Stents for treating aortic arch dissection

Abstract

A stent having a cylindrical shape when in a self-expanded state, wherein said stent is equipped with a first wire group comprising a plurality of wires and a second wire group comprising a plurality of wires intersecting the wires of the first wire group at a plurality of locations, the wires of the first wire group and the second wire group intersect and form a plurality of cells having a substantially rhomboid shape when in the cylindrical, self-expanded state, and the cross-sectional shape of each of the wires forms a thick rectangular shape in the radial direction of the cylindrical shape.

Description

[Technical field]

[0001] The present invention relates to the technical field of stents, and more particularly to the structure of a self-expanding stent suitable for surgery for aortic dissection. [Background technology]

[0002] Traditionally, open-chest surgery was the most common treatment for aortic disease. Open-chest surgery literally involves opening the chest and replacing the diseased area with an artificial blood vessel, but it places a heavy physical burden on the patient and has a high mortality rate. Even if the surgery was successful, the reality was that patients would often develop complications and become bedridden.

[0003] In reality, "stent graft surgery" is then performed via the aorta using a catheter inserted through the groin, without opening the chest (see Non-Patent Document 1). Since "stent graft surgery" does not require opening the chest, it has the advantage of being shorter in operation time and reducing the physical and financial burden on the patient. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-57018 [Non-patent literature]

[0005] [Non-Patent Document 1] Japanese Society for Thoracic Surgery Website on thoracic aortic aneurysms http: / / www.jpats.org / modules / general / index.php?content_id=16 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the case of diseases such as aortic arch dissection, which is common among Japanese people, surgery using this stent graft is extremely difficult because the aortic arch has branching blood vessels. Since the stent graft has a "membrane" structure on the surface of the stent, if the stent graft is placed in the aortic arch as is, it will obstruct blood flow to the branching blood vessels. Therefore, a method has been proposed in which this membrane is partially opened (fenestrated) only at the position corresponding to the branching blood vessel. However, when placing a stent graft with this opening at the diseased site using a catheter, it is extremely difficult to accurately position the position of the branching blood vessel and the position of the opening, and complications due to mismatch are not uncommon.

[0007] On the other hand, there is a demand for the use of a general stent without a membrane structure (see Patent Document 1), but a general stent has poor flexibility in bending in a direction perpendicular to the axial direction, and is generally not suitable for use in the aortic arch. For example, in the case of a full-link stent shown in FIG. 19, if an attempt is made to bend it, the hollow portion collapses as shown in FIG. 20, making it impossible to ensure blood flow. In addition, in the case of a partial-link stent shown in FIG. 21, although it exhibits a certain degree of flexibility in bending in a specific direction (see FIG. 22), there is a problem that it kinks when bent with a certain degree of curvature or more (see FIG. 23). In addition, when the stent is contracted and housed in a catheter, the breaks in the links tend to get caught in the catheter, making it difficult to house it in the catheter, and there are problems with handling.

[0008] The present invention has been made to solve these problems, and has an object to provide a stent that does not have a membrane like a stent graft, has sufficient kink resistance and excellent flexibility, and a method for manufacturing a stent. [Means for solving the problem]

[0009] In other words, the stent of the present invention is a stent that becomes tubular in a self-expanded state, and comprises a first wire group consisting of a plurality of wires, and a second wire group consisting of a plurality of wires that intersect with wires of the first wire group at multiple locations, and in the self-expanded tubular state, the wires of the first wire group and the second wire group intersect to form a plurality of approximately diamond-shaped cells, and the cross-sectional shape of each wire is a rectangle that is thick in the radial direction of the tube.

