Patent Publication Number: US-2021186724-A1

Title: Stent

Description:
The present invention relates to a stent. Priority is claimed on PCT/JP2018/033291, filed Sep. 7, 2018, and PCT/JP2019/034701, filed on Sep. 4, 2019, the contents of which are incorporated herein by reference. 
    
    
     BACKGROUND 
     In recent years, stent placement has been used to expand and hold a lumen of a tubular organ by placing a stent made of a wire rod (wire) or the like in a diseased part in which a stenosis or occlusion has occurred in the lumen of the tubular organ in the living body. 
     A stent having self-expandability (self-expandable stent) is delivered by a delivery system to a diseased part in which a stenosis or occlusion has occurred in a reduced diameter state. The stent released from the delivery system expands in diameter by self-expandability to expand the stenosis and occlusion. 
     In many cases, the lumen in which such a stent is placed is bent, and thus the stent needs to have a function of maintaining the shape corresponding to the shape of the bent lumen (pipeline shape-maintaining function). In a case where the stent having the pipeline shape-maintaining function is placed in a bent lumen, the stent can maintain a shape corresponding to the shape of the bent lumen without returning to the original shape of the stent due to reaction force. 
     The expansion mechanism using the shape memory alloy disclosed in Japanese Patent No. 3708923 can expand the stenosis part of the body. The expansion mechanism disclosed in Japanese Patent No. 3708923 has a “meshing portion” that is extendible and contractible in the axial direction, and can maintain the shape corresponding to the shape of the lumen regardless of the lumen shape of the stenosis part. 
     SUMMARY 
     A first aspect relates to a stent that expands a lumen of a living body, the stent including a first tubular unit that has a cylindrical tubular shape and a mesh circumferential surface; and a second tubular unit that has a cylindrical tubular shape and a mesh circumferential surface, and is connected to the first tubular unit in a longitudinal axis direction of the stent. The first tubular unit has a first-first direction bent portion which is bent to be convex toward the first direction side that is one side of the longitudinal axis direction, the second tubular unit has a second-second direction bent portion which is bent to be convex toward the second direction side that is the other side of the longitudinal axis direction, and the first-first direction bent portion and the second-second direction bent portion form a first connecting portion that is connected so as to be relatively movable. 
     A second aspect relates to a stent including a first region having a cylindrical tubular shape; a second region that has a cylindrical tubular shape and is connected to the first region in a longitudinal axis direction of the stent; a first-first direction bending portion provided at the first region and which is bent to be convex toward the first direction side that is one side of the longitudinal axis direction; a second-second direction bending portion provided at the second region and which is bent to be convex toward the second direction side that is the other side of the longitudinal axis direction; and a first connecting portion configured to be formed by connecting the first-first direction bending portion and the second-second direction bending portion so as to be relatively movable. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing an overall configuration of a stent according to a first embodiment. 
         FIG. 2  is a developed view of the stent which is developed in a circumferential direction. 
         FIG. 3  is a diagram showing a weaving method of a tubular unit of the stent. 
         FIG. 4  is a diagram showing a weaving method of another tubular unit that is connected from a second direction side to the woven tubular unit positioned on a first direction side. 
         FIG. 5  is an enlarged view of a portion indicated by a dashed line in  FIG. 2 . 
         FIG. 6  shows the bending stent. 
         FIG. 7  shows the stent in a case of being released from a delivery system. 
         FIG. 8  is a developed view of a connecting portion of a stent according to a second embodiment which is developed in a circumferential direction. 
         FIG. 9  is a diagram showing a modification example of a connecting wire of the stent. 
         FIG. 10  is a diagram showing an overall configuration of a stent according to a third embodiment. 
         FIG. 11  is an enlarged view of a part of the stent shown in  FIG. 10 . 
         FIG. 12  is a diagram showing an overall configuration of a stent according to a fourth embodiment. 
         FIG. 13  is a diagram showing an overall configuration of a stent according to a fifth embodiment. 
         FIG. 14  is a diagram showing an overall configuration of a stent according to a sixth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
     A first embodiment will be described with reference to  FIGS. 1 to 7 . 
       FIG. 1  is a diagram showing an overall configuration of a stent  100  according to the present embodiment.  FIG. 1  shows an overall configuration of the stent  100  in a state of being self-expanded.  FIG. 2  is a developed view of the stent  100  which is developed in the circumferential direction. 
     The stent  100  is formed by weaving wires and has a cylindrical tubular shape. The stent  100  is placed in the body lumen of alimentary system in the body, such as the bile duct, esophagus, duodenum, small intestine, and large intestine. The stent  100  is mainly used to expand and hold the lumen. The stent  100  according to the present embodiment is not a so-called covered stent in which an outer circumferential surface side thereof is coated with a resin film or the like, but an uncovered stent that is not coated with the film or the like. However, the stent  100  can also be used as a covered stent by being coated with a resin film or the like. 
