WO2025142412A1 - Stent - Google Patents

Abstract

Provided is a stent that is highly safe and that has excellent expandability.　A stent 1 comprises: an outer stent body 10 in which a plurality of outer cells 12 surrounded by an outer strut 11 are arranged at least in the central axis direction; and an inner stent body 20 in which a plurality of inner cells 22 surrounded by an inner strut 21A, 21B are arranged in at least the central axis direction and which is inserted into the outer stent body 10 in at least a region for expanding a biological lumen. In a cylindrical shape part 1a of which the diameter expands to form a cylindrical shape in a free state in which the diameter of the stent 1 is freely expanded, the outer outermost surface has a blade part which has an area smaller than that of the inner outermost surface and makes an incision into a lesion site in the biological lumen.

Description

Stents

This disclosure relates to stents.

　Conventionally, catheter therapy has been known in which a stent is deployed at the lesion site in the blood vessel lumen.

Furthermore, as a stent with a larger surface area and excellent shape conformability to the vascular structure and diameter reduction properties, a stent with an outer stent body and an inner stent body inserted into the outer stent body (hereinafter also referred to as a two-layer structure stent) has been disclosed (see Patent Document 2). In the two-layer structure stent described in Patent Document 2, the outer stent body and the inner stent body have the same stent pattern.

There are also known medical devices called cutting balloon catheters and scoring balloon catheters that are used to treat and expand narrowed areas caused by calcified lesions in blood vessels, etc. (see Patent Document 3).

U.S. Pat. No. 1,039,0982 International Publication No. 2022/085313 Special Publication No. 2008-519654

However, the cutting balloon catheter disclosed in Patent Document 3 is manufactured by attaching a cutting member to a balloon, which makes manufacturing difficult and also poses the risk of the cutting member falling off the balloon.

The objective of this disclosure is to provide a stent that is highly safe and has excellent expandability.

The present disclosure solves the above problems by the following solutions. Note that, for ease of understanding, the following explanations are given with reference symbols corresponding to the embodiments of the present disclosure, but the present disclosure is not limited to these.

The first disclosure is a stent (1) comprising an outer stent body (10, 10B) in which a plurality of outer cells (12) surrounded by outer struts (11) are arranged at least in the central axis direction, and an inner stent body (20, 20B) in which a plurality of inner cells (22, 22A, 22B, 22C) surrounded by inner struts (21, 21A, 21B) are arranged at least in the central axis direction, and which is inserted into the outer stent body (10, 10B) at least in a region that expands a biological lumen. In the cylindrical section (1a) in which the stent (1, 1B) expands into a cylindrical shape when the stent (1, 1B) is in a free state, the surface located most outside in the radial direction of the inner stent body (20, 20B) is the inner outermost surface, and the surface located most outside in the radial direction of the outer stent body (10, 10B) is the outer outermost surface. The outer outermost surface has an area smaller than that of the inner outermost surface, and has a blade portion for cutting into a lesion in a biological lumen.

The second disclosure is a stent (1, 1B) in which, in the stent (1) described in claim 1, the outer struts (11) are arranged in an area of the cylindrical portion (1a) where the mesh pattern of the outer stent body (10) is coarser than the mesh pattern of the inner stent body (20), and function as the blade portion.

The third disclosure is a stent (1B) as described in claim 1, in which the partially twisted portion of the outer strut (11) functions as the blade portion.

The fourth disclosure is a stent (1, 1B) according to claim 3, in which the blade portion where the outer strut (11) is partially twisted in the cylindrical portion (1a) that expands into a cylindrical shape in a freely expanding state protrudes outward from the cylindrical shape formed by the surface of the outer strut (11) other than the blade portion.

The fifth disclosure is a stent (1, 1B) according to any one of claims 1 to 4, in which the width of the outer stent body (10, 10B) in a direction perpendicular to the extending direction of the blade portion as viewed from the radial direction is 0.5 mm or less.

The sixth disclosure is a method for expanding a biological organ having a luminal structure using a stent (1, 1B), the stent (1, 1B) comprising an outer stent body (10, 10B) in which a plurality of outer cells (12) surrounded by outer struts (11) are arranged at least in the central axis direction, and an inner stent body (20, 20B) in which a plurality of inner cells (22, 22A, 22B, 22C) surrounded by inner struts (21, 21A, 21B) are arranged at least in the central axis direction and inserted into the outer stent body (10, 10B) at least in the region in which the biological lumen is expanded, and in a cylindrical portion (1a) in which the stent (1, 1B) expands into a cylindrical shape in a free state in which the diameter of the stent (1, 1B) is freely expanded, the outermost portion in the radial direction of the inner stent body (20, 20B) is inserted into the outer stent body (10, 10B). When the surface located on the side of the outer stent body (10, 10B) is defined as the inner outermost surface, and the surface located on the outermost side in the radial direction of the outer stent body (10, 10B) is defined as the outer outermost surface, the outer outermost surface has an area smaller than that of the inner outermost surface and has a blade portion for cutting into a lesion site in a biological lumen, and the method includes delivering the stent (1, 1B) housed in a catheter (50) in a contracted state together with the catheter (50) through the biological organ to a planned position of expansion of the biological organ, withdrawing the catheter (50) proximally and starting the expansion of the stent (1, 1B) from the distal side, completing the expansion of the stent (1, 1B), and re-accommodating the expanded stent (1, 1B) into the catheter (50).

This disclosure makes it possible to provide a stent that is highly safe and has excellent expandability.