[0010] In addition, the method for manufacturing a stent according to the present invention includes the steps of: forming a mesh tubular body made of a shape memory alloy by laser processing to arrange in the axial direction a serpentine structure in which the wire meanders circumferentially at an equal pitch and connects the tops of the arc portions of adjacent serpentine structures to form an integrated mesh tubular body; expanding the mesh tubular body to a predetermined diameter; and allowing the mesh tubular body to memorize its shape in the expanded state, wherein when the mesh tubular body is expanded to the predetermined diameter, the wire crosses to form a plurality of approximately diamond-shaped cells and the cross-sectional shape of the wire is a rectangle that is thick in the radial direction. Effect of the Invention

[0011] According to the present invention, it is possible to provide a stent that does not include a membrane like a stent graft, has sufficient kink resistance and is excellent in flexibility, and a method for manufacturing a stent. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic front view of a stent in a self-expanded state according to one embodiment of the present invention; [Diagram 2] 2 is an enlarged photograph showing the wire intersection portion in the range C of FIG. 1. [Diagram 3] FIG. 2 is an enlarged schematic diagram of the cell S of FIG. [Figure 4] FIG. 3 is a cross-sectional view taken along line DD in FIG. [Diagram 5] This is a photograph of a shape memory alloy tube before processing. [Figure 6]1 is a photograph of a shape memory alloy stent after it has been processed into a tube. [Figure 7] (a) Overall view of the stent before self-expansion, (b) Enlarged view of area E in (a). [Figure 8] 1 is a photograph showing a state before a stent according to an embodiment of the present invention is exposed from a catheter. [Figure 9] 1 is a photograph showing a state in which a stent according to an embodiment of the present invention is beginning to be exposed from a catheter. [Figure 10] 1 is a photograph showing a state in which a stent according to an embodiment of the present invention is further exposed from a catheter. [Figure 11] 1 is a photograph showing a state in which placement of a stent according to one embodiment of the present invention has been completed. [Figure 12] FIG. 12 is an enlarged photograph of a portion of FIG. [Figure 13] 1 is a schematic front view of a stent according to one embodiment of the present invention when curved in a self-expanded state. [Figure 14] 14 is a bottom view of range F in FIG. 13 as viewed from the stress direction. [Figure 15] FIG. 2 is a cross-sectional view comparing a wire cross section of a stent according to one embodiment of the present invention with a wire cross section of a comparative example. [Figure 16] 14 is an enlarged front view comparing the wire in the range G of FIG. 13 with a wire of a comparative example. [Figure 17] 1 is a photograph showing the state in which the stent of Example 4 is fitted into an R50 mold. [Figure 18] 1 is a photograph showing the state in which the stent of Example 4 is fitted into an R45 mold. [Figure 19] 1 is a photograph of an entire structure of a conventional full-link stent. [Figure 20] 20 is a photograph showing the full-link stent of FIG. 19 in a bent state. [Figure 21] 1 is a photograph of a partial link type stent as a conventional example. [Figure 22] 22 is a photograph showing the partially linked stent of FIG. 21 bent in a particular direction. [Figure 23] 22 is a photograph showing the partially linked stent of FIG. 21 bent in a direction other than the specific direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, a stent and a method for manufacturing a stent according to an embodiment of the present invention will be described with reference to the attached drawings. Note that in order to facilitate understanding of the drawings, the size and dimensions of each part are exaggerated and may not necessarily match the actual product.

[0014] (Stent configuration) Fig. 1 shows a schematic front view of a stent according to one embodiment of the present invention in a self-expanded state, Fig. 2 shows an enlarged photograph of the wire intersection portion in range C in Fig. 1, Fig. 3 shows an enlarged schematic view of cell S in Fig. 1, and Fig. 4 shows a cross-sectional view taken along line DD in Fig. 2. The configuration of stent 100 in a self-expanded state will be described below with reference to these figures. The self-expanded state refers to a state in which the stent has expanded to a diameter set in its specifications for use.

[0015] 1 is made of a metal. The metal constituting the stent 100 is, for example, a nickel-titanium alloy, a cobalt alloy, tantalum, stainless steel, etc., and is preferably a shape-memory alloy that can be transformed from a contracted state to a self-expanded state by body temperature or the like.