     The stent  100  includes a plurality of tubular units  1  and a connecting portion  2 , as shown in  FIG. 1 . The plurality of tubular units  1  are arranged in a longitudinal axis direction, and the adjacent tubular units  1  are connected by the connecting portion  2 . In the following description, one side of the longitudinal axis direction of the stent  100  is referred to as a “first direction D 1 ”, and the other side of the longitudinal axis direction of the stent  100  is referred to as a “second direction D 2 ”. 
     The tubular unit (tubular portion)  1  is formed in a cylindrical tubular shape having a mesh on the circumferential surface by a wire repeatedly bent and obliquely extending in the circumferential direction. The tubular unit  1  includes a first bent part  11  in which the wires are bent, a second bent part  12  in which the wires are bent, and a straight crossing portion  13  in which the wires cross each other in a straight line. 
     The first bent part (bending portion on the first direction side)  11  is a convex portion in which the wire obliquely extending in the circumferential direction is folded and bent in the longitudinal axis direction to be convex toward a first direction D 1  side, and a plurality of the first bent parts  11  are formed in an end portion of the first direction D 1 . The plurality of first bent parts  11  are arranged in the circumferential direction. 
     The second bent part (bending portion on second direction side)  12  is a convex portion in which the wire obliquely extending in the circumferential direction is folded and bent in the longitudinal axis direction to be convex toward a second direction D 2  side, and a plurality of the second bent parts  12  are formed in an end portion of the second direction D 2 . The plurality of second bent parts  12  are arranged in the circumferential direction. 
     The connecting portion (first connecting portion)  2  is a portion in which the adjacent tubular units  1  are connected in the longitudinal axis direction, and the first bent part  11  of the tubular unit  1  on the second direction D 2  side and the second bent part  12  of the tubular unit  1  on the first direction D 1  side are formed to cross each other. In the connecting portion  2 , since the first bent part  11  and the second bent part  12  cross each other in a “hook shape” in a radial direction and the longitudinal axis direction, the adjacent tubular units  1  are inseparably connected so as to be relatively movable. 
       FIG. 3  is a diagram showing a weaving method of the tubular unit  1 . 
     The tubular unit  1  is manufactured using a known manufacturing jig, as shown in  FIG. 5  in Japanese Patent No. 3708923, for example. The manufacturing jig is formed of a cylindrical main body and a plurality of pins P erected on the outer circumferential surface of the main body.  FIG. 3  is a developed view of the outer circumferential surface of the main body of the manufacturing jig in a plane. The pins P are arranged in the circumferential direction in two rows. 
     As shown in  FIG. 3 , the wires forming the tubular unit  1  obliquely extend in the circumferential direction from a start position S, and repeatedly form the first bent part  11  and the second bent part  12 . The wire loops to form a first loop in the circumferential direction, and then further loops to form a second loop (portion I shown in  FIG. 3 ). 
     The wire of the second loop (shown by a solid line in  FIG. 3 ) obliquely extends in the circumferential direction, and repeatedly forms the first bent part  11  and the second bent part  12 . The first bent part  11  formed by the wire of the second loop is formed between the first bent parts  11  formed by the wire of the first loop. The second bent part  12  formed by the wire of the second loop is formed between the second bent parts  12  formed by the wire of the first loop. 
     The wire of the second loop forms the straight crossing portion  13  crossing the wire of the first loop. The wire loops to form a second loop in the circumferential direction, and then further loops to form a third loop (portion II shown in  FIG. 3 ). 
     The wire of the third loop (shown by a dashed line in  FIG. 3 ) obliquely extends in the circumferential direction, and repeatedly forms the first bent part  11  and the second bent part  12 . The first bent part  11  formed by the wire of the third loop is formed between the first bent parts  11  formed by the wire of the first loop and the first bent part  11  formed by the wire of second loop. The second bent part  12  formed by the wire of the third loop is formed between the second bent parts  12  formed by the wire of the first loop and the second bent part  12  formed by the wire of second loop. 
     The wire of the third loop forms the straight crossing portion  13  crossing the wire of the first loop and the wire of the second loop. The wire loops to form the third loop in the circumferential direction, and then is woven to an end point E. 
     Both end portions of the wire positioned at the start position S and the end point E are connected using a joining method, such as caulking, laser welding, or brazing. In  FIG. 3 , the wire joins the end portion of the second bent part  12 , but the wire W may join the straight line portion instead of the end portion of the first bent part  11  or the second bent part  12  in consideration that stress concentration is likely to occur at the end portion. 
     The wire is made of a super-elastic alloy containing Nitti as a main material. The super-elastic alloy containing Nitti as the main material is not permanently deformed at the time of weaving, and the woven shape is maintained by applying heat treatment in the woven state. 
     The tubular unit  1  woven as described above configures two straight crossing portions  13  in a line segment of the wire connecting the first bent part  11  and the second bent part  12 , as shown in  FIG. 3 . 
