Stent

Abstract

Provided is a stent that is unlikely to kink, can uniformly expand blood vessels, and can sufficiently ensure blood flow.　A stent 1 includes: a first stent body 10 in which a plurality of first cells 12 surrounded by a plurality of first struts 11 are arrayed in a circumferential direction and a central axis direction; and a second stent body 20 in which a plurality of second cells 22 surrounded by a plurality of second struts 21 are arrayed in the circumferential direction and the central axis direction, and which is inserted into the first stent body 10. At least one of the first struts 11 and the second struts 21 has a portion in which the strut width w in a direction perpendicular to an extension direction of the first struts 11 or the second struts 21 is wider than the strut thickness t in a direction perpendicular to the central axis.

Description

stents

[0001] The present disclosure relates to stents.

[0002] 2. Description of the Related Art Catheter therapy is known in the art, in which a stent is deployed at a lesion site in a blood vessel lumen.

[0003] Conventional stents have a configuration in which the strut width and strut thickness are similar or narrower than the strut thickness, because increasing the strut width and decreasing the strut thickness of a conventional stent increases the rigidity of the stent when it is contracted, which can make it difficult to load and deliver it onto a small-diameter catheter or can cause buckling.

[0004] However, in order to uniformly dilate a stenotic blood vessel with a stent, it is essentially desirable for the struts to be wide and have a large surface area in contact with the inner wall of the blood vessel. Furthermore, in order to ensure sufficient antegrade blood flow, it is essentially desirable to thin the strut wall thickness to increase the cross-sectional area of ​​the lumen when deployed. Ensuring sufficient blood flow reduces the risk of thrombus adhesion, so from this perspective as well, a thin strut wall structure is essentially desirable. However, Patent Document 1, which discloses a stent, does not disclose any design concepts for the width and thickness of the struts.

[0005] Japanese Patent Application Laid-Open No. 2020-78549

[0006] An object of the present disclosure is to provide a stent that is less likely to kink, can uniformly expand blood vessels, and can ensure sufficient blood flow.

[0007] The present disclosure solves the above-mentioned problems by the following means: For ease of understanding, the following description will be given with reference numerals corresponding to the embodiments of the present disclosure, but the present disclosure is not limited to these.

[0008] The first disclosure is a stent (1) comprising: a first stent body (10) in which a plurality of first cells (12) consisting of a plurality of first struts (11) are arranged in the circumferential direction and in the central axis direction; and a second stent body (20) in which a plurality of second cells (22) consisting of a plurality of second struts (21) are arranged in the circumferential direction and in the central axis direction, and in which at least a region for expanding a narrowed portion of a biological lumen is inserted into the first stent body (10), and at least one of the first struts (11) and the second struts (21) has a portion in which the strut width w in a direction perpendicular to the extending direction of the first struts (11) or the second struts (21) is wider than the strut thickness t in the direction perpendicular to the central axis.

[0009] The second disclosure is a stent (1) according to the first disclosure, which has a portion satisfying 0.2≦t / w.

[0010] A third disclosure is a stent (1) according to the first disclosure or the stent (1) according to the first disclosure, which has a portion satisfying 30 μm≦w≦250 μm.

[0011] A fourth disclosure is a stent (1) according to any one of the first to third disclosures, which has a portion that satisfies 20 μm≦t≦150 μm.

[0012] A fifth disclosure is a stent (1) according to any one of the first to fourth disclosures, which has a portion that satisfies t1 > t2, where t1 is the thickness t of the first strut (11) and t2 is the thickness t of the second strut (21).

[0013] A sixth disclosure is a stent (1) according to any one of the first to fifth disclosures, which has a portion where w1 > w2 is satisfied, where w1 is the width w of the first strut (11) and w2 is the width w of the second strut (21).

[0014] A seventh disclosure is a stent (1) according to any one of the first to sixth disclosures, wherein the stent (1) is used for applications in which the stent (1) is temporarily placed in a biological lumen and then retrieved outside the body.

[0015] The eighth disclosure is a method for expanding a biological organ having a luminal structure using a stent (1), the stent (1) comprising: a first stent body (10) in which a plurality of first cells (12) consisting of a plurality of first struts (11) are arranged in the circumferential direction and in the central axis direction; and a second stent body (20) in which a plurality of second cells (22) consisting of a plurality of second struts (21) are arranged in the circumferential direction and in the central axis direction, and in which at least a region for expanding a narrowed portion of a biological lumen is inserted into the first stent body (10), and at least one of the first struts (11) and the second struts (21) is arranged in a direction perpendicular to the central axis. The method includes delivering the stent (1) housed in a catheter (50) in a contracted state together with the catheter (50) through the biological organ to a position in the biological organ where the stent (1) is to be expanded from the distal side, withdrawing the catheter (50) proximally and starting to expand the stent (1) from the distal side, completing the expansion of the stent (1), and re-accommodating the expanded stent (1) into the catheter (50).

