WO2022176826A1

WO2022176826A1 - Stent

Info

Publication number: WO2022176826A1
Application number: PCT/JP2022/005809
Authority: WO
Inventors: 智哉小松; 翔平海田
Original assignee: テルモ株式会社
Priority date: 2021-02-19
Filing date: 2022-02-15
Publication date: 2022-08-25

Abstract

[Problem] To provide a stent that, even with a reduced profile, affords a stable stent-retaining force with respect to a balloon due to the generation of a distinct difference in strut spacing in the circumferential direction. [Solution] A stent 100 is configured such that, in at least one of four basic units 30A, 30B, 30C, and 30D included in one annular body 10, an angle ratio (a/b), which is obtained by dividing a first angle (a) formed between a major oblique linear section 33 and a first minor oblique linear section 32a, or between the major oblique linear section 33 and a second minor oblique linear section 32b, by a second angle formed between an axial parallel linear section 31a and the first minor oblique linear section, or between the axial parallel linear section and the second minor oblique linear section, satisfies the relationship of 2.17-2.96, and a length ratio (t/s1 or t/s2), which is obtained by dividing a length (t) of the major oblique linear section by a length (s1) of the first minor oblique linear section or by a length (s2) of the second minor oblique linear section, satisfies the relationship of 1.24-1.51.

Description

stent

The present invention relates to stents.

In order to treat various diseases caused by stenosis or blockage of biological lumens such as blood vessels, stents are delivered to lesions in biological lumens by a stent delivery system and left in place. It is a medical device that expands lesions such as ulcers and secures the lumen. The stent is formed by linear components, struts, into a cylindrical body with gaps that can be radially expanded and contracted.

Stents are classified into balloon-expandable and self-expandable according to the expansion method. Among them, the balloon-expandable stent is attached to a balloon catheter in a crimped state, delivered to a target lesion, and left in a living body lumen. Stents must be prevented from falling out of the balloon during delivery. Therefore, the stent is crimped (pressure crimped) while inflating the balloon at a low pressure so that the balloon protrudes outside 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 the outer surface of the balloon to facilitate ejection of the balloon through the interstices of the struts.

The characteristics required for a stent include, for example, suppressing changes in the axial length of the stent before and after expansion, flexibly following the shape of the biological lumen, and achieving peripheral reach during delivery. For example, the outer diameter (profile) of the stent-mounted portion of the catheter is small. In the case of a balloon-expandable stent, in addition to the above characteristics, a high retention force between the stent and the balloon (stent retention force) is required so that the stent does not fall off the balloon during delivery.

However, the shape of wrinkles generated during pre-expansion of the balloon is random, and it is difficult to project the balloon from the desired position between the struts during pressure crimping. Since the protrusion of the balloon affects the stent retention force, there will be individual differences in the stent retention force when mass-producing stent delivery systems with crimped stents.

A stent disclosed in Patent Document 1 below has been proposed as a stent that can solve the problem of stent retention force as described above. In the stent of Patent Document 1 below, the struts forming the wavy annular body are not uniformly spaced in the circumferential direction. The interval between the inclined curved portion and the first inclined linear portion and the interval between the inclined curved portion and the second inclined linear portion are larger than the interval of .

As described above, in the stent of Patent Document 1, small gaps and large gaps are formed in the circumferential direction of the struts. In the gap where the strut spacing is small, the balloon is less likely to protrude, while in the gap where the strut spacing is large, the balloon tends to protrude. For this reason, the stent of Patent Document 1 has less variation in the number of gaps that cause balloon protrusion when mass-produced than a stent with uniform strut intervals in the circumferential direction, and the stent retention force is reduced. the difference becomes smaller. Therefore, the stent of Patent Document 1 can exhibit a stable stent holding force.

JP 2008-86463 A

As described above, a stent with a smaller profile is desired in order to improve peripheral reachability. deformation can occur. The stent of Patent Document 1 also has the same possibility.

One embodiment of the present invention has been made in view of the above-mentioned circumstances, and even if the profile is reduced, a clear difference in the circumferential spacing of the struts is generated, and the stent retention force to the balloon is stabilized. The purpose is to provide a stent.

The stent according to this embodiment is a stent formed in a cylindrical shape extending in the longitudinal direction, having a proximal end and a distal end, an axis-parallel linear portion extending parallel to the longitudinal direction, and a proximal end. A first slightly inclined linear portion having a tip end and extending obliquely with respect to the major axis direction, and a second small inclined linear portion having a base end and a tip end and extending obliquely with respect to the major axis direction. a large inclined linear portion having a proximal end and a distal end, extending obliquely with respect to the longitudinal direction and disposed between the first small inclined linear portion and the second small inclined linear portion; a first small curved portion connecting the distal end of the axis-parallel linear portion and the distal end of the first small inclined linear portion; a base end of the first small inclined linear portion and a proximal end of the large inclined linear portion; a second large curved portion connecting the distal end of the large inclined linear portion and the distal end of the second small inclined linear portion; and the proximal end of the second small inclined linear portion. are arranged in the circumferential direction around the longitudinal direction, and the second small curved portion in one of the basic units and the one of the A plurality of annular bodies formed by connecting a basic unit to the proximal end of the axially parallel linear portion in the other basic unit adjacent in the circumferential direction are arranged in the same phase in the longitudinal direction. The first small curved portion or the second small curved portion of one of the annular bodies, and the second small curved portion of the other annular body adjacent to the one annular body in the longitudinal direction, or At least one of the four basic units included in one annular body has at least one link portion connecting the first small curved portion and the large inclined linear portion and the first linear portion. A first angle formed between the small inclined linear portions or between the large inclined linear portion and the second small inclined linear portion is defined between the axis-parallel linear portion and the first small inclined linear portion. , or an angle ratio obtained by dividing the second angle between the axis-parallel linear portion and the second small-inclined linear portion satisfies a relationship of 2.17 or more and 2.96 or less, and the large-inclined linear portion The length ratio obtained by dividing the length of the portion by the length of the first small-slanted linear portion or the length of the second small-slanted linear portion satisfies the relationship of 1.24 or more and 1.51 or less.

