Stents and stent delivery systems

Abstract

[Problem] To make uniform a stent-retaining force that is stable with respect to a balloon, and a radial force that is localized even during a large diametric expansion. [Solution] A stent 100 is configured such that a second distance L2, which is the separation distance in the circumferential direction between a longitudinal endpoint of a second curved section 35 connected to a first-side end of a second linear section 34 and a longitudinal endpoint of the second curved section 35 connected to a second-side end of the second linear section 34, is longer than a first distance L1, which is the separation distance in the circumferential direction between a longitudinal endpoint of a first curved section 32 connected to a first-side end of any first linear section 31 and a longitudinal endpoint of the first curved section 32 or the second curved section 35 connected to a second-side end of the first linear section 31. At least four first linear sections 31 are arranged in a wave-shaped unit 33.

Description

[Technical Field]

[0001] The present invention relates to stents and stent delivery systems. [Background technology]

[0002] A stent is a medical device that is delivered to a lesion in a biological lumen by a stent delivery system and then placed there to expand the lesion, such as a stenosis or occlusion, and secure the lumen in order to treat various diseases caused by narrowing or occlusion of a lumen such as a blood vessel. A stent is formed with a cylindrical outer periphery that can expand and contract radially, with gaps formed by struts, which are linear components.

[0003] Stents are classified into balloon-expandable and self-expandable types based on their function and placement method. Balloon-expandable stents are mounted on a balloon catheter in a crimped (reduced diameter) state, delivered to the target lesion, and then placed inside the body lumen. Stents must be prevented from falling off the balloon during delivery. Therefore, stents are crimped (pressure crimped) while inflating the balloon at low pressure so that the balloon protrudes outward from the inner surface of the stent through the gaps between the struts when crimped. Prior to pressure crimping, the balloon is pre-expanded to form wrinkles on its outer surface, making it easier for the balloon to protrude through the gaps between the struts.

[0004] However, the wrinkles that occur during pre-expansion of the balloon are random in shape, making it difficult to protrude the balloon from the intended position between the struts during pressure crimping. Therefore, when balloon catheters with crimped stents are mass-produced, there is a large difference in the stent retention strength between individual balloon catheters.

[0005] A stent disclosed in Patent Document 1 below is known to solve the above-mentioned problem of stent retention. In the stent disclosed in Patent Document 1, the circumferential spacing of the struts forming the wavy annular body is not uniform. The spacing between the inclined curved section and the first inclined straight section, and between the inclined curved section and the second inclined straight section, is greater than the spacing between the parallel straight section and the first inclined straight section, and the spacing between the parallel straight section and the second inclined straight section. Because the circumferential spacing of the struts in the stent disclosed in Patent Document 1 is nonuniform, compared to a case in which the circumferential spacing of the struts is uniform, the balloon is less likely to protrude from areas where the circumferential spacing of the struts is small, and more likely to protrude from areas where the circumferential spacing of the struts is large. Therefore, the stent disclosed in Patent Document 1 reduces variation in whether or not the balloon protrudes during pressurized crimping, enabling stable stent retention. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-86463 Summary of the Invention [Problem to be solved by the invention]

[0007] As a stent expands to a larger diameter, the spacing between adjacent struts in the circumferential direction increases. The amplitude of the strut-formed annular structure decreases, changing its shape from wavy to linear. Therefore, the distance from any location where no strut is present to a strut is generally closer when the strut is wavy than when it is linear.

[0008] Therefore, the local distribution of radial force (compressive force in the radial direction) acting on the inner surface of the blood vessel can be more uniform when the annular body is wavy than when it is straight. Also, if the stent is a drug-eluting stent, the local distribution of the drug can be more uniform when the annular body is wavy than when it is straight. The more uniform the local distribution of radial force and drug, the lower the clinical risk of restenosis at the lesion.

[0009] As described above, even when a stent is applied with a large diameter, it is preferable to maintain the strut shape in a wavy line shape, considering the clinical risks. Therefore, there is a need for a stent that has the excellent stent retention force of the stent in Patent Document 1, but can reduce the clinical risks by equalizing the local radial force even when applied with a large diameter.

[0010] At least one embodiment of the present invention has been made in consideration of the above-mentioned circumstances, and specifically, an object of the present invention is to provide a stent and a stent delivery system that can achieve stable stent retention force against a balloon and uniform local radial force even during large diameter expansion. [Means for solving the problem]

[0011] The stent according to this embodiment is a stent that is expandable and contractible in a radial direction of the cylindrical shape, and includes a plurality of annular bodies formed in an annular shape by linear elements folded back in a wavy manner and arranged along the longitudinal axis direction of the cylindrical shape to form a cylindrical shape, and link portions connecting adjacent annular bodies to each other, and the annular bodies are configured to include a wavy unit formed by a plurality of first linear portions extending from a base end side to a tip end side in the longitudinal axis direction and arranged continuously in the circumferential direction of the cylindrical shape, and a first curved portion connecting end portions on the base end side or the tip end side of two of the first linear portions adjacent to each other in the circumferential direction, a second linear portion extending from a base end side to a tip end side in the longitudinal axis direction and arranged adjacent to the first linear portion in the circumferential direction, and a link portion connecting the first linear portion and the second linear portion adjacent to each other in the circumferential direction to each other. and a second curved portion connecting ends of linear portions on the base end side or the tip end side to each other, and arranging a plurality of basic units in the circumferential direction, and connecting adjacent basic units with the second curved portion, wherein a second distance, which is a separation distance in the circumferential direction between a longitudinally outermost end of the second curved portion connected to one end side end of the second linear portion and a longitudinally outermost end of the second curved portion connected to the other end side end of the second linear portion, is longer than a first distance, which is a separation distance in the circumferential direction between a longitudinally outermost end of the first curved portion connected to one end side end of any of the first linear portions and a longitudinally outermost end of the first curved portion or the second curved portion connected to the other end side end of the first linear portion, and wherein there are four or more first linear portions arranged in the wavy unit. The link portion is connected only to the first linear portion that constitutes the wave-shaped unit. .

[0012] The stent delivery system of this embodiment is a stent delivery system comprising a stent having the above-mentioned configuration and a balloon catheter having an expandable and contractible balloon, wherein the stent is held in close contact with the contracted balloon in a contracted state, and the balloon protrudes outward from the radial position of the inner surface of the stent only at a position between the first linear portion and the second linear portion. [Effects of the Invention]

[0013] According to one embodiment of the present invention, it is possible to achieve stable stent retention force against the balloon and uniform local radial force during large diameter expansion. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic plan view of a stent delivery system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a development view of a portion of the outer periphery of a stent according to this embodiment, cut linearly along the longitudinal axis and developed. [Figure 3] FIG. 2 is a diagram showing a state of a basic unit forming the annular body of the stent according to the present embodiment before the stent is expanded. [Figure 4] FIG. 10 is a diagram showing the state of the basic unit of the stent according to the present embodiment after the stent is expanded. [Figure 5A] FIG. 2 is a partially enlarged view of a first curved portion, a link portion, and the vicinity thereof of the stent according to the present embodiment. [Figure 5B] FIG. 2 is a partially enlarged view of a second curved portion and its vicinity of the stent according to the present embodiment. [Figure 6] FIG. 2 is a diagram showing the state of the link portion of the stent according to the present embodiment and its surrounding area before the stent is expanded. [Figure 7] 1 is a diagram showing the state of the link portion of the stent according to the present embodiment and its surrounding area after the stent has been expanded. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The embodiments shown here are merely examples for embodying the technical concept of the present invention and are not intended to limit the present invention. Furthermore, all other embodiments, examples, and operational techniques that can be conceived by those skilled in the art without departing from the spirit of the present invention are included within the scope and spirit of the present invention, as well as within the scope of the claims and their equivalents.