[0016] The stent 100 of this embodiment has a length and diameter suitable for use in the aortic arch, and for example, in a self-expanded state, has a total length of 80 mm or more, or 100 mm or more, and 200 mm or less, or 250 mm or less, and a diameter of 15 mm or more, or 20 mm or more, and 30 mm or less, or 40 mm or less.

[0017] In a self-expanded state as shown in Fig. 1, the stent 100 has a first wire group 100a consisting of six wires 101, 102, 103, 104, 105, 106 that are parallel to one direction oblique to the axial direction (solid arrow A in Fig. 1) and extend helically on the same axis (axis O). The stent 100 also has a second wire group 100b consisting of six wires 111, 112, 113, 114, 115, 116 that are parallel to the first wire group 100a in a diagonal direction (dotted arrow B in Fig. 1) symmetrical to the axis O and extend helically on the same axis (axis O) as the first wire group 100a.

[0018] Specifically, the six wires 101-106 of the first wire group 100a are spirally shaped with a phase difference of 60°. The six wires 111-116 of the second wire group 100b are also spirally shaped with a phase difference of 60°. The first wire group 100a and the second wire group 100b are spirally shaped in different directions, so they cross each other at multiple points, and as a whole, they form a mesh that extends in a cylindrical shape in the direction of the axis O. In the stent 100 thus configured, the first wire group 100a and the second wire group 100b cross each other to form multiple cells S in a substantially diamond shape (including a square shape), as shown by the hatched areas in FIG. 1.

[0019] Each intersection of the wires 101-106 of the first wire group and the wires 111-116 of the second wire group is formed integrally without overlapping in the radial direction of the stent 100. For example, as shown in Fig. 2 which is an enlarged view of range C in Fig. 1, the intersection 120 has a shape in which the wire 102 of the first wire group 100a and the wire 112 of the second wire group 100b are integrated by fusing the apexes of two arcuate portions α, β facing each other in the direction of the axis O. The same is true for the other intersections.

[0020] In addition, in the stent 100 of this embodiment, the first crossing angle γ, which is the angle in the axis O direction at the crossing portion 120 in the self-expanded state, is equal to or smaller than the second crossing angle σ, which is the angle in the circumferential direction (i.e., the opening angle of the arc portions α and β). The relationship between the first crossing angle γ and the second crossing angle σ is preferably σ / γ≧1.22, and more preferably σ / γ≧1.36. The basis for these values ​​will be explained in the examples described later. The upper limit of σ / γ is preferably σ / γ≦2.0 (e.g., γ=60°, σ=120°) so that the stent 100 can secure a sufficient length in the axis O direction in the self-expanded state.

[0021] That is, such a relationship between the first crossing angle γ and the second crossing angle σ is such that, in the self-expanded state of the stent 100, each cell S formed by the first wire group 100a and the second wire group 100b has a square or a rhomboid shape that is long in the circumferential direction. When the cell S has a rhomboid shape, as shown in FIG. 3, which is an enlarged view of the cell S portion of FIG. 1, the first crossing angle γ is an acute interior angle, and the second crossing angle σ is an obtuse interior angle. In addition, the long diagonal dl of the cell S extends in the circumferential direction of the stent 100, and the short diagonal ds extends in the direction of the axis O of the stent 100. In other words, when the value of σ / γ increases, the long diagonal dl becomes longer, resulting in a rhomboid shape that is longer in the circumferential direction. Note that each vertex of the cell S is the center position of the intersection portion 120, that is, the vertex of the two arcuate portions α and β.

[0022] Furthermore, as shown in FIG. 4, which is a cross-sectional view taken along line DD in FIG. 2, the cross-sectional shape perpendicular to the extension direction of each of the wires 101-106 of the first wire group 100a and each of the wires 111-116 of the second wire group 100b is a rectangle that is thick in the radial direction of the stent 100.