       FIG. 4  is a diagram showing a weaving method of another tubular unit  1  (hereinafter, referred to as a “tubular unit  1 B”) connected from the second direction D 2  side to the woven tubular unit  1  (hereinafter, referred to as a “tubular unit  1 A”) positioned on the first direction D 1  side. In  FIG. 4 , the tubular unit  1 A is indicated by a two-dot dashed line. 
     In a case where the tubular unit  1 B is manufactured using the manufacturing jig, some of the pins are used in a case where the tubular unit  1 A is shared, as shown in  FIG. 4 . Specifically, in  FIG. 4 , among the pins P arranged in the circumferential direction in two rows, the pins P arranged in one row on the first direction side are shared. 
     As shown in  FIG. 4 , the wires forming the tubular unit  1 B obliquely extend in the circumferential direction from a start position S, and repeatedly form the first bent part  11  and the second bent part  12 , as in the tubular unit  1 A. 
       FIG. 5  is an enlarged view of a portion indicated by the dashed line in  FIG. 2 . 
     In a case of forming the first bent part  11 , the wire forming the tubular unit  1 B cross the second bent part  12  of the tubular unit  1 A in a “hook shape” in the radial direction and the longitudinal axis direction to form the connecting portion  2 . 
     As in the tubular unit  1 A, the wire loops to form the third loop in the circumferential direction, and then is woven to an end point E. Both end portions of the wire positioned at the start position S and the end point E are connected using a joining method, such as caulking, laser welding, or brazing. 
     The tubular unit  1 A and the tubular unit  1 B are inseparably connected by the connecting portion  2  so as to be relatively movable. The tubular unit  1 A and the tubular unit  1 B is connected without adding a new connecting member. 
     Other tubular units  1  are connected by the connecting portion  2  by the same method as that used to connect the adjacent tubular units  1 , the tubular unit  1 A, and the tubular unit  1 B by means of the connecting portion  2 . The stent  100  is formed by connecting all of the tubular units  1 . 
     Hereinafter, the operation of the stent  100  will be described. 
     The stent  100  is stored in the delivery system in a reduced diameter state and delivered to the affected area in which a stenosis or occlusion has occurred. The stent  100  released from the delivery system expands in diameter by self-expandability to expand stenosis and occlusion. The stent  100  has a simple configuration, and thus the storage diameter can be reduced in a case where the stent  100  is stored in the delivery system. 
       FIG. 6  shows the bending stent  100 . The connecting portion  2  connects the adjacent tubular units  1  in a hook shape, and the adjacent tubular units  1  is capable of moving relatively each other. Hereinafter, the deformation of the connecting portion  2  caused due to such a movement of the adjacent tubular units  1  is referred to as “slip-deformation”. 
     In the stent  100 , in a case where the entire stent  100  is bent with respect to the longitudinal axis, as shown in  FIG. 6 , the connecting portion  2  arranged in the circumferential direction is “slip-deformed” and bent without “elastic deformation” of the wire that is made of super-elastic alloy. As a result, the stent  100  does not return to its original shape, and is capable of maintaining a bent shape. That is, the stent  100  has a function of maintaining a shape corresponding to the shape of the bent lumen (pipeline shape-maintaining function). 
     As shown in  FIG. 1 , in the stent  100 , the connecting portions  2  are arranged in a row in the circumferential direction between the straight crossing portions  13  arranged in two rows in the circumferential direction. That is, the connecting portion  2  that can be slip-deformed and the straight crossing portion  13  that cannot be slip-deformed are disposed in the longitudinal axis direction at a ratio of 1 to 2. Therefore, the entire stent  100  is likely to be “slip-deformed”, and even in a case where the lumen is significantly bent, the shape thereof corresponding to the shape of the lumen is capable of being maintained. 
       FIG. 7  shows the stent  100  in a case of being released from the delivery system. In a case where the stent  100  is released from an outer sheath A at a distal end of the delivery system, since a spread angle  0  of the stent  100  is capable of being reduced, the stent  100  is capable of being easily restored (recaptured) in the delivery system. That is, the stent  100  has a recapture function capable of being easily restored (recaptured) in the delivery system. 
     In the expansion mechanism disclosed in Japanese Patent No. 3708923, the number of “meshing portions” crossing in the hook shape is large and the spread angle of the expansion mechanism is significantly large when the expansion mechanism is released. Therefore, it is necessary to apply a large force for restoring the expansion mechanism (recaptured) in the delivery system, and making restoring (recapturing) difficult. 