[0016] Furthermore, for the convenience of illustration and ease of understanding, the drawings attached to this specification may be represented schematically with the scale, aspect ratio, shape, etc. appropriately changed from the actual product, but these are merely examples and do not limit the interpretation of the present invention.

[0017] In this specification, the longitudinal direction of the cylindrical stent 100 formed by struts, which are linear components (the longitudinal direction of the stent 100, for example, the left-right direction in the drawing along the central axis X (two-dot chain line) of the stent 100 shown in FIG. 2) is simply referred to as the "longitudinal direction." Furthermore, the circumferential direction of the stent 100 (annular body 10) shown in FIG. 2 (the up-down direction in the drawing) is simply referred to as the "circumferential direction," and the radial direction of the stent 100 (annular body 10) is simply referred to as the "radial direction." Furthermore, the side inserted into the living body is referred to as the "distal side," and the side opposite the distal side where the surgeon operates the medical device is referred to as the "proximal side."

[0018] In the following description, when ordinal numbers such as "first" and "second" are used, unless otherwise specified, they are used for convenience and do not stipulate any particular order.

[0019] The stent 100 according to this embodiment is used to treat strictures or obstructions occurring in blood vessels, bile ducts, tracheas, esophagus, urethra, or other biological lumens. The stent 100 is a so-called balloon-expandable stent that is mounted (attached) in a crimped state on a balloon 220, delivered to the lesion, and then expanded and placed at the lesion.

[0020] The stent delivery system 300 includes a stent 100 and a balloon catheter 200. The balloon catheter 200 is used to deliver the stent 100 in a contracted state to a lesion, expand it, and place it in the lesion.

[0021] The balloon catheter 200 comprises a long catheter body 210 , a balloon 220 provided at the tip of the catheter body 210 , and a hub 230 fixed to the base end of the catheter body 210 .

[0022] The catheter main body 210 comprises an outer tube and an inner tube disposed inside the outer tube.

[0023] An inflation lumen is formed inside the outer tube, through which inflation fluid flows for inflating the balloon 220. The distal end of the outer tube is fixed to the proximal end of the balloon 220. The proximal end of the outer tube is fixed to the hub 230.

[0024] A guidewire lumen into which a guidewire is inserted is formed inside the inner tube. The distal end of the inner tube penetrates the inside of the balloon 220 and opens distally of the balloon 220. The proximal end of the inner tube penetrates the side wall of the outer tube proximal to the balloon 220 and is fixed to the outer tube.

[0025] The catheter main body 210 is preferably made of a material having a certain degree of flexibility, and examples thereof include polyolefins such as polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer, or a mixture of two or more of these; thermoplastic resins such as polyvinyl chloride resin, polyamide, polyamide elastomer, polyester, polyester elastomer, polyurethane, and fluororesin; silicone rubber; and latex rubber.

[0026] The balloon 220 is a member that, for example, expands inside a stricture to widen the stricture. The distal end of the balloon 220 is fixed to the outer wall surface of the inner tube. The proximal end of the balloon 220 is fixed to the outer wall surface of the distal end of the outer tube. Therefore, the inside of the balloon 220 communicates with an expansion lumen formed in the outer tube. An expansion fluid can flow into the balloon 220 from a proximal opening 231 via the expansion lumen. The balloon 220 expands when the expansion fluid flows in, and contracts and returns to a folded state when the inflowing expansion fluid is discharged.

[0027] The balloon 220 is preferably made of a flexible material that expands and contracts with the inflow and outflow of an inflation fluid. Examples include polymeric materials such as polyolefin, cross-linked polyolefin, polyester, polyester elastomer, polyvinyl chloride, polyurethane, polyurethane elastomer, polyphenylene sulfide, polyamide, polyamide elastomer, and fluororesin, as well as silicone rubber and latex rubber. The balloon 220 is not limited to a single polymeric material; a film formed by appropriately laminating multiple polymeric materials may also be used. The inflation fluid may be either a gas or a liquid, such as helium gas, CO2 gas, or O2 gas, or a liquid such as saline or an X-ray contrast medium.

[0028] The hub 230 has a proximal opening 231 that communicates with the inflation lumen of the outer tube. The proximal opening 231 functions as a port for the inflow and outflow of inflation fluid.

[0029] The material of which the hub 230 is made is not particularly limited, but examples include thermoplastic resins such as polyethylene, polyurethane, polyester, polypropylene, polycarbonate, polyamide, polysulfone, polyarylate, and methacrylate-butylene-styrene copolymer.

[0030] Next, the stent 100 will be described with reference to Figures 2 to 7. In Figures 2 to 7, the right side of the figure is the "base end side" and the left side of the figure is the "distal end side."

[0031] The stent 100 is formed from struts, which are linear components, and includes a plurality of annular bodies 10 aligned in the longitudinal direction, and link portions 20 connecting adjacent annular bodies 10 in the longitudinal direction, as shown in Figure 2. The stent 100 is formed into a cylindrical shape in which adjacent annular bodies 10 are connected by the link portions 20. In this specification, any component of the stent 100 is referred to as a strut.

[0032] As shown in Fig. 2, the annular body 10 is formed by arranging wavy struts that are repeatedly folded back in a zigzag pattern along the circumferential direction into a ring. The phases of the multiple annular bodies 10 in the circumferential direction are aligned.

[0033] 3, the wavy unit 33 has a plurality of first linear portions 31 (31a to 31d) extending from the base end side to the tip end side in the longitudinal direction and arranged continuously in the circumferential direction, and first curved portions 32 (32a to 32c) connecting the base end side or tip end side of two circumferentially adjacent first linear portions 31. The first linear portions 31 and the first curved portions 32 are connected continuously in a wavy manner along the circumferential direction.

[0034] The first linear portions 31 have a substantially linear shape, and four or more first linear portions 31 are arranged consecutively along the circumferential direction so that their tips point toward the distal end or proximal end in the longitudinal direction. In this embodiment, the four first linear portions 31 are arranged consecutively along the circumferential direction as shown in FIG.

[0035] In the first linear portion 31, the first linear portion 31a and the first linear portion 31d adjacent to the second linear portion 34 are arranged in an attitude inclined at a predetermined angle with respect to the longitudinal direction. The first linear portion 31b and the first linear portion 31c arranged between the first linear portion 31a and the first linear portion 31d are arranged substantially parallel to the longitudinal direction. The first linear portion 31c functions as an "axis-parallel linear portion" that is parallel to the longitudinal direction before and after the expansion of the stent 100.