[0016] According to the present disclosure, it is possible to provide a stent that is less likely to kink, can uniformly expand blood vessels, and can ensure sufficient blood flow.

[0017] 6 is a side view of the stent 1 of the first embodiment. FIG. 7 is a perspective view of the stent 1 shown in FIG. 1. FIG. 8 is a virtual development view of a portion of the first stent body 10 of the first embodiment. FIG. 9 is a virtual development view of a portion of the second stent body 20 of the first embodiment. FIG. 10 is a virtual development view of a portion of the stent 1 of the first embodiment. FIG. 11 is a view illustrating the outer diameter D1 of the first stent body 10 before assembly. FIG. 12 is a view illustrating the outer diameter D2 of the second stent body 20 before assembly. FIG. 13 is a view illustrating the process of inserting the second stent body 20 into the first stent body 10. FIG. 14 is a cross-sectional view taken along the s1-s1 line of FIG. 1. FIG. 6 is a cross-sectional view showing an enlarged view of range B in FIG. 6. FIG. 15 is a view illustrating the internal state of the stent 1 when it is bent. FIG. 7 is a cross-sectional view of the stent 1 of the second embodiment cut at the same position as in FIG. 7 of the first embodiment. FIG. 7 is a cross-sectional view of the stent 1 of the third embodiment cut at the same position as in FIG. 7 of the first embodiment. FIG. 7 is a cross-sectional view of the stent 1 of the fourth embodiment cut at the same position as in FIG. 7 of the first embodiment. FIG. 16 is a side view of the stent 1 of the fifth embodiment. Fig. 1 is a perspective view of a stent 1 with an open end on the distal side LD2. Fig. 2 is a side view of a stent 1 with an open end on the distal side LD2. Fig. 3 is a schematic diagram showing a procedure for dilating a stenotic site in a blood vessel using the stent 1. Fig. 4 is a schematic diagram showing a procedure for dilating a stenotic site in a blood vessel using the stent 1. Fig. 5 is a schematic diagram showing a procedure for dilating a stenotic site in a blood vessel using the stent 1. Fig. 6 is a schematic diagram showing a procedure for dilating a stenotic site in a blood vessel using the stent 1.

[0018] Hereinafter, an embodiment of a stent will be described. Note that the drawings attached to this specification are all schematic diagrams, and the shape, scale, aspect ratio, etc. may be modified or exaggerated from the actual product. Furthermore, in the drawings, hatching indicating the cross section of a member may be omitted as appropriate.

[0019] In this specification, terms specifying the shape, geometric conditions, and the degree of these, such as "orthogonal" and "direction," include not only the strict meaning of the terms but also the range in which they can be considered to be nearly orthogonal and the range in which they can be considered to be roughly in that direction. In this specification, the axial direction (longitudinal direction) LD refers to the side closer to the practitioner (proximal) as the LD1 side, and the side farther from the practitioner (distal) as the LD2 side, and the direction orthogonal to the axial direction LD is referred to as the radial direction RD. Also, in this specification, the direction in which the cells are arranged is referred to as the circumferential direction OD. The circumferential direction may be the radial direction RD or a direction inclined relative to the radial direction RD.

[0020] (First embodiment) Fig. 1 is a side view of a stent 1 of the first embodiment. Fig. 2 is a perspective view of the stent 1 shown in Fig. 1. Fig. 3A is a virtual developed view of a portion of a first stent body 10 of the first embodiment. Fig. 3B is a virtual developed view of a portion of a second stent body 20 of the first embodiment. Fig. 3C is a virtual developed view of a portion of a stent 1 of the first embodiment. Fig. 4A is a view illustrating the outer diameter D1 of the first stent body 10 before assembly. Fig. 4B is a view illustrating the outer diameter D2 of the second stent body 20 before assembly. Fig. 5 is a view illustrating the process of inserting the second stent body 20 into the first stent body 10. Fig. 6 is a cross-sectional view taken along line s1-s1 in Fig. 1.

[0021] In the drawings, to facilitate distinction between the first stent body 10 and the second stent body 20, struts of the first stent body 10 are shown in black, and struts of the second stent body 20 are shown in white. Furthermore, in this specification, etc., a "cell" refers to a portion surrounded by struts that form a stent. The "cells" may be identical in shape and size, or may differ from one another. A "strut" refers to a portion made of the wire-like material. In this specification, etc., the opening of a cell is referred to as an "opening portion," and the portion where struts of adjacent cells are connected or overlapped is referred to as an "overlap portion." Within an overlap portion, the point where struts intersect is also referred to as an "intersection portion." An overlap portion has a certain range (area). An overlap portion includes one or more intersection portions.

