stent

Abstract

The present invention provides a stent with good kink resistance, good pushability, and minimal change in overall length in the axial direction between the expanded and contracted diameter states. [Solution] If α is the angle formed by the direction in which the linear range 11a of the first strut 11 extends and the direction in which the connecting strut 21 extends, then 0°

Description

Technical Field

[0001] The present disclosure relates to a stent for being placed in a lumen structure.

Background Art

[0002] Regarding stents for being placed in a lumen structure (for example, blood vessels, tracheas, intestines), so-called open-cell structure stents have high shape followability. On the other hand, stents with a closed-cell structure have the advantage that the struts do not protrude outward. Also, stents with a closed-cell structure having high flexibility have been proposed (for example, refer to Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the cell structure of the stent of Patent Document 1, when the radius of bending becomes somewhat small, a phenomenon called so-called "kinking" occurs. Kinking means that the stent collapses and becomes substantially elliptical in a cross section orthogonal to the axial direction of the stent. For stents, not only shape followability but also kink resistance is required.

[0005] Stents are configured to transition from a state with a small, contracted outer diameter (i.e., a contracted state) to a state with a large, expanded outer diameter (i.e., an expanded state). In the cell structure of the stent described in Patent Document 1, there was a significant difference between the total length of the stent in the contracted state (total length in the axial direction, hereinafter the same) and the total length of the stent in the expanded state. This phenomenon, where the total length of the stent in the expanded state is shorter than in the contracted state, is also called "shortening." If the change in the total length of the stent due to this shortening is large, it can be difficult to use, for example, when expanding the stent to the intended position during a procedure, making it difficult to place the stent at the target position. Furthermore, the stent in Patent Document 1 had poor pushability when the operator pushed the stent distally.

[0006] The object of this disclosure is to provide a stent that has good kink resistance, good pushability, and minimal change in overall length in the axial direction between the expanded and contracted diameter states. [Means for solving the problem]

[0007] For ease of understanding, the present invention will be described below with reference numerals corresponding to embodiments, but the present invention is not limited thereto.

[0008] The first disclosure includes a zigzag pattern unit (10) having a zigzag pattern formed by alternating arrangements of a first strut (11) and a second strut (12) intersecting the first strut (11) along the circumferential direction around the axial direction, and a plurality of connecting struts (21) connected to the zigzag pattern unit (10), wherein the zigzag pattern unit (10) protrudes proximally toward the connection between the first strut (11) and the second strut (12) The proximal apex (13) and distal apex (14) that protrudes distally where the first strut (11) and the second strut (12) are connected are arranged alternately, and the first strut (11), the second strut (12), and the connecting strut (21) all have linear ranges (11a, 12a, 21a) that extend linearly without bending, extending distally to the zigzag pattern unit (10) At least a portion of the proximal part of the connecting strut (21) is connected to an intermediate connecting part (15) located in the linear range (11a) of the first strut (11) and proximal to the distal top part (14), and the first strut and the connecting strut are connected to each other in the linear range of the first strut, and the linear range (21a) of the connecting strut (21) is in the direction in which the linear range (11a) of the first strut (11) extends and the linear range (21a) of the connecting strut (21) If α is the angle between the direction in which the zigzag pattern unit (10) extends and the axial direction, then in the expanded free state, the relationship 0° < α is satisfied, and the distal portion of the connecting strut (21) extending from the proximal side to the zigzag pattern unit (10) is connected to the proximal top portion (13), and if γ is the angle between the direction in which the linear range (21a) of the connecting strut (21) extends and the axial direction, then in the free state, 20° < γ < 60° Stent (1) satisfies the following relationship.

[0009] The second disclosure is a stent (1) described in the first disclosure, characterized in that, if β is the angle formed at the distal apex between the direction in which the linear range (11a) of the first strut (11) extends and the direction in which the linear range (12a) of the second strut (12) extends, then in the free state, the relationship 100° < β < 150° is satisfied.

[0010] The third disclosure is a stent (1) described in the first or second disclosure, characterized in that the distal end of the stent (1) has a number of distal end cells (55) that are multiples of 3 arranged in the circumferential direction, and three marker portions (102) that suppress the transmission of radiation are provided in the circumferential direction at three locations on the distal end cells (55), arranged substantially evenly in the circumferential direction.