[0036] The first curved portions 32 connect the proximal or distal end portions of two circumferentially adjacent first linear portions 31 to form a wavy unit 33. In the present embodiment, as shown in FIG. 3, three first curved portions 32 are arranged in the wavy unit 33 along the circumferential direction. As shown in FIG. 3, the first curved portions 32 include a first curved portion 32a connecting the first linear portion 31a and the first linear portion 31b, a first curved portion 32b connecting the first linear portion 31b and the first linear portion 31c, and a first curved portion 32c connecting the first linear portion 31c and the first linear portion 31d.

[0037] The basic unit 36 ​​has a wavy unit 33 extending toward the base end or tip end in the longitudinal direction, a second linear portion 34 arranged circumferentially adjacent to the wavy unit 33, and a second curved portion 35 connecting the base end or tip end of the wavy unit 33 and the second linear portion 34 that are adjacent to each other in the circumferential direction.

[0038] The second linear portion 34 has an S-shaped curved shape and is disposed adjacent to the wavy unit 33 in the circumferential direction. The distal end or proximal end of the second linear portion 34 is connected to the distal end or proximal end of the first linear portion 31d that is closest to the first linear portions 31 that form the circumferentially adjacent wavy units 33 via a second curved portion 35. The second linear portion 34 is disposed at an inclination angle with respect to the longitudinal axis direction. The inclination angle of the second linear portion 34 with respect to the longitudinal axis direction is greater than the inclination angles of the first linear portion 31a and the first linear portion 31d with respect to the longitudinal axis direction.

[0039] The second curved portion 35 has one end connected to the distal end or proximal end of the second linear portion 34, and the other end connected to the most adjacent first linear portion 31d in the circumferentially adjacent corrugated unit 33. As shown in Fig. 3 , the second curved portion 35 has a second curved portion 35a connecting the second linear portion 34 and the first linear portion 31a of another circumferentially adjacent basic unit 36, a second curved portion 35b connecting the first linear portion 31d and the second linear portion 34, and a second curved portion 35c connecting the second linear portion 34 and the first linear portion 31a of another circumferentially adjacent basic unit 36.

[0040] The struts that form the annular body 10 are formed by continuously arranging a plurality of basic units 36 in the circumferential direction. In this embodiment, a strut is formed by connecting four basic units 36, as shown in Figure 2. In other words, the annular body 10 is formed by four basic units 36.

[0041] 3, the basic unit 36 ​​is formed so that a second distance L2, which is the circumferential distance between the longitudinally outermost end of the second curved portion 35 connected to one end of the second linear portion 34 and the longitudinally outermost end of the second curved portion 35 connected to the other end of the second linear portion 34, is longer than a first distance L1, which is the circumferential distance between the longitudinally outermost end of the first curved portion 32 connected to one end of any of the first linear portions 31 and the longitudinally outermost end of the first curved portion 32 or the second curved portion 35 connected to the other end of the first linear portion 31. The relationship between the first distance L1 and the second distance L2 is maintained before and after the expansion of the stent 100, as shown in FIGS.

[0042] The annular bodies 10 adjacent to each other in the longitudinal direction are integrally connected by link portions 20. The adjacent annular bodies 10 are connected by at least one link portion 20 in the gap D between the annular bodies 10. In this embodiment, the adjacent annular bodies 10 are connected by the link portions 20 at two locations.

[0043] The distal end of the link portion 20 is connected to the first curved portion 32c of the annular body 10 located on the distal side. The proximal end of the link portion 20 is connected to the first curved portion 32b of the annular body 10 located on the proximal side. The first linear portion 31b and the first linear portion 31c, which is an axis-parallel linear portion, are connected to the first curved portion 32b connected to the link portion 20. The first linear portion 31c and the first linear portion 31d, which are axis-parallel linear portions, are connected to the first curved portion 32c connected to the link portion 20. The first curved portion 32c connected to the link portion 20 is a curved region connecting the proximal end of the first linear portion 31c and the proximal end of the first linear portion 31d. 5A, the outer curved line of the first curved portion 32c, i.e., the boundary line between the link portion 20 and the first curved portion 32c, is an arc inscribed in the edge line of the first linear portion 31c on the first linear portion 31b side and the edge line of the first linear portion 31d on the second linear portion 34 side. The first curved portion 32b also has a curved region and outer curved line (not shown) similar to those of the first curved portion 32c.

[0044] Examples of materials that can be used to form the struts include metal materials such as stainless steel, cobalt-based alloys such as cobalt-chromium alloys (e.g., CoCrWNi alloys), platinum-chromium alloys (e.g., PtFeCrNi alloys), and nickel-titanium alloys, as well as biodegradable polymer materials such as polylactic acid, polyglycolic acid, lactic acid-glycolic acid copolymer, polycaprolactone, lactic acid-caprolactone copolymer, and glycolic acid-caprolactone copolymer.

[0045] The outer surface of the strut may be provided with a covering containing a drug. The covering is preferably formed on the outer surface of the strut located radially outward, but is not limited to this. The covering may contain a drug capable of suppressing neointima proliferation and a drug carrier for carrying the drug. The covering may be composed solely of the drug. The drug contained in the covering is, for example, at least one selected from the group consisting of sirolimus, everolimus, zotarolimus, paclitaxel, etc. The material of the drug carrier is not particularly limited, but a biodegradable material is preferred.

[0046] In the stent 100 of this embodiment, the second distance L2 is longer than the first distance L1. Therefore, when the stent 100 is pressurized and crimped onto the balloon 220, the balloon 220 is less likely to protrude from the region between circumferentially adjacent first linear portions 31 and more likely to protrude from the region between circumferentially adjacent first linear portions 31 and second linear portions 34, thereby stabilizing the stent retention force on the balloon 220. Furthermore, the stent 100 of this embodiment has four or more first linear portions 31 that constitute the wavy unit 33. Therefore, when expanded to a large diameter, the shape of the annular body 10 becomes more wavy than a stent with fewer than four first linear portions 31, and local radial force is more uniform.

[0047] In the stent 100 of this embodiment, the number of first linear portions 31 forming the wavy units 33 is four or more, and is an even number. Furthermore, the number of second linear portions 34 forming the basic units 36 is one. With this configuration, the second linear portions 34 in the circumferentially adjacent basic units 36 of the stent 100 are inclined in the longitudinal direction from the base end to the tip end in an opposite (approximately V-shaped) manner, and the design of the annular body 10 is point-symmetric. Therefore, even if, in one basic unit 36 ​​of the annular body 10, curved portions that are easy or difficult to open during radial expansion are concentrated on the base end side, and conversely, curved portions that are difficult or easy to open during radial expansion are concentrated on the tip end side, the curved portions that are easy or difficult to open are not concentrated on one end of the annular body 10, thereby improving expansion uniformity.