[0022] The stent 1 of the first embodiment can be used, for example, to dilate a narrowed or blocked blood vessel by being housed in a catheter (not shown) and being pushed out of the catheter in the lumen of the blood vessel to expand its diameter. The stent 1 is used in applications where it is temporarily placed in the blood vessel and then retrieved from the body, but it can also be used to leave the stent 1 in the blood vessel without being retrieved from the body. When used in such applications, it is preferable that the pusher wire 2 and the stent 1 can be separated by an operator's operation.

[0023] 1 and 2 , the stent 1 has a substantially cylindrical shape in an expanded state. The stent 1 has a long, thin cylindrical shape in a contracted state. A pusher wire 2 is connected to an end of the proximal side LD1, and a distal end shaft 3 is connected to an end of the distal side LD2. The method for connecting the proximal end of the stent 1 to the pusher wire 2 is not particularly limited as long as it is a connection method used in general medical devices, and examples include welding, UV bonding, and infiltration with silver solder.

[0024] The practitioner advances or retreats the stent 1 within the catheter or blood vessel by pushing or pulling the pusher wire 2 via an operating unit (not shown) outside the body that is connected to the proximal side LD1 of the pusher wire 2. The distal end shaft 3 is a mark for confirming the position of the distal side X2 of the stent 1 in an X-ray image, and at least a portion of the distal end shaft 3 is made of a radiopaque material.

[0025] The stent 1 comprises a first stent body 10 and a second stent body 20, each of which has a substantially cylindrical structure. The stent 1 is a double-layered stent in which the second stent body 20 is inserted into the first stent body 10 at least in the region where the stenotic site of a biological lumen is dilated. Here, the region where the stenotic site of a biological lumen is dilated refers to the region that substantially contributes to the dilation of the stenotic site during use, and in the case of the stent 1 of this embodiment, it refers to the region that is expanded into a substantially cylindrical shape in the expanded state shown in Figures 1 and 2. The above-mentioned "at least" means that the second stent body 20 must be inserted into the first stent body 10 in the region where the stenotic site is dilated. The range in which the second stent body 20 is inserted into the first stent body 10 is not limited to the region that substantially expands the narrowed area described above (in this embodiment, the region that expands into an approximately cylindrical shape), and in this embodiment, the second stent body 20 is inserted into the first stent body 10 up to the point where it is connected to the pusher wire 2 and the distal end shaft 3.

[0026] The first stent body 10 and the second stent body 20 are not connected to each other in the radial direction. Specifically, the first stent body 10 and the second stent body 20 are indirectly connected via the pusher wire 2 or via the distal end shaft 3, but there is no connection between the pusher wire 2 and the distal end shaft 3. Therefore, the first stent body 10 and the second stent body 20 can flexibly deform independently of each other.

[0027] Note that the first stent body 10 and the second stent body 20 may be directly connected at their proximal ends, and one of the first stent body 10 and the second stent body 20 may be connected to the pusher wire 2, but the other of the first stent body 10 and the second stent body 20 may not be connected to the pusher wire 2. In other words, it is sufficient that the first stent body 10, the second stent body 20, and the pusher wire 2 are integrally connected. In other words, the proximal end of the first stent body 10 and the proximal end of the second stent body 20 are inseparably connected to the pusher wire 2, and axial movement of the second stent body 20 relative to the first stent body 10 is restricted. Similarly, the first stent body 10 and the second stent body 20 may be directly connected at the distal end, with one of the first stent body 10 and the second stent body 20 connected to the distal end shaft 3, but the other of the first stent body 10 and the second stent body 20 not connected to the distal end shaft 3. In other words, it is sufficient that the first stent body 10, the second stent body 20, and the distal end shaft 3 are integrally connected. Note that while the first stent body 10 and the second stent body 20 are connected at the proximal end or the distal end, they are not connected (linked) in the radial direction at other locations. Furthermore, even in the radially expanded state, the first stent body 10 and the second stent body 20 are merely in close contact with each other in the radial direction, but are not linked (linked) in the radial direction. Therefore, the first stent body 10 and the second stent body 20 are in a state where they can deform independently of each other, and they do not restrict each other's deformation.