     The stent  100  of the present embodiment has the connecting portions  2  crossing in the hook shape. Since the connecting portion  2  performs “slip-deformed”, the connecting portion  2  is likely to spread in the radial direction as compared with the straight crossing portion  13  that uniformly spreads in the longitudinal axis direction, when releasing the stent  100 . However, in the stent  100 , the connecting portion  2  that can be slip-deformed, and the straight crossing portion  13  that cannot be slip-deformed are disposed in the longitudinal axis direction at a ratio of 1 to 2. Therefore, in a case where the stent  100  is released, the spread angle  0  of the stent  100  can be reduced as compared with the expansion mechanism disclosed in Japanese Patent No. 3708923. 
     According to the present embodiment, the stent  100  is capable of achieving both a pipeline shape-maintaining function, and a recapture function. 
     As described above, the first embodiment has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the scope of the present invention. Further, the constituent elements shown in the embodiment described above and modification examples described below can be appropriately combined and configured. 
     MODIFICATION EXAMPLE 1 
     For example, in the stent  100  of the above embodiment, since the connecting portion  2  that is capable of being slip-deformed and the straight crossing portion  13  that is not slip-deformed are disposed in the longitudinal axis direction at a ratio of 1 to 2, the stent  100  is capable of achieving both the pipeline shape-maintaining function and the recapture function. However, the aspect of the stent is not limited thereto. In a case where the recapture function is further improved, in the stent, the connecting portion  2  that can be slip-deformed and the straight crossing portion  13  that cannot be slip-deformed may be disposed in the longitudinal axis direction at a ratio of 1 to 3 (or 3 or more). However, since the pipeline shape-maintaining function is suppressed as the ratio of the straight crossing portion  13  increases, it is desirable that the ratio of the straight crossing portion  13  be determined in consideration of the balance between the recapture function and the pipeline shape-maintaining function. 
     Second Embodiment 
     A second embodiment will be described with reference to  FIGS. 8 and 9 . In the following description, the same components as those already described will be designated by the same reference numerals and the description thereof will be omitted. A stent  100 B according to the second embodiment has a different configuration to that of the connecting portion from the stent  100  according to the first embodiment. 
     The stent  100 B includes the plurality of tubular units  1  and a connecting portion  2 B. The plurality of tubular units  1  are arranged in a longitudinal axis direction, and the adjacent tubular units  1  are connected by the connecting portion  2 B. 
       FIG. 8  is a developed view of the connecting portion  2 B which is developed in the circumferential direction. 
     The connecting portion  2 B is a portion in which the adjacent tubular units  1  are connected in the longitudinal axis direction, and has a connecting wire  20 . 
     The connecting wire  20  is repeatedly bent and obliquely extends in the circumferential direction, and forms a first bending portion  21  in which the connecting wire  20  is bent and a second bending portion  22  in which the connecting wire  20  is bent. 
     The first bending portion  21  of the connecting wire  20  is a convex portion in which the connecting wire  20  obliquely extending in the circumferential direction is folded and bent in the longitudinal axis direction to be convex toward a first direction D 1  side. A plurality of the first bending portions  21  are formed in an end portion of the connecting wire  20  in the first direction D 1 . The plurality of first bending portions  21  are arranged in line in the circumferential direction. 
     The second bending portion  22  of the connecting wire  20  is a convex portion in which the connecting wire  20  obliquely extending in the circumferential direction is folded and bent in the longitudinal axis direction to be convex toward the second direction D 2  side. A plurality of the second bending portions  22  are formed in an end portion of the connecting wire  20  in the second direction D 2 . The plurality of second bending portions  22  are arranged in line in the circumferential direction. 
     The connecting portion  2 B is formed by the connecting wire  20  connecting the tubular unit  1  on the second direction D 2  side and the tubular unit  1  on the first direction D 1  side such that the tubular units  1  on both sides D 1  and D 2  are relatively movable with each other. 
     The first bending portion  21  of the connecting wire  20  is wound and fixed to a part of the tubular unit  1  on the first direction D 1  side, as shown in  FIG. 8 . A fixing method and a fixing place are not limited as long as the first bending portion  21  is not separated from the tubular unit  1  on the first direction D 1  side. 
     The second bending portion  22  of the connecting wire  20  crosses the first bent part  11  of the tubular unit  1  on the second direction D 2  side. The second bending portion  22  and the first bent part  11  cross each other in a “hook shape” in the radial direction and the longitudinal axis direction. 
     Since the second bending portion  22  and the first bent part  11  cross each other in a “hook shape” in a radial direction and the longitudinal axis direction, the adjacent tubular units  1  connected by the connecting portion  2 B are inseparably connected and are relatively movable. As a result, the first bent part  11  of the tubular unit  1  on the second direction D 2  side and the second bent part  12  of the tubular unit  1  on the first direction D 1  side are connected so as to be relatively movable. 
     Other tubular units  1  are connected to the adjacent tubular units  1  in the longitudinal direction by the connecting wire  20  of the connecting portion  2 B in the same manner. The stent  100 B is formed by connecting all of the tubular units  1 . 
     According to the stent  100 B of the present embodiment, both the pipeline shape-maintaining function and the recapture function capable of being restored in the delivery system is capable of being achieved, as in the stent  100  according to the first embodiment. 