[0048] The stent 100 of this embodiment has four first linear portions 31 that form the wavy units 33. With this configuration, the stent 100 satisfies the requirements of stabilizing the stent retention force and uniforming the local radial force, while reducing the outer diameter (profile) when contracted when mounted on the balloon 220, allowing smooth delivery to the lesion in the peripheral region.

[0049] Furthermore, the stent 100 of this embodiment is formed so that the line width of the first curved portion 32 is smaller than the line width of the first linear portion 31 connected thereto. Furthermore, the line width of the second curved portion 35 is formed so that it is smaller than the line width of the second linear portion 34 connected thereto.

[0050] Typically, when the stent 100 is expanded and deformed, tensile stress acts on the inner curved side of the "curved portion" including the first curved portion 32 and the second curved portion 35, and compressive stress acts on the outer curved side. The neutral plane is located near the center of the curved portion, and the magnitude of each stress is proportional to the distance from the neutral plane. Therefore, when a stent with a small curved portion width and a stent with a large curved portion width are expanded to the same diameter, the tensile stress acting on the inner curved portion is smaller in the stent with a small curved portion width than in the stent with a large curved portion width. Furthermore, when the stent is expanded and deformed to the expansion limit diameter at which fracture occurs, the expansion limit diameter is larger in the stent with a small curved portion width than in the stent with a large curved portion width. Therefore, when the line width of the curved portion is smaller than the line width of the linear portion in a connected linear portion and curved portion, as in the stent 100 of this embodiment, the tensile stress acting on the inner side of the curved portion is smaller than when the line width of the curved portion is the same under conditions where the degree of opening of the curved portion is the same, i.e., when the angle formed by the linear portion connected to one end of the curved portion and the linear portion connected to the other end is the same, the risk of stent fracture can be reduced.

[0051] The tensile stress and expansion limit diameter on the inner bay side of the curved section also vary depending on the radius of curvature on the inner bay side of the curved section. The larger the radius of curvature on the inner bay side, the smaller the tensile stress acting on the inner bay side of the curved section when a deformation that gives the same expansion diameter is applied to the curved section, and the larger the expansion limit diameter. If a stent contains curved sections with both large and small radii of curvature on the inner bay side, the curved section with the larger radius of curvature on the inner bay side will open more easily during expansion. Therefore, adjusting the radius of curvature on the inner bay side of each curved section within the stent changes the ease with which each curved section opens, and changes the expansion uniformity, which refers to the degree of distribution of the degree of opening of the curved sections.

[0052] 5A and 5B, the stent 100 of this embodiment is formed such that, with respect to the inward bay side radius of curvature R1 of the curved portion, the second radius R1b, which is the inward bay side radius of curvature of the second curved portion 35, is larger than the first radius R1a, which is the inward bay side radius of curvature of the first curved portion 32. With this configuration, the stent 100 can reduce the risk of stent breakage.

[0053] The stent 100 of this embodiment is formed so that the radius of curvature on the inward bay side of the first curved portion 32 to which the link portion 20 is connected is larger than the radius of curvature on the inward bay side of the first curved portion 32 to which the link portion 20 is not connected. With this configuration, the first curved portions 32 of the stent 100 connected to the link portion 20 open more easily than when the first curved portions 32 have the same radius of curvature on the inward bay side, and the expansion uniformity is also improved.

[0054] 6 and 7, in the stent 100 of this embodiment, before and after stent expansion, the portion from the base end side of the first linear portion 31c, which is the axis-parallel linear portion of the base-end side annular body 10, via the link portion 20, to the tip end side of the first linear portion 31c, which is the axis-parallel linear portion of the tip-end side annular body 10 (the portion surrounded by the dotted line in the figure) is parallel to the longitudinal axis. With this configuration, shortening of the length of the stent 100 in the longitudinal direction during stent expansion is prevented.

[0055] In the stent 100 of this embodiment, two link portions 20 are arranged in the gaps D between adjacent annular bodies 10, facing each other in the radial direction of the annular bodies 10, and further, the phase of the link portion 20 arranged in one gap D is shifted by 90° in the circumferential direction from the phase of the link portion 20 arranged in another gap D adjacent to the first gap D in the longitudinal direction. With this configuration, in the stent 100, the link portion 20 in the adjacent other gap D is located at the circumferential intermediate position between the circumferentially adjacent link portions 20 arranged in one gap D, and the circumferential positions at which the link portions 20 are located are dispersed over the entire length of the stent, resulting in more uniform flexibility of the stent in the circumferential position.

[0056] Here, specific example dimensions of the stent 100 will be described. The dimensions of the stent 100 actually manufactured may vary slightly from the values ​​shown due to variations during manufacturing. The total length of the stent 100 in the longitudinal direction is 5 mm to 200 mm, preferably 9 mm to 50 mm. The crimped outer diameter of the stent 100 is 0.5 mm to 2 mm. The expanded diameter of the stent 100 is 3.0 mm to 6.5 mm, preferably 3.5 mm to 4.5 mm. The wall thickness of the strut is 40 μm to 150 μm.

[0057] The length in the major axis direction of the annular bodies 10 (the distance between the major axis end portions of adjacent curved portions in the circumferential direction, hereinafter also referred to as "amplitude") is 500 μm to 1500 μm. The number of the annular bodies 10 is 4 to 80, preferably 8 to 40.

[0058] The first distance L1 in the basic unit 36 ​​is 50 μm to 500 μm, preferably 100 μm to 300 μm, before being crimped onto the balloon 220. The first distance L1 in the basic unit 36 ​​is 50 μm to 500 μm, preferably 100 μm to 200 μm, after being crimped onto the balloon 220. The first distance L1 in the basic unit 36 ​​is 200 μm to 1200 μm, preferably 200 μm to 900 μm, after the stent 100 crimped onto the balloon 220 is expanded until the stent inner diameter becomes 4.0 mm and the balloon 220 is removed. The first distance L1 in the basic unit 36 ​​is 200 μm to 1200 μm, preferably 300 μm to 1000 μm, when the stent 100 crimped on the balloon 220 is expanded until the stent inner diameter reaches 4.18 mm and the balloon 220 is removed.

[0059] The second distance L2 in the basic unit 36 ​​is 500 μm to 1000 μm, preferably 200 μm to 900 μm, before being crimped onto the balloon 220. The second distance L2 in the basic unit 36 ​​is 100 μm to 1000 μm, preferably 200 μm to 500 μm, after being crimped onto the balloon 220. The second distance L2 in the basic unit 36 ​​is 200 μm to 1500 μm, preferably 500 μm to 1200 μm, after the stent 100 crimped onto the balloon 220 is expanded until the stent inner diameter becomes 4.0 mm and the balloon 220 is removed. The second distance L2 in the basic unit 36 ​​is 200 μm to 1500 μm, preferably 500 μm to 1200 μm, when the stent 100 crimped on the balloon 220 is expanded until the stent inner diameter reaches 4.18 mm and the balloon 220 is removed.