[0011] The fourth disclosure is a stent (1) as described in the third disclosure, characterized in that the number of cells arranged circumferentially in the zigzag pattern unit (10) is different from the number of cells in the distal end cells (55) arranged circumferentially, an adjustment cell (60) is provided between the zigzag pattern unit (10) and the distal end cells (55) to adjust the difference in the number of cells between the zigzag pattern unit (10) and the distal end cells (55), and the proximal end of each of the adjustment cells (60) is connected to the zigzag pattern unit (10). [Effects of the Invention]

[0012] According to this disclosure, it is possible to provide a stent that has good kink resistance, good pushability, and little change in overall length in the axial direction between the expanded and contracted diameter states. [Brief explanation of the drawing]

[0013] [Figure 1] This is a perspective view showing the expanded diameter state of stent 1 according to this disclosure. [Figure 2] This is a side view showing the expanded diameter state of stent 1. [Figure 3] This is a planar unfolded view of the expanded diameter state of stent 1. [Figure 4] This is a magnified view of a portion of Figure 3. [Figure 5] This diagram shows an enlarged unfolded view of stent 1 in its reduced diameter state, virtually laid out on a planar surface. [Modes for carrying out the invention]

[0014] The following describes one embodiment for implementing this disclosure with reference to drawings and other materials.

[0015] (Embodiment) Figure 1 is a perspective view showing the expanded diameter state of stent 1 according to this disclosure. Figure 2 is a side view showing the expanded diameter state of stent 1. Figure 3 is an unfolded view of the expanded diameter state of stent 1 laid out in a planar plane. Note that the form in Figure 3 is a hypothetical representation of the unfolded state of the stent. Figure 3 is a planar representation of the natural state of the cylindrical stent 1 as simulated, and corresponds to a planar representation of the shape of the actual product in its natural state. Figure 4 is an enlarged view of a part of Figure 3. Note that markers 101 and 102 are omitted from the illustration in Figures 1 and 3. In this specification, the proximal LD1 side means the upstream side in the direction of insertion of the catheter and stent into the body during the procedure. The proximal LD1 side may usually be the side closer to the practitioner. In this specification, the distal LD2 side means the downstream side in the direction of insertion of the catheter and stent into the body during the procedure. The distal LD2 side may usually be the side further from the practitioner.

[0016] Stent 1 has a structure in which linear or wire-shaped struts are connected in a mesh-like manner, and the entire stent 1 is formed in a substantially cylindrical shape. The part enclosed by each strut will also be called a "cell." Stent 1 in this embodiment is composed of a combination of multiple types of struts, the details of which will be described later.

[0017] The stent 1 of the present embodiment can be manufactured by appropriately using materials used in conventionally known stents. The stent 1 can preferably use a material having superelastic properties such as a nickel-titanium (Ni-Ti) alloy. Further, the stent 1 of the present embodiment may be in a form that supports a drug so that various drugs elute in the living body.

[0018] The stent 1 can be manufactured by laser processing a substantially cylindrical thin tube made of the above material or braiding (weaving) struts. Specifically, for example, laser processing is performed on a stent material in the shape of a tube with an outer diameter of about 2 mm to 3 mm, leaving a part corresponding to the strut and removing a part corresponding to the cell. Then, by performing a process of stretching this in the radial direction and deforming it to a desired outer diameter, which is 4 mm in the present embodiment, a stent can be manufactured. In this specification, the "radial direction" refers to a direction extending radially with respect to the axial direction of the stent. In this specification, the "axial direction" refers to a direction along the central axis of the substantially cylindrical stent in the expanded diameter state. FIGS. 1 to 4 show the stent 1 in the natural state, that is, the expanded diameter state in which the outer diameter expands to 4 mm at the central position in the axial direction of the stent 1. Note that the outer diameter of the stent 1 when expanded may be, for example, 3 mm or 5 mm, and can be appropriately manufactured according to the site where it is used.

[0019] When the stent 1 is inserted into the body, it is accommodated in a catheter (not shown) in a reduced diameter state and delivered together with the catheter to the vicinity of the target position. The stent 1 expands itself by being pushed out from the catheter and abuts against the inner wall of a blood vessel or the like and is left there. Further, before the stent 1 is completely exposed from the catheter, the stent 1 can be re-accommodated (released) into the catheter by operating so that the catheter and the stent 1 approach each other relatively.

[0020] As shown in FIGS. 1 to 4, the stent 1 of the present embodiment includes a plurality of zigzag pattern units 10 extending in the circumferential direction and a plurality of connection struts 21. In this specification, the "circumferential direction" refers to the direction around the axial direction of the stent 1. The plurality of zigzag pattern units 10 are arranged side by side in the axial direction. Each zigzag pattern unit 10 may be closed in the circumferential direction.

[0021] As the zigzag pattern unit of the present embodiment, an intermediate zigzag pattern unit 10 is provided. As other zigzag pattern units, a first proximal pattern 30, a second proximal pattern 40, and a distal pattern 50 are provided. In addition, an adjustment cell 60 is formed between the intermediate zigzag pattern unit 10 and the distal pattern 50.