     According to the stent  100 B of the present embodiment, since the plurality of tubular units  1  are individually manufactured, and then connected by the connecting wire  20 , the stent is capable of being easily manufactured. 
     According to the stent  100 B of the present embodiment, since the connecting wire  20  has a zigzag structure (structure that obliquely extends in the circumferential direction and repeats bending) like the other wires, the diameter of the stent is capable of being easily reduced when the stent  100 B is stored in the delivery system, and easily expanded when the stent  100 B is released. 
     As described above, the second embodiment has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment and includes design changes and the like without departing from the scope of the present invention. Further, the constituent elements shown in the above embodiments described above and the modification examples can be appropriately combined and configured. 
     MODIFICATION EXAMPLE 2 
     For example, in the above embodiment, the tubular unit  1  is formed by weaving the wires, but the aspect of the tubular unit is not limited thereto. The tubular unit may be a laser cut type in which a mesh is formed on the circumferential surface of a cylindrical material by laser cutting. A plurality of tubular units may be formed by laser cutting, and then the tubular units may be connected by the connecting wire  20  to form the stent  100 B. 
     Even in a case where the tubular unit is a laser cut type, intersection of two meshes is formed on the line connecting the first bent part  11  and the second bent part  12 . In the stent  100 B, the connecting portion  2  that is capable of being slip-deformed and the intersection that is not slip-deformed are disposed in the longitudinal axis direction at a ratio of 1 to 2, so that the stent  100 B is capable of achieving both the pipeline shape-maintaining function and the recapture function. 
     MODIFICATION EXAMPLE 3 
     For example, in the above embodiment, the connecting wire  20  is prepared separately from the tubular unit  1 , but the aspect of the connecting wire is not limited thereto.  FIG. 9  is a diagram showing a connecting wire  20 B that is a modification example of the connecting wire  20  of the stent. The connecting wire  20 B is integrally formed with the wire forming the tubular unit  1 , and is used for connecting the adjacent tubular units  1  similar to the connecting wire  20 . It is not necessary to prepare the connecting wire  20  separately, and the handling is easy. 
     Third Embodiment 
     A third embodiment will be described with reference to  FIGS. 10 and 11 . In the following description, the same components as those already described will be designated by the same reference numerals and the description thereof will be omitted. A stent  100 C according to the third embodiment has a different configuration to that of the tubular unit from the stent  100  according to the first embodiment. 
       FIG. 10  is a diagram showing an overall configuration of a stent  100 C according to the present embodiment. 
     The stent  100 C is formed by weaving wires and has a cylindrical tubular shape as in the stent  100  according to the first embodiment. 
     The stent  100 C includes at least one first tubular unit  3  and at least one second tubular unit  4 . The first tubular unit  3  and the second tubular unit  4  are arranged alternately in the longitudinal axis direction. 
     The first tubular unit  3  is formed in a cylindrical tubular shape having a mesh on the circumferential surface by a wire W 1  repeatedly bent and obliquely extending in the circumferential direction. The first tubular unit  3  includes a first direction bent portion  31  in which the wires W 1  are bent, a first direction bent portion  32  in which the wires W 1  are bent, and a first straight crossing portion  33  in which the wires W 1  cross each other in a straight line. 
     The first direction bent portion  31  is a convex portion in which the wire W 1  obliquely extending in the circumferential direction is folded and bent in the longitudinal axis direction to be convex toward the first direction D 1  side, and a plurality of the first direction bent portions  31  are formed in an end portion of the first direction D 1 . The plurality of first direction bent portions  31  are arranged in the circumferential direction. 
     The first direction bent portion  32  is a convex portion in which the wire W 1  obliquely extending in the circumferential direction is folded and bent in the longitudinal axis direction to be convex toward the second direction D 2  side, and a plurality of the first direction bent portions  32  are formed in an end portion of the second direction D 2 . The plurality of first direction bent portions  32  are arranged in the circumferential direction. 
     The second tubular unit  4  is formed in a cylindrical tubular shape having a mesh on the circumferential surface by a wire W 2  repeatedly bent and obliquely extending in the circumferential direction. The second tubular unit  4  includes a second direction bent portion  41  in which the wires W 2  are bent, a second direction bent portion  42  on the second direction side in which the wires W 2  are bent, and a second straight crossing portion  43  in which the wires W 2  cross each other in a straight line. The second tubular unit  4  has a different shape from that of the first tubular unit  3 , and in the present embodiment, the diameter dimension of the wire W 1  is different from the diameter dimension of the wire W 2 . 
     The second direction bent portion  41  is a convex portion in which the wire W 2  obliquely extending in the circumferential direction is folded and bent in the longitudinal axis direction to be convex toward the first direction D 1  side, and a plurality of the second direction bent portions  41  are formed in an end portion of the first direction D 1 . The plurality of second direction bent portions  41  are arranged in the circumferential direction. 