According to one embodiment of the present invention, even if the profile is made small, a clear difference occurs in the spacing of the struts in the circumferential direction, making it possible to provide a stent that stabilizes the stent holding force with respect to the balloon.

1 is a schematic plan view of a stent delivery system according to this embodiment; FIG. FIG. 2 is a developed view obtained by linearly cutting a portion of the outer circumference of the stent according to the present embodiment along the long axis direction and developing the stent. It is a figure which expands and shows the broken line part A of FIG. FIG. 4 is an enlarged view of the dashed line portion B in FIG. 3, showing the basic unit of the stent according to the present embodiment. FIG. 2 is an enlarged schematic perspective view of a portion of the stent according to the present embodiment in a state crimped to a balloon; 6A is an orthogonal cross-sectional view of a portion of the stent in the direction indicated by arrows 6A-6A in FIG. 5; FIG.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. The embodiment shown here is an example for embodying the technical idea of the present invention, and does not limit the present invention. In addition, other practicable modes, embodiments, operation techniques, etc. that can be conceived by those skilled in the art without departing from the gist of the present invention are all included in the scope and gist of the present invention, and are described in the scope of claims. included within the scope of the claimed invention and its equivalents.

Furthermore, the drawings attached to this specification may be represented schematically by appropriately changing the scale, length-to-width ratio, shape, etc. from the actual thing for the convenience of illustration and ease of understanding. and does not limit the interpretation of the present invention.

In this specification, the longitudinal direction of the cylindrical stent 100 formed by struts, which are linear structural elements, is the longitudinal direction of the stent 100. In FIG. X) is simply referred to as the "longitudinal direction". In addition, the circumferential direction around the long axis of the stent 100 (annular body 10) shown in FIG. 2 (the direction perpendicular to the central axis X of the stent 100 indicated by the two-dot chain line in FIG. 2) is simply referred to as the "circumferential direction." , the radial direction of the stent 100 (annular body 10) is simply referred to as "radial direction". In addition, the side where the medical device is inserted into the living body is defined as the "distal side", and the side opposite to the distal side where the medical device is operated by the operator is defined as the "proximal side". The distal side is indicated by an arrow X1 in the drawing, and the proximal side is indicated by an arrow X2 in the drawing.

It should be noted that, in the following description, when describing with ordinal numbers such as "first" and "second", unless otherwise specified, it is used for convenience and does not prescribe any order.

The stent 100 according to this embodiment is used to treat constrictions and obstructions in blood vessels, bile ducts, trachea, esophagus, urethra, or other body lumens. The stent 100 is a so-called balloon-expandable stent that is attached to the balloon 220 in a crimped state, delivered to the lesion site, and then expanded and retained at the lesion site.

A stent delivery system 300 includes a stent 100 and a balloon catheter 200, as shown in FIG. The balloon catheter 200 is used to deliver the stent 100 in a contracted state to the lesion site, expand it and leave it in the lesion site.

The balloon catheter 200 includes an elongated catheter main body 210 , a balloon 220 provided at the distal end of the catheter main body 210 , and a hub 230 fixed to the proximal end of the catheter main body 210 .

The catheter main body 210 includes an outer tube and an inner tube arranged inside the outer tube.

An expansion lumen through which an expansion fluid for expanding the balloon 220 flows is formed inside the outer tube. The distal end of the outer tube is fixed to the proximal end of balloon 220 . The proximal end of the outer tube is fixed to hub 230 .

A guide wire lumen into which a guide wire is inserted is formed inside the inner tube. The distal end of the inner tube passes through the inside of the balloon 220 and is open on the distal side of the balloon 220 . The proximal end of the inner tube penetrates the side wall of the outer tube on the proximal side of the balloon 220 and is fixed to the outer tube.

The constituent material of the catheter main body 210 is preferably a material having a certain degree of flexibility, and examples thereof include polyethylene, polypropylene, polybutene, ethylene-propylene copolymer, ethylene-vinyl acetate copolymer, ionomer, or two of these. Examples include polyolefins such as mixtures of the above, thermoplastic resins such as polyvinyl chloride resins, polyamides, polyamide elastomers, polyesters, polyester elastomers, polyurethanes, fluororesins, silicone rubbers, and latex rubbers.

The balloon 220 is, for example, a member that expands the narrowed portion by expanding inside the narrowed portion. The distal end side of the balloon 220 is fixed to the outer wall surface of the inner tube. The proximal end side of the balloon 220 is fixed to the outer wall surface of the distal end portion of the outer tube. Therefore, the inside of the balloon 220 communicates with the expansion lumen formed in the outer tube. The balloon 220 is capable of receiving inflation fluid from the proximal opening 231 via the inflation lumen. The balloon 220 is expanded by the inflow of the expansion fluid, and is contracted and folded by discharging the expansion fluid.

The constituent material of the balloon 220 is preferably a flexible material that expands and contracts with the inflow and outflow of the expansion fluid. Examples include polyolefin, crosslinked polyolefin, polyester, polyester elastomer, polyvinyl chloride, polyurethane, polyurethane elastomer, Polymeric materials such as polyphenylene sulfide, polyamide, polyamide elastomer, fluororesin, silicone rubber, latex rubber, and the like. The constituent material of the balloon 220 is not limited to the form in which the above polymer material is used alone, and a film obtained by appropriately laminating the above polymer materials may be applied. Further, the expansion fluid may be gas or liquid, and examples thereof include gases such as helium gas, CO2 gas, and O2 gas, and liquids such as physiological saline and X-ray contrast medium.