[0028] The proximal side LD1 of the first stent body 10, the proximal side LD1 of the second stent body 20, and the distal side LD2 of the pusher wire 2 are directly or indirectly connected. Here, "directly connected" means, for example, that the proximal side LD1 of the first stent body 10 is connected to the distal side LD2 of the pusher wire 2, and that the proximal side LD1 of the second stent body 20 is connected to the distal side LD2 of the pusher wire 2. In this case, the position where the proximal side LD1 of the first stent body 10 is connected to the pusher wire 2 and the position where the proximal side LD1 of the second stent body 20 is connected to the pusher wire 2 may be the same as or different from each other. On the other hand, being indirectly connected refers to, for example, a configuration in which the proximal side LD1 of the first stent body 10 is connected to the distal side LD2 of the pusher wire 2, and the proximal side LD1 of the first stent body 10 is connected to the proximal side LD1 of the second stent body 20 (or a configuration in which the connections between the two stent bodies are reversed). In this case, the proximal side LD1 of the second stent body 20 is indirectly connected to the pusher wire 2 via the proximal side LD1 of the first stent body 10. Alternatively, this configuration refers to a configuration in which the proximal side LD1 of the first stent body 10 and the proximal side LD1 of the second stent body 20 are connected via a pipe-shaped sleeve (not shown) fitted onto the distal side LD2 of the pusher wire 2. In this case, the proximal side LD1 of the first stent body 10 and the proximal side LD1 of the second stent body 20 are indirectly connected to the distal side LD2 of the pusher wire 2 via the sleeve. Thus, in this specification, "indirectly connected" includes a form in which one of the proximal side LD1 of the first stent body 10 or the proximal side LD1 of the second stent body 20 is directly connected to the pusher wire 2, and the other stent body is indirectly connected to the pusher wire 2 via the directly connected stent body. Methods for connecting the proximal end of each stent body to the pusher wire 2 include, for example, welding, UV bonding, impregnation with silver solder, etc., but are not particularly limited as long as they are connection methods used in general medical devices.

[0029] As will be described later, the stent 1 of the first embodiment is produced by inserting a second stent body 20, which has an outer diameter larger than that of the first stent body 10 in its natural state, in a contracted state into the first stent body 10. As a result, the second stent body 20 constantly presses the first stent body 10 outward in the radial direction RD, so that the first stent body 10 and the second stent body 20 come into close contact with each other.

[0030] 1 , the proximal side LD1 ends of the first stent body 10 and the second stent body 20 are tapered and connected to a pusher wire 2. Similarly, the distal side LD2 ends of the first stent body 10 and the second stent body 20 are tapered and connected to a distal end shaft 3. This restricts the axial movement of the second stent body 20 relative to the first stent body 10.

[0031] As shown in Fig. 3A , the first stent body 10 has a plurality of first cells 12 surrounded by first struts 11 arranged in the circumferential direction OD. In the first stent body 10, the plurality of first cells 12 are arranged in the axial direction LD. That is, the first stent body 10 has a pattern in which the plurality of first cells 12 are arranged in the circumferential direction OD and the axial direction LD. Adjacent first cells 12 are connected at intersections 14.

[0032] As shown in Fig. 3B , the second stent body 20 has a plurality of inner cells (second cells) 22 surrounded by second struts 21, which are arranged in the circumferential direction OD. The second cells 22 are arranged in the axial direction LD. That is, the second stent body 20 has a pattern in which the second cells 22 are arranged in the circumferential direction OD and the axial direction LD. Adjacent second cells 22 are connected at intersections 24.

[0033] 3A and 3B, in the stent 1 of the first embodiment, the first cells 12 and the second cells 22 have, for example, the same size, shape, and arrangement. That is, in the first embodiment, the pattern shown in Fig. 3A and the pattern shown in Fig. 3B are substantially the same. However, the pattern of the first stent body 10 and the pattern of the second stent body 20 may be different.

[0034] As shown in Figure 3C, the first stent body 10 and the second stent body 20 are arranged in their natural state such that the openings 13 of the first cells 12 (first stent body 10) overlap the intersections 24 of the second cells 22 (second stent body 20). Specifically, the openings 13 of one first cell 12 overlap the intersections 24 of one second cell 22. This increases the strut density throughout the stent, thereby increasing the surface area of ​​the stent 1. In the stent 1 of the first embodiment, the proportion of the non-opening areas to the area of ​​the overlapping portions of the first stent body 10 and the second stent body 20 may be 7 to 45%.

[0035] In the first embodiment, the relationship between the outer diameter D1 of the first stent body 10 before assembly and the outer diameter D2 of the second stent body 20 before assembly is D1<D2. Therefore, as shown in Fig. 5 , the second stent body 20A, which is obtained by reducing the diameter of the second stent body 20, is inserted into the first stent body 10. Then, as shown in Fig. 6 , the self-expansion force of the second stent body 20 causes the second stent body 20 to adhere closely to the inside of the first stent body 10 in the circumferential direction OD.

[0036] This reduces the likelihood of the first stent body 10 and the second stent body 20 becoming misaligned relative to each other in the axial direction LD (see FIG. 1) of the stent 1. For ease of understanding, FIG. 5 shows only the annular cell rows arranged in the circumferential direction in each stent body.

[0037] In the first embodiment, the second stent body 20 inserted into the first stent body 10 in a contracted state constantly presses the first stent body 10 outward in the radial direction RD. Therefore, the first stent body 10 and the second stent body 20 can be brought into close contact with each other even if they are not connected to each other in the radial direction. Furthermore, because the first stent body 10 and the second stent body 20 of the stent 1 are not connected to each other in the radial direction, the first stent body 10 and the second stent body 20 can flexibly deform independently. Furthermore, the stent 1 has an expansion force that is the sum of the expansion force of the first stent body 10 and the expansion force of the second stent body 20. Therefore, the ratio of expansion force to surface area can be increased compared to a single-layer stent.