     The second direction bent portion  42  is a convex portion in which the wire W 2  obliquely extending in the circumferential direction is folded and bent in the longitudinal axis direction to be convex toward the second direction D 2  side, and a plurality of the second direction bent portions  42  are formed in an end portion of the second direction D 2 . The plurality of second direction bent portions  42  are arranged in the circumferential direction. 
     The wire W 1  which forms the first tubular unit  3  has an outer diameter of 0.17 mm to 0.18 mm 
     On the other hand, the wire W 2  which forms the second tubular unit  4  has an outer diameter of 0.15 mm, which is thinner than the wire W 1 . Therefore, the first tubular unit  3  has a larger expansion force to widen the stenosis radially outward as compared with the second tubular unit  4 . In a case where there is inflammation or the like at the placement position of the stent  100 C, the outer diameter of the wire W 1  may be set to about 0.15 mm and the outer diameter of the wire W 2  may be set to 0.12 mm to 0.13 mm to weaken the expansion force of the entire stent  100 C. By changing the material of the wire instead of the outer diameter of the wire, the expansion force of the first tubular unit  3  may be larger than the expansion force of the second tubular unit  4 . 
     The weaving methods of the first tubular unit  3  and the second tubular unit  4  are the same as the weaving method of the tubular unit  1  according to the first embodiment. 
       FIG. 11  is an enlarged view of a part of the stent  100 C shown in  FIG. 10 . 
     The first direction bent portion  31  of the first tubular unit  3  and the second direction bent portion  42  of the second tubular unit  4  cross each other in a “hook shape” in a radial direction and the longitudinal axis direction to form a first connecting portion  5  inseparably connected so as to be relatively movable. 
     The direction first bent portion  32  of the first tubular unit  3  and the second direction bent portion  41  of the second tubular unit  4  cross each other in a “hook shape” in a radial direction and the longitudinal axis direction to form a second connecting portion  6  inseparably connected so as to be relatively movable. 
     Next, the operation of the stent  100 C will be described. 
     The stent  100 C released from the delivery system expands in diameter by self-expandability to expand stenosis and occlusion. The stent  100 C includes the first connecting portion  5  and the second connecting portion  6  which are “slip-deformed” and bent as in the stent  100  according to the first embodiment, and has a function of maintaining the shape corresponding to the shape of the bent lumen (pipeline shape-maintaining function). Also, the stent  100 C includes the first straight crossing portion  33  and the second straight crossing portion  43  as in the stent  100  according to the first embodiment, and has a recapture function capable of being easily restored (recaptured) in the delivery system. 
     With the stent  100 C according to the present embodiment, the pipeline shape-maintaining function and the recapture function capable of being restored in the delivery system can be achieved at the same time. 
     Further, in the stent  100 C, the first tubular unit  3  and the second tubular unit  4  having different expansion forces in the radial direction are alternately arranged in the longitudinal axis direction. Therefore, the outer circumferential surface of the stent  100 C placed in the stenosis or the like has an uneven shape along the longitudinal axis direction. As a result, even in a case where the stent  100 C is placed in a curved stenosis or the like, migration can be suitably prevented. Further, as compared with the stent having an increased total expansion force, the second tubular unit  4  having a small expansion force can be included, so that the burden on the stenosis or the like given by the entire stent  100 C can be reduced, and the first tubular unit  3  having a large expansion force can be included, so that the anchor effect can be sufficiently exhibited. 
     As described above, the third embodiment has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the scope of the present invention. Further, the constituent elements shown in the above embodiments described above and the modification examples can be appropriately combined and configured. 
     Fourth Embodiment 
     A fourth embodiment will be described with reference to  FIG. 12 . In the following description, the same components as those already described will be designated by the same reference numerals and the description thereof will be omitted. A stent  100 D according to the fourth embodiment has a different configuration to that of the tubular unit and the connecting portion from the stent  100 C according to the third embodiment. 
       FIG. 12  is a diagram showing an overall configuration of a stent  100 D according to the present embodiment. 
     The stent  100 D is formed by weaving wires and has a cylindrical tubular shape as in the stent  100  according to the first embodiment. 
     The stent  100 D includes at least one first tubular unit  3  and at least two second tubular units  4 . The first tubular unit  3  and two adjacent second tubular units  4  are arranged alternately in the longitudinal axis direction. The first tubular unit  3  and three or more adjacent second tubular units  4  to each other may be arranged alternately in the longitudinal axis direction. 
     In two adjacent second tubular units  4 , the second direction bent portion  42  of the second tubular unit  4  on the first direction D 1  side and the second direction bent portion  41  of the second tubular unit  4  on the second direction D 2  side form a third connecting portion  7  that is connected so as to be relatively movable. 