The hub 230 has a proximal opening 231 that communicates with the expansion lumen of the outer tube. Proximal opening 231 functions as a port for inflow and outflow of dilation fluid.

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

Next, the stent 100 will be described with appropriate reference to FIGS. 2 to 6. FIG. 2-4 show stent 100 prior to being crimped to balloon 220, and FIGS. 5 and 6 show stent 100 crimped to balloon 220. FIG.

As shown in FIGS. 2 and 3, the stent 100 has a cylindrical shape in which a plurality of annular bodies 10 are arranged in the longitudinal direction. Each annular body 10 is arranged with the phases in the circumferential direction aligned (in the same phase).

The stent 100 has a plurality of

link portions

20A, 20B connecting annular bodies 10 adjacent in the longitudinal direction.

As shown in FIGS. 3 and 4, one annular body 10 includes four basic units 30 arranged in the circumferential direction. In the description of the specification, each basic unit 30 is called a first basic unit 30A, a second basic unit 30B, a third basic unit 30C, and a fourth basic unit 30D in order along the circumferential direction.

The four basic units 30 are composed of struts that are zigzag folded back along the circumferential direction.

As shown in FIG. 4, the basic unit 30 includes an axis-parallel linear portion 31a, a first small inclined linear portion 32a, a second small inclined linear portion 32b, a large inclined linear portion 33, and a first It has a small curved portion 34a, a first large curved portion 35a, a second large curved portion 35b, and a second small curved portion 34b. The detailed structure of the first basic unit 30A among the four basic units 30 will be described below as an example.

The axis-parallel line portion 31a has a proximal end and a distal end and extends parallel to the longitudinal direction.

The first small inclined linear portion 32a has a proximal end and a distal end, and extends obliquely with respect to the longitudinal direction.

The second small-slanted linear portion 32b has a base end and a tip, and extends obliquely with respect to the longitudinal direction.

The large inclined linear portion 33 has a base end and a distal end, and is arranged between the first small inclined linear portion 32a and the second small inclined linear portion 32b.

The first small curved portion 34a connects the tip of the axis-parallel linear portion 31a and the tip of the first small inclined linear portion 32a.

The first large curved portion 35a connects the base end of the first small slanted linear portion 32a and the base end of the large slanted linear portion 33 .

The second large curved portion 35b connects the tip of the large inclined linear portion 33 and the tip of the second small inclined linear portion 32b.

The second small curved portion 34b is connected to the proximal end of the second small inclined linear portion 32b. The second small curved portion 34b connects the base end of the second small inclined linear portion 32b to the base end of the axis-parallel linear portion 31b of the second basic unit 30B adjacent to the first basic unit 30A.

The second basic unit 30B and the third basic unit 30C, and the third basic unit 30C and the fourth basic unit 30D, which are adjacent to each other in the circumferential direction, each have a second small curved portion 34b and an axis-parallel linear portion 31a. , 31b (see FIG. 3).

As shown in FIG. 4, the tip of the first small inclined linear portion 32a is formed with a first bent portion 36a that protrudes toward the axis-parallel linear portion 31a in the first basic unit 30A. there is

The first bent portion 36a can be formed, for example, in a convex shape gently curved toward the axis-parallel linear portion 31a. The specific shape of the first bent portion 36a is not limited as long as it protrudes toward the axis-parallel linear portion 31a. For example, the first bent portion 36a may have a convex shape or a rectangular convex shape projecting at an acute angle toward the axis-parallel linear portion 31a.

As shown in FIG. 4, at the proximal end of the second small inclined linear portion 32b, a second basic unit 30B (another basic unit) adjacent to the first basic unit 30A (one basic unit) in the circumferential direction is provided. A second bent portion 36b is formed so as to protrude toward the axis-parallel linear portion 31b.

The second bent portion 36b can be formed, for example, in a convex shape gently curved toward the axis-parallel linear portion 31b. The specific shape of the second bent portion 36b is not particularly limited, similarly to the first bent portion 36a.

The stent 100 according to this embodiment has nine annular bodies 10, as shown in FIG. In the description of the specification, each of the nine annular bodies 10 includes a first annular body 10A, a second annular body 10B, a third annular body 10C, and a fourth annular body in order from the proximal side to the distal side in the longitudinal direction. 10D, fifth annular body 10E, sixth annular body 10F, seventh annular body 10G, eighth annular body 10H and ninth annular body 10I.

Two annular bodies 10 adjacent in the longitudinal direction are connected via two

link portions

20A and 20B.

As shown in FIG. 3, the first small curved portion 34a of the second basic unit 30B of the first annular body 10A (one annular body) and the first basic unit 30A of the second annular body 10B (other annular body) The second small curved portion 34b is connected via one link portion 20A.

Also, the first small curved portion 34a of the fourth basic unit 30D of the first annular body 10A and the second small curved portion 34b of the third basic unit 30C of the second annular body 10B are connected via another link portion 20B. is doing.

In this embodiment, the first annular body 10A and the second annular body 10B are connected by two

link portions

20A and 20B that face each other in the radial direction on an axis-perpendicular cross-section perpendicular to the longitudinal direction. In other words, the one link portion 20A and the other link portion 20B are arranged at an angle of 180 degrees in the circumferential direction on the axis-perpendicular cross-section of the stent 100 . The angular difference in the circumferential direction provided between the

link portions

20A and 20B is the same for the link portions other than the link portion connecting the first annular body 10A and the second annular body 10B.

As shown in FIG. 3, the first small curved portion 34a of the first basic unit 30A of the second annular body 10B and the second small curved portion 34b of the fourth basic unit 30D of the third annular body 10C form one link. It is connected via the part 20A.

Also, the first small curved portion 34a of the third basic unit 30C of the second annular body 10B and the second small curved portion 34b of the second basic unit 30B of the third annular body 10C are connected via another link portion 20B. Connected.