FIG. 1 is a side view of a stent 1 according to a first embodiment. FIG. 2 is a virtual development view of a part of a cylindrical portion 1a of an outer stent body 10 and an inner stent body 20 of the first embodiment. FIG. 2 is a virtual development view of a part of the cylindrical portion 1a of the outer stent body 10 of the first embodiment. FIG. 2 is a virtual development view of a part of the cylindrical portion 1a of the inner stent body 20 of the first embodiment. FIG. 2 is a diagram illustrating the outer diameter D1 of the outer stent body 10 before assembly. FIG. 2 is a diagram illustrating the outer diameter D2 of the inner stent body 20 before assembly. 1A to 1C are diagrams showing a process of inserting an inner stent body 20 into an outer stent body 10. This is a cross-sectional view taken along line s1-s1 in FIG. FIG. 13 is a schematic side view of a stent 1B according to a second embodiment. FIG. 11 is a virtual development view of a part of a cylindrical portion 1a of an outer stent body 10B and an inner stent body 20B of a second embodiment. FIG. 11 is a virtual development view of a part of a cylindrical portion 1a of an outer stent body 10B of a second embodiment. FIG. 11 is a virtual development view of a part of a cylindrical portion 1a of an inner stent body 20B of the second embodiment. 2 is an enlarged perspective view of a twisted portion 16. FIG. 13 is a diagram showing a state before the twisting portion 16 is twisted. FIG. FIG. 13 is a view of a stent 1B of a second embodiment as viewed from the distal LD2 side. FIG. 13 is a diagram showing a modification of the second embodiment. FIG. 1C is a side view of a stent 1C according to a third embodiment. 1A to 1C are schematic diagrams showing a procedure for expanding a stenosed area in a blood vessel using a stent 1. 1A to 1C are schematic diagrams showing a procedure for expanding a stenosed area in a blood vessel using a stent 1. 1A to 1C are schematic diagrams showing a procedure for expanding a stenosed area in a blood vessel using a stent 1. 1A to 1C are schematic diagrams showing a procedure for expanding a stenosed area in a blood vessel using a stent 1.

Below, an embodiment of a stent will be described. Note that all drawings attached to this specification are schematic diagrams, and the shape, scale, aspect ratio, etc. may be modified or exaggerated from the actual product. In addition, hatching showing the cross section of a component may be omitted as appropriate in the drawings.

In this specification, terms specifying the shape, geometric conditions, and the degree of these, such as "orthogonal" and "direction", include the strict meaning of the term as well as the range in which it can be considered nearly orthogonal and the range in which it can be considered roughly in that direction. In this specification, the side closer to the practitioner in the axial direction (longitudinal direction) LD is the LD1 side (or proximal LD1 side), and the side farther from the practitioner is the LD2 side (or distal LD2 side), and the direction perpendicular to the axial direction LD is the radial direction RD. Also, in this specification, the direction in which the cells are arranged is the circumferential direction OD. The circumferential direction may be the radial direction RD or a direction inclined relative to the radial direction RD.

First Embodiment
Fig. 1 is a side view of a stent 1 of the first embodiment. Fig. 2A is a virtual development view of a part of a cylindrical portion 1a of an outer stent body 10 and an inner stent body 20 of the first embodiment. Fig. 2B is a virtual development view of a part of a cylindrical portion 1a of the outer stent body 10 of the first embodiment. Fig. 2C is a virtual development view of a part of a cylindrical portion 1a of the inner stent body 20 of the first embodiment.

In the drawings, in order to easily distinguish between the outer stent body 10 and the inner stent body 20, the struts of the outer stent body 10 are shown in black, and the struts of the inner stent body 20 are shown in white. In addition, in this specification, etc., a "cell" refers to a portion surrounded by struts that form a stent. The "cells" may be the same in shape and size, or may be different from each other. A "strut" refers to a portion made of the wire-like material. In this specification, etc., the opening of a cell is called an "opening portion," and the portion where the struts of adjacent cells are connected or overlapped is called an "overlapping portion."

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 and being pushed out of the catheter in the blood vessel lumen to expand in 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 to configure the stent 1 so that the wire 2 and the stent 1 can be separated by the operator's operation.

The stent 1 has a cylindrical portion 1a and a converging portion 1b. In a free state where the diameter is freely expanded, the cylindrical portion 1a has a cylindrical shape as shown in Figs. 3A and 3B described later, and has a mesh pattern structure composed of outer cells 12 and inner cells 22 described later. The converging portion 1b is a portion where the proximal LD1 side of the cylindrical portion 1a converges to the wire 2. The stent 1 is configured to have a substantially cylindrical shape when it is taken out of the catheter and expanded in a free state (see Figs. 3A and 3B described later). Although not shown, the stent 1 has an elongated cylindrical shape in a contracted state. In addition, the wire 2 is connected to the end of the stent 1 on the proximal LD1 side. The connection between the proximal end of the stent 1 and the wire 2 is not particularly limited as long as it is a connection method used in general medical devices, and examples of such methods include welding, UV adhesion, and infiltration with silver solder.

The wire 2 is a member that is operated by the practitioner when moving the stent 1. The practitioner advances and retreats the stent 1 within the catheter or blood vessel by pushing and pulling the wire 2 via an operating unit (not shown) connected to the proximal LD1 side of the wire 2. The practitioner can also pull (retreat) and push (advance) the catheter without moving the wire 2 (stent 1), thereby expanding the stent 1 out of the catheter or storing it back in the catheter.

The stent 1 comprises an outer stent body 10 and an inner stent body 20, which are substantially cylindrical structures. The stent 1 is configured as a two-layered stent in which the inner stent body 20 is inserted into the outer stent body 10 at least in the region that expands the narrowed portion of the biological lumen. Here, the region that expands the narrowed portion of the biological lumen refers to the region that substantially contributes to the expansion of the narrowed portion when in use, and in the case of the stent 1 of this embodiment, it refers to the region that expands into a substantially cylindrical shape in the expanded state shown in Figure 1. The above-mentioned "at least" means that the inner stent body 20 must be inserted into the outer stent body 10 in the region that expands the narrowed portion. The range in which the inner stent body 20 is inserted into the outer stent body 10 is not limited to the region that substantially expands the narrowed area described above (the cylindrical portion 1a that expands into a substantially cylindrical shape in this embodiment), and in this embodiment, the inner stent body 20 is inserted into the outer stent body 10 up to the point where it is connected to the wire 2.