     In the two adjacent second tubular units  4 , the second direction bent portion  41  of the second tubular unit  4  on the first direction D 1  side forms the first tubular unit  3  and the second connecting portion  6 . 
     In the two adjacent second tubular units  4 , the second direction bent portion  42  of the second tubular unit  4  on the second direction D 2  side forms the first tubular unit  3  and the first connecting portion  5 . 
     With the stent  100 D according to the present embodiment, the pipeline shape-maintaining function and the recapture function capable of being restored in the delivery system can be achieved at the same time, as in the stent  100 C according to the third embodiment. 
     Further, in the stent  100 D, the first tubular unit  3  and the second tubular unit  4  having different expansion forces in the radial direction are arranged in the longitudinal axis direction. Therefore, migration can be suitably prevented as in the stent  100 C according to the third embodiment. Further, in the stent  100 D, the number of second tubular units  4  is different from the number of first tubular units  3 . Therefore, the balance between the effect of reducing the burden on stenosis and the anchor effect can be adjusted. 
     As described above, the fourth embodiment has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the scope of the present invention. Further, the constituent elements shown in the above embodiments described above and the modification examples can be appropriately combined and configured. 
     MODIFICATION EXAMPLE 4 
     In the above embodiment, the first tubular unit  3  and the two adjacent second tubular units  4  are alternately arranged in the longitudinal axis direction, but the aspect of the combination of the tubular units is not limited thereto. The stent includes at least two first tubular units  3  and at least one second tubular unit  4 , and two adjacent first tubular units  3  and the second tubular unit  4  may be alternately arranged in the longitudinal axis direction. In the two adjacent first tubular units  3 , the first-second direction bent portion  32  of the first tubular unit  3  positioned on the first direction D 1  side and the first first-first direction bent portion  31 of the first tubular unit  3  positioned on the second direction D 2  side form a fourth connecting portion  8  that is connected so as to be relatively movable. Three or more adjacent first tubular units  3  and the second tubular units  4  to each other may be arranged alternately in the longitudinal axis direction. Further, a large number of the second tubular unit  4  may be disposed at a distal end or a proximal end of the stent as compared with the first tubular unit  3 . Migration can be prevented by increasing the expansion force of the distal end or the proximal end of the stent. Further, a large number of the second tubular unit  4  may be disposed at a center of the stent as compared with the first tubular unit  3 . By increasing the expansion force at the center of the stent, the expandability of the stenosis part can be enhanced. 
     Fifth Embodiment 
     A fifth embodiment will be described with reference to  FIG. 13 . In the following description, the same components as those already described will be designated by the same reference numerals and the description thereof will be omitted. A stent  100 E according to the fifth embodiment has a different configuration to that of the tubular unit from the stent  100 C according to the third embodiment. 
       FIG. 13  is a diagram showing an overall configuration of a stent  100 E according to the present embodiment. 
     The stent  100 E is formed by weaving wires and has a cylindrical tubular shape as in the stent  100  according to the first embodiment. 
     The stent  100 E includes at least one first tubular unit  3 B and at least one second tubular unit  4 B. The first tubular unit  3 B and the second tubular unit  4 B are arranged in the longitudinal axis direction. 
     The first tubular unit  3 B is formed in a cylindrical tubular shape having a mesh on the circumferential surface by a wire W 3  repeatedly bent and obliquely extending in the circumferential direction. The first tubular unit  3 B includes a first direction bent portion  31  in which the wires W 3  are bent, a first direction bent portion  32  in which the wires W 3  are bent, and a first straight crossing portion  33  in which the wires W 3  cross each other in a straight line. 
     The second tubular unit  4 B is formed in a cylindrical tubular shape having a mesh on the circumferential surface by the wire W 3  repeatedly bent and obliquely extending in the circumferential direction. The second tubular unit  4 B includes a second direction bent portion  41  in which the wires W 3  are bent, a second direction bent portion  42  in which the wires W 3  are bent, and a second straight crossing portion  43  in which the wires W 3  cross each other in a straight line. 
     The first tubular unit  3 B and the second tubular unit  4 B are formed by the same wire W 3 . The first tubular unit  3 B has a different length in the longitudinal axis direction from the second tubular unit  4 B. A length L 3  of the first tubular unit  3 B in the longitudinal axis direction is smaller than a length L 4  of the second tubular unit  4 B in the longitudinal axis direction. Therefore, the first tubular unit  3 B has a larger expansion force to widen the stenosis radially outward as compared with the second tubular unit  4 B. 
     The first direction bent portion  31  of the first tubular unit  3 B and the second direction bent portion  42  of the second tubular unit  4 B form the first connecting portion  5  inseparably connected so as to be relatively movable. 
     The first direction bent portion  32  of the first tubular unit  3 B and the second direction bent portion  41  of the second tubular unit  4 B form the second connecting portion  6  inseparably connected so as to be relatively movable. 