As shown in FIGS. 2 and 3, the

link portions

20A and 20B are circumferentially connected as the annular body 10 to be connected is displaced from the base end side to the tip end side along the long axis direction. Alternating 90 degrees in each direction. Therefore, the circumferential positions of the

link portions

20A and 20B connecting the first ring-shaped body 10A and the second ring-shaped body 10B are different from those of the

link portions

20A and 20B connecting the third ring-shaped body 10C and the fourth ring-shaped body 10D. It becomes substantially the same as the position in the circumferential direction. On the other hand, the circumferential positions of the

link portions

20A and 20B connecting the second annular body 10B and the third annular body 10C are the same as those of the

link portions

20A and 20B connecting the fourth annular body 10D and the fifth annular body 10E. is substantially the same as the position in the circumferential direction of

In the stent 100, since the

link portions

20A and 20B are arranged as described above, as shown in FIG. In the annular body 10, the axis-parallel

linear portions

31a and 31b of the four

basic units

30A, 30B, 30C, and 30D arranged in the circumferential direction are connected to adjacent other annular bodies 10. As shown in FIG. On the other hand, the annular bodies 10A and 10I located at both ends in the long axis direction have axis-parallel

linear portions

31a and 31b that are not connected to other annular bodies 10 adjacent in the long axis direction. For example, as shown in FIG. 3, in the first annular body 10A, the axis-parallel line portion 31a of the first basic unit 30A and the axis-parallel line portion 31a of the third basic unit 30C are adjacent to each other in the longitudinal direction. It is not connected with the annular body 10B.

When the stent 100 is crimped to the balloon 220, the first gap g1 formed between the axis-parallel linear portion 31a and the first small inclined linear portion 32a, the large inclined linear portion 33 and the first gap g1 are formed. It has a second gap g2 formed between it and the one small inclined linear portion 32a.

As a measure of the sizes of the first gap g1 and the second gap g2, the angle range (θ1) and the angle range (θ1) and Angular range (θ2) is used. θ1 is defined on the axis-perpendicular cross-section at the base end position of the axis-parallel linear portion 31a shown in FIG. shall be defined.

When the stent outer diameter is 1 mm, the angle range (θ1) of the first gap g1 is more preferably, for example, 2° or more and 7° or less.

When the stent outer diameter is 1 mm, the angle range (θ2) of the second gap g2 is more preferably 15° or more and 30° or less, for example.

In the stent 100, as shown in FIGS. 5 and 6, the second small inclined linear portion 32b of the first basic unit 30A and the axis of the second basic unit 30B adjacent to the first basic unit 30A in the circumferential direction A gap g1 is also formed between it and the parallel linear portion 31b. This gap g1 has substantially the same circumferential interval (size) as the gap g1 formed between the axis-parallel linear portion 31a and the first small inclined linear portion 32a of the first basic unit 30A.

Similarly, in the stent 100, as shown in FIGS. 5 and 6, a gap g2 is also formed between the large inclined linear portion 33 and the second small inclined linear portion 32b of the first basic unit 30A. . This gap g2 has substantially the same circumferential interval (size) as the gap g2 formed between the large inclined linear portion 33 and the first small inclined linear portion 32a of the first basic unit 30A.

Materials forming each part of the stent 100 (annular body 10,

link parts

20A and 20B, basic unit 30) include, for example, stainless steel, cobalt-based alloys such as chromium alloys (eg, CoCrWNi alloys), platinum-chromium alloys ( metal materials such as PtFeCrNi alloy), nickel-titanium alloys, and raw materials such as polylactic acid, polyglycolic acid, lactic acid-glycolic acid copolymer, polycaprolactone, lactic acid-caprolactone copolymer, glycolic acid-caprolactone copolymer. Examples include degradable polymeric materials.

The stent 100 can be manufactured, for example, by irradiating a tubular member (hollow pipe member) made of the above material with a laser to form a desired stent design. In addition, for example, the stent 100 may be manufactured by a method such as etching, and the manufacturing method is not limited to the method using a laser.

The outer surface of the stent 100 may be provided with a coating containing a drug. Of the outer surfaces of the stent 100, the covering is preferably formed on the outer surface facing the inner peripheral surface of the biological lumen, but is not limited to this. The covering may contain a drug capable of suppressing neointimal proliferation and a drug carrier for carrying the drug. The covering may be composed only of the drug. The drug contained in the coating is, for example, at least one selected from the group consisting of sirolimus, everolimus, zotarolimus, paclitaxel, and the like. The constituent material of the drug carrier is not particularly limited, but biodegradable materials are preferred.

Next, an example of dimensions of each part of the basic unit 30 will be described with reference to FIG. Below, the 1st basic unit 30A of the 2nd annular body 10B is made into an example, and is demonstrated. In the stent 100, the angle ratio (a/b) and length ratio (t/s1 and t/s2) described below are applied to at least one basic unit 30 included in the annular body 10. As long as this is the case, the effects of the present invention, which will be described later, can be suitably exhibited.

The first angle (a), the second angle (b), etc. are parameters that change depending on the outer diameter of the stent. Each dimension example described below is the value at the outer diameter before the stent 100 is crimped to the balloon 220 (outer diameter of the tubular member from which the stent 100 is based), here the value at the stent outer diameter of 2 mm. . The outer diameter can be obtained from information described in pharmaceutical application documents and the like.

<Regarding the angle ratio (a/b)>
In the stent 100, the first angle (a) is the angle formed between the large inclined linear portion 33 and the first small inclined linear portion 32a or between the large inclined linear portion 33 and the second small inclined linear portion 32b. defined as Hereinafter, this angle is simply referred to as "first angle (a)".

