stent

Abstract

Where α is the angle formed by the direction in which a linear range (11a) of a first strut (11) extends and the direction in which a connecting strut (21) extends, the relationship 0° < α is satisfied. A distal portion of the connecting strut (21), which extends from a point further to the proximal side than an intermediate zigzag pattern unit (10) to the intermediate zigzag pattern unit (10), is connected to a proximal apex (13). Where γ is the angle formed by the direction in which a linear range (21a) of the connecting strut (21) extends and an axial direction (LD), the relationship 20° < γ < 60° is satisfied.

Description

Stent

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

[0002] Regarding a stent for being placed in a luminal structure (e.g., blood vessel, trachea, intestine), a so-called open cell structure stent has high shape followability. On the other hand, a closed cell structure stent has the advantage that the struts do not protrude outward. Also, a closed cell structure stent having high flexibility has been proposed (for example, see Patent Document 1).

[0003] Japanese Patent Translation No. 2010-535075

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

[0005] The stent is configured to transition from a state having a small outer diameter that is shrunk, i.e., a reduced diameter state, to a state having a largely expanded outer diameter, i.e., an expanded diameter state. In the cell structure of the stent of Patent Document 1 described above, there was a large difference between the overall length of the stent in the reduced diameter state (the overall length in the axial direction, the same hereinafter) and the overall length of the stent in the expanded diameter state. The phenomenon that the overall length of the stent in the expanded diameter state is shorter than that in the reduced diameter state is also called "shortening". If the change in the overall length of the stent due to this shortening is large, for example, when the stent is expanded and placed at the intended position during the operation, it may be difficult to place the stent at the target position, etc., and it may be difficult to use. Furthermore, in the stent of Patent Document 1, the pushability when the operator pushes the stent distally was poor.

[0006] An object of the present disclosure is to provide a stent having good kink resistance, good pushability, and little change in the overall length in the axial direction between the expanded diameter state and the reduced diameter state.

[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 towards the connection between the first strut (11) and the second strut (12) The proximal apex portion (13) and the distal apex portion (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 of the zigzag pattern unit (10) 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, the relationship 20° < γ < 60° is satisfied, which is the stent (1).

[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 three 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).

[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.

[0013] This is a perspective view showing the expanded diameter state of the stent 1 according to this disclosure. This is a side view showing the expanded diameter state of the stent 1. This is an unfolded view of the expanded diameter state of the stent 1 laid out on a plane. This is a magnified view of a part of Figure 3. This is a magnified view of an unfolded view of the stent 1 in its reduced diameter state, virtually laid out on a plane.

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

[0015] (Embodiments) Figure 1 is a perspective view showing the expanded diameter state of the stent 1 according to this disclosure. Figure 2 is a side view showing the expanded diameter state of the stent 1. Figure 3 is an unfolded view of the expanded diameter state of the stent 1 laid out in a 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 the marker parts 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 this embodiment can be manufactured using materials commonly used in conventionally known stents. The stent 1 can preferably be made of a material having superelastic properties, such as a nickel-titanium (Ni-Ti) alloy. Furthermore, the stent 1 of this embodiment may be configured to carry various drugs so that they are eluted within the body.

[0018] Stent 1 can be manufactured by laser processing a small-diameter, substantially cylindrical tube made of the above material, or by braiding (braiding) struts. Specifically, for example, a stent material in the shape of a tube with an outer diameter of about 2 mm to 3 mm is laser processed to remove the parts corresponding to cells, leaving the parts corresponding to struts. Then, it is stretched radially and deformed to a desired outer diameter, 4 mm in this embodiment, thereby manufacturing the stent. In this specification, "radial direction" refers to the direction extending radially with respect to the axial direction of the stent. In this specification, "axial direction" refers to the direction along the central axis of the substantially cylindrical stent in the expanded state. Figures 1 to 4 show stent 1 in its natural state, that is, the expanded state in which the outer diameter of stent 1 is expanded to 4 mm at the central position in the axial direction of stent 1. The outer diameter of stent 1 in the expanded state may be, for example, 3 mm or 5 mm, and can be manufactured as appropriate according to the part in which it is used.