[0038] The stent 1 (first stent body 10, second stent body 20) may be made of a highly biocompatible material. While not particularly limited, a material with superelastic properties, such as a nickel-titanium (Ni-Ti) alloy, is preferred. The first stent body 10 and the second stent body 20 can be fabricated, for example, by laser processing a substantially cylindrical tube made of the above material.

[0039] The stent 1 may be loaded with a drug such as a physiologically active substance (such as a drug that suppresses intimal hyperplasia), and specifically, may carry the drug so that the drug is eluted in the lumen structure.

[0040] The first stent body 10 and the second stent body 20 are fabricated, for example, by laser processing a tube with a diameter of approximately 0.4 to 3 mm to form a mesh pattern, and then stretching the tube in the radial direction to achieve the desired diameter. As described above, a two-layer stent 1 can be fabricated by inserting the second stent body 20 into the first stent body 10. This two-layer stent 1 is housed in the lumen of a catheter (not shown) in a state where its diameter is reduced in the radial direction from its natural state. If the stent 1 is made of an elastic material such as a superelastic alloy or a shape-memory alloy, pushing the stent 1 out of the catheter will cause it to expand in diameter by its own self-expansion force.

[0041] Figure 7 is an enlarged cross-sectional view of area B in Figure 6. Note that Figure 7 illustrates the cross-sectional shapes of the first strut 11 and the second strut 21 in a direction perpendicular to the direction in which the first strut 11 and the second strut 21 extend (the same applies to Figures 9, 10, and 11). As shown in Figure 7, the strut width w (w1, w2) of each of the first strut 11 and the second strut 21 in a direction perpendicular to the direction in which the first strut 11 or the second strut 21 extends is greater than the strut thickness t (t1, t2) in a direction perpendicular to the central axis of the stent 1. That is, the first strut 11 has a relationship of t1 < w1, and the second strut 21 has a relationship of t2 < w2. In this embodiment, t1 = t2 = 60 µm and w1 = w2 = 120 µm. It is desirable that the strut thickness t (t1, t2) satisfy the relationship 20 µm ≤ t ≤ 150 µm. If the strut thickness t is less than 20 μm, the expansion force will be reduced, which may result in insufficient dilation of the stenotic lesion, while if the strut thickness t is greater than 150 μm, the expansion force will be increased, which may result in excessive blood vessel dilation and vascular damage. Furthermore, it is desirable that the strut width w (w1, w2) satisfy the relationship 30 μm≦w≦250 μm. If the strut width w is less than 30 μm, the surface area of ​​the portion in contact with the lesion will be reduced, increasing the force acting per unit area of ​​the strut, which may result in localized strong force and vascular damage. Furthermore, if the strut width w is greater than 250 μm, the struts will collide with each other when contracted, increasing the stiffness within the catheter and making it difficult to deliver the catheter to the lesion. The range satisfying the relationship of 20 μm≦t≦150 μm and the range satisfying the relationship of 30 μm≦w≦250 μm may be the entire range or a part of the range in which the second stent body 20 is inserted into the first stent body 10. When it is a part, it is desirable that it is the region where the narrowed part of the biological lumen is expanded (in the example of this embodiment, the region expanded into a substantially cylindrical shape), but it may also be an even narrower part of the region where the narrowed part is expanded.

[0042] In this embodiment, by satisfying t<w (t1<w1, t2<w2), the surface area of ​​the surface abutting the inner wall of the blood vessel can be significantly increased. This allows for more uniform blood vessel dilation. Furthermore, the large surface area reduces the pressure pressing against the inner wall of the blood vessel, thereby reducing the risk of vascular damage. Furthermore, if the strut width w is increased while t and w are approximately equal, i.e., the cross-sectional shape perpendicular to the strut extension direction is approximately square, as in the conventional configuration, the strut thickness t also increases, reducing the cross-sectional area of ​​the lumen upon deployment. However, by satisfying the relationship t<w in this embodiment, the strut thickness t can be reduced, thereby increasing the cross-sectional area of ​​the lumen upon deployment. This ensures sufficient antegrade blood flow and reduces the risk of thrombus adhesion. It is also desirable to set the relationship between the strut thickness t (t1, t2) and the strut width w (w1, w2) so that 0.2≦t / w is satisfied. This is because if t / w<0.2, the various effects described above cannot be fully achieved. The range satisfying the relationship 0.2≦t / w may be the entire range or a part of the range in which the second stent body 20 is inserted into the first stent body 10. When it is a part, it is desirable that it is the region where the narrowed part of the biological lumen is expanded (in the example of this embodiment, the region expanded into a substantially cylindrical shape), but it may also be an even narrower part of the region where the narrowed part is expanded.