In addition, the fact that the inner stent body 20 is disposed (or inserted) inside the outer stent body 10 does not mean that the inner stent body 20 is completely inside the outer stent body 10 at all positions of the stent. In other words, even in a region where the inner stent body 20 is disposed (inserted) inside the outer stent body 10, a part of the inner stent body 20 may be radially outside the inner surface of the outer stent body 10, or outside the surface (outer surface) of the outer stent body 10. As above, a part of the outer stent body 10 may be radially inside the surface (outer surface) of the inner stent body 20.

When the inner stent body 20 is inserted into the outer stent body 10, the outer stent body 10 and the inner stent body 20 are not connected to each other in the radial direction. In detail, the outer stent body 10 and the inner stent body 20 are connected via the wire 2, but are not connected in other areas. Therefore, the stent 1 allows the outer stent body 10 and the inner stent body 20 to deform independently on each layer. Even in the expanded state, the outer stent body 10 and the inner stent body 20 are only in close contact with each other in the radial direction and are not connected (connected) to each other in the radial direction. Therefore, the outer stent body 10 and the inner stent body 20 are in a state where they can deform independently and do not restrict each other's deformation.

The proximal LD1 side of the outer stent body 10, the proximal LD1 side of the inner stent body 20, and the distal LD2 side of the wire 2 are directly connected. Here, directly connected means, for example, that the proximal LD1 side of the outer stent body 10 is connected to the distal LD2 side of the wire 2, and the proximal LD1 side of the inner stent body 20 is connected to the distal LD2 side of the wire 2. In this case, the position where the proximal LD1 side of the outer stent body 10 is connected to the wire 2 and the position where the proximal LD1 side of the inner stent body 20 is connected to the wire 2 may be the same or different.

The proximal LD1 side of the outer stent body 10, the proximal LD1 side of the inner stent body 20, and the distal LD2 side of the wire 2 may be indirectly connected. Here, indirect connection means, for example, a form in which the proximal LD1 side of the outer stent body 10 is connected to the distal LD2 side of the wire 2, and the proximal LD1 side of the outer stent body 10 is connected to the proximal LD1 side of the inner stent body 20 (or a connection form in which the connection of the two stent bodies is inverse). In this case, the proximal LD1 side of the inner stent body 20 is indirectly connected to the wire 2 via the proximal LD1 side of the outer stent body 10. Alternatively, the proximal LD1 side of the outer stent body 10 and the proximal LD1 side of the inner stent body 20 are connected via a pipe-shaped sleeve (not shown) that is inserted onto the distal LD2 side of the wire 2. In this case, the proximal LD1 side of the outer stent body 10 and the proximal LD1 side of the inner stent body 20 are indirectly connected to the distal LD2 side of the wire 2 via the sleeve. Thus, in this specification, indirect connection includes a form in which one of the proximal LD1 side of the outer stent body 10 or the proximal LD1 side of the inner stent body 20 is directly connected to the wire 2, and the other stent body is indirectly connected to the wire 2 via the directly connected stent body. Examples of the method of connecting the proximal end of each stent body to the wire 2 include welding, UV bonding, impregnation with silver solder, etc., but are not particularly limited as long as it is a connection method used in general medical devices.

As described later, the stent 1 of the first embodiment is produced by inserting the inner stent body 20, which has an outer diameter larger than that of the outer stent body 10, into the outer stent body 10 in a contracted state. As a result, in the stent 1 in the contracted and expanded states, the inserted inner stent body 20 is always pressing the outer stent body 10 outward in the radial direction RD. Therefore, the stent 1 can more firmly adhere the outer stent body 10 to the inner stent body 20 while maintaining a state in which the outer stent body 10 and the inner stent body 20 can deform independently on each layer.

As shown in FIG. 1, on the proximal LD1 side of the stent 1, the ends of the outer stent body 10 and the inner stent body 20 are provided with converging portions 1b, which are gradually reduced in diameter toward the wire 2 side and connected to the wire 2. This restricts the axial movement of the inner stent body 20 relative to the outer stent body 10.

The stent 1 is provided with a first wire marker portion 31 and a second wire marker portion 32 as markers. These markers are components that serve as landmarks for confirming the position and state of the stent 1 under radiographic observation within tubular organs such as blood vessels, and are made of a material that is highly radiopaque (highly contrast-enhancing). Here, radiopaque refers to having a higher radiopaqueness than parts of the stent 1 other than the markers (other parts that do not have radiopaqueness) under radiographic observation during treatment, and being radiopaque to the extent that the markers can be observed as an image. "Radiopaque" is necessary to obtain "visibility" and "contrast" under radiographic observation.

Materials with high radiopacity that can be used as markers may be metals or synthetic resins. Metal materials include, for example, gold, tantalum, platinum, tungsten, iridium, platinum tungsten, etc., and alloy materials thereof. Also included are radiopaque polymer materials to which radiopaque fillers or the like have been added. When configuring the marker as a linear member, for example, a wire made of a composite material having a core material made of the aforementioned metal material coaxially within a nickel-titanium wire can be used.

The method of attaching the marker to the stent 1 can be any suitable method that has been used to attach a marker to a conventionally known stent, such as, for example, laser soldering of gold-tin or silver-tin, mechanical crimping, or resin bonding.

The first wire marker portion 31 is a coil marker formed by forming a linear member made of a highly radiopaque material into a coil shape, and is fixed by welding at a position covering the end of the proximal LD1 side of the outer strut 11. The second wire marker portion 32 is a ring marker formed by soldering a marker part formed in a cylindrical shape made of a highly radiopaque material to the strut, and is fixed by solder at a position covering the end of the proximal LD1 side of the inner stent body 20. Note that the first wire marker portion 31 and the second wire marker portion 32 in this embodiment are examples of some of the specific forms of the marker, and the locations and numbers can be changed as appropriate. For example, a marker may also be provided on the stent portion.