     In the two adjacent second tubular units  4 B, the second direction bent portion  42  of the second tubular unit  4 B on the first direction D 1  side and the second direction bent portion  41  of the second tubular unit  4 B on the second direction D 2  side form a third connecting portion  7  that is connected so as to be relatively movable. 
     In the two adjacent first tubular units  3 B, the first direction bent portion  32  of the first tubular unit  3 B on the first direction D 1  side and the first direction bent portion  31  of the first tubular unit  3 B on the second direction D 2  side form a fourth connecting portion  8  that is connected so as to be relatively movable. 
     With the stent  100 E according to the present embodiment, the pipeline shape-maintaining function and the recapture function capable of being restored in the delivery system can be achieved at the same time, as in the stent  100 C according to the third embodiment. 
     Further, in the stent  100 E, the first tubular unit  3 B and the second tubular unit  4 B having different expansion forces in the radial direction are arranged in the longitudinal axis direction. As a result, migration can be suitably prevented as in the stent  100 C according to the third embodiment. 
     As described above, the fifth embodiment has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the scope of the present invention. Further, the constituent elements shown in the above embodiments described above and the modification examples can be appropriately combined and configured. 
     Sixth Embodiment 
     A sixth embodiment will be described with reference to  FIG. 14 . In the following description, the same components as those already described will be designated by the same reference numerals and the description thereof will be omitted. A stent  100 F according to the sixth embodiment has a different configuration to that the tubular unit from the stent  100 C according to the third embodiment. 
       FIG. 14  is a diagram showing an overall configuration of a stent  100 F according to the present embodiment. 
     The stent  100 F is formed by weaving wires and has a cylindrical tubular shape as in the stent  100  according to the first embodiment. 
     The stent  100 F includes at least one first tubular unit  3 C and at least one second tubular unit  4 C. The first tubular unit  3 C and the second tubular unit  4 C are arranged alternately in the longitudinal axis direction. 
     The first tubular unit  3 C is formed in a cylindrical tubular shape having a mesh on the circumferential surface by a wire W 3  repeatedly bent and obliquely extending in the circumferential direction. The first tubular unit  3 C includes a first direction bent portion  31  in which the wires W 3  are bent, a first direction bent portion  32  in which the wires W 3  are bent, and a first straight crossing portion  33  in which the wires W 3  cross each other in a straight line. The first tubular unit  3 C configures five first straight crossing portions  33  in a line segment of the wire connecting the first direction bent portion  31  and the first direction bent portion  32 , as shown in  FIG. 14 . 
     The second tubular unit  4 C is formed in a cylindrical tubular shape having a mesh on the circumferential surface by the wire W 3  repeatedly bent and obliquely extending in the circumferential direction. The second tubular unit  4 C includes a second direction bent portion  41  in which the wires W 3  are bent, a second direction bent portion  42  in which the wires W 3  are bent, and a second straight crossing portion  43  in which the wires W 3  cross each other in a straight line. The second tubular unit  4 C configures three second straight crossing portions  43  in a line segment of the wire connecting the second direction bent portion  41  and the second direction bent portion  42 , as shown in  FIG. 14 . 
     The number (five) of the first straight crossing portions  33  formed on a line segment of the wire W 3  connecting the first direction bent portion  31  of the first tubular unit  3 C to the first direction bent portion  32  is larger than the number (three) of the second straight crossing portions  43  formed on a line segment of the wire W 3  connecting the second direction bent portion  41  to the second direction bent portion  42  of the second tubular unit  4 C. Therefore, the first tubular unit  3 C has a larger expansion force to widen the stenosis radially outward as compared with the second tubular unit  4 C. 
     The first direction bent portion  31  of the first tubular unit  3 C and the second direction bent portion  42  of the second tubular unit  4 C form the first connecting portion  5  inseparably connected so as to be relatively movable. 
     The first direction bent portion  32  of the first tubular unit  3 C and the second direction bent portion  41  of the second tubular unit  4 C form the second connecting portion  6  inseparably connected so as to be relatively movable. 
     With the stent  100 F according to the present embodiment, the pipeline shape-maintaining function and the recapture function capable of being restored in the delivery system can be achieved at the same time, as in the stent  100 C according to the third embodiment. 
     Further, in the stent  100 F, the first tubular unit  3 C and the second tubular unit  4 C having different expansion forces in the radial direction are arranged in the longitudinal axis direction. As a result, migration can be suitably prevented as in the stent  100 C according to the third embodiment. 
     As described above, the sixth embodiment has been described in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and includes design changes and the like without departing from the scope of the present invention. Further, the constituent elements shown in the above embodiments described above and the modification examples can be appropriately combined and configured. 
     MODIFICATION EXAMPLE 5 
     In the above embodiment, the first tubular unit  3  and the second tubular units  4  are arranged in the longitudinal axis direction, but the aspect of the stent is not limited thereto. The stent may be formed by connecting three or more tubular units by connecting portions.