[0022] As shown in FIG. 3, the intermediate zigzag pattern unit 10 has a zigzag pattern formed by alternately connecting a first strut 11 and a second strut 12 along the circumferential direction CD around the axial direction LD. In the intermediate zigzag pattern unit 10, the first strut 11 and the second strut 12 forming the zigzag pattern are connected along the circumferential direction CD. As shown in FIG. 4, the intermediate zigzag pattern unit 10 includes a first strut 11, a second strut 12, a proximal top 13, a distal top 14, and an intermediate connection part 15, and is formed in an annular shape around the axial direction LD. The first strut 11 and the second strut 12 are directly connected to each other. The proximal top 13 and the distal top 14 correspond to the connection parts of the first strut 11 and the second strut 12. In this embodiment, eight columns of intermediate zigzag pattern units 10 are provided side by side along the axial direction LD. Instead, the number of intermediate zigzag pattern units 10 may be more or less than eight columns.

[0023] The multiple first struts 11 constituting the intermediate zigzag pattern unit 10 extend in substantially the same direction when viewed as a whole in the unfolded state in which the expanded diameter state of the stent 1 is unfolded on a plane. Each first strut 11 has a linear range 11a that extends in a straight line. The linear range 11a is a range that extends in a straight line without bending or curving along the way. The linear ranges 11a of the multiple first struts 11 constituting the intermediate zigzag pattern unit 10 extend in substantially the same direction to each other in the unfolded state. In addition, an intermediate connection portion 15 is provided near the center of each first strut 11. This intermediate connection portion 15 is provided within the range of the linear range 11a. The intermediate connection portion 15 corresponds to the part connected to the connecting strut 21.

[0024] The length of the first strut 11 is preferably, for example, 1.0 mm or more and 2.0 mm or less. If the length of the first strut 11 is 1.0 mm or more, the length of the axial LD ​​of one intermediate zigzag pattern unit 10 will not become too short. Therefore, the amount (density) of intermediate zigzag pattern units 10 in the axial LD ​​will not increase too much, and the rigidity during diameter reduction will be lower, which can improve the diameter reduction and delivery performance of the stent 1. If the length of the first strut 11 is 2.0 mm or less, the length of the axial LD ​​of one intermediate zigzag pattern unit 10 will not become too long. Therefore, the amount (density) of intermediate zigzag pattern units 10 in the axial LD ​​will not decrease too much, which can suppress a decrease in the expansion force of the stent 1.

[0025] Furthermore, it is desirable that the length of the first strut 11 from the proximal apex 13 to the intermediate connection portion 15 be between 0.3 mm and 0.6 mm. If the length of the first strut 11 from the proximal apex 13 to the intermediate connection portion 15 is 0.3 mm or more, the amount (density) of intermediate zigzag pattern units 10 in the axial LD ​​during diameter reduction is reduced, which increases the rigidity during diameter reduction and can improve the diameter reduction and delivery of the stent 1. If the length of the first strut 11 from the proximal apex 13 to the intermediate connection portion 15 is 0.6 mm or less, the amount (density) of intermediate zigzag pattern units 10 in the axial LD ​​is not reduced too much, thus maintaining the expansion force of the stent 1.

[0026] The intermediate second struts 12 constituting the intermediate zigzag pattern unit 10 extend in substantially the same direction when viewed as a whole in the deployed state. The second struts 12 are connected to the first struts 11. The second struts 12, like the first struts 11, have a linear range 12a that extends in a straight line. The linear range 12a is a range that extends in a straight line without bending or curving along its course. The linear ranges of the multiple second struts 12 constituting the intermediate zigzag pattern unit 10 extend in substantially the same direction to each other when deployed. The first struts 11 and the second struts 12 are symmetrical with respect to a straight line parallel to the axial direction LD and passing through the intersection of the first struts 11 and the second struts 12. Therefore, it is desirable that the length of the second struts 12 be 1.0 mm or more and 2.0 mm or less, similar to the first struts 11. However, the first struts 11 and the second struts 12 do not necessarily have to be symmetrical. As described above, the first strut 11 and the second strut 12 are connected alternately to form a zigzag pattern.

[0027] The first strut 11 has a linear range 11a, and the intermediate connection portion 15 to which the connecting strut 21 connects is within the range of the linear range 11a. Therefore, when the stent 1 is pushed distally, the force vector is less likely to branch. Thus, it is less prone to kinking and has good pushability (ability to transmit force).

[0028] The proximal apex 13 is connected to the first strut 11 and the second strut 12 and protrudes toward the proximal LD1 in the axial direction LD. A connecting strut 21 is also connected to the proximal apex 13.

[0029] The distal vertex portion 14 is connected to the first strut 11 and the second strut 12 and protrudes toward the distal LD2 in the axial direction LD. In the intermediate zigzag pattern unit 10, these proximal vertex portions 13 and distal vertex portions 14 are arranged alternately along the circumferential direction CD.

[0030] The intermediate connection section 15 is located on the first strut 11 and is provided between the proximal vertex 13 and the distal vertex 14, to which the connecting strut 21, described later, is connected.