The first angle (a) is defined by an imaginary straight line H1 connecting the innermost curved point p1 of the first small curved portion 34a and the outermost curved point p2 of the first large curved portion 35a, and the outermost curved portion of the first large curved portion 35a. The angle formed by the imaginary straight line H2 connecting the point p2 and the outermost bending point p3 of the second large bending portion 35b, or the innermost bending point p4 of the second small bending portion 34b and the outermost bending point p3 of the second large bending portion 35b can be defined by an angle formed by a virtual straight line H3 and a virtual straight line H2 connecting

In the stent 100, the second angle (b) is the angle formed between the axis-parallel linear portion 31a and the first small-slanted linear portion 32a or between the axial-parallel linear portion 31b and the second small-slanted linear portion 32b. defined as Hereinafter, this angle is simply referred to as "second angle (b)".

The second angle (b) can be defined by the angle formed by the axis-parallel linear portion 31a and the virtual straight line H1, or by the angle formed by the axial-parallel linear portion 31b and the virtual straight line H3. Since the axis-parallel

linear portions

31a and 31b are parallel to the central axis X, either the axis-parallel linear portion 31a or the axis-parallel linear portion 31b is used when defining the second angle (b). good too.

In the first basic unit 30A of the stent 100, with the geometric center position O in plan view shown in FIG. And each of the large

curved portions

35a and 35b has a symmetrical shape. Therefore, the first angle formed between the large inclined linear portion 33 and the first small inclined linear portion 32a and the first angle formed between the large inclined linear portion 33 and the second small inclined linear portion 32b are approximately The second angle formed between the axis-parallel linear portion 31a and the first small inclined linear portion 32a and the second angle formed between the axial-parallel linear portion 31b and the second small inclined linear portion 32b are the same. are also substantially the same. Further, the length (s1) of the first small-slanted linear portion 32a and the length (s2) of the second small-slanted linear portion 32b, which will be described later, are also substantially the same.

The stent 100 can be formed such that the angle ratio (a/b) obtained by dividing the first angle (a) by the second angle (b) is 2.17 or more and 2.96 or less. More preferably, the stent 100 is formed with an angular ratio (a/b) of 2.37 or more and 2.62 or less.

For example, the first angle (a) is preferably 60.10° or more and 62.74° or less, more preferably 61.08° or more and 61.97° or less.

For example, the second angle (b) is preferably 20.30° or more and 28.94° or less, more preferably 23.28° or more and 26.16° or less.

<Length ratio (t/s1 and t/s2)>
In the stent 100, the length (t) of the large inclined linear portion 33 is divided by the length (s1) of the first small inclined linear portion 32a or the length (s2) of the second small inclined linear portion 32b. The length ratio (t/s1 or t/s2) can be 1.24 or more and 1.51 or less. More preferably, the stent 100 is formed with a length ratio (t/s1 or t/s2) of 1.33 or more and 1.42 or less.

The length (t) of the highly inclined linear portion 33 can be defined by the length of the imaginary straight line H2. Also, the length (s1) of the first small inclined linear portion 32a can be defined by the length of the imaginary straight line H1. Also, the length (s2) of the second small slope linear portion 32b can be defined by the length of the imaginary straight line H3.

The length (t) of the large inclined linear portion 33 is, for example, preferably 0.995 mm or more and 1.313 mm or less, more preferably 1.064 mm or more and 1.234 mm or less.

The length (s1) of the first small inclined linear portion 32a and the length (s2) of the second small inclined linear portion 32b are, for example, 0.800 mm or more and 0.870 mm or less (measured value in the embodiment: 0 .832 mm only) is preferable, and 0.810 mm or more and 0.850 mm or less is more preferable.

<Other dimension examples>
In the stent 100, the length (L) of one link portion 20A (or the other link portion 20B) is the length (s1) of the first small inclined linear portion 32a or the length of the second small inclined linear portion 32b. The link length ratio (L/s1 or L/s2) divided by the length (s2) can be 0.35 or more and 0.44 or less. More preferably, the stent 100 is formed with a link length ratio (L/s1 or L/s2) of 0.35 or more and 0.38 or less.

The extending direction of the link portion 20A is the direction from the innermost curved point p1 of the first small curved portion 34a to the innermost curved point p4 of the second small curved portion 34b. A circular arc inscribed in the edge line of the second small inclination linear portion 32b side of the first small inclination linear portion 32a and the edge line of the large inclination linear portion 33 side of the first small inclination linear portion 32a, and the first small inclination linear portion 31b of the axis-parallel linear portion 31b. It is defined as an arc inscribed in the edge line of the inclined linear portion 32a and the edge line of the second small inclined linear portion 32b on the large inclined linear portion 33 side. The length L of the link portion 20A is defined as the distance parallel to the longitudinal direction from one end to the other end in the extending direction of the link portion 20A, as shown in FIG.

The length of the link portion 20A is, for example, preferably 0.20 mm or more and 0.35 mm or less (measured value in the example: only 0.295 mm is described), and more preferably 0.22 mm or more and 0.30 mm or less.

The first bent portion 36a formed at the tip of the first small inclined linear portion 32a can be formed, for example, at a position 0.1825 mm away from the innermost bending point p1 of the first small curved portion 34a. The distance between the first bent portion 36a and the innermost curved point p1 is the length of the longitudinal direction between the position of the first bent portion 36a that protrudes most toward the axis-parallel linear portion 31a and the innermost curved point p1. can be defined by length.

The second bent portion 36b formed at the proximal end of the second small inclined linear portion 32b can be formed, for example, at a position 0.1825 mm away from the innermost bending point p4 of the second small curved portion 34b. The distance between the second bent portion 36b and the innermost curved point p4 is the length of the longitudinal direction between the position of the second bent portion 36b that protrudes most toward the axis-parallel linear portion 31b and the innermost curved point p4. can be defined by length.

The length (total length) along the longitudinal direction of the stent 100 can be set to, for example, 3.9 mm to 51.6 mm.

The profile of the stent 100 crimped to the balloon 220 can be, for example, 0.80 mm to 1.26 mm when the outer diameter of the tubular member forming the stent 100 is 2.0 mm. More preferably, stent 100 has a profile of 1.0 mm.