[0060] The length in the longitudinal direction of the link portion 20, i.e., the axial length between the proximal-most end of the first curved portion 32c connected to the link portion 20 and the distal-most end of the first curved portion 32b connected to the link portion 20, is 200 μm to 600 μm. The minimum line width of the link portion 20 is 50 μm to 400 μm. The maximum line width of the link portion 20 is 200 μm to 500 μm.

[0061] The line width of the first linear portion 31 is 50 μm to 200 μm. The line width of the first curved portion 32 is 50 μm to 200 μm. The line width of the second linear portion 34 is 50 μm to 200 μm. The line width of the second curved portion 35 is 50 μm to 200 μm.

[0062] The inward bay side radius of curvature of the first curved portion 32 (first radius R1a) and the inward bay side radius of curvature of the second curved portion 35 (second radius R1b) are 20 μm to 120 μm. Of these, the inward bay side radius of curvature of the first curved portion 32 not connected to the link portion 20 is preferably 20 μm to 90 μm, and the inward bay side radius of curvature of the first curved portion 32 connected to the link portion 20 is preferably 50 μm to 120 μm. Furthermore, the inward bay side radius of curvature of the second curved portion 35 is preferably 50 μm to 120 μm.

[0063] 5A, the radius of curvature R2 on the inner bay side of the connecting portion 37, which is the connecting portion between the first curved portion 32 (or the second curved portion 35) and the first linear portion 31 (or the second linear portion 34), is 50 μm to 500 μm, and preferably 100 μm to 300 μm. The radius of curvature R3 of the outer edge of the link portion 20 is 200 μm to 2000 μm, and preferably 300 μm to 800 μm.

[0064] [Action and effect] As described above, the stent 100 of this embodiment is formed into a ring shape by linear elements folded back in a wavy pattern, and comprises a plurality of ring-shaped bodies 10 arranged along the longitudinal axis of the cylindrical shape to form a cylindrical shape, and link portions 20 connecting adjacent ring-shaped bodies 10, and is configured to be expandable and contractible in the radial direction of the cylindrical shape. In addition, in a stent 100 having such a configuration, the annular body 10 is formed by arranging a plurality of basic units 36 in the circumferential direction, each basic unit 36 ​​being formed by a wavy unit 33 formed by a plurality of first linear portions 31 extending from the base end side to the tip end side in the longitudinal direction and arranged continuously in the circumferential direction of the cylindrical shape, a first curved portion 32 connecting the base end or tip end portions of two circumferentially adjacent first linear portions 31, a second linear portion 34 extending from the base end side to the tip end side in the longitudinal direction and arranged at a position adjacent to the first linear portion 31 in the circumferential direction, and a second curved portion 35 connecting the base end or tip end portions of the circumferentially adjacent first linear portions 31 and second linear portions 34, and connecting adjacent first linear portions 31 and second linear portions 34 at the base end or tip end portions. In addition, the stent 100 has a second distance L2, which is the circumferential distance between the longitudinal end of the second curved portion 35 connected to one end of the second linear portion 34 and the longitudinal end of the second curved portion 35 connected to the other end of the second linear portion 34, that is longer than the first distance L1, which is the circumferential distance between the longitudinal end of the first curved portion 32 connected to one end of any first linear portion 31 and the longitudinal end of the first curved portion 32 or the second curved portion 35 connected to the other end of the first linear portion 31, and there are four or more first linear portions 31 arranged within the wavy unit 33.

[0065] With this configuration, when the stent 100 is pressurized and crimped onto the balloon 220, the balloon 220 is less likely to protrude from the region between circumferentially adjacent first linear portions 31 and more likely to protrude from the region between circumferentially adjacent first linear portions 31 and second linear portions 34, stabilizing the stent retention force on the balloon 220. Furthermore, when the stent 100 is expanded to a large diameter, the shape of the annular body 10 becomes more wavy than that of a stent with fewer than four first linear portions 31, and local radial force is more uniform.

[0066] Furthermore, in the stent 100 according to this embodiment, the basic unit 36 ​​may have an even number of first linear portions 31 and one second linear portion 34.

[0067] With this configuration, the stent 100 has the second linear portions 34 in the circumferentially adjacent basic units 36 with respect to the longitudinal axis direction from the base end to the tip end opposite to each other (approximately V-shaped), and the design of the annular body 10 is point-symmetric. Therefore, even if, in one basic unit 36 ​​in the annular body 10, curved portions that are easy or difficult to open when radially expanded are concentrated on the base end side, and conversely, curved portions that are difficult to open or easy to open when radially expanded are concentrated on the tip end side, the annular body 10 does not have curved portions that are easy or difficult to open concentrated at one end, thereby improving expansion uniformity.

[0068] Furthermore, the stent 100 according to this embodiment may have four first linear portions 31.

[0069] With this configuration, the stent 100 satisfies the requirements of stabilizing the stent retention force and uniforming the local radial force, while reducing the outer diameter (profile) when contracted when mounted on the balloon 220, allowing it to be delivered smoothly to the lesion in the peripheral area.

[0070] In the stent 100 according to this embodiment, the line width of the first curved portion 32 may be smaller than the line width of the first linear portion 31 connected thereto.

[0071] With this configuration, the stent 100 has a smaller tensile stress acting on the inner bay side of the first curved portion 32 when a deformation that gives the same expansion diameter is applied to the first curved portion 32 than when the line width of the first curved portion 32 is the same as the line width of the first linear portion 31, thereby reducing the risk of stent fracture.

[0072] In the stent 100 according to this embodiment, the line width of the second curved portion 35 may be smaller than the line width of the first linear portion 31 and the second linear portion 34 connected thereto.

[0073] With this configuration, the stent 100 can reduce the risk of stent fracture because the tensile stress acting on the inner bay side of the second curved portion 35 when a deformation that gives the same expansion diameter is applied to the second curved portion 35 is smaller than when the line width of the second curved portion 35 is the same as the line widths of the first linear portion 31 and the second linear portion 34. Furthermore, the second curved portion 35 opens more easily during stent expansion than when the line width of the second curved portion 35 is the same as the line widths of the first linear portion 31 and the second linear portion 34, improving expansion uniformity.

[0074] In the stent 100 according to this embodiment, the second radius R1b, which is the radius of curvature of the second curved portion 35 on the inner bay side, may be larger than the first radius R1a, which is the radius of curvature of the first curved portion 32 on the inner bay side.

[0075] This configuration can reduce the risk of stent fracture in the stent 100. In addition, the second curved portion 35 opens more easily than the first curved portion 32, improving uniformity of expansion.

[0076] Furthermore, in the stent 100 of this embodiment, the radius of curvature on the inner bay side of the first curved portion 32c to which the link portion 20 is connected may be larger than the radius of curvature on the inner bay side of the first curved portions 32a, 32b to which the link portion 20 is not connected.

[0077] With this configuration, the first curved portions 32 of the stent 100 connected to the link portions 20 are easier to open than when the inner bay side curvature radius of each first curved portion 32 is the same, and the uniformity of expansion is also improved.