[0031] Each connecting strut 21 connects a pair of intermediate zigzag pattern units 10 adjacent to each other in the axial direction LD. As shown in Figures 2 and 3, the proximal LD1 portion of the connecting strut 21 extending from the distal side of the intermediate zigzag pattern unit 10 to the intermediate zigzag pattern unit 10 is connected to the intermediate connecting portion 15 of the first strut 11. Also, the distal LD2 portion of the connecting strut 21 extending from the proximal side of the intermediate zigzag pattern unit 10 to the intermediate zigzag pattern unit 10 is connected to the proximal top portion 13. Therefore, each connecting strut 21 is connected to the intermediate connecting portion 15 of the first strut 11 of the proximal zigzag pattern unit 10 of the pair of adjacent intermediate zigzag pattern units 10, and to the proximal top portion 13 of the distal zigzag pattern unit 10 of the pair of adjacent intermediate zigzag pattern units 10.

[0032] Multiple connecting struts 21 connect pairs of intermediate zigzag pattern units 10 adjacent to each other in the axial direction LD. A cell is formed surrounded by intermediate zigzag pattern units 10 adjacent to each other in the axial direction LD and connecting struts 21 adjacent in the circumferential direction. The formation of multiple cells constitutes the main body of the mesh-like stent.

[0033] Because the proximal LD1 side of the connecting strut 21 is connected to the intermediate connecting portion 15 rather than the distal apex portion 14, the distal apex portion 14 becomes a free end that protrudes toward the distal LD2 side. Therefore, the stent 1 of this embodiment is formed so that a part of the closed-cell structure is locally an open-cell structure. For this reason, the stent 1 of this embodiment is highly flexible and has excellent shape conformability. In addition, since the distal apex portion 14 is a free end that protrudes toward the distal LD2 side rather than the proximal LD1 side, it is possible to prevent the distal apex portion 14 from getting caught when the stent 1 is inserted into the catheter from the proximal side. In this way, the stent 1 of this embodiment can be easily inserted into the catheter while partially having an open-cell structure. In the stent 1 of this embodiment, since the free end of the distal apex portion 14 protrudes only toward the distal LD2 side, it is possible to reinsert the stent, which is a feature of a closed-cell structure, while having an open-cell structure. Therefore, in the stent 1 of this embodiment, if the deployment position of the stent, which has been partially deployed from the catheter, is incorrect, it is possible to retract it and change the deployment position.

[0034] Furthermore, the connecting strut 21 has a linear range 21a that extends in a straight line. The linear range 21a is a range that extends in a straight line without bending or curving along the way. The linear ranges 21a of multiple connecting struts 21 may extend in substantially the same direction. Because the connecting strut 21 has a linear range 21a, the stent 1 is less likely to kink when pushed distally, and the pushability of the stent 1 is good.

[0035] Furthermore, it is desirable that the length of the connecting strut 21 be shorter than the lengths of the first strut 11 and the second strut 12 that constitute the intermediate zigzag pattern unit 10. By making the length of the connecting strut 21 shorter than the lengths of the first strut 11 and the second strut 12, it becomes possible to arrange the intermediate zigzag pattern units 10 more densely in the axial direction LD. This increases the expansion force of the stent 1. In particular, in this embodiment, since the intermediate zigzag pattern unit 10 has a zigzag pattern formed by connecting the first strut 11 and the second strut 12 alternately along the circumferential direction, it is possible to arrange the intermediate zigzag pattern units 10 closer together in the axial direction LD. Therefore, it is possible to further increase the expansion force of the stent 1. Also, in this embodiment, the length of the connecting strut 21 is shorter than the length from the intermediate connection portion 15 on the first strut 11 to the distal top portion 14 of the same first strut 11. This point will be explained later with reference to Figure 5.

[0036] Regarding the first strut 11 and the connecting strut 21, which are connected to each other in the linear range 11a of the first strut 11, as shown in Figure 4, if α is the angle formed by the direction in which the linear range 11a of the first strut 11 extends and the direction in which the connecting strut 12 extends, it is desirable that α satisfies the relationship 0° < α. Here, in Figure 4, the angle α is shown in the unfolded state for explanatory purposes, but it should be noted that the angle α is actually defined in the expanded free state, i.e., in a three-dimensional state. Because 0° < α, the connecting strut 21 moves away from the first strut 11 as you move toward the distal LD2 side. As a result, the angle γ, which will be described later, becomes smaller, resulting in less shortening and making it easier to place the stent 1.

[0037] The angle α is preferably 10° or more, more preferably 15° or more. This makes it possible to reduce the degree of shortening of the stent 1 when transitioning from a reduced diameter state to an expanded diameter state. The angle α is preferably 60° or less, more preferably 50° or less. This makes it possible to provide a stent 1 that is less prone to kinking.