[Effect]
In the stent 100, as described above, the angle ratio (a/b) is 2.17 or more and 2.96 or less, and the length ratio (t/s1 or t/s2) is 1.24 or more and 1.51 or less. It is Therefore, the following effects are obtained.

Since the relationship in which the first gap g1 is smaller than the second gap g2 is maintained even when the stent 100 is reduced in diameter by a large amount, when the stent 100 is press-crimped to the balloon 220, the first gap g1 The balloon 220 is less likely to protrude from the second gap g2, and the balloon 220 is more likely to protrude from the second gap g2. Therefore, when the stent delivery system 300 is mass-produced, even if the profile is small, variations in the number of gaps in the stent 100 at which the balloon 220 protrudes are reduced, and the stent retention force is stabilized.

In the stent 100, the first loop 10A (one loop) and the second loop 10B (the other loop) are perpendicular to the longitudinal direction within the gap between the

respective loops

10A, 10B. They are connected by two

link portions

20A and 20B that face each other in the radial direction on a cross section perpendicular to the axis (see FIG. 2). In addition, the circumferential phase of the

link portions

20A and 20B arranged in one gap and the circumferential direction phase of the

link portions

20A and 20B arranged in another gap adjacent in the longitudinal direction are out of phase by 90°. .

With such a configuration, the positions in the circumferential direction where the

link portions

20A and 20B are placed are distributed over the entire length of the stent 100, and the flexibility of the stent 100 at the circumferential positions is made uniform. The relationship that the first gap g1 is smaller than the second gap g2 is maintained even when the diameter reduction amount of the stent 100 is large.

In the stent 100, a first bent portion 36a is formed at the distal end of the first small inclined linear portion 32a so as to protrude toward the axis-parallel linear portion 31a in the first basic unit 30A. A second bent portion 36b is formed at the proximal end of the second small inclined linear portion 32b so as to protrude toward the axis-parallel linear portion 31b in the second basic unit 30B.

With such a configuration, the concave portion of the first small curved portion 34a located near the distal end of the first small inclined linear portion 32a and the inner curved portion located near the proximal end of the second small inclined linear portion 32b. Since the arc length of the inner curved portion of the second small curved portion 34b is longer, stress concentration in these portions is reduced, and the risk of stent fracture occurring in the first small curved portion 34a and the second small curved portion 34b is reduced. be.

In the stent 100, the link length obtained by dividing the length (L) of the

link portions

20A and 20B by the length (s1) of the first small inclined linear portion 32a or the length (s2) of the second small inclined linear portion 32b The thickness ratio (L/s1 or L/s2) is 0.35 or more and 0.44 or less.

With such a configuration, even if the diameter of the stent 100 is reduced, the first large curved portion 35a of one annular body 10 (for example, the second annular body 10B) and other adjacent annular bodies 10 It is possible to prevent the contact of the first small curved portion 34a of the annular body (eg, the first annular body 10A) (see FIG. 5). As a result, the risk of the balloon 220 being excessively sandwiched between the first large curved portion 35a of one annular body 10 and the first small curved portion 34a of the other annular body 10 to cause pinholes in the balloon 220 is reduced. be done.

In the stent 100, in all annular bodies 10, the angle ratio (a/b) between the

basic units

30A and 30C in one annular body 10 and the

basic units

30B and 30D in another adjacent annular body 10 is 2.17. 2.96 or less, and the length ratio (t/s1 or t/s2) is 1.24 or more and 1.51 or less. The circumferential positions of the

basic units

30A and 30C in one annular body 10 are shifted by 90° from the circumferential positions of the

basic units

30B and 30D in the other adjacent annular body 10 .

By adopting such a configuration, the variation in the number of gaps in the stent 100 at which the balloon 220 protrudes is further reduced, and the stent retention force is stabilized.

In the stent 100, all the

basic units

30A, 30B, 30C, and 30D have an angle ratio (a/b) of 2.17 or more and 2.96 or less, and a length ratio (t/s1 or t/s2) of 1.5. 24 or more and 1.51 or less.

By adopting such a configuration, the variation in the number of gaps in the stent 100 at which the balloon 220 protrudes further decreases among individuals, and the stent retention force is stabilized.

Note that the larger the length ratio (t/s1 or t/s2), the greater the amount of change in the outer diameter of the stent per unit angle of the first angle (a) and/or the second angle (b). Larger limit diameter. The length ratio (t/s1 or t/s2) of the stent 100 according to the present embodiment is 1.24 or more and 1.51 or less. s2) is preferably large.

The present invention will be specifically described below with reference to examples, but the scope of the present invention is not limited to the following examples.

[Evaluation test]
In the evaluation test, FEM analysis application software "Abaqus (manufactured by Dassault Systems)" was used to model the stent 100 with an outer diameter of 2 mm, and after simulating the diameter reduction behavior until the outer diameter became 1 mm, the center of the stent 100 In the angular range with respect to the axis X, the angular range (θ1) of the first gap g1 and the angular range (θ2) of the second gap g2 were analyzed. θ1 is measured on the axis-perpendicular cross-section at the base end position of the axis-parallel linear portion 31a shown in FIG. It was measured.

The conditions used in conducting this analysis are shown below.
- Material properties: A material having a correlation between true stress and true strain obtained by a tensile test of a CoCr alloy as a raw material was used.
・Element properties: Elastoplastic.
- Size of the element: The height of the strut divided into four in the thickness direction, and the width and length of the strut in the line width direction and the extension direction of the same size.
- Element type: C3D8R+M3D4M, which is a three-dimensional reduction integral element wrapped with a three-dimensional reduction element, is used.
• Boundary conditions: A cylindrical part with an inner diameter greater than the outer diameter of the stent was placed around the stent and the part was contracted until the stent outer diameter was 1 mm. The material properties of the parts were superelastic properties.