[0019] When stent 1 is inserted into the body, it is delivered together with the catheter (not shown) in a reduced diameter state to the vicinity of the target location. Stent 1 expands on its own by being pushed out of the catheter and is positioned in contact with the inner wall of a blood vessel or other vessel. Furthermore, before stent 1 is completely exposed from the catheter, it can be re-sheathed (re-embedded) into the catheter by manipulating the catheter and stent 1 to bring them relatively closer together.

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

[0021] In this embodiment, an intermediate zigzag pattern unit 10 is provided as part of the zigzag pattern unit. Other zigzag pattern units include a first proximal pattern 30, a second proximal pattern 40, and a distal pattern 50. An adjustment cell 60 is formed between the intermediate zigzag pattern unit 10 and the distal pattern 50.

[0022] As shown in Figure 3, the intermediate zigzag pattern unit 10 has a zigzag pattern formed by the alternating arrangement and connection of first struts 11 and second struts 12 along the circumferential direction CD around the axial direction LD. In the intermediate zigzag pattern unit 10, the first struts 11 and second struts 12 that form the zigzag pattern are connected along the circumferential direction CD. As shown in Figure 4, the intermediate zigzag pattern unit 10 comprises a first strut 11, a second strut 12, a proximal top portion 13, a distal top portion 14, and an intermediate connection portion 15, and is formed in an annular shape around the axial direction LD. The first struts 11 and second struts 12 are directly connected to each other. The proximal top portion 13 and the distal top portion 14 correspond to the connection portions between the first struts 11 and second struts 12. In this embodiment, eight rows of intermediate zigzag pattern units 10 are arranged along the axial direction LD. Alternatively, the number of intermediate zigzag pattern units 10 may be more or less than 8 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 in the middle. The linear ranges 11a of the multiple first struts 11 constituting the intermediate zigzag pattern unit 10 extend in substantially the same direction from one another 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 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 performance 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 unfolded 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 along the way. 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 in the unfolded state. 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 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. Specifically, the intermediate connection portion 15 to which the connecting strut 21 connects is within the linear range 11a of the first strut 11, excluding the ends 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 adjacent intermediate zigzag pattern units 10 in the axial direction LD. As shown in Figures 2 and 3, the 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 on the proximal LD1 side is connected to the intermediate connecting portion 15 of the first strut 11. Also, the 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 on the distal LD2 side 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 configuration. 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, while having an open cell configuration. 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 in any way. The linear ranges 21a of multiple connecting struts 21 may extend in substantially the same direction to each other. 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 LD ​​direction. 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 LD ​​direction. 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°. Here, in Figure 4, the angle γ is shown in the unfolded state for explanatory purposes, but it should be noted that the 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 the angle γ is 20° < γ ≤ 40°, and even more desirable that it is 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 the 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 direction CD around the axial direction 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 direction 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 direction 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, distal vertex 34s that connect to the proximal vertex 13 of the intermediate zigzag pattern unit 10 and two adjacent distal vertex 34s 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 34s that are free ends and do not connect to the proximal vertex 13. These two adjacent distal vertex 34s 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 part 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 has 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 disposed adjacent to the proximal LD1 side of the first proximal pattern 30. Specifically, the distal top 44 of the second proximal pattern 40 is connected to the proximal top 33 of the first proximal pattern 30. As a result, a rhombic cell 45 is provided, which is surrounded by the first strut 31, the second strut 32, the first strut 41, and the second strut 42 and formed in a substantially rhombic shape. An extension 46 is connected to a part (three places in this embodiment) of the proximal top 43 of the second proximal pattern 40. The extension 46 extends from the proximal top 43 of the second proximal pattern 40 toward the proximal LD1 side. A marker part 101 is provided on this extension 46. The plurality of extensions 46 are arranged substantially evenly in the circumferential direction CD. The extension 46 is provided with a marker part 101 that suppresses the transmission of radiation (radiation impermeability). The specific form of the marker part 101 itself can appropriately utilize the forms of conventionally known markers. Since the extensions 46 are arranged substantially evenly in the circumferential direction CD, in the developed view of FIG. 4, the distances L46 in the circumferential direction CD between adjacent extensions 46 are all the same.