As shown in FIG. 2B, the outer stent body 10 has multiple outer cells 12 arranged in the circumferential direction OD, each of which is made up of outer struts 11 arranged to surround an area in a predetermined shape. In the outer stent body 10, the multiple outer cells 12 arranged in the circumferential direction OD are arranged in the axial direction LD. In other words, the outer stent body 10 has a mesh pattern in which the multiple outer cells 12 are arranged in the circumferential direction OD and the axial direction LD. The outer cells 12 have openings 13 formed therein. Furthermore, the outer cells 12 adjacent to each other in the circumferential direction OD are connected at overlapping portions 14.

The overlapping portion 14 is a portion where the outer struts 11 of the four adjacent outer cells 12 are connected. The overlapping portion 14 has an elongated, approximately rectangular shape in the axial direction LD. Each outer strut 11 is connected to the four corners of the overlapping portion 14. A curved portion 15 is formed in each outer strut 11 at the portion where it is connected to the overlapping portion 14. Therefore, when the expanded stent 1 is bent into an approximately U-shape, each outer strut 11 connected to the overlapping portion 14 can be deformed independently. Therefore, the outer cells 12 arranged in the circumferential direction OD can be bent more flexibly. In this way, the outer stent body 10 has excellent shape conformability and diameter reduction properties because the outer cells 12 arranged in the circumferential direction OD can be bent flexibly.

As shown in FIG. 2C, the inner stent body 20 has multiple inner cells (22A, 22B, 22C) arranged in the circumferential direction OD, each of which is made up of inner struts 21A, 21B arranged to surround an area in a predetermined shape. More specifically, a first inner cell 22A, a second inner cell 22B, and a third inner cell 22C are arranged in the circumferential direction OD.

As shown in FIG. 2A, the first inner cell 22A has a similar shape to the outer cell 12, is surrounded by inner struts 21A, and is smaller than the outer cell 12. The width in the circumferential direction OD of the first inner cell 22A can be, for example, 20% to 60% of the width in the circumferential direction OD of the outer cell 12. The first inner cell 22A is arranged so that the center position of the first inner cell 22A and the center position of the outer cell 12 coincide when viewed from the radial direction RD.

2A, the second inner cell 22B is surrounded by the inner struts 21B and is formed in a similar shape to the outer cell 12 of the outer stent body 10, but smaller than the outer cell 12. Also, as shown in FIGS. 2A and 2B, the second inner cell 22B is formed in a similar shape to the outer cell 12, but larger than the first inner cell 22A. The second inner cell 22B is arranged so that the center position of the first inner cell 22A and the center position of the overlapping portion 14 of the outer stent body 10 coincide when viewed from the radial direction RD. Also, both ends of the second inner cell 22B in the circumferential direction OD are connected to the overlapping portion 24A provided at both ends of the circumferential direction OD of the first inner cell 22A. In other words, the size of the second inner cell 22B is formed to be large enough that both ends of the circumferential direction OD can be connected to the overlapping portion 24A provided at both ends of the circumferential direction OD of the first inner cell 22A. Therefore, the size of the second inner cell 22B is set to match the size of the first inner cell 22A. In this embodiment, as described above, the second inner cell 22B is formed in a similar shape to the outer cell 12, which is larger than the first inner cell 22A. Conversely, the second inner cell 22B may be formed in a similar shape to the outer cell 12, which is smaller than the first inner cell 22A, or the size of the second inner cell 22B may be the same as the size of the first inner cell 22A.

The first inner cell 22A and the second inner cell 22B, which are connected and arranged in the circumferential direction OD as described above, are arranged in the axial direction LD. In the axial direction LD, the first inner cell 22A and the second inner cell 22B are connected at the overlapping portion 24B. That is, the inner stent body 20 has a mesh pattern in which a plurality of first inner cells 22A and second inner cells 22B are arranged in the circumferential direction OD and the axial direction LD. In this mesh pattern, the area surrounded by the first inner cell 22A and the second inner cell 22B is the third inner cell 22C, which is an irregularly shaped cell that is dissimilar in shape to the first inner cell 22A and the second inner cell 22B.

The first inner cell 22A has a first opening 23A and overlapping portions 24A at both ends in the circumferential direction OD. The overlapping portions 24A are the portions where the inner struts 21A, 21B of the four adjacent cells are connected. The overlapping portions 24A are elongated and approximately rectangular in the axial direction LD. The second inner cell 22B has a second opening 23B and is connected to the first inner cell 22A at the overlapping portions 24A at both ends in the circumferential direction OD. The third inner cell 22C has a third opening 23C and overlapping portions 24B at both ends in the circumferential direction OD. The overlapping portions 24B are the portions where the inner struts 21A, 21B of the four adjacent cells are connected. The overlapping portions 24B are elongated and approximately rectangular in the axial direction LD. Each inner strut 21A, 21B is connected to the four corners of the overlapping portion 24A or the overlapping portion 24B. Each inner strut 21A, 21B has a curved portion 25 formed at the portion connected to the overlapping portion 24A or the overlapping portion 24B. Therefore, when the expanded stent 1 is bent into a substantially U-shape, each inner strut 21A, 21B connected to the overlapping portion 24 or the overlapping portion 24B can be deformed independently. Therefore, the first inner cell 22A, the second inner cell 22B, and the third inner cell 22C arranged in the circumferential direction OD can be bent more flexibly. In this way, the inner stent body 20 has excellent shape conformability and diameter reduction properties because the first inner cell 22A, the second inner cell 22B, and the third inner cell 22C arranged in the circumferential direction OD can be bent more flexibly.