[0043] Here, the effect of the stent 1 of the first embodiment when it is temporarily placed in a curved blood vessel and then removed will be described.

[0044] In the stent 1 of this embodiment, by satisfying the relationship t<w (t1<w1, t2<w2) as described above, blood vessels can be expanded more uniformly, the risk of vascular damage can be reduced, the cross-sectional area of ​​the lumen can be increased upon stent deployment, sufficient antegrade blood flow can be ensured, and the risk of thrombus adhesion can be reduced. In conventional single-layer stents, increasing the strut width w and decreasing the thickness t increases the rigidity upon contraction, which can lead to difficulties in loading and delivery into small-diameter catheters and the risk of buckling (kinking). However, in this embodiment, the double-layer stent is configured such that t<w (t1<w1, t2<w2). Because a double-layer stent is divided into two layers even with a wide strut width w, its circumferential density is lower than that of a single-layer stent. This allows it to be inserted into a small-diameter catheter and prevents its rigidity from increasing upon contraction. For example, the stent 1 of this embodiment can be inserted into a small-diameter catheter with an inner diameter of 0.4 to 0.55 mm. Furthermore, as described above, the double-structure stent is configured such that the second stent body 20 is always pressing the first stent body 10 from the inside, so even if it is configured such that t<w (t1<w1, t2<w2), it can be deployed without kinking when bent.

[0045] By deploying the stent 1 of the first embodiment at a lesion site in the lumen of a blood vessel, the lumen of the blood vessel is expanded, thereby ensuring patency of the lesion site. By removing (retrieving) the stent 1 from the lumen of the blood vessel after a predetermined period of time has passed, complications caused by the indwelling stent, such as restenosis, re-occlusion, and thrombosis, can be prevented. Furthermore, the stent 1 of the first embodiment has excellent shape-following properties, and therefore is highly protective of the blood vessel. The stent 1 of the first embodiment can be used not only for the treatment of blood vessels, but also for the treatment of luminal structures in general, such as the esophagus and large intestine.

[0046] The stent 1 of the first embodiment can also be used to treat cerebral vasospasm. Note that the stents of other embodiments described below also exhibit the same effects as the stent 1 of the first embodiment.

[0047] Second Embodiment Figure 9 is a cross-sectional view of the stent 1 of a second embodiment taken at the same position as in Figure 7 of the first embodiment. The stent 1 of the second embodiment is similar to the first embodiment except that the thickness t and width w of the struts are different from those of the stent 1 of the first embodiment. Therefore, parts that perform the same functions as in the first embodiment described above are given the same reference numerals, and redundant explanations will be omitted where appropriate.

[0048] The second embodiment is similar to the first embodiment in that the width w1 of the first strut is equal to the width w2 of the second strut, but satisfies the relationship "thickness t1 of the first strut < thickness t2 of the second strut." That is, the thickness t of the second stent body 20 disposed on the inside is thicker than that of the first stent body 10 disposed on the outside. This allows the stent 1 of the second embodiment to increase the pressing force (radial force) with which the second stent body 20 presses the first stent body 10 outward. In this embodiment, t1 = 40 μm and t2 = 80 μm, but these values ​​can be changed as appropriate. Note that, to more effectively increase the radial force, it is desirable to satisfy the relationship 1.2 < t2 / t1. In the second embodiment, by making only t2 thicker than in the first embodiment and keeping t1 the same as in the first embodiment, it is possible to increase the radial force and improve kink resistance while suppressing a decrease in the cross-sectional area of ​​the lumen during stent deployment, thereby further improving deployability. More specifically, thinning the stent increases the cross-sectional area of ​​the lumen, but this can have the disadvantage of reducing kink resistance and expansion force. However, in the stent 1 of this embodiment, the second stent body 20 presses the first stent body 10 from the inside, thereby improving kink resistance. Therefore, by thinning only the first stent body 10, rather than both the first stent body 10 and the second stent body 20, it is possible to achieve good lumen cross-sectional area, kink resistance, and expansion force.

[0049] (Third embodiment) Figure 10 is a cross-sectional view of the stent 1 of a third embodiment taken at the same position as in Figure 7 of the first embodiment. The stent 1 of the third embodiment is similar to the first embodiment except that the thickness t and width w of the struts are different from those of the stent 1 of the first embodiment. Therefore, parts that perform the same functions as in the first embodiment described above are given the same reference numerals, and redundant explanations will be omitted as appropriate.

