the bending direction of the connecting portions 12 adjacent to each other in the axial direction is reversed, so that the stent 10 can be prevented from being twisted when the stent 10 transitions to the expanded state. Also from this point, the transition from the contracted state to the expanded state can be favorably performed.

(Second Embodiment)
Another type of stent 20 will be described with reference to FIG. FIG. 2A is a development view when the stent 20 is manufactured, and FIG. 2B is a partially enlarged view of FIG.

  In the present stent 20, as shown in FIG. 2A, the connecting portions 24 that are adjacent in the axial direction across the annular portion 21 are connected to the first return portion 22 and the second portion adjacent to each other around the axis in the annular portion 21. Are connected to each of the return portions 23. Thereby, compared with the stent 10, the positions of the connecting portions 24 adjacent in the axial direction are set closer.

  As shown in FIG. 2B, the connection portion 24 is connected to the outer periphery side of each of the first return portion 22 and the second return portion 23 that are adjacent in the axial direction. Each return portion 22, 23 has boundary portions 22 a, 23 a continuing to one straight line portion 25 and boundary portions 22 b, 23 b continuing to the other straight line portion 26. One end of the connecting portion 24 is connected to one outer periphery side of both the boundary portions 22 a and 22 b in the first return portion 22, and the other end is connected to both boundary portions 23 a and 23 a in the second return portion 23. 23b is connected to the outer periphery side of the boundary portion 23b on the side close to the boundary portion 22b to which one end of the connection portion 24 is connected. In addition, although the combination of the boundary part to which the connection part 24 is connected is different for every connection part 24 adjacent to the axial direction across the annular part 21, the combination of the boundary part may be the same.

  In each return portion 22, 23, the inner side of the boundary portion 22 b, 23 b on the side to which the connection portion 24 is connected is recessed first toward the base side of the connection portion 24 as compared to the adjacent region around it. The recess 27 is formed. In addition, a second concave portion 28 is formed in the boundary portions 22a and 23a on the side where the connection portion 24 is not connected. The second concave portion 28 is recessed from the inner periphery side to the outer periphery side of the return portions 22 and 23. The first concave portion 27 and the second concave portion 28 have different dent amounts, and the first concave portion 27 has a wider range in which the concave portion is formed than the second concave portion 28. In addition, the depth of the dent is set large.

  Further, in the stent 20, a third recess 29 that is recessed from the inner side toward the outer side is also formed in each of the boundary portions 22 a, 22 b, 23 a, 23 b of the return portions 22, 23 to which the connection portion 24 is not connected. Has been. The amount of recess of the third recess 29 is approximately the same as that of the second recess 28.

  As described above, not only the first concave portion 27 but also the second concave portion 28 is formed, so that the boundary portion on the side where the root of the connecting portion 24 exists in the return portions 22 and 23 to which the connecting portion 24 is connected. The stress concentration is not only caused by the deformation along the outer peripheral surface of the stent 20 at 22b and 23b but also by the deformation along the outer peripheral surface of the stent 20 at the boundary portions 22a and 23a on the side where the root of the connecting portion 24 does not exist. It can be suppressed.

  In addition, since the first recess 27 is set to have a greater amount of recess than the second recess 28, the recess amount of the second recess 28 is set to be approximately the same as that of the first recess 27. In contrast, the concentration of stress on the side where the root of the connecting portion 24 is present can be more intensively suppressed while suppressing the strength of the return portions 22 and 23 from being extremely lowered.

  Further, in the configuration in which the second recess 28 is formed as described above, the stent 20 is in an expanded state because the third recess 29 is formed in the return portions 22 and 23 to which the connection portion 24 is not connected. When the transition is made, the extent of expansion of the boundary portions of the return portions 22 and 23 to which the connection portion 24 is not connected is determined so that the second recess 28 of the return portions 22 and 23 to which the connection portion 24 is connected is formed. It is about the same as the border on the other side. Therefore, it becomes easy to expand the stent 20 uniformly.

  The configuration in which the connecting portions 24 adjacent in the axial direction across the annular portion 21 are in a mirror image relationship is the same as that of the stent 10. Further, when comparing the first concave portion 27 and the second concave portion 28, the depth of the concave is set larger in the former than in the latter while making the range where the concave is formed in both the same or substantially the same. It is also possible to adopt a configuration in which the depth of the recess is the same or substantially the same in both, and the range in which the recess is formed wider than the latter is set in the former. Even in this case, the amount of depression of the first recess 27 can be set larger than that of the second recess 28.

(Third embodiment)
Another type of stent 30 will be described with reference to FIG. FIG. 3 is a partially enlarged view of the stent 30 at the time of manufacture.