[0023] Specifically, when the radial thickness of each wire is t and the length of the short side perpendicular to the thickness (i.e., the wire width) is w, the relationship between the thickness t and the wire width w is preferably w / t<0.9. More preferably, w / t<0.81. The basis for these numerical values ​​will be explained in the examples below. In addition, taking into consideration the processing for manufacturing the stent 100 and the strength of the stent 100 when in use, the lower limit of w / t is preferably w / t≧0.5.

[0024] In this manner, in the stent 100 of this embodiment, the wires of the first wire group 100a and the second wire group 100b form a rectangular shape that is thick in the radial direction, and the cell S formed by the first wire group 100a and the second wire group 100b forms a square or a rhomboid that is elongated in the circumferential direction.

[0025] (Stent manufacturing method) Fig. 5 shows a photograph of a tube made of shape memory alloy before processing, Fig. 6 shows a photograph of a stent made of shape memory alloy after processing the tube, and Fig. 7 shows (a) an overall view of the stent before self-expansion and (b) an enlarged view of range E in (a). Below, a method for manufacturing the stent 100 will be described based on these figures.

[0026] A stent 100 according to an embodiment of the present invention is first formed from a tube (tubular body) 200 made of a shape-retaining alloy as shown in Fig. 5. Specifically, the tube 200 is laser processed (cut) to cut out unnecessary portions, and then surface treatment such as chemical treatment and electrolytic polishing is performed to remove burrs and edges, forming a mesh tubular body as shown in Fig. 6. That is, this mesh tubular body corresponds to the stent 100 in a contracted state. The stent 100 is expanded to a predetermined diameter (for example, the maximum diameter that satisfies the relationship between the first intersection angle γ and the second intersection angle σ described above), and is subjected to heat treatment or the like in the expanded state to memorize the shape, and is finished as a self-expanding stent 100.

[0027] As shown in Fig. 7(a), the stent 100 before self-expansion, i.e., in the contracted state, forms meandering structures 201, 202, 203, 204, 205... that extend in a circumferential direction at an equal pitch by the wire, and each meandering structure 201, 202, 203, 204, 205... is arranged in a row in the direction of the axis O and connected. Specifically, as shown in Fig. 7(b), each meandering structure 201, 202, 203, 204, 205... is composed of a straight portion extending in the direction of the axis O and a semicircular arc portion that turns back in the circumferential direction, and the tops of the semicircular arc portions of adjacent meandering structures are connected to each other to form an integrated unit. In the contracted stent 100 configured in this manner, the cell S portion that is rhombic in the self-expanded state forms a substantially oval space that is long in the direction of the axis O in the contracted state.

[0028] (Action and function of stents) 8 to 12 are photographs showing the state of the stent 100 according to one embodiment of the present invention when placed in an aortic arch model 400 that imitates the human aortic arch. Hereinafter, the action and function of the stent 100 will be described with reference to these drawings and using the aortic arch model 400.

[0029] FIG. 8 shows a photograph of the stent 100 before it is exposed from the catheter 300. As shown in FIG. 8, the aortic arch model 400 has branched blood vessels, such as the brachiocephalic artery 411, the left common carotid artery 412, and the left subclavian artery 413, at the top (toward the head of the human body), just like the human body. The stent 100 is housed in the catheter 300 in a contracted state. When actually used in the human body, the catheter 300 is inserted from the femoral aorta, etc., through the abdominal aorta and the thoracic aorta, to the aortic arch. As shown in FIG. 8, the tip of the catheter 300 is curved along the curved shape of the aortic arch model 400, and the stent 100 in the contracted state housed in the catheter 300 also has a shape that follows the curved shape.