[0078] Furthermore, in the stent 100 of this embodiment, the first linear portion 31 has first linear portions 31b, 31c that are axis-parallel linear portions parallel to the longitudinal axis direction, the circumferential phases of each of the multiple annular bodies 10 are aligned, and the link portion 20 connects the first curved portion 32 that connects to the tip side of the axis-parallel linear portion of the annular body 10 arranged on the base end side and the first curved portion 32 that connects to the base end side of the axis-parallel linear portion of the annular body 10 arranged on the tip side adjacent to the annular body 10 arranged on the base end side, and before and after expansion of the stent 100, the section from the base end side of the axis-parallel linear portion of the annular body 10 on the base end side to the tip side of the axis-parallel linear portion of the annular body 10 on the tip end side may be parallel to the longitudinal axis direction via the link portion 20.

[0079] This configuration makes it possible to prevent shortening when the stent is expanded.

[0080] In addition, in the stent 100 of this embodiment, two link portions 20 are arranged in the gap D between adjacent annular bodies 10, facing each other in the radial direction of the annular bodies 10, and further, the phase of the link portion 20 arranged in one gap D may be shifted by 90° circumferentially from the phase of the link portion 20 arranged in another gap D adjacent to the one gap D in the longitudinal direction.

[0081] With this configuration, the stent 100 has a link portion 20 of an adjacent gap D located at the circumferential midpoint between two circumferentially adjacent link portions 20 provided in one gap D, and the circumferential positions at which the link portions 20 are located are distributed over the entire length of the stent, resulting in more uniform flexibility in the circumferential positions of the stent.

[0082] In addition, the stent delivery system 300 of this embodiment comprises any of the stents 100 described above and a balloon catheter 200 having an expandable and contractible balloon 220, and the stent 100 is held in close contact with the contracted balloon 220 in a contracted state, and the balloon 220 protrudes outward from the radial position of the inner surface of the stent 100 only at a position between the first linear portion 31 and the second linear portion 34.

[0083] With this configuration, the stent 100 has a more stable retention force against the balloon 220, allowing it to be delivered more reliably to the target lesion.

[0084] [Variations] The above-described embodiment can be modified as appropriate according to the environment of use, etc., as described below. The following modifications can also be combined in any manner without departing from the spirit of the present invention.

[0085] In the stent 100 of the present embodiment described above, the second linear portion 34 has a curved shape, but is not limited to this shape and may be linear. Also, the first linear portion 31 has a substantially linear shape, but is not limited to this shape and may be curved.

[0086] Furthermore, the stent 100 of this embodiment has a curved connecting portion 37 between the first linear portion 31 or the second linear portion 34 and the first curved portion 32 or the second curved portion 35, but the connecting portion 37 may also be linear. The first linear portion 31 or the second linear portion 34 and the first curved portion 32 or the second curved portion 35 may be connected without providing the connecting portion 37.

[0087] Furthermore, at least some of the curves on the inner bay side and / or outer bay side of the first curved portion 32, the second curved portion 35, and the link portion 20 may be formed so as to be a series of multiple circular arcs.

[0088] The line width of at least a portion of the first curved portions 32 or second curved portions 35 may be constant or may gradually decrease from one end to the other end or from the middle to the ends. Alternatively, the line width of at least a portion of the first linear portions 31 or second linear portions 34 may be constant or may gradually decrease from one end to the other end or from the middle to the ends. [Example]

[0089] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to the following examples.

[0090] [Evaluation Test 1] In Evaluation Test 1, stents were fabricated and the first distance L1 and second distance L2 were measured for each stent diameter when the stent diameter was varied. Stents were fabricated by preparing a drawing depicting the stent design and then cutting out the stent design from a CoCr alloy pipe with an outer diameter of 2 mm using a laser. The stent was then polished and heat-treated. The first distance L1 and second distance L2 were measured in this state before crimping. The stent was mounted on the balloon of a balloon catheter using the crimping method, and the first distance L1 and second distance L2 were measured. The balloon and stent were then inflated at 11 atm. The balloon was then depressurized and the balloon catheter was removed from the stent. The first distance L1 and second distance L2 were then measured. Another stent was fabricated in the same manner and mounted on the balloon in the same manner. The balloon and stent were then inflated at 16 atm. Thereafter, the balloon was decompressed and the balloon catheter was removed from the stent, after which the first distance L1 and the second distance L2 were measured. Note that when measuring the first distance L1 and the second distance L2 at each time point, the outer diameter of the stent was also measured.

[0091] The balloons used in this evaluation test 1 were 4.0 mm and 4.18 mm in diameter under pressures of 11 atm and 16 atm, respectively. The stent outer diameter, and the first distance L1 and second distance L2 at each stent outer diameter were measured using a digital microscope "VHX-5000 (manufactured by KEYENCE Corporation)" and measured as distances projected onto a plane. Note that the distance projected onto a plane and the distance along the circumferential direction have a geometrically unique conversion relationship, so regardless of which distance is selected for comparison, the magnitude relationship when comparing multiple distances will be the same.

[0092] The stent design dimensions prepared in the drawings are as follows. The drawings were created using computer-available drafting software, and the dimensions are the values ​​on the software. These dimensions are also the target values ​​for the dimensions after polishing when actually fabricating the stent, but the dimensions of the actual stent will deviate from the target values ​​due to manufacturing variations.

[0093] <Dimensions> Outer diameter: 2.00mm First distance L1a between the second curved portion 35a and the first curved portion 32a: 260 μm First distance L1b between the first curved portion 32a and the first curved portion 32b: 185 μm First distance L1c between the first curved portion 32b and the first curved portion 32c: 200 μm First distance L1d between the first curved portion 32c and the second curved portion 35b: 245 μm Second distance L2 between the second curved portion 35b and the second curved portion 35c: 680 μm Amplitude between the second curved portion 35a and the first curved portion 32a: 1065 μm Amplitude between the first curved portion 32a and the first curved portion 32b: 1065 μm Amplitude between the first curved portion 32b and the first curved portion 32c: 1080 μm Amplitude between the first curved portion 32c and the second curved portion 35b: 1030 μm Amplitude between the second curved portion 35b and the second curved portion 35c: 1030 μm Amplitude between the second curved portion 35a and the first curved portion 32c or the second curved portion 35c, which corresponds to the amplitude of the basic unit 36: 1080 μm Length of the link part 20 in the longitudinal direction: 230 μm Minimum line width of link 20: 183 μm Maximum line width of link 20: 290 μm Line width of the first linear portion 31 and the second linear portion 34: 120 μm Line width of the first curved portion 32 and the second curved portion 35: 95 μm The radius of curvature R1 on the inner bay side of the second curved portions 35a, 35b, and 35c: 70 μm The radius of curvature R2 on the inner bay side of the connecting portion 37 connected between the second curved portion 35a and the first linear portion 31a: 100 μm The radius of curvature R1 of the first curved portion 32a on the inner bay side: 50 μm The radius of curvature R2 on the inner bay side of the connecting portion 37 connected between the first curved portion 32a and the first linear portion 31a: 100 μm The radius of curvature R1 of the first curved portion 32b on the inner bay side: 50 μm The radius of curvature R2 on the inner bay side of the connecting portion 37 connected between the first curved portion 32b and the first linear portion 31b: 100 μm - Radius of curvature R1 of the first curved portion 32c on the inner bay side: 65 μm The radius of curvature R2 on the inner bay side of the connecting portion 37 connected between the first curved portion 32c and the first linear portion 31c: 100 μm Radius of curvature of outer edge of link part 20 R3: 400 μm Strut thickness: 85μm

[0094] [Table 1]

[0095] <Evaluation Results> The test results of evaluation test 1 are shown in Table 1. In Table 1, "Area A" refers to area A surrounded by a dashed line in Fig. 2, and "Area B" refers to area B surrounded by a dashed line in Fig. 2. In other words, areas A and B are areas including basic units 36 arranged at radially opposite positions in one annular body 10.