[0038] Furthermore, if γ is the angle between the direction in which the linear range 21a of the connecting strut 21 extends and the axial direction LD, it is desirable that γ satisfies the relationship 20° < γ < 60°. Note that in Figure 4, angle γ is shown in the unfolded state for explanatory purposes, but angle γ is actually defined in the expanded free state, i.e., in a three-dimensional state. When γ is greater than 20°, the stent 1 becomes difficult to change in a cross section perpendicular to the axial direction, i.e., kink resistance is improved. Also, when γ is less than 60°, the change in overall length due to shortening of the stent 1 becomes small, and the unfolding operation becomes easier. It is more desirable that angle γ be 20° < γ ≤ 40°, and even more desirable that it be 25° < γ ≤ 35°.

[0039] The sum of angles α and γ is preferably 50° or more, and more preferably greater than 50°. The larger the sum of angles α and γ, the better the kink resistance of stent 1. The sum of angles α and γ may be, for example, less than 90°, preferably 80° or less, and more preferably 70° or less. This further improves the pushability of stent 1.

[0040] Furthermore, in the same intermediate zigzag pattern unit 10, if β is the angle formed at the distal apex 14 between the direction in which the linear range 11a of the first strut 11 extends and the direction in which the linear range 12a of the second strut 12 extends, it is desirable that the relationship 100° < β < 150° is satisfied. Here, in Figure 4, the angle β is shown in the unfolded state for explanatory purposes, but it should be noted that the angle β is actually defined in the expanded free state, i.e., in a three-dimensional state. If 100° < β, kink resistance is further improved. Also, if β < 150°, the rigidity of the stent 1 when contracted does not become too high, making delivery with a small-diameter catheter easier. It is more desirable that the angle β be 110° < β ≤ 140°, and even more desirable that it be 120° < β ≤ 130°.

[0041] At the end of stent 1 on the proximal LD1 side, a first proximal pattern 30 and a second proximal pattern 40 are provided adjacent to each other. The first proximal pattern 30 comprises a first strut 31, a second strut 32, a proximal apex 33, and a distal apex 34. The first proximal pattern 30 is formed in an annular shape along the circumferential CD around the axial LD. The first proximal pattern 30 has a zigzag pattern formed by the alternating connection of the first strut 31 and the second strut 32. In the first proximal pattern 30, the first strut 31 and the second strut 32 that form the zigzag pattern both extend in a substantially straight line and are arranged and connected along the circumferential CD. The proximal apex 33 is formed by the connection of the first strut 31 and the second strut 32 and protrudes toward the proximal LD1 side in the axial LD. The distal apex 34 is connected to the first strut 31 and the second strut 32 and protrudes toward the distal LD2 in the axial direction LD. In the first proximal pattern 30, these proximal apex 33 and distal apex 34 are arranged alternately in the circumferential direction CD.

[0042] On the distal LD2 side of the first proximal pattern 30, a distal vertex 34 that connects to the proximal vertex 13 of the intermediate zigzag pattern unit 10 and two adjacent distal vertex 34 that are free ends and do not connect to the proximal vertex 13 are arranged alternately in the circumferential direction CD. That is, next to the distal vertex 34 that connects to the proximal vertex 13, there are two adjacent distal vertex 34 that are free ends and do not connect to the proximal vertex 13. These two adjacent distal vertex 34 that are free ends and do not connect to the proximal vertex 13 are arranged in the circumferential direction CD so as to be sandwiched between the distal vertex 34 that connects to the proximal vertex 13. This is because the number of first struts 31 and second struts 32 in the first proximal pattern 30 is 12 each, which is three times the number of first struts 11 and second struts 12 (4) in the intermediate zigzag pattern unit 10. By making a portion of the distal apex 34 a free end on the proximal LD1 side of the stent 1, a locally open cell structure is also created. Therefore, the proximal LD1 side of the stent 1 also exhibits high flexibility and excellent shape conformability.

[0043] The second proximal pattern 40 comprises a first strut 41, a second strut 42, a proximal apex 43, and a distal apex 44. The second proximal pattern 40 is formed in an annular shape along the circumferential direction CD around the axial direction LD. The second proximal pattern 40 has a zigzag pattern formed by the alternating connection of the first strut 41 and the second strut 42. In the second proximal pattern 40, the first strut 41 and the second strut 42 that form the zigzag pattern both extend in a substantially linear manner and are arranged and connected along the circumferential direction CD. The proximal apex 43 is formed by the connection of the first strut 41 and the second strut 42 and protrudes toward the proximal LD1 side in the axial direction LD. The distal apex 44 is formed by the connection of the first strut 41 and the second strut 42 and protrudes toward the distal LD2 side in the axial direction LD. In the second proximal pattern 40, these proximal vertices 43 and distal vertices 44 are arranged alternately in the circumferential direction CD.