[0030] Fig. 9 is a photograph showing the state where the stent 100 starts to be exposed from the catheter 300, and Fig. 10 is a photograph showing the state where the stent 100 is completely exposed from the catheter 300. As shown in Fig. 9, the stent 100 is gradually exposed from the tip side of the catheter 300. The stent 100 self-expands from the portion exposed from the catheter 300 due to the superelasticity of the shape memory alloy. Then, as shown in Fig. 10, when the stent 100 is completely exposed from the catheter 300, the entire stent 100 is in an expanded state.

[0031] Fig. 11 shows a photograph illustrating the state in which the stent 100 has been placed in the aortic arch (model) 400, and Fig. 12 shows an enlarged view of the main part of Fig. 11. As shown in Figs. 11 and 12, when the expansion of the stent 100 is completed over the entire area, the catheter 300 is removed from the blood vessel, and only the stent 100 is placed over the entire area of ​​the aortic arch (model) 400.

[0032] In this embodiment, when the catheter 300 housing the stent 100 is placed in the aortic arch model 400 and the stent 100 is fed out, the stent 100 expands (self-expands) to a shape-memorized state due to temperature (body temperature in the body). Therefore, the stent 100 adheres to the inner circumferential wall of the aortic arch model 400 so as to sufficiently expand it, and also flexibly follows the curved shape.

[0033] The kink resistance of the stent 100 of this embodiment will be described in detail below.

[0034] Figure 13 shows a schematic front view of a stent of one embodiment of the present invention when bent in a self-expanded state, Figure 14 shows a bottom view of range F of Figure 13 viewed from the stress direction (lower side of Figure 13), Figure 15 shows a cross-sectional view comparing the wire cross-section of this embodiment with the wire cross-section of a comparative example, and Figure 16 shows an enlarged front view comparing the wire of this embodiment with the wire of the comparative example in range G of Figure 13.

[0035] As shown in Fig. 13, when the stent 100 of this embodiment is curved, for example, along the aortic arch, stress is concentrated in the central portion in the direction of axis O, which is the apex of the curve, i.e., the greatest load is applied. In other words, the inside of the curve of the central portion (the center side of the curved arc) receives stress s in a direction perpendicular to the direction of axis O, as shown by the white arrow in Fig. 13. Meanwhile, in the stent 100, the portions between the intersections of the wires, which are circled in Fig. 13, become fragile portions f1 and f2 that are likely to become the starting points of kinks.

[0036] As shown in Fig. 14, which is an enlarged view of the range F in Fig. 13 corresponding to the stress concentration portion, the cell S1 (hatched portion) corresponding to the stress concentration portion is particularly subjected to stress in the stent 100. The weak points f1 in the cell S1 are located at the center positions of each side of the diamond shape.

[0037] A cross section perpendicular to the extension direction of the wire corresponding to each weak portion f1 is thick in the radial direction of the stent 100, as shown in Fig. 15(a). On the other hand, the wire cross section of the comparative example shown in Fig. 15(b) has a width w' longer than the thickness t'. In the range F of Fig. 13 corresponding to the stress concentration portion, the stress s acts in the radial direction of the stent 100, so the wire cross section of this embodiment, which has a thickness t in the radial direction, has higher strength against the stress s and is more excellent in kink resistance than the comparative example.

[0038] 13, stress is also concentrated relatively on the side surface of the central portion in the direction of axis O. Since the wire extends obliquely to the direction of axis O in the weakened portion f2 in this side surface portion as shown in FIG 16(a), the stress s acts obliquely to the extension direction of the wire.

[0039] As described above, in the stent 100 of this embodiment, the first crossing angle γ, which is the angle in the direction of the axis O, is equal to or smaller than the second crossing angle σ, which is the angle in the circumferential direction. On the other hand, in the comparative example shown in Fig. 16(b), the wire width w is the same as that of the wire of this embodiment, but the first crossing angle γ' is larger than the second crossing angle σ'.