In carrying out this analysis, a total of seven stents 100 of Examples 1-5 and Comparative Examples 1-2 were modeled. Angle ratio (a/b), length ratio (t/s1 or t/s2), link length ratio (L/s1 or L/s2), angle ratio (θ1/θ2), and related dimensions are shown. 1. Among these, the angle range (θ1) of the first gap g1 and the angle range (θ2) of the second gap g2 are the values after diameter reduction, and the other ratios and dimensions are the values before diameter reduction. Table 2 shows other dimensions before diameter reduction common between Examples 1-5 and Comparative Examples 1-2. In all annular bodies 10, two

basic units

30A, 30C or

basic units

30B, 30D in the annular body 10 have dimensions shown in Tables 1 and 2. The circumferential positions of the basic units to which the dimensions shown in Tables 1 and 2 are applied are shifted by 90° between one annular body 10 and another adjacent annular body 10 .

In Table 2 above, *1 means the following. The minimum line width of the link portion and the maximum line width of the link portion are the minimum and maximum values in the line width direction within the range in the extending direction of the link portion. The line width direction of the link portion is a direction perpendicular to the extending direction of the link portion.

In Table 2 above, *2 means the following. The position of the bent portion is the length in the longitudinal direction between the position where the first bent portion 36a protrudes most toward the axis-parallel linear portion 31a and the innermost bending point p1 of the first small curved portion 34a, or the second It is defined as the length in the longitudinal direction between the position of the bending portion 36b that protrudes most toward the axially parallel linear portion 31b and the innermost bending point p4 of the second small curved portion 34b.

[Evaluation results]
In Comparative Example 2, θ1 was 9.5°. It is presumed that this is because the angle ratio (a/b) is less than 2.17, and thus the second angle (b) is difficult to decrease. When the diameter of the stent 100 is reduced, the axis-parallel

linear portions

31a, 31b and the slightly inclined

linear portions

32a, 32b are arranged in opposite directions in the tangential direction of the circumference of the cross section of the stent (synonymous with the cross section orthogonal to the axis). receive an external force. At this time, if the second angle (b) is large, that is, if the angle of the small slant

linear portions

32a and 32b with respect to the central axis X is large, the external force received by the small slant

linear portions

32a and 32b will be The contribution in the line width direction when decomposed into the extending direction of 32b and the line width direction is reduced. Since the external force in the line width direction component promotes the decrease of the second angle (b), the first angle (a) is relatively large with respect to the second angle (b), that is, the angle ratio (a/b) is The smaller the value, the less likely the second angle (b) will decrease. Therefore, in Comparative Example 2, θ1 is assumed to be a relatively large value of 9.5°. At this value of θ1, the balloon 220 can protrude from the first gap g1. This suggests that forming the angle ratio (a/b) at 2.17 or more as shown in Example 5 promotes the reduction of the second angle (b) at an early stage when diameter reduction is started. be.

In Comparative Example 1, θ1 was 3.1° and θ2 was 5.2°. This is because the angle ratio (a/b) is greater than 2.96, so the second angle (b) tends to decrease, and the length ratio (t/s1 or t/s2) is greater than 1.51, so the first It is presumed that this is because the angle (a) tends to decrease. In Comparative Example 1, since the angle ratio (a/b) is large, the second angle (b) decreases at an early stage when the diameter reduction of the stent 100 is started. It is presumed that the

portions

32a and 32b are in contact with each other. When the axis-parallel

linear portions

31a, 31b and the small-slanted

linear portions

32a, 32b abut against each other, the axial-parallel

linear portions

31a, 31b absorb the external force in the tangential direction of the circumference of the cross section of the stent, which is caused by the diameter reduction, into the small-slanted linear portions. It is received from the side of the large

curved portions

35a, 35b of the

portions

32a, 32b. As a result, the axis-parallel

linear portions

31 a and 31 b receive a moment in a direction parallel to the extending direction of the large inclined linear portion 33 . The

link portions

20A and 20B connected to the axis-

parallel portions

31a and 31b have the effect of supporting the axis-

parallel portions

31a and 31b so that they do not rotate on the outer peripheral surface of the stent 100. The axial parallel

linear portions

31a and 31b that are not connected to the

link portions

20A and 20B rotate more easily than the axial parallel

linear portions

31a and 31b that are connected to the

link portions

20A and 20B. In Comparative Example 1, the length ratio (t/s1 or t/s2) is large, but this moment increases as the length of the large inclined linear portion 33 increases. The parallel

linear portions

31a and 31b become easier to rotate. Then, when the axis-parallel

linear portions

31a and 31b rotate, the small inclined

linear portions

32a and 32b also rotate in conjunction with the rotation, and it is presumed that the first angle (a) decreases. Therefore, in Comparative Example 1, θ2 is assumed to be a relatively small value of 5.2°. At this value of θ2, the balloon 220 can protrude from the second gap g2. This suggests that the length ratio (t/s1 or t/s2) of 1.51 or less as shown in Example 4 can prevent the first angle (a) from decreasing.

The stents 100 of Examples 1 to 5 are formed with an angle ratio (a/b) of 2.17 or more and 2.96 or less, and a length ratio (t/s1 or t/s2) of 1.24. 1.51 or less. In the stents 100 of Examples 1 to 5, a clear difference was confirmed between the circumferential spacing of the first gap g1 and the circumferential spacing of the second gap g2 after diameter reduction. Specifically, in the stents 100 of Examples 1 to 5, the angle range (θ1) of the first gap g1 is 2.5° to 5.2°, and the angle range (θ2) of the second gap g2 is 2.5° to 5.2°. was 18.0° to 27.7°. In the stents 100 of Examples 1 to 5, the angle range (θ2) of the second gap g2 is formed sufficiently larger than the angle range (θ1) of the first gap g1. The balloon 220 is less likely to protrude from the second gap g2, and the balloon 220 is more likely to protrude from the second gap g2. Therefore, when the stent delivery system 300 is mass-produced using the stent 100, the number of inter-individual variability in the number of gaps in which balloon protrusion occurs in the stent is reduced, and the stent retention force is stabilized.