3A is a diagram illustrating the outer diameter D1 of the single outer stent body 10. FIG. 3B is a diagram illustrating the outer diameter D2 of the single inner stent body 20. FIG. 4 is a diagram illustrating the procedure for inserting the inner stent body 20 into the outer stent body 10. As shown in FIGS. 3A and 3B, in the first embodiment, the relationship between the outer diameter D1 of the single outer stent body 10 and the outer diameter D2 of the single inner stent body 20 is set to be D1 < D2. Therefore, according to the procedure shown by the arrows in FIG. 4, the inner stent body 20, which has an outer diameter larger than that of the outer stent body 10, is reduced in diameter to form the inner stent body 20A, and this is inserted into the outer stent body 10. A two-layered stent 1 can be produced in which the inner stent body 20 is in close contact with the inside of the outer stent body 10 due to the self-expansion force of the inner stent body 20. In addition, in order to facilitate understanding, Figure 4 shows only the annular cell rows arranged in the circumferential direction in each stent body, and the number of cells is greater than in other figures and the shape of the cells is simplified to make it easier to understand the tubular shape.

In the stent 1 produced as described above, the outer stent body 10 and the inner stent body 20 are in close contact with each other without any gaps in the radial direction RD due to the self-expansion force of the inner stent body 20 described above (see FIG. 5 described later). Therefore, the outer stent body 10 and the inner stent body 20 are less likely to be misaligned relative to each other in the axial direction LD of the stent 1 (see FIG. 1).

In the first embodiment, the inner stent body 20 inserted into the outer stent body 10 in a contracted state is itself a self-expanding body (elastic body). Therefore, the inner stent body 20 is always in a state of pressing the outer stent body 10 outward in the radial direction RD. Therefore, even if the outer stent body 10 and the inner stent body 20 are not connected to each other in the radial direction, the outer stent body 10 and the inner stent body 20 can be more firmly attached to each other. In addition, since the outer stent body 10 and the inner stent body 20 are not connected to each other in the radial direction, the outer stent body 10 and the inner stent body 20 can maintain a state in which they can deform independently on each layer. Furthermore, the two-layered stent 1 has an expansion force that is the sum of the expansion force of the outer stent body 10 and the expansion force of the inner stent body 20. Therefore, even if the surface area is the same, the expansion force can be made larger than that of a single-layered stent.

The stent 1 (outer stent body 10, inner stent body 20) may be made of a material that is highly biocompatible. Although not particularly limited, a material with superelastic properties such as a nickel-titanium (Ni-Ti) alloy is preferable. The outer stent body 10 and inner stent body 20 can be produced, for example, by laser processing a roughly cylindrical tube made of the above material.

The stent 1 may be loaded with a drug such as a physiologically active substance (such as a drug that inhibits intimal thickening), and more specifically, may carry the drug so that the drug is dissolved in the lumen structure.

The outer stent body 10 and the inner stent body 20 are produced, for example, by laser processing a tube with an outer diameter of about 0.4 to 3 mm to form a mesh pattern, and then stretching it radially to obtain the desired diameter. As described above, a two-layered stent 1 can be produced by inserting the inner stent body 20 into the outer stent body 10. This two-layered stent 1 is housed in the lumen of a catheter (not shown) in a state where it has been radially contracted from its natural state. If the stent is made of an elastic material such as a superelastic alloy or a shape-memory alloy, the stent 1 housed in the catheter will attempt to expand in diameter by its own expansion force when pushed outward.

In this embodiment, as described above, the first inner cell 22A is formed in a similar shape to the outer cell 12, which is smaller than the outer cell 12, and is arranged so that the center position of the first inner cell 22A coincides with the center position of the outer cell 12 when viewed from the radial direction RD. In other words, the mesh pattern of the outer stent body 10 is coarser than the mesh pattern of the inner stent body 20. In addition, when the stent 1 is viewed from the radial direction RD, the width of the outer strut 11 of the outer stent body 10 is approximately equal to the width of the inner strut 21A and the inner strut 21B of the inner stent body 20, or is narrower than the width of the inner strut 21A and the inner strut 21B of the inner stent body 20.

Here, in the cylindrical portion 1a in which the stent 1 expands into a cylindrical shape in a free state, the surface located most outside in the radial direction of the inner stent body 20 is called the inner outermost surface, and the surface located most outside in the radial direction of the outer stent body 10 is called the outer outermost surface. In the first embodiment, the outer outermost surface is the surface of the shape of the outer stent body 10 within the range of the cylindrical portion 1a shown in the development diagram of FIG. 2B. Similarly, the inner outermost surface is the surface of the shape of the inner stent body 20 within the range of the cylindrical portion 1a shown in the development diagram of FIG. 2C. In the first embodiment, the mesh pattern of the outer stent body 10 is coarser than the mesh pattern of the inner stent body 20. Therefore, the area of the outer outermost surface is smaller than the area of the inner outermost surface. As a result, the outer outermost surface of the outer stent body 10, mainly the outer struts 11, function as a blade portion that makes an incision into the diseased site in the biological lumen.

5 is a cross-sectional view taken along line s1-s1 in FIG. 1. The mesh pattern of the outer stent body 10 is coarser than that of the inner stent body 20, so the outermost surface area of the outer struts 11 of the outer stent body 10, which come into contact with the inner wall of the biological lumen first, is small, and the expansion force of the entire stent 1 is concentrated and acts on this small surface area. The expansion force of the entire stent 1 is the sum of the expansion forces of the outer stent body 10 and the inner stent body 20. Therefore, a large expansion force is concentrated and acts on the outer struts 11 of the outer stent body 10, which have a small surface area and come into contact with the inner wall of the biological lumen first. As a result, the outer struts 11 act as a blade that presses a very thin linear body strongly against the inner wall of the biological lumen, making it possible to cut, for example, calcified lesions in blood vessels during the expansion process of the stent 1. Here, in order to make it easier to cut into calcified lesions in blood vessels, it is desirable that the width of the blade portion (outer strut 11) in the expanded state in the direction perpendicular to the extension direction as viewed from the radial direction of the outer stent body 10 is 0.5 mm or less.