[0040] As a result, the width ws in the stress direction (circumferential direction) of the wire of this embodiment in FIG. 16(a) (hereinafter referred to as the stress direction width ws) is longer than the stress direction width ws' of the comparative example in FIG. 16(b). In other words, the wire of this embodiment has a sufficient cross-sectional area in the stress direction. Therefore, even in the side portion of the stent 100 where the stress s acts radially in the stress concentration portion, a large cross-sectional area along the stress direction can be ensured, and the wire has higher strength against the stress s and is superior in kink resistance than the comparative example.

[0041] In this way, the stent 100 of this embodiment realizes a flexible stent 100 with excellent kink resistance, even without a membrane like a stent graft. By not having a membrane, blood flow to the branched blood vessels is less likely to be obstructed. In particular, the stent 100 of this embodiment is even less likely to obstruct blood flow because each wire has a narrow line width w relative to its thickness t. This reduces the difficulty for doctors in precisely positioning the stent, which is necessary to align the position of the opening provided in the stent graft with the branched blood vessel.

[0042] Furthermore, since the crossing portion (e.g., 120) is integrally formed without overlapping in the radial direction of the stent 100, the thickness of the crossing portion (e.g., 120) is reduced by half compared to the overlapping type, and no unevenness occurs in the crossing portion, so that it is possible to insert a catheter 300 with a smaller diameter, there is less frictional resistance, and the catheter 300 can be operated more smoothly when the stent is placed. Furthermore, there is less impact (irritation) on the blood vessel wall. In addition, compared to a wire-knitted stent, the expansion force of the stent itself can be secured to be strong, and the stent is resistant to crushing due to the pressing force of blood flow that may flow into the peeling side.

[0043] In the above embodiment, the stent 100 is formed by laser processing a metal tube so that the wires 101-106 of the first wire group and the wires 111-116 of the second wire group are integrated together. However, the crossing parts of the spiral wires may be fixed by heat or the like. The stent 100 may be made of a spring material. When the stent 100 is in an expanded state, the spring material is annealed so that it is in a free state, and is contracted when the stent 100 is inserted into the catheter. Then, the stent 100 is exposed from the catheter, and the stent 100 expands in diameter due to the reaction force of the spring. Even in this case, by making the cross sections of the wires 101-106 of the first wire group and the wires 111-116 of the second wire group into a radially thick rectangular shape and setting the first crossing angle γ to be equal to or less than the second crossing angle σ, the first wires 101-106 and the second wires 111-116 expand into a tubular shape, thereby ensuring the internal space of the stent 100 while ensuring kink resistance against bending and ensuring overall flexibility.

[0044] (Example) Hereinafter, the results of the kink resistance test of the stent according to this embodiment will be described with reference to Tables 1 to 5 and FIGS.

[0045] Table 1 shows the design specifications of the base material and stent for each embodiment, Table 2 shows the specifications of the final stent after molding for each embodiment, and Table 3 shows the results of the kink resistance test for each embodiment. [Table 1]

[0046] Specifically, Table 1 shows the outer diameter and thickness of the base material, which is a shape memory alloy tube, and the outer diameter of the base material in each example is 3 mm and the thickness is 0.3 mm. The design specifications of the stent include the line width, the width of the link part (the axial length of the wire intersection part), the number of crowns, the number of cells, the slit length (the axial length of the approximately oval space), the presence or absence of a marker, and the total length (the axial length). The marker is a material with high radiopacity, such as tantalum, welded to both ends of the stent to improve the visibility of the stent during X-ray photography. The number of cells is the number of cells between the markers at both ends of the stent (M to M). [Table 2]

[0047] Table 2 shows the specifications of the stent in a self-expanded state immediately before the kink resistance test, and lists the maximum expanded diameter, total length (length in the direction of axis O), shortening rate (total length in self-expanded state / total length in contracted state), polishing rate by electrolytic polishing, thickness t, wire width w, wire cross-sectional area, cell width (short diagonal of the cell), cell height (long diagonal of the cell), cell area, first crossing angle γ, second crossing angle σ, and 80% [N / cm] (pressure value per 1 cm when the stent is contracted to 80%, with the maximum expanded state being 100%) for each embodiment. [Table 3]