[0044] The second proximal pattern 40 is positioned adjacent to the proximal LD1 side of the first proximal pattern 30. Specifically, the distal apex 44 of the second proximal pattern 40 is connected to the proximal apex 33 of the first proximal pattern 30. This provides a rhombic cell 45 that is surrounded by the first strut 31, the second strut 32, the first strut 41, and the second strut 42, forming a roughly rhombic shape. Extension portions 46 are connected to a part (three locations in this embodiment) of the proximal apex 43 of the second proximal pattern 40. The extension portions 46 extend from the proximal apex 43 of the second proximal pattern 40 toward the proximal LD1 side. A marker portion 101 is provided on this extension portion 46. The multiple extension portions 46 are arranged roughly equally in the circumferential direction CD. The extended portion 46 is provided with a marker portion 101 that suppresses the transmission of radiation (radiopaque). The specific form of the marker portion 101 itself can be any conventionally known marker form as appropriate. Since the extended portions 46 are arranged substantially evenly in the circumferential direction CD, the distance L46 between adjacent extended portions 46 in the circumferential direction CD is the same in the unfolded view of Figure 4.

[0045] In this embodiment of the stent 1 delivered using a small-diameter catheter, it is desirable that there be three marker portions 101 and 102 (not shown) each located at the proximal end and the distal end (described later). Having three or more marker portions 101 and 102 allows for accurate determination of the stent 1's expanded state. Furthermore, having four or fewer marker portions 101 and 102 prevents the marker portions from overlapping and becoming difficult to see, making it easier to accommodate the stent 1 within the small-diameter catheter. Therefore, in this embodiment, three marker portions 101 are evenly arranged in the circumferential direction on the second proximal pattern 40.

[0046] Furthermore, the number of first struts 31 and second struts 32 in the first proximal pattern 30, and the number of first struts 41 and second struts 42 in the second proximal pattern 40, were increased compared to the number of first struts 11 and second struts 12 in the intermediate zigzag pattern unit 10. This makes it possible to make the expansion force near the proximal end of the stent 1 even higher than the expansion force in other parts of the stent 1. In this embodiment, by increasing the density of struts near the proximal end of the stent 1 and increasing the expansion force of the stent 1, it is possible to ensure sufficient contact between the stent 1 and the blood vessel on the proximal side of the stent 1, thereby suppressing the risk of interference when passing guidewires, catheters, etc., through the stent 1.

[0047] At the distal end of stent 1 on the LD2 side, a distal pattern 50 and an adjustment cell 60 are provided adjacent to each other in the axial direction. The distal pattern 50 comprises a first strut 51, a second strut 52, a proximal apex 53, and a distal apex 54. The distal pattern 50 is formed in an annular shape along the circumferential direction CD around the axial direction LD. The distal pattern 50 has a zigzag pattern formed by the alternating connection of the first strut 51 and the second strut 52. In the distal pattern 50, the first strut 51 and the second strut 52 that form the zigzag pattern both extend in a substantially straight line and are arranged and connected along the circumferential direction CD. The proximal apex 53 is formed by the connection of the first strut 51 and the second strut 52 and protrudes toward the proximal LD1 side in the axial direction LD. The distal vertex 54 is connected to the first strut 51 and the second strut 52 and protrudes toward the distal LD2 in the axial direction LD. In the distal pattern 50, these proximal vertex 53 and distal vertex 54 are arranged alternately in the circumferential direction CD. Extension portions 56 are connected to some of the distal vertex 54 of the distal pattern 50 (three locations in this embodiment). The extension portions 56 extend from the distal vertex 54 toward the distal LD2. These extension portions 56 are arranged substantially evenly in the circumferential direction CD. The extension portions 56 are provided with a marker portion 102 that suppresses the transmission of radiation (radiopaque). Since the extension portions 56 are arranged substantially evenly in the circumferential direction CD, the distance L56 between adjacent extension portions 56 in the circumferential direction CD is the same in the unfolded view of Figure 4.

[0048] The adjustment cell 60 is located between the intermediate zigzag pattern unit 10 and the distal pattern 50. The adjustment cell 60 adjusts the difference between the number of cells in the intermediate zigzag pattern unit 10 and the number of cells in the distal pattern 50. Specifically, the cells of the intermediate zigzag pattern unit 10 are arranged in a circumferential direction CD of four, but as mentioned above, it is desirable that the marker portions 102 provided at the distal end be evenly arranged in a circumferential direction CD of three. Therefore, the adjustment cell 60 is provided between the intermediate zigzag pattern unit 10 and the distal pattern 50 to adjust (convert) the number of cells so that the number of distal apex portions 54 located at the distal end where the marker portions 102 are provided is a multiple of three.