[0096] As shown in Table 1, the stent outer diameters before pressure crimping, after pressure crimping, after decompression after inflation of the balloon to 11 atm, and after decompression after inflation of the balloon to 16 atm were 1.95 mm, 1.21 mm, 3.96 mm, and 4.09 mm, respectively. Regardless of these stent outer diameters, the relationship between the first distance L1 (L1a to L1d) and the second distance L2 was L1. <L2であった。

[0097] In light of the above results, the following supplementary information is provided regarding the stent according to this embodiment. The stent according to this embodiment is characterized in that the second distance L2 is longer than the first distance L1, but this is not limited to a specific stent diameter. Therefore, the stent according to the claims of the present invention should not be interpreted as being limited to a specific stent diameter. A stent having a stent diameter in which the second distance L2 is longer than the first distance L1 is included in the stent according to the claims of the present invention. The first distance L1 and the second distance L2 are affected by the distribution of external forces applied during the diameter reduction and expansion operations. Because this distribution varies with each operation, the first distance L1 and the second distance L2 vary significantly in the stent diameter after each operation. Therefore, even in the stent according to the claims of the present invention, the first distance L1 may be longer than the second distance L2 within the range of variation. However, if the second distance L2 is longer than the first distance L1 at a certain stent diameter in the average value between individuals, such a stent may contribute to stabilizing the stent retention force, and therefore such a stent is also within the scope of the present invention.

[0098] [Evaluation Test 2] In evaluation test 2, stent designs (Examples 1 to 13 in Table 2) were created based on the stent design prepared in evaluation test 1, with the values ​​of R1 to R3 of the first curved portion 32, the second curved portion 35, and the link portion 20 appropriately changed. These designs were modeled on the FEM analysis application software "Abaqus (manufactured by Dassault Systems)," and the expansion limit diameter and expansion distance shown below were analyzed during stent expansion.

[0099] The "expansion limit diameter" is the diameter at which the maximum tensile strain reaches a predetermined value (0.6) when the stent model is expanded. In Examples 1 to 13, the fracture point of the CoCr alloy, which is the constituent material, is approximately 0.6, so this diameter value serves as a guide for the diameter at which the stent will fracture. The larger this diameter value, the more unlikely the stent is to fracture.

[0100] The "expansion distance" is the circumferential distance between the longitudinal end of the first curved portion 32b and the longitudinal end of the second curved portion 35b. From the perspective of expansion uniformity, if the circumferential distances between adjacent curved portions within the annular body are all equal when the stent is expanded, this means that the expansion state is uniform. If the number of curved portions within the annular body 10 is "10" and the stent inner diameter is 3.5 mm, the distance is calculated to be 1.10 mm. Therefore, in this case, the closer the expansion distance is to 1.10 mm, the higher the expansion uniformity.

[0101] The conditions used in this analysis are shown below. ·Material properties: The material has a correlation between true stress and true strain obtained through tensile testing of the raw material CoCr alloy. -Element properties: Elastic-plastic body. Element type: C3D8R+M3D4M, which is a 3D reduced integral element wrapped around a 3D reduced element, was used. Boundary conditions: A cylindrical part (A) with an inner diameter larger than the outer diameter of the stent was placed around the stent and contracted until the outer diameter of the stent was 1.2 mm. Part (A) was then removed, and a cylindrical part (B) with an outer diameter smaller than the inner diameter of the stent was placed inside the contracted stent and expanded until the inner diameter of the stent was 3.5 mm. The material properties of parts (A) and (B) were hyperelastic.

[0102] [Table 2]

[0103] <Evaluation Results> The test results of evaluation test 2 are as shown in Table 2 above. In Table 2, the "second curved portion" corresponds to all of second curved portions 35a, 35b, and 35c, the "first curved portion A" corresponds to first curved portion 32a, the "first curved portion B" corresponds to first curved portion 32b, and the "first curved portion C" corresponds to first curved portion 32c connected to link portion 20. In Table 2, the units of R1 to R3 are all "μm."

[0104] As shown in Table 2, in the stent 100 of Example 1, the radius of curvature R1 (first radius R1a) on the inward bay side of the first curved portion 32 and the radius of curvature R1 (second radius R1b) on the inward bay side of the second curved portion 35 are the same value. In the stent 100 of Example 2, the second radius R1b, which is the radius of curvature on the inward bay side of the second curved portion 35, is larger than the first radius R1a, which is the radius of curvature on the inward bay side of the first curved portion 32. Comparing the stent 100 of Example 1 with the stent 100 of Example 2, the expansion limit diameter of the stent 100 of Example 2 was larger. It is presumed that, in the stent 100 of Example 2, the second radius R1b is larger than the first radius R1a, which reduces stress concentration on the second curved portion 35 during stent expansion, resulting in a larger expansion limit diameter. Similar results can also be understood from a comparison between the stents of Examples 6 and 7. As described above, in the stent 100 according to this embodiment, the second radius R1b is larger than the first radius R1a, thereby reducing the risk of stent fracture.

[0105] As shown in Table 2, the radius of curvature R1 on the inward bay side of the first curved portion C of the stent 100 of Example 3 is smaller than the radius of curvature R1 on the inward bay side of the first curved portion C of the stent 100 of Example 4. The radius of curvature R1 on the inward bay side of the first curved portion C of the stent 100 of Example 4 is smaller than the radius of curvature R1 on the inward bay side of the first curved portion C of the stent 100 of Example 5. Comparing the stents 100 of Examples 3, 4, and 5, the expansion distance increased as the radius of curvature R1 on the inward bay side of the first curved portion C increased. Since the first curved portion C is connected to the link portion 20, it is more difficult to open than the other first curved portions A and B. However, it is presumed that the radius of curvature of the first curved portion C is larger than the radii of curvature of the first curved portion A and B, making it easier to open. As described above, in the stent 100 of this embodiment, the radius of curvature on the inner bay side of the first curved portion 32 to which the link portion 20 is connected is larger than the radius of curvature on the inner bay side of the first curved portion 32 to which the link portion 20 is not connected, so that the first curved portion 32 connected to the link portion 20 opens more easily than the first curved portion 32 not connected to the link portion 20, and the uniformity of expansion is also improved.