[0048] Table 3 shows the results of the kink resistance test, and indicates whether or not kinking occurred for each example when it was fitted into molds with different curvatures. Cases where kinking did not occur are indicated by a circle, and cases where kinking occurred are indicated by an x. For example, Fig. 17 shows the stent of Example 4 fitted into a mold with R50 (radius of curvature 50 mm), and if it is curved in a smooth curve as in the figure, it is determined that no kinking occurs. On the other hand, Fig. 18 shows the stent of Example 4 fitted into a mold with R45 (radius of curvature 45 mm), and if bending occurs in the central part of the stent in the direction of axis O as in the figure, it is determined that a kink occurs.

[0049] From Table 3, it can be seen that Examples 1 and 6 to 9 are excellent in kink resistance, followed by Examples 2, 3, and 5, and then Examples 4 and 10. Since the curvature of the aortic arch is usually R45 or more, Examples other than Examples 4 and 10 are suitable for use in the aortic arch. [Table 4]

[0050] Table 4 shows the results of calculating the w / t of each example based on the thickness t and line width w in Table 2, and sorting the results in descending order of w / t together with the results of the kink resistance test in Table 3. As shown in Table 4, it can be seen that when w / t is 0.87 or less, kink resistance up to R45 is achieved, and when w / t is 0.81 or less, kink resistance up to R40 is assured. Therefore, in the relationship between the wire thickness t and line width w in the stent, w / t<0.90 is preferable, and w / t≦0.81 is more preferable. [Table 5]

[0051] Table 5 shows the results of calculating σ / γ for each Example based on the first crossing angle γ and the second crossing angle σ in Table 2, and sorting the σ / γ in ascending order together with the results of the kink resistance test in Table 3. As shown in Table 5, when σ / γ is 1.22 or more, kink resistance up to R40 is obtained. However, since Example 4, in which σ / γ is 1.21, has a kink at R45, in order to have more reliable kink resistance, σ / γ is preferably 1.22 or more. Therefore, in the relationship between the first crossing angle γ and the second crossing angle σ in the stent, σ / γ≧1.22 is preferable, and σ / γ≧1.36 is more preferable.

[0052] The above is the description of the embodiment and examples of the present invention, but the aspects of the present invention are not limited to these embodiment and examples. [Explanation of symbols]

[0053] 100 stents 100a First wire group 100b Second wire group 101~106, 111~116 Wires 120 Intersection 200 Tube (tubular body) 201~205 Serpentine structure 300 Catheter 400 Aortic arch model 411 Innominate artery 412 Left common carotid artery 413 Left subclavian artery

Claims

1. A stent for treating aortic arch dissection that becomes cylindrical when self-expanded, a first wire group consisting of a plurality of wires; a second wire group including a plurality of wires intersecting the wires of the first wire group at a plurality of locations; In a state where the wires are self-expanded into a cylindrical shape, the wires of the first wire group and the wires of the second wire group cross each other to form a plurality of substantially diamond-shaped cells, and the cross-sectional shape of each of the wires is a rectangular shape that is thick in the radial direction of the cylindrical shape, When the radial thickness of the cross-sectional shape of the wires of the first wire group and the second wire group is t and the width of the short side perpendicular to the thickness is w, w / t<0.90; The cells in the cylindrical self-expanded state have an oblique rhombus with a long diagonal extending in the circumferential direction, The stent has an interior angle of the cells in the cylindrical self-expanded state, where σ is an obtuse angle and γ is an acute angle, and the ratio σ / γ is 1.22 or more.

2. A stent as described in claim 1, wherein the intersecting portions of the first wire group and the second wire group are integrally molded without overlapping in the radial direction, and at the intersecting portions, the tops of two opposing arc portions in the axial direction are fused to form an integrated shape.

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