[0049] Specifically, in this embodiment, the number of cells in the intermediate zigzag pattern unit 10 is naturally adjusted (converted) by the adjustment cell 60 to the number of cells in the distal end cell 55 formed by the distal pattern 50, which is 6. In this embodiment, the adjustment cell 60 has a first adjustment cell 61 and a second adjustment cell 62 provided proximal to the first adjustment cell 61. There are four first adjustment cells 61 arranged in the circumferential direction. The first adjustment cells 61 that are adjacent to each other in the circumferential direction are arranged so as to sandwich the second adjustment cell 62 in their distal portions. There are four second adjustment cells 62 arranged in the circumferential direction. As a result, a total of eight vertices, including the four vertices of the first adjustment cells 61 and the four vertices of the second adjustment cells 62, are arranged in the circumferential direction and protrude distally from the adjustment cell 60. The proximal top portion 53 of the distal pattern 50 is connected to six of the eight distal vertices of the adjustment cell 60. Furthermore, the remaining two of the eight distal vertices of the adjustment cell 60 are not connected to any point, thus acting as free ends, resulting in a configuration close to an open cell structure. This improves the flexibility of the distal end of the stent 1. On the other hand, all of the proximal ends of the adjustment cell 60 are connected to the zigzag pattern unit 10, and there are no free ends on the proximal side of the adjustment cell 60. Therefore, it is easy to re-adjust the stent 1 into the catheter.

[0050] By providing the adjustment cell 60, discontinuities caused by differences in the number of cells between the intermediate zigzag pattern unit 10 and the distal end cell 55 are mitigated. This allows the stent 1 to deform almost uniformly during diameter reduction and expansion. Thus, by providing the adjustment cell 60, the difference in the number of cells between the intermediate zigzag pattern unit 10 and the distal end (distal apex 54) where the marker portion 102 is located can be adjusted, and the marker portion 102 can be evenly distributed in three locations in the circumferential direction at the distal end (distal apex 54).

[0051] As shown in Figures 1 and 2, in the stent 1 of this embodiment, the outer diameter near the proximal LD1 and distal LD2 ends gradually increases compared to the outer diameter of the intermediate zigzag pattern unit 10 near the center of the axial LD. As a result, the stent 1 has a roughly funnel-shaped form (which can also be described as the shape of a trumpet mouth, a morning glory flower, a flare, etc.). This shape not only suppresses the occurrence of coning, but also allows the proximal and distal ends to be properly locked to the inner wall of a tubular structure such as a blood vessel, making it easier to maintain the placement position of the stent 1.

[0052] Figure 5 is an enlarged view of a hypothetical unfolded diagram of the stent 1 in its reduced diameter state. As mentioned earlier, in this embodiment, the first strut 11 and the second strut 12 in the intermediate zigzag pattern unit 10 are aligned in the direction along the circumferential direction CD. As a result, the stent 1 can deform naturally when its diameter is reduced, and as shown in Figure 5, each strut is neatly arranged when the diameter is reduced. Therefore, the stent 1 can bend naturally even when bent in the reduced diameter state, and can exhibit good flexibility. In addition, since each strut is arranged so that there is almost no wasted space, the outer diameter of the stent 1 can be made even smaller when the diameter is reduced.

[0053] In this embodiment, the distal top 14 of the intermediate zigzag pattern unit 10 is located more proximal to the proximal top 13 of another intermediate zigzag pattern unit 10 adjacent to the distal side of the same intermediate zigzag pattern unit 10 when the diameter is expanded (see Figures 3 and 4). As previously mentioned, in this embodiment, the length of the connecting strut 21 is shorter than the length from the intermediate connecting portion 15 on the first strut 11 to the distal top 14 of the same first strut 11. As a result, the distal top 14 of the intermediate zigzag pattern unit 10 is located more distal to the proximal top 13 of another intermediate zigzag pattern unit 10 adjacent to the distal side of the same intermediate zigzag pattern unit 10 when the diameter is reduced (see Figure 5). In other words, the distal apex 14, which was distal to the proximal apex 13 of the distally adjacent intermediate zigzag pattern unit 10 during diameter reduction, moves to a position proximal to the proximal apex 13 of the distally adjacent intermediate zigzag pattern unit 10 during diameter expansion. In this case, the ability to widen the lumen structure can be enhanced. Alternatively, the length of the connecting strut 21 may be longer than the length from the intermediate connecting portion 15 on the first strut 11 to the distal apex 14 of the same first strut 11. In this case, the distal apex 14 does not move as described above during diameter reduction, and diameter reduction (fit to thin catheters) can be improved.

[0054] Furthermore, since the distal LD2 portion of the connecting strut 21 is connected to the proximal apex 13, the movement of the proximal apex 13 of the intermediate zigzag pattern unit 10 is appropriately restrained by the connecting strut 21, and a locally closed-cell structure is formed. As a result, the proximal apex 13 is prevented from protruding outward, preventing it from getting caught when the stent 1 is inserted into the catheter from the proximal side, and facilitating insertion into the catheter.