[0050] In the third embodiment, the first struts 11 satisfy the relationship t1<w1, as in the first embodiment, but the second struts 21 are configured so that t2=w2. Furthermore, in the third embodiment, t1>t2 and w1>w2 are satisfied, so that the second struts 21 are smaller in both thickness and width than the first struts 11. This configuration facilitates the contraction of the second stent body 20, which contracts to a smaller diameter than the first stent body 10 in a contracted state, and improves the storability of the second stent body 20 when housed in the lumen of a catheter (not shown). In the third embodiment, both the relationships t1>t2 and w1>w2 are satisfied. However, for example, the relationships t1>t2 and w1=w2 may also be satisfied, or the relationships t1=t2 and w1>w2 may also be satisfied. The range in which the relationships t1>t2 and / or w1>w2 are satisfied may be the entire range in which the second stent body 20 is inserted into the first stent body 10, or may be a portion of the range. If it is a part, it is desirable that it be an area that expands the narrowed part of the biological lumen (in the example of this embodiment, an area that expands into an approximately cylindrical shape), but it may also be an even narrower part of the area that expands the narrowed part.

[0051] (Fourth embodiment) Figure 11 is a cross-sectional view of the stent 1 of the fourth embodiment taken at the same position as in Figure 7 of the first embodiment. The stent 1 of the fourth embodiment is similar to the first embodiment except that the thickness t and width w of the struts are different from those of the stent 1 of the first embodiment. Therefore, parts that perform the same functions as in the first embodiment described above are given the same reference numerals, and duplicate explanations will be omitted as appropriate.

[0052] In the fourth embodiment, the second struts 21 satisfy the relationship t2<w2, as in the first embodiment, but the first struts 11 are configured so that t1=w1. This configuration increases the area over which the second struts 21 contact the first struts 11, allowing the second struts 21 to press against the first struts 11 more stably and improving expandability.

[0053] 12 is a side view of a stent 1 of a fifth embodiment. The stent 1 of the fifth embodiment is similar to the first embodiment except that the thickness t and width w of the struts are partially changed from those of the stent 1 of the first embodiment, except for range C. Therefore, parts that perform the same functions as those of the first embodiment described above are given the same reference numerals, and redundant explanations will be omitted as appropriate.

[0054] In the fifth embodiment, in the range C shown in FIG. 12 , t<w (t1<w1, t2<w2) is satisfied as in the first embodiment, but in the ranges other than range C, t=w (t1=w1, t2=w2) is satisfied as in the conventional configuration. This configuration increases the width and thickness only in range C, which corresponds to the stenotic lesion, thereby enhancing the effect of dilating the stenotic lesion. Meanwhile, since the areas other than range C correspond to normal blood vessels, reducing the width and thickness reduces the dilating force, preventing excessive force from being applied to normal blood vessels and enhancing safety. Furthermore, the rigidity during diameter contraction is reduced, improving diameter contraction performance.

[0055] (Method of Use) Next, an example of a method of using the stent 1 of each embodiment will be described. Figures 15A to 15D are schematic diagrams showing the procedure for dilating a stenotic site in a blood vessel using the stent 1. Figures 15C and 15D show a simplified shape of the stent 1. Here, a procedure for widening a stenotic site CS formed in a blood vessel BV to ensure blood flow will be described. Note that the following procedure is performed by identifying the position of the stent, etc., using a visible marker (radiopaque marker).

[0056] First, as shown in Fig. 15A, a guidewire 40 is passed through the stenosis site CS. A catheter 50 is fitted onto the guidewire 40. Next, as shown in Fig. 15B, the tip of the catheter 50 fitted onto the guidewire 40 is inserted into the stenosis site CS along the passed guidewire 40 and passed through until it reaches the distal LD2 side of the stenosis site CS. Next, although not shown, the guidewire 40 is pulled out of the living body and recovered from the catheter 50. Then, a stent 1 is inserted from the proximal LD1 side of the catheter 50. The stent 1 is inserted into the catheter 50 in a contracted state.

[0057] 15C , the stent 1 is deployed from the tip of the catheter 50 on the distal LD2 side of the stenosis site CS. The tip of the catheter 50 is positioned on the distal LD2 side of the stenosis site CS, and the catheter 50 is retracted toward the proximal LD1 side, thereby deploying the stent 1 from the tip of the catheter 50. When the stent 1 is deployed from the tip of the catheter 50, the stent 1 expands by its own expansion force, thereby pushing open the stenosis site CS from the inside. By pushing open the stenosis site CS from the inside with the expanded stent 1, blood flow in the blood vessel BV can be ensured.

[0058] After it is confirmed that blood flow in the blood vessel BV is ensured, follow-up observation is performed for, for example, about 5 to 60 minutes. After the follow-up observation, as shown in Figure 15D, the tip of the catheter 50 is advanced toward the distal end LD2 of the stent 1, and the entire stent 1 is retracted into the catheter 50. This allows the stent 1 and the catheter 50 to be retrieved outside the body.

[0059] (Modifications) The present disclosure is not limited to the above-described embodiment, and various modifications and variations are possible, and these are also within the scope of the present disclosure.