  As shown in FIG. 3, the stent 30 is set so that the wavy shape of the adjacent annular portions 34 has an antiphase relationship in the state at the time of manufacture. That is, the first return portions 32 are set not to line up in the axial direction in the adjacent annular portions 34, and the second return portions 33 are set not to line up in the axial direction. As a result, the wavy line shape of the adjacent annular portions 34 in the expanded state of the stent 30 is likely to have the same phase relationship. Since the adjacent annular portions 34 in the expanded state have the same phase relationship, there is a portion where the distance between the linear elements (or struts) constituting the annular portion 34 is locally larger than when the phases are shifted. It becomes difficult to exist. Thereby, in a state where the stent 30 is indwelled at the treatment target location, occurrence of prolapse in which the tube wall of the treatment target location enters between the linear elements is suppressed.

  In the stent 30, the connection portion 31 is connected to the outside of each of the first return portion 32 and the second return portion 33 that are adjacent in the axial direction. In this case, the return portions 32b and 33b that are adjacent to each other around the axis with respect to the return portions 32a and 33a to which the connection portion 31 is connected and that are not connected to the connection portion 31 are the return portions 32a to which the connection portion 31 is connected. , 33a, the projection amount in the axial direction is small.

  Specifically, when compared between the first return portions 32a and 32b adjacent to each other around the axis, the first return portions 32a adjacent to each other as compared to the first return portion 32a to which the connection portion 31 is connected. In the return portion 32b, the protruding amount toward the second return portions 33a and 33b in the annular portion 34 facing in the axial direction is suppressed to be small by X1. Further, when compared between the second return portions 33a and 33b adjacent to each other around the axis, the second return portion adjacent to the periphery of the axis compared to the second return portion 33a to which the connection portion 31 is connected. In 33b, the protruding amount toward the first return portions 32a and 32b in the annular portion 34 facing in the axial direction is suppressed to be small by X2. In addition, although X1 and X2 are the same, it is good also as a different structure.

  In addition, there are a pair of return portions adjacent to each other around the axis with respect to the return portions 32a and 33a to which the connection portion 31 is connected. The protrusion amount is not suppressed in both the return portions, but only the return portions 32b and 33b on the side close to the connection portion 31 in the contracted state are suppressed.

  In the case of the present stent 30, the first return portion 32a and the second return portion 33a to which the connection portion 31 is connected do not face each other in the axial direction during manufacturing, and the return portion 32a to which the connection portion 31 is connected. , 33a is opposed to the return portions 32b, 33b adjacent to each other around the axis in the axial direction. Further, the connecting portion 31 is substantially S-shaped, and in a contracted state, the curved portions 35 and 36 swell toward the adjacent return portions 32b and 33b. On the other hand, the protrusion amount of the adjacent return portions 32b and 33b corresponding to the swelled sides of the curved portions 35 and 36 is suppressed.

  As described above, the protruding amount in the axial direction of the return portions 32b and 33b adjacent to each other around the axis with respect to the return portions 32a and 33a to which the connection portion 31 is connected is suppressed, so that the stent 30 is brought into a contracted state. In this case, the adjacent return portions 32b and 33b can be prevented from interfering with the connection portion 31 in which the bulges of the bending portions 35 and 36 are increased. Therefore, the transition of the stent 30 from the manufacturing state to the contracted state can be performed satisfactorily.

  Also in the present stent 30, the return portions 32 a and 33 a to which the connection portion 31 is connected are formed with a recess 37 that is recessed from the inner periphery side toward the root side of the connection portion 31. However, when attention is paid to the effect that the transition of the stent 30 from the manufacturing state to the contracted state can be performed satisfactorily, the corresponding configuration may be applied to a stent that does not include the recess 37.

(Other embodiments)
The present invention is not limited to the description of the above embodiments, and may be implemented as follows, for example.

  (1) In each of the above embodiments, the recesses 18, 27, 28, 37 are formed in all the portions of the annular portions 11, 21, 34 where the connection portions 12, 24, 31 are connected. If the degree of stress concentration is different at the locations, the recesses 18, 27, 28, 37 may be formed only at the connection locations where stress concentration is likely to occur.

  (2) Instead of forming the recesses 18, 27, 28, and 37 at the locations where the connecting portions 12, 24, and 31 are connected, the connection location is formed narrower than the surrounding region by a tapered shape or the like. Also good. However, in order to narrow down the locations where deformation is allowed in order to suppress stress concentration, it is preferable that the recesses 18, 27, 28, 37 are formed as in the above embodiments.

  In addition, although there is a possibility that the strength of the connection portion is reduced as compared with each of the above embodiments, if the purpose is only to suppress the concentration of stress, a recess is formed on the base side of the connection portions 12, 24, 31. May be. Moreover, in the structure by which the connection parts 12, 24, and 31 are connected to the vertex of the return parts 13, 14, 22, 23, 32, and 33, the recessed part may be formed with respect to the said vertex.

  (3) Rather than stents 10, 20, and 30 having annular portions 11, 21, and 34 having an annular shape as a base portion, a stent having an elliptical base portion and a base portion having a discontinuous annular shape such as a C shape You may apply the characteristic structure in each said embodiment with respect to a stent. Moreover, you may apply the characteristic structure in said each embodiment with respect to the structure where the axis line of the annular parts 11, 21, and 34 cross | intersect with the axis line of the stent 10,20,30.