[0055] Furthermore, since the first strut 11 and the second strut 12 that form the intermediate zigzag pattern unit 10 are connected along the circumferential direction CD, the total length of the stent 1 along the axial direction LD hardly changes between the expanded and contracted diameter states. Therefore, the operator only needs to pay attention to the radial dimensional change of the stent 1, making it easy to use.

[0056] As described above, the stent 1 of this embodiment has a zigzag pattern formed by the alternating arrangement and connection of the first strut 11 and the second struts 12 along the circumferential direction CD around the axial direction LD. Furthermore, the connecting strut 21 extending from the distal LD2 side to the intermediate zigzag pattern unit 10 is connected to the intermediate connection portion 15 of the first strut 11. In addition, the angles α and γ at which each strut intersect are configured to be the appropriate values ​​described above. As a result, kink resistance is improved, and the change in the overall length in the axial direction is small between the expanded and contracted diameter states, thus suppressing shortening. Furthermore, the first strut 11, the second strut 12, and the connecting strut 21 all have linear ranges (11a, 12a, 21a) that extend linearly without bending. From this, kink resistance can be further improved and pushability can be improved. Furthermore, since the distal apex 14 of the intermediate zigzag pattern unit 10 is a free end, a partially open cell structure is formed. Therefore, the stent 1 of this embodiment can be made to conform well to the shape.

[0057] Furthermore, the angle β formed by the linear range 11a of the first strut 11 and the linear range 12a of the second strut 12 was configured to be the appropriate value described above. This further improves kink resistance and facilitates delivery with a small-diameter catheter.

[0058] The embodiments may be used in combination as appropriate, but a detailed explanation is omitted. Furthermore, this disclosure is not limited to the embodiments described above. [Explanation of Symbols]

[0059] 1 stent 10 Intermediate Zigzag Pattern Unit 11. First strut 11a Linear range 12. Second strut 12a Linear range 13 Proximal vertex 14. Distal vertex 15 Intermediate connection section 21 Connecting strut 21a Linear range 30. First proximal pattern 31. First strut 32 2nd strut 33 Proximal vertex 34 Distal vertex 40. Second proximal pattern 41. First strut 42. Second strut 43 Proximal vertex 44 Distal vertex 45 rhombus cells 46 Extension part 50 Distal pattern 51. First strut 52 2nd strut 53 Proximal vertex 54 Distal vertex 55 distal end cell 56 Extension part 60 Adjustment Cells 61 First Adjustment Cell 62 Second Adjustment Cell

Claims

1. A zigzag pattern unit having a zigzag pattern in which a first strut and a second strut intersecting the first strut are alternately arranged along the circumferential direction around the axial direction, The system comprises a plurality of connecting struts connected to the zigzag pattern unit, In the aforementioned zigzag pattern unit, The proximal top portion that protrudes proximally where the first strut and the second strut are connected, The distal apex portion that protrudes distally to where the first strut and the second strut are connected, They are arranged alternately, The first strut, the second strut, and the connecting strut all have a linear range that extends in a straight line without bending. At least a portion of the proximal part of the connecting strut that extends from the distal side of the zigzag pattern unit to the zigzag pattern unit is connected to an intermediate connecting portion located within the linear range of the first strut and proximal to the distal top portion. With respect to the first strut and the connecting strut connected to each other within the linear range of the first strut, if α is the angle formed by the direction in which the linear range of the first strut extends and the direction in which the linear range of the connecting strut extends, then in the expanded free state, ０°＜α Satisfying the relationship, The distal portion of the connecting strut extending from the proximal side of the zigzag pattern unit to the zigzag pattern unit is connected to the proximal top portion. If γ is the angle between the direction in which the linear range of the connecting strut extends and the axial direction, then in the free state, 20° < γ < 60° A stent that satisfies the following conditions.

2. In the stent according to claim 1, If β is the angle formed at the distal apex between the direction in which the linear range of the first strut extends and the direction in which the linear range of the second strut extends, then in the free state, １００°＜β＜１５０° Satisfying the relationship, A stent characterized by the following features.

3. In the stent according to claim 1 or claim 2, At the distal end of the stent, distal end cells in multiples of three are arranged circumferentially. The distal end cell has three marker portions arranged circumferentially, which are substantially evenly spaced in the circumferential direction to suppress the transmission of radiation. A stent characterized by the following features.

4. In the stent described in claim 3, In the zigzag pattern unit, the number of cells arranged in the circumferential direction is different from the number of cells in the distal end cells arranged in the circumferential direction. Between the zigzag pattern unit and the distal end cell, an adjustment cell is provided to adjust the difference in the number of cells between the zigzag pattern unit and the distal end cell. The proximal ends of the adjustment cells are all connected to the zigzag pattern unit. A stent characterized by the following features.

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