On the other hand, the mesh pattern of the inner stent body 20 is finer than that of the outer stent body 10. When the stent 1 is viewed from the radial direction RD, the width of the inner struts 21A and 21B of the inner stent body 20 is equal to or wider than the width of the outer struts 11 of the outer stent body 10. Therefore, the inner stent body 20 abuts against the inner wall of the biological lumen, preventing the outer struts 11 from cutting into the inner wall of the biological lumen more than necessary. Therefore, in hard areas such as calcified lesions of blood vessels, the outer struts 11 can promote expansion by making cuts, and in a situation where the inner stent body 20 abuts against the inner wall of the biological lumen, the cuts made by the outer struts 11 are suppressed. In this way, the stent 1 of this embodiment has high expandability and is highly safe.

Next, a method of using the stent 1 of the first embodiment in a blood vessel lumen will be described. When the stent 1 of the first embodiment is expanded in the same way as a conventional normal stent is expanded, the outer struts 11 acting as blades strike first, applying concentrated force and cutting into the lesion, causing it to break. By making the cuts, even hard lesions can be expanded with less force than with a stent, and by making the cuts, it is possible to obtain the effect of smoothly expanding without expanding into a distorted shape due to the lesion. The stent 1 of the first embodiment has a self-expanding structure, and the operation itself is the same as that of a conventionally known two-layered stent, and it self-expands and spreads when deployed from a microcatheter.

Furthermore, although the stent 1 of the first embodiment can cut into the lesion, cutting is not the purpose. The stent 1 of the first embodiment can be expanded appropriately by cutting. Therefore, the expanded state of the stent 1 of the first embodiment can be confirmed in the same manner as in the past, using a conventional confirmation method using X-rays. For example, during treatment using the stent 1 of the first embodiment, the state of the lesion and the stent 1 can be observed by angiography before, during, and after expansion. The state of the stent 1 may also be confirmed using cone beam CT.

In addition, the stent 1 of the first embodiment can cut into the lesion, but does not require any special operation compared to conventional stents that cannot cut into the lesion. Therefore, even after expanding the stent 1, the lesion can be expanded and blood flow can be resumed for a certain period of time, as in the conventional method, to treat the lesion.

In addition, after expanding and deploying for a certain period of time, the stent 1 may be temporarily retrieved into the microcatheter, and the stent 1 may be rotated around the central axis within the microcatheter or together with the microcatheter, and then the microcatheter alone may be moved toward the proximal LD1 side to expand the stent 1 again. This allows incisions to be made at multiple locations, making it possible to expand even harder lesions.

In addition, depending on the condition of the lesion, it may be expected that fragments will be generated at the lesion site due to the incision made by the stent 1. In such a case, a filter member may be placed on the LD2 side distal to the stent 1, or a suction catheter may be placed on the LD1 side proximal to the stent 1 to perform suction.

Furthermore, the retrieval (resheathing) of the stent 1 of the first embodiment can be performed in the same manner as the conventionally known two-layered stent. That is, instead of pulling the stent 1 toward the proximal LD1 side, the microcatheter is advanced toward the distal LD2 side to retrieve the stent 1 into the microcatheter. This operation prevents the part acting as a blade from damaging the inner wall of the blood vessel, and allows the stent 1 to be retrieved safely.

By deploying the stent 1 of the first embodiment at the lesion site in the vascular lumen, the vascular lumen is expanded, ensuring patency of the lesion site. By removing (retrieving) the stent 1 from the vascular lumen after a predetermined period of time has elapsed, it is possible to prevent complications such as restenosis, re-occlusion, and thrombosis caused by the placement of the stent. Furthermore, the stent 1 of the first embodiment has excellent shape-following properties, and is therefore highly blood-protective. The stent 1 of the first embodiment can be used to treat not only blood vessels, but also tubular structures in general, such as the esophagus and large intestine.

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

The stent 1 of the first embodiment may also be used for purposes of placement in a blood vessel for a predetermined period of time or permanently. An example of a purpose of placing a stent in a blood vessel is a stent for treating an aneurysm. The stent for treating an aneurysm is deployed at a target position and placed at the site. The purpose of placing the stent for treating an aneurysm at a target position is, for example, to reduce blood flowing into an aneurysm at the target position or to hold an embolization coil placed in the aneurysm. After placing the stent for treating an aneurysm at a target position, an embolization coil (both not shown) can be sent to the distal LD2 side via a microcatheter inserted in the catheter, so that the embolization coil can be placed in the aneurysm through the mesh of the stent for treating an aneurysm. Furthermore, since the mesh of the stent 1 is fine, the stent alone can be used to reduce blood flow into the aneurysm without using a coil and to treat the aneurysm by thrombosis.

Furthermore, an example of an application for placing a stent in a blood vessel is a stent for placement in a cerebrovascular vessel, and the stent 1 of the first embodiment can be used to treat cerebrovascular disorders. Cerebrovascular disorders are mainly classified into ischemic cerebrovascular disorders and hemorrhagic cerebrovascular disorders. Ischemic cerebrovascular disorders include cerebral infarction such as atherothrombotic cerebral infarction, lacunar infarction, and cardiogenic cerebral embolism, while hemorrhagic cerebrovascular disorders include cerebral hemorrhage and subarachnoid hemorrhage. Furthermore, the stent 1 can be used to treat cerebral vasospasm and the like. The stent placed in a blood vessel or the like is removed after a predetermined period of time has passed or after the purpose of placing the stent has been achieved.

Second Embodiment
Fig. 6 is a schematic side view of the stent 1B of the second embodiment. Fig. 7A is a development view of a part of the cylindrical part 1a of the outer stent body 10B and the inner stent body 20B of the second embodiment, which is virtually expanded into a flat surface. Fig. 7B is a development view of a part of the cylindrical part 1a of the outer stent body 10B of the second embodiment, which is virtually expanded into a flat surface. Fig. 7C is a development view of a part of the cylindrical part 1a of the inner stent body 20B of the second embodiment, which is virtually expanded into a flat surface. The stent 1B of the second embodiment is similar to the first embodiment, except that the mesh patterns of the outer stent body 10B and the inner stent body 20B are different from those of the first embodiment, and that the stent 1B of the second embodiment is provided with a twisted part 16. Therefore, the same reference numerals are given to parts that perform the same functions as those of the first embodiment described above, and duplicated explanations are omitted as appropriate.