  (4) Stents having connection portions in which only one bending portion is formed, or three or more bending portions, rather than stents 10, 20, and 30 having connection portions 12, 24, and 31 having an S-shape. The characteristic configuration in each of the above embodiments may be applied to a stent having a connected portion. Even in this case, in order to suppress the twisting of the stent at the time of transition to the expanded state, it is preferable that the relationship between the directions of the curved portions of the connecting portions adjacent in the axial direction is reversed. Moreover, you may employ | adopt a bending part instead of a bending part as a structure for bending the connection parts 12,24,31.

  Moreover, you may form the connection parts 12, 24, and 31 linearly with the material which expands / contracts, such as a synthetic rubber. In this case, for example, if the connection parts 12, 24, and 31 are held in a stretched state, a load is continuously applied to the connection part. By applying a configuration that suppresses the concentration of stress at connection points such as 18, 27, and 28, it is possible to appropriately cope with a state in which a load is continuously applied.

  (5) The characteristic configuration described in each of the above embodiments may be applied to a stent formed of a biodegradable material, and may be applied to a stent that can release a drug. Alternatively, the present invention may be applied to a stent having neither biodegradability nor drug release.

  (6) When attention is paid to the effect that the stent 10 can be prevented from being twisted at the time of transition to the expanded state, the recesses 18, 27, 28, 37 are formed in the respective embodiments in the corresponding configurations. The present invention may be applied to a stent that is not made or a self-expanding stent. Further, when attention is paid to the effect that generation of prolapse can be suppressed, a configuration corresponding to that in each of the above embodiments is a stent in which the recesses 18, 27, 28, 37 are not formed, or a self-expanding stent. You may apply to.

  DESCRIPTION OF SYMBOLS 10 ... Stent, 11 ... The annular part as a base part, 12 ... Connection part, 13 ... 1st return part, 14 ... 2nd return part, 15, 16 ... Curved part, 17 ... Straight part, 18 ... Recessed part, 20 ... Stent, 21 ... annular part as base, 22 ... first return part, 23 ... second return part, 24 ... connecting part, 25,26 ... straight part, 27 ... first recess, 28 ... second , 30 ... stent, 31 ... connection portion, 32 ... first return portion, 33 ... second return portion, 34 ... annular portion as a base, 35, 36 ... curved portion, 37 ... recess.

Claims (6)

A plurality of bases are arranged side by side in the axial direction so as to be able to transition from a contracted state to an expanded state when a force spreading from the central axis side to the outside is applied. A stent provided with a connecting part for connecting parts,
Each of the base portions is formed by a linear element, and a first return portion that returns the linear element toward the other end side at one end side in the axial direction, and the other in the axial direction. Second end portions that are returned toward the one end side on the end side are alternately arranged around the axis, and the first return portion and the second return portion adjacent to each other around the axis are connected. Has an intermediate site for
The connecting portion connects between an outer periphery side of the first return portion in one base portion and an outer periphery side of the second return portion in the other base portion between the adjacent end portions of the adjacent base portions. Is formed,
At least a part of the return portion to which the connection portion is connected in each of the base portions includes a concave portion that is recessed toward the root side at an inner periphery side edge portion, and due to the presence of the concave portion, the root of the connection portion is provided. The area where there is is formed thinner than the surrounding area that continues to the area ,
In the first return portion, one end portion in the axial direction is a top portion of the return portion,
In the second return part, the other end part in the axial direction is a top part of the return part,
The connecting portion is formed so that a root exists on the outer periphery side of the position biased to the intermediate portion side than the top portion of the returning portion in the returning portion to which the connecting portion is connected,
At least a part of the return portion to which the connection portion is connected is such that the region where the base of the connection portion exists is narrower than the region on the opposite side with respect to the top portion of the return portion. A stent characterized in that is formed . In the return portion where the recess is formed, no recess is formed in the opposite region,
The amount of recesses of the recesses is set to an amount of 5 to 10% with respect to the width dimension in the direction orthogonal to the stent radial direction in the opposite region. Stent. On the inner periphery side edge of the return portion where the concave portion is formed, a concave portion different from the concave portion is formed in the region on the opposite side,
Of these recesses, a recess that is recessed toward the root side is set to have a larger amount of recess than the other recess, so that the region where the root of the connection portion exists is the opposite region. The stent according to claim 1 , wherein the stent is thinner . At least a part of the intermediate portion is formed so that a surface constituting the outer peripheral portion of the stent is widened toward a central side between both turn-back portions adjacent to the intermediate portion. Item 4. The stent according to any one of Items 1 to 3 . Together are formed by bending the connecting portion, any one of claims 1 to 4 connecting portions adjacent in the axial direction across the base orientation of the bend is characterized in that has a reverse relationship 1 The stent according to 1. As barbs before Symbol same type adjacent to the return portion and the shaft around which the connecting portions are connected at each base the connecting portion is not connected, in and compared with the return portion connecting portion is connected axes The stent according to any one of claims 1 to 5 , further comprising a non-connected return portion that is set to have a small amount of protrusion outward in the direction.

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