[0045] In the stent 1 of the present embodiment delivered using a small-diameter catheter, it is desirable that the number of marker parts 101 and 102 arranged at the proximal end and the distal end (not shown) described later be three each. If the number of marker parts 101 and 102 is three or more each, it is possible to accurately grasp that the stent 1 is in an expanded diameter state. Also, if the number of marker parts 101 and 102 is four or less, it is possible to prevent the marker parts from overlapping and becoming difficult to see, and to easily accommodate the stent 1 in the small-diameter catheter. Therefore, in the present embodiment, the marker part 101 is arranged at three equal positions 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, are greater than 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., into the stent 1.

[0047] At the distal end of the 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 apex 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 apex 53 and distal apex 54 are arranged alternately in the circumferential direction CD. Extension portions 56 are connected to some of the distal apex 54 of the distal pattern 50 (three locations in this embodiment). The extension portions 56 extend from the distal apex 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 marker portions 102 that suppress 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 provided between the intermediate zigzag pattern unit 10 and the distal pattern 50. The adjustment cell 60 adjusts the difference in the number of cells between the intermediate zigzag pattern unit 10 and the distal pattern 50. That is, although four cells of the intermediate zigzag pattern unit 10 are arranged side by side in the circumferential direction CD, as described above, it is desirable that the markers 102 provided at the distal end are evenly arranged in three in the circumferential direction CD. Therefore, an adjustment cell 60 is provided between the intermediate zigzag pattern unit 10 and the distal pattern 50 so that the number of distal tops 54 arranged at the distal end where the marker 102 is provided is a multiple of three, and the number of cells is adjusted (converted).

[0049] Specifically, in the present embodiment, the adjustment cell 60 naturally adjusts (converts) the number of cells from 4 of the cells of the intermediate zigzag pattern unit 10 to 6 of the distal end cells 55 formed by the distal pattern 50. In the present embodiment, the adjustment cell 60 includes a first adjustment cell 61 and a second adjustment cell 62 provided closer to the proximal side than the first adjustment cell 61. Four first adjustment cells 61 are arranged side by side in the circumferential direction. The first adjustment cells 61 adjacent to each other in the circumferential direction are arranged so as to sandwich the second adjustment cell 62 at the distal side portion thereof. Four second adjustment cells 62 are arranged side by side in the circumferential direction. As a result, a total of eight vertices including the four vertices of the first adjustment cell 61 and the four vertices of the second adjustment cell 62 are arranged in the circumferential direction and protrude to the distal side of the adjustment cell 60. The proximal tops 53 of the distal pattern 50 are connected to six of the eight vertices on the distal side of the adjustment cell 60. Further, since the remaining two vertices of the eight vertices on the distal side of the adjustment cell 60 are not connected to any location, they are free ends, and the structure is close to an open cell structure. Thereby, the flexibility near the distal end of the stent 1 is improved. On the other hand, the proximal ends of the adjustment cell 60 are all connected to the zigzag pattern unit 10, and there is no free end on the proximal side of the adjustment cell 60. Therefore, it is easy to re-accommodate 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 portion 14 of the intermediate zigzag pattern unit 10 is located more proximal to the proximal top portion 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 portion 14 of the same first strut 11. As a result, the distal top portion 14 of the intermediate zigzag pattern unit 10 is located more distal to the proximal top portion 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 adjacent intermediate zigzag pattern unit 10 when the diameter is reduced, moves to a position proximal to the adjacent intermediate zigzag pattern unit 10 when the diameter is increased. 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 when the diameter is reduced, and the diameter reduction capability (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 strut 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, according to the stent 1 of this embodiment, good shape conformability can be achieved.

[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 using a small-diameter catheter.