The outer stent body 10B of the second embodiment is similar to the outer stent body 10 of the first embodiment, except that it has a twisted portion 16 instead of the overlapping portion 14 of the first embodiment. The twisted portion 16 is formed to have a longer length in the axial direction LD than the overlapping portion 14 of the first embodiment. The twisted portion 16 has a form in which the outer strut 11 is partially twisted. Figure 8 is an enlarged perspective view of the twisted portion 16. Figure 9 is a diagram showing the state before the twisted portion 16 is twisted. The twisted portion 16 takes the form shown in Figure 8 by twisting the wide portion 160, which is a partially widened portion of the portion corresponding to the overlapping portion where multiple outer struts 11 gather, by approximately 90 degrees. Therefore, in the expanded state of the stent 1, the twisted portion 16 is in a form that partially protrudes outward from the cylindrical shape formed by the surface of the outer strut 11 other than the twisted portion 16. The surface formed on the outermost side of the twisted portion 16 becomes the outermost surface, and its area is smaller than the area of the innermost surface. As a result, in the outer stent body 10B of the second embodiment, the twisted portion 16 functions as a blade portion that cuts into the lesion site in the biological lumen. Here, in order to make it easier to cut into calcified lesions in blood vessels, the width of the twisted portion 16 in the direction perpendicular to the extension direction as viewed from the radial direction of the outer stent body 10B in the expanded state is desirably 0.5 mm or less.

As shown in FIG. 7C, the inner stent body 20B has multiple inner cells 22 arranged in the circumferential direction OD, each of which is made up of inner struts 21 arranged to surround an area in a predetermined shape. In the inner stent body 20B, the multiple inner cells 22 arranged in the circumferential direction OD are arranged in the axial direction LD. In other words, the inner stent body 20B has a mesh pattern in which the multiple inner cells 22 are arranged in the circumferential direction OD and the axial direction LD. An opening portion 23 is formed in the inner cells 22. In addition, the inner cells 22 adjacent to each other in the circumferential direction OD are connected at an overlapping portion 24.

The overlapping portion 24 is a portion where the inner struts 21 of the four adjacent inner cells 22 are connected. The overlapping portion 24 has an approximately rectangular shape elongated in the axial direction LD. Each inner strut 21 is connected to the four corners of the overlapping portion 24. Each inner strut 21 has a curved portion 25 formed at the portion connected to the overlapping portion 24. Therefore, when the expanded stent 1 is bent into an approximately U-shape, each inner strut 21 connected to the overlapping portion 24 can be deformed independently. Therefore, the inner cells 22 arranged in the circumferential direction OD can be bent more flexibly. In this way, the inner stent body 20B has excellent shape tracking and diameter reduction properties because the inner cells 22 arranged in the circumferential direction OD can be bent flexibly. In the second embodiment, the innermost surface is the surface of the shape of the inner stent body 20B in the range of the cylindrical portion 1a shown in the development view in FIG. 7C.

As shown in FIG. 7A, the outer stent body 10B and the inner stent body 20B of the second embodiment have the same mesh pattern except for the twisted portion 16 and the overlapping portion 24, and the relative positions of the two are shifted so that the twisted portion 16 and the overlapping portion 24 do not overlap. That is, as shown in FIG. 7A, in the stent 1B, the outer stent body 10B and the inner stent body 20B are overlapped such that the overlapping portion 24 of the inner cell 22 (the inner stent body 20B) is disposed in the opening portion 13 of the outer cell 12 (the outer stent body 10B). Specifically, in a configuration in which the overlapping portion 24 of the inner cell 22 is disposed in the opening portion 13 of the outer cell 12, the overlapping portions 24 of one inner cell 22 are disposed in the opening portion 13 of one outer cell 12.

FIG. 10 is a view of the stent 1B of the second embodiment as seen from the distal LD2 side. As shown in FIG. 10, the twisted portion 16, when the stent 1 is in an expanded state, is in a form that partially protrudes outward from the outer shape of the outer strut 11, and constitutes the outermost surface. Thus, the twisted portion 16 functions as a blade that cuts into the lesion in the biological lumen. The twisted portion 16 of the second embodiment constitutes an outermost surface with an even smaller surface area than the outer strut 11 of the first embodiment, and therefore has an even higher ability to cut into the lesion in the biological lumen. Thus, the stent 1B of the second embodiment can provide a stent that has even higher expandability than the first embodiment and is as safe as the first embodiment.

Third Embodiment
12 is a schematic side view of a stent 1C of the third embodiment. The third embodiment differs from the stent 1 of the first embodiment in that the stent patterns of the outer stent body 10B and the inner stent body 20B are the same, and that the distal end shaft 3 is connected to the end of the distal side LD2. The stent 1C of the third embodiment also differs from the stent 1 of the first embodiment in that it includes a sub-strut 51. The other configurations of the stent 1C of the third embodiment are similar to those of the stent 1 of the first embodiment, so that repeated explanations will be omitted.

The distal end shaft 3 is a marker for identifying the position of the distal LD2 side of the stent 1 in an X-ray image, and at least a portion of it is made of an X-ray opaque material. The ends of the outer stent body 10 and the inner stent body 20 are gradually tapered toward the distal end shaft 3 and are connected to the distal end shaft 3.