Further, in the stents 100 of Examples 1 to 5, contact between the first large curved portion 35a of the second annular body 10B and the first small curved portion 34a of the first annular body 10A was not confirmed after the diameter was reduced. Thus, the angle ratio (a/b) is 2.17 or more and 2.96 or less, and the length ratio (t/s1 or t/s2) is 1.24 or more and 1.51 or less. In the formed stent 100, when the link length ratio (L/s1 or L/s2) is 0.35 or more, the first large curved portion 35a and the first small curved portion of the adjacent annular body 10 It was confirmed that the abutment of 34a could be suitably prevented, and the risk of pinhole occurrence could be reduced.

This application is based on Japanese Patent Application No. 2021-024888 filed on February 19, 2021, the disclosure of which is incorporated by reference in its entirety.

10 toroids,
10A first annular body,
10B second annular body,
10C third annular body,
10D fourth annular body,
10E fifth annular body,
10F sixth annular body,
10G 7th annulus,
10H eighth annular body,
10I ninth annulus,
20A one link part (link part),
20B another link part (link part),
30 basic units,
30A first basic unit,
30B second basic unit,
30C third basic unit,
30D fourth basic unit,
31a axis-parallel linear portion,
31b axis-parallel linear portion,
32a first small inclined linear portion,
32b second small inclined linear portion,
33 large inclined linear part,
34a first small curved portion,
34b second small curved portion,
35a first large curved portion,
35b second large curved portion,
36a first bent portion,
36b second bend,
100 stents,
200 balloon catheter,
220 balloon,
300 stent delivery system,
g1 first gap;
g2 second gap,
a first angle,
b second angle,
t the length of the linear portion with a large inclination;
s1 length of the first small inclined linear portion,
s2 the length of the second small inclined linear portion;
θ1 angle range of the first gap,
θ2 angle range of the second gap;
Length of L link part.

Claims

A longitudinally extending cylindrically shaped stent comprising:
an axis-parallel linear portion having a proximal end and a distal end and extending parallel to the longitudinal direction;
a first slightly inclined linear portion having a proximal end and a distal end and extending obliquely with respect to the longitudinal direction;
a second slightly inclined linear portion having a proximal end and a distal end and extending obliquely with respect to the longitudinal direction;
a large inclined linear portion having a proximal end and a distal end, extending obliquely with respect to the longitudinal direction, and disposed between the first small inclined linear portion and the second small inclined linear portion;
a first small curved portion connecting the tip of the axis-parallel linear portion and the tip of the first small inclined linear portion;
a first large curved portion connecting the base end of the first small slope linear portion and the base end of the large slope linear portion;
a second large curved portion connecting the tip of the large inclination linear portion and the tip of the second small inclination linear portion;
and a second small curved portion connected to the base end of the second small inclined linear portion, four basic units are arranged in a circumferential direction around the longitudinal direction,
By connecting the second small curved portion in one of the basic units to the base end of the axis-parallel linear portion in the other basic unit adjacent to the one basic unit in the circumferential direction A plurality of annular bodies to be formed are arranged in the same phase in the longitudinal direction,
The first small curved portion or the second small curved portion of the one annular body, and the second small curved portion or the first small curved portion of the other annular body adjacent to the one annular body in the longitudinal direction. Having at least one or more link portions connecting the small curved portion,
In at least one of the four basic units contained in one annular body,
A first angle formed between the large inclined linear portion and the first small inclined linear portion or between the large inclined linear portion and the second small inclined linear portion is defined as the axis-parallel linear portion. A relationship in which an angle ratio divided by a second angle formed between the first small-slanted linear portions or between the axis-parallel linear portion and the second small-slanted linear portion is 2.17 or more and 2.96 or less. and
The length ratio obtained by dividing the length of the large inclined linear portion by the length of the first small inclined linear portion or the length of the second small inclined linear portion is 1.24 or more and 1.51 or less. A stent, characterized in that it satisfies a relationship.
The link portions are arranged at two positions facing each other in the radial direction on an axis-perpendicular cross-section perpendicular to the longitudinal direction within the gap between the annular bodies adjacent in the longitudinal direction. ,
The circumferential phase of each of the link portions arranged in one of the gaps, and the circumferential direction of each of the link portions arranged in the other gap adjacent to the one gap in the longitudinal direction. are 90 degrees out of phase.
A first bent portion having a shape projecting toward the axis-parallel linear portion in the one basic unit is formed at the tip of the first small inclined linear portion,
2. The base end of the second slightly inclined linear portion is formed with a second bent portion projecting toward the axis-parallel linear portion in the other basic unit. 3. The stent of claim 2.
Claims 1 to 3, wherein a link portion length ratio obtained by dividing the length of the link portion by the length of the first small-slanted linear portion or the length of the second small-slanted linear portion is 0.35 or more. The stent according to any one of Claims 1 to 3.
The four basic units are out of phase with each other in the circumferential direction by 90°,
in the two basic units in the one annular body that face each other in the radial direction and in the other annular body that is adjacent to the one annular body in the longitudinal direction, In the two basic units whose phases are 90° out of phase with the circumferential phases of the two basic units in the one annular body,
The angle ratio satisfies the relationship of 2.17 or more and 2.96 or less, and
The stent according to any one of claims 1 to 4, wherein the length ratio satisfies the relationship of 1.24 or more and 1.51 or less.
Within all said basic units,
The angle ratio satisfies the relationship of 2.17 or more and 2.96 or less, and
6. The stent according to claim 5, wherein the length ratio satisfies the relationship of 1.24 or more and 1.51 or less.