[0060] (1) In each embodiment, an example has been described in which the ends of the first stent body 10 and the second stent body 20 at the distal side LD2 of the stent 1 are gradually reduced in diameter toward the distal end shaft 3 and are connected to the distal end shaft 3. This is not limiting, and for example, the end of the distal side LD2 of the stent 1 may be open. FIG. 13 is a perspective view of the stent 1 with an open end at the distal side LD2. FIG. 14 is a side view of the stent 1 with an open end at the distal side LD2. The stent 1 of each of the above-described embodiments may be open at the end at the distal side LD2, as shown in FIGS. 13 and 14 .

[0061] In the stent 1 of each of the above-described embodiments, six cells are arranged in the circumferential direction OD. However, the present invention is not limited to this. For example, the number of cells arranged in the circumferential direction OD may be reduced as shown in Figures 13 and 14. Figures 13 and 14 show an example in which two cells are arranged in the circumferential direction OD.

[0062] Furthermore, although no particular reference has been made to markers in the stent 1 of each of the above-described embodiments, markers may be provided as appropriate as shown in Figures 13 and 14. For example, the stent 1 shown in Figures 13 and 14 is provided with markers 15, 16, 25, and 26. The markers 15, 16, 25, and 26 are members that serve as landmarks for confirming the position of the stent 1 within a tubular organ such as a blood vessel, and are made of a radiopaque material.

[0063] Marker 15 is formed in a cylindrical shape and is adhesively fixed to the joint portion of the end portion of the proximal side LD1 of the first stent body 10. Marker 25 is formed in a cylindrical shape and is adhesively fixed to the joint portion of the end portion of the proximal side LD1 of the second stent body 20. Marker 15 and marker 25 are arranged with a shift in the LD direction. By arranging marker 15 and marker 25 with a shift, the positions of the ends of the proximal side LD1 of the first stent body 10 and the second stent body 20 can be correctly confirmed.

[0064] The marker 16 is formed in a generally square pipe shape and is fixed by crimping to the end of the distal side LD2 of the first stent body 10. The marker 26 is formed in a generally square pipe shape and is fixed by crimping to the end of the distal side LD2 of the second stent body 20. Furthermore, the marker 26 is positioned closer to the distal side LD2 than the marker 16, which allows the positions of the end of the distal side LD2 of each of the first stent body 10 and the second stent body 20 to be correctly confirmed. Note that the form of each marker is not limited to the configuration described above, and various conventionally known forms of markers can be used.

[0065] (2) In each embodiment, a configuration having a two-layer structure consisting of a first stent body 10 and a second stent body 20 has been exemplified. This is not limiting, and for example, another stent body may be provided on the outside of the first stent body 10 and / or on the inside of the second stent body 20. In this case, the relationship between the another stent body and the first and second stent bodies may be the same as the relationship between the first stent body and the second stent body in the above-mentioned embodiment.

[0066] The embodiments and modifications may be used in combination as appropriate, but detailed description thereof will be omitted. The present disclosure is not limited to the embodiments described above.

[0067] REFERENCE SIGNS LIST 1 Stent 2 Pusher wire 3 Distal end shaft 10 First stent body 11 First strut 12 First cell 13 Opening portion 14 Intersection portion 20 Second stent body 21 Second strut 22 Second cell 23 Opening portion 24 Intersection portion t Thickness of strut t1 Thickness of first strut t2 Thickness of second strut w Width of strut w1 Width of first strut w2 Width of second strut

Claims

1. A first stent body in which a plurality of first cells surrounded by a plurality of first struts are arranged in a circumferential direction and a central axis direction, and a second stent body in which a plurality of second cells surrounded by a plurality of second struts are arranged in a circumferential direction and a central axis direction, and at least a region for expanding a stenotic part of a biological lumen is inserted into the first stent body. At least one of the first strut and the second strut has a portion where a strut width w in a direction orthogonal to the extending direction of the first strut or the second strut is wider than a strut thickness t in a direction orthogonal to the central axis. A stent.

2. The stent according to claim 1, having a portion satisfying 0.2 ≦ t / w. A stent.

3. The stent according to claim 1 or 2, having a portion satisfying 30 μm ≦ w ≦ 250 μm. A stent.

4. The stent according to claim 3, having a portion satisfying 20 μm ≦ t ≦ 150 μm. A stent.

5. The stent according to claim 1 or 2, where the thickness t of the first strut is t1 and the thickness t of the second strut is t2, having a portion satisfying t1 > t2. A stent.

6. The stent according to claim 1 or 2, where the width w of the first strut is w1 and the width w of the second strut is w2, having a portion satisfying w1 > w2. A stent.

7. The stent according to claim 1 or 2, where the stent is used for a purpose of being temporarily placed in a biological lumen and then retrieved outside the body. A stent.

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