The sub-strut 51 is wound in a spiral shape around the outer stent body 10C located outside the stent 1C. One end 51a of the sub-strut 51 is connected to the proximal LD1 side of the outer stent body 10C. The other end 51b of the sub-strut 51 is connected to the distal LD2 side of the outer stent body 10C. It is desirable that the wire diameter of the sub-strut 51 is smaller than the width in the direction perpendicular to the extension direction of the outer strut 11. By winding the sub-strut 51 in a spiral shape around the outer stent body 10C, when the sub-strut 51 first abuts against the lesion site on the inner wall of the blood vessel, the contact area is small, so that the effect of cutting into the lesion site can be obtained. Note that multiple sub-struts 51 may be wound. Note that the sub-strut 51 may be connected to the outer strut 11 of the outer stent body 10C by welding or the like. The sub-strut 51 may also be formed from a material with high contrast properties. In addition, in this embodiment, the stent patterns of the outer stent body 10C and the inner stent body 20C are the same, but the stent patterns of the outer stent body 10C and the inner stent body 20C may be different.

The third embodiment of the stent 1C can be a highly expandable stent that can make incisions into the lesion site without being affected by the stent patterns of the outer stent body 10C and the inner stent body 20C.

(How to use)
Next, an example of a method of using the stents 1, 1B, and 1C of each embodiment will be described. Here, the stent 1 of the first embodiment will be described, but the same applies to the stents 1B and 1C of the other embodiments. Figures 13A to 13D are schematic diagrams showing a procedure for expanding a stenosed area in a blood vessel using the stent 1. In Figures 13C and 13D, the shape of the stent 1 is shown in a simplified form. Here, a procedure for expanding a stenosed area CS formed in a blood vessel BV to ensure blood flow will be described. Note that the following procedure is performed by grasping the position of the stent, etc., using a visible marker (radiopaque marker).

First, as shown in FIG. 13A, a guidewire 40 is passed through the stenosis site CS. A catheter 50 is fitted around the guidewire 40. Next, as shown in FIG. 13B, the tip of the catheter 50 fitted around the guidewire 40 is inserted into the stenosis site CS along the passed guidewire 40, and passed through to reach the distal LD2 side of the stenosis site CS. Next, although not shown, the guidewire 40 is pulled out of the catheter 50 and collected outside the living body. 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.

Next, as shown in FIG. 13C, stent 1 is deployed from the tip of catheter 50 on the distal LD2 side of the stenosis site CS. The tip of catheter 50 is positioned on the distal LD2 side of the stenosis site CS, and catheter 50 is retracted toward the proximal LD1 side, allowing stent 1 to be deployed from the tip of catheter 50. When stent 1 is deployed from the tip of catheter 50, stent 1 expands due to its own expansion force, so that stenosis site CS is pushed open from the inside. By pushing open stenosis site CS from the inside with the expanded stent 1, blood flow in the blood vessel BV can be ensured.

After it has been confirmed that blood flow in the blood vessel BV has been secured, the patient is observed for a period of time, for example, 5 to 60 minutes. After the observation, as shown in FIG. 13D, the tip of the catheter 50 is advanced toward the distal LD2 side of the stent 1, and the entire stent 1 is stored back into the catheter 50. This allows the stent 1 to be retrieved together with the catheter 50 from the living body.

(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.

FIG. 11 is a diagram showing a modified form of the second embodiment. In the second embodiment, a twisted portion 16 is provided at a portion where multiple outer struts 11 gather. This is not limiting, and for example, as shown in FIG. 11, a twisted portion 16B may be provided by twisting a wide portion 160B provided in the middle of one outer strut 11 by approximately 90 degrees. The twisted portion 16B of this modified form may also be provided on other outer struts 11 in positions other than those illustrated in FIG. 11 to increase the density of the twisted portion 16B. The twisted portion 16B of this modified form may also be arranged together with the twisted portion 16 of the second embodiment.

Note that the various embodiments and variations can be used in appropriate combination, but detailed explanations will be omitted. Furthermore, the present disclosure is not limited to the various embodiments described above.

1 Stent 1B Stent 1a Cylindrical portion 1b Converging portion 2 Wire 10 Outer stent body 10B Outer stent body 11 Outer strut 12 Outer cell 13 Opening portion 14 Overlapping portion 15 Curved portion 16 Twisted portion 16B Twisted portion 20 Inner stent body 20A Inner stent body 20B Inner stent body 21 Inner strut 21A Strut 21B Strut 22 Inner cell 22A First inner cell 22B Second inner cell 22C Third inner cell 23 Opening portion 23A First opening portion 23B Second opening portion 23C Third opening portion 24 Overlapping portion 24A Overlapping portion 24B Overlapping portion 25 Curved portion 31 First wire marker portion 32 Second wire marker portion 51 Sub-strut 160 Wide portion 160B Wide portion

Claims (5)

1. A stent comprising:
an outer stent body having a plurality of outer cells surrounded by outer struts arranged at least in a central axis direction;
an inner stent body in which a plurality of inner cells surrounded by inner struts are arranged at least in a central axis direction and which is inserted into the outer stent body at least in a region where the biological lumen is expanded;
Equipped with
In a cylindrical portion in which the stent freely expands in diameter into a cylindrical shape in a free state, when the surface located most outside in the radial direction of the inner stent body is defined as the inner outermost surface, and the surface located most outside in the radial direction of the outer stent body is defined as the outer outermost surface,
The outermost surface has an area smaller than that of the innermost surface, and has a blade portion for cutting into a diseased site in a biological lumen. 2. The stent of claim 1,
A stent in which the outer struts function as the blade portion when the mesh pattern of the outer stent body is arranged in an area of the cylindrical portion where the mesh pattern of the outer stent body is coarser than the mesh pattern of the inner stent body. 2. The stent of claim 1,
A stent wherein partially twisted portions of the outer struts function as the blades. 4. The stent of claim 3,
A stent having a cylindrical portion that expands into a cylindrical shape in a free state in which the blade portions where the outer struts are partially twisted protrude outward from the cylindrical shape formed by the surface of the outer struts other than the blade portions. The stent according to any one of claims 1 to 4,
A stent, wherein the width of the outer stent body in a direction perpendicular to the extending direction of the blade portion as viewed from a radial direction of the outer stent body is 0.5 mm or less.

Images