[0106] As shown in Table 2, the radius of curvature R2 on the inward bay side of the connecting portion 37 of the stent 100 of Example 1 is 100 μm, and the radius of curvature R2 on the inward bay side of the connecting portion 37 of the stent 100 of Example 6 is 300 μm. Furthermore, the radius of curvature R2 on the inward bay side of the connecting portion 37 of the stent 100 of Example 2 is 100 μm, and the radius of curvature R2 on the inward bay side of the connecting portion 37 of the stent 100 of Example 7 is 300 μm. When the stents 100 of Example 1 and Example 6, and the stents 100 of Example 2 and Example 7 were compared, there were no significant differences in the expansion limit diameter and expansion distance.

[0107] As shown in Table 2, the radius of curvature R3 of the outer edge of the link portion 20 of the stent 100 of Example 2 was 690 μm, and the radius of curvature R3 of the outer edge of the link portion 20 of the stent 100 of Example 3 was 400 μm. The radius of curvature R3 of the outer edge of the link portion 20 of the stent 100 of Example 7 was 690 μm, and the radius of curvature R3 of the outer edge of the link portion 20 of the stent 100 of Example 8 was 400 μm. The expansion distance of the stent 100 of Example 2 was slightly smaller than that of the stent 100 of Example 3, but the difference was not significant. The expansion distance of the stent 100 of Example 7 was slightly smaller than that of the stent 100 of Example 8, but the difference was not significant.

[0108] In the stent 100 of Example 9 and the stent 100 of Example 10, the radius of curvature R1 on the inner bay side of each curved portion is the same, but the radius of curvature R2 on the inner bay side of the connecting portion 37 connected to each curved portion is different. As a result of comparing the stent 100 of Example 9 and the stent 100 of Example 10, there was no significant difference in the expansion limit diameter and expansion distance.

[0109] The radius of curvature R1 on the inward bay side of the first curved portion C of the stent 100 of Example 11, the radius of curvature R1 on the inward bay side of the first curved portion C of the stent 100 of Example 12, and the radius of curvature R1 on the inward bay side of the first curved portion C of the stent 100 of Example 13 were all smaller than the radius of curvature R1 on the inward bay side of the first curved portions A and B. The stents 100 of Examples 11, 12, and 13 had shorter expansion distances than the stents 100 of the other Examples. The first curved portion C is connected to the link portion 20 and is therefore more difficult to open than the other first curved portions A and B. In addition, the radius of curvature of the first curved portion C being smaller than the radius of curvature of the first curved portion A and B makes the first curved portion C even more difficult to open, which is presumably why the expansion uniformity was reduced.

[0110] This application is based on Japanese Patent Application No. 2021-024885, filed on February 19, 2021, the disclosure of which is incorporated by reference in its entirety. [Explanation of symbols]

[0111] 10 cyclic bodies, 20 Link section, 31(31a~31d) 1st linear part, 32 (32a to 32c) first curved portion, 33 wavy units, 34 second linear part, 35 (35a to 35c) second curved portion, 36 basic units, 37 connection part, 100 stents, 200 balloon catheters, 220 balloons, 300 Stent Delivery System R1 Radius of curvature of the curved part (R1a First radius, R1b Second radius).

Claims

1. a plurality of annular bodies formed in an annular shape by linear elements folded back in a wave-like manner and arranged along a longitudinal axis direction of the cylindrical shape to form the cylindrical shape; a link portion connecting the adjacent annular bodies to each other, and the stent is expandable and contractible in the radial direction of the cylindrical shape, The annular body is a wavy unit formed of a plurality of first linear portions extending from a base end side to a tip end side in the longitudinal direction and continuously arranged in a circumferential direction of the cylindrical shape, and a first curved portion connecting end portions on the base end side or the tip end side of two first linear portions adjacent to each other in the circumferential direction; a second linear portion extending from a base end side to a tip end side in the longitudinal direction and disposed adjacent to the first linear portion in the circumferential direction; a plurality of basic units each formed of the first linear portion and a second curved portion connecting end portions of the base end side or the tip end side of the second linear portion adjacent to each other in the circumferential direction are arranged in the circumferential direction, and adjacent basic units are connected by the second curved portion, a second distance, which is a distance in the circumferential direction between the long-axis outermost end of the second curved portion connected to one end side end of the second linear portion and the long-axis outermost end of the second curved portion connected to the other end side end of the second linear portion, is longer than a first distance, which is a distance in the circumferential direction between the long-axis outermost end of the first curved portion connected to one end side end of any of the first linear portions and the long-axis outermost end of the first curved portion or the second curved portion connected to the other end side end of the first linear portion, the number of the first linear portions arranged in the wave-shaped unit is four or more, A stent, wherein the link portion is connected only to the first linear portion that constitutes the wavy unit.

2. The stent according to claim 1 , wherein the basic unit has an even number of first linear portions and one second linear portion.

3. The stent according to claim 2 , wherein the number of the first linear portions is four.

4. The stent according to any one of claims 1 to 3, wherein the line width of the first curved portion is smaller than the line width of the first linear portion connected thereto.

5. The stent according to claim 4 , wherein the second curved portion has a line width smaller than the line widths of the first linear portion and the second linear portion connected thereto.

6. The stent according to any one of claims 1 to 5, wherein a second radius, which is the radius of curvature on the inward side of the second curved portion, is larger than a first radius, which is the radius of curvature on the inward side of the first curved portion.

7. 7. The stent according to claim 6, wherein a radius of curvature on an inward side of the first curved portion to which the link portion is connected is larger than a radius of curvature on an inward side of the first curved portion to which the link portion is not connected.

8. the first linear portion has an axis-parallel linear portion parallel to the long axis direction, the axis-parallel linear portion is connected to the other first linear portion via the first curved portion on both sides in the circumferential direction, the annular bodies are arranged with their phases aligned in the circumferential direction, the link portion connects the first curved portion connected to a tip end side of the axis-parallel linear portion of the annular body arranged on the base end side, and the first curved portion connected to a base end side of the axis-parallel linear portion of the annular body arranged on the tip end side adjacent to the annular body arranged on the base end side, The stent according to any one of claims 1 to 7, wherein the link portion and the axis-parallel linear portions arranged on the base end side and the tip end side of the link portion are each parallel to the longitudinal axis direction from the base end side of the axis-parallel linear portion of the annular body on the base end side via the link portion to the tip end side of the axis-parallel linear portion of the annular body on the tip end side before and after expansion.

9. two link portions are arranged in a gap between adjacent annular bodies so as to face each other in a radial direction of the annular bodies, The stent according to any one of claims 1 to 8, further comprising a link portion arranged in one gap and a link portion arranged in another gap adjacent to the one gap in the longitudinal axis direction, the link portion being shifted in phase by 90° in the circumferential direction.

10. A stent according to any one of claims 1 to 9; a balloon catheter having an inflatable and deflatable balloon, A stent delivery system in which the stent is held in close contact with the deflated balloon in a contracted state, and the balloon protrudes outward from the radial position of the inner surface of the stent only at a position between the first linear portion and the second linear portion.

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