[0058] Furthermore, please note that, based on the above description, at least the inventions described in the following appendix are also disclosed in this specification. [Note] The first zigzag pattern unit is formed in an annular shape in the circumferential direction around the axial direction, the second zigzag pattern unit is adjacent to the first zigzag pattern unit in the axial direction and is formed in an annular shape in the circumferential direction, and the first zigzag pattern unit and the second zigzag pattern unit are connected to each other, the first zigzag pattern unit and the second zigzag pattern unit have a zigzag pattern formed in which first struts and second struts intersecting the first struts are alternately arranged along the circumferential direction, the first zigzag pattern unit and the second zigzag pattern unit have, at the connection portion between the first strut and the second strut, a proximal top portion that protrudes proximally in the axial direction, and at the connection portion between the first strut and the second strut, a distal top portion that protrudes distally in the axial direction, The first strut has a linear range that extends in a straight line without bending between the connection portions of the first strut and a pair of adjacent second struts, the second strut has a linear range that extends in a straight line without bending between the connection portions of the second strut and a pair of adjacent first struts, the connecting strut has a linear range that extends in a straight line without bending, the proximal portion of the connecting strut is connected to an intermediate connection portion provided in the linear range of the first strut of the first zigzag pattern unit, excluding the ends of the linear range of the first strut of the first zigzag pattern unit, and the distal portion of the connecting strut is connected to the proximal top portion of the second zigzag pattern unit. If α is the angle formed by the direction in which the linear range of the first strut of the first zigzag pattern unit extends and the direction in which the linear range of the connecting strut connected to the linear range of the first strut of the first zigzag pattern unit extends, then in the expanded free state, the relationship 0° < α is satisfied.A stent that satisfies the relationship 20° < γ < 60° in the free state, where γ is the angle between the direction in which the linear range of the connecting strut extends and the axial direction.

[0059] 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.

[0060] This application claims priority under Japanese Patent Application No. 2024-160645, filed on 18 September 2024, the entire contents of said patent application are incorporated herein by reference.

[0061] 1 Stent; 10 Intermediate zigzag pattern unit; 11 First strut; 11a Linear section; 12 Second strut; 12a Linear section; 13 Proximal apex; 14 Distal apex; 15 Intermediate connection section; 21 Connecting strut; 21a Linear section; 30 First proximal pattern; 31 First strut; 32 Second strut; 33 Proximal apex; 34 Distal apex; 40 Second proximal pattern; 41 First strut; 42 Second strut; 43 Proximal apex; 44 Distal apex; 45 Rhombus cell; 46 Extension section; 50 Distal pattern; 51 First strut; 52 Second strut; 53 Proximal apex; 54 Distal apex; 55 Distal end cell; 56 Extension section; 60 Adjustment cell; 61 First adjustment cell; 62 Second adjustment cell

Claims

1. A zigzag pattern unit having a zigzag pattern formed by first struts and second struts intersecting the first struts being alternately arranged along the circumferential direction around the axial direction, and a plurality of connecting struts connected to the zigzag pattern unit, wherein the zigzag pattern unit has alternating proximal top portions protruding towards the proximal side where the first struts and the second struts are connected, and distal top portions protruding towards the distal side where the first struts and the second struts are connected, and each of the first struts, the second struts and the connecting struts has a linear range that extends in a straight line without bending in the middle, and at least a portion of the proximal portion of the connecting struts extending from the distal side of the zigzag pattern unit to the zigzag pattern unit is connected to an intermediate connecting portion provided within the linear range of the first strut and proximal to the distal top portion. A stent in which, 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 between 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, the relationship 0° < α is satisfied, 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, and 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, the relationship 20° < γ < 60° is satisfied.

2. The stent according to claim 1, wherein, 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, the relationship 100° < β < 150° is satisfied in the free state.

3. A stent according to claim 1 or claim 2, characterized in that the distal end of the stent has a number of distal end cells that are multiples of 3 arranged in the circumferential direction, and three marker portions that suppress the transmission of radiation are arranged in the circumferential direction at three locations on the distal end cells, with these portions being arranged substantially evenly in the circumferential direction.

4. A stent according to claim 3, characterized in that the number of cells arranged circumferentially in the zigzag pattern unit is different from the number of cells of the distal end cell arranged circumferentially, an adjustment cell is provided between the zigzag pattern unit and the distal end cell to adjust the difference in the number of cells between the zigzag pattern unit and the distal end cell, and the proximal end of each of the adjustment cells is connected to the zigzag pattern unit.

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