WO2016103941A1

WO2016103941A1 - Method for producing stent

Info

Publication number: WO2016103941A1
Application number: PCT/JP2015/081655
Authority: WO
Inventors: 洋平松崎
Original assignee: テルモ株式会社
Priority date: 2014-12-24
Filing date: 2015-11-10
Publication date: 2016-06-30
Also published as: JP2018027105A

Abstract

[Problem] To provide a method for producing a stent in which recoil is reduced. [Solution] A method for producing a stent 10 provided with a stent base 30 configured by forming struts 41 on a base material 20, the stent being expanded in diameter and deformed by only expansion of an expansion member (balloon 91) that has traveled to a target site within the body while the stent is in contact with the expansion member, wherein the method has a formation step S110 for processing a base material to form a stent base having a cylindrical shape as the overall outer shape, and a diameter expansion step S140 for expanding the diameter of the stent base after the forming step and before the stent base is held on the expansion member.

Description

Stent manufacturing method

The present invention relates to a method for manufacturing a stent.

A stent is a medical device used to expand a stenosis or occlusion site and secure a lumen in order to treat various diseases caused by stenosis or occlusion of a lumen such as a blood vessel. As examples of stents conventionally used, those manufactured by processing a cylindrical metal tube and those manufactured by molding or the like using a polymer material as a main component are known. Stents are classified into balloon expandable stents (see Patent Document 1 below) and self-expandable stents depending on the function and placement method.

バルーン Balloon expandable stents do not have an expansion function. For this reason, when using a balloon expandable stent, the stent is crimped (reduced diameter) and mounted on the outer surface of the balloon in a deflated state, and the stent is delivered to the target site together with the balloon. Work to expand the diameter of the stent by expanding from the inside. The expanded stent is brought into close contact with the inner surface of the lumen and pushes the lumen. Thereafter, the stent is placed over a predetermined period with the lumen expanded to a certain size.

JP 2014-1111157 A

As described above, the balloon expandable stent is held on the balloon in a state where the diameter has been once reduced after manufacture, and is expanded by expanding the balloon after being introduced into the living body. At this time, if the expanded balloon is reduced in diameter and removed, recoil, which is a phenomenon in which the elastic deformation of the expanded and deformed stent returns to the original size and is reduced again, may occur. When this recoil becomes prominent (when the recoil rate is high), the radial force acting on the inner surface of the lumen from the stent is reduced, so that it is difficult to stably place the stent at a desired position. Become.

In the production of a conventional balloon expandable stent, a material having a relatively small diameter is used for the base material constituting the stent in order to improve the yield of the material when the strut is processed. For this reason, the outer diameter of the expanded stent, that is, the outer diameter of the stent when placed in the lumen, depends on the target lumen, but is generally larger than the outer diameter of the substrate. Set to large dimensions. When the outer diameter of the expanded stent is set to be larger than the outer diameter of the base material, a contraction force (reducing force) that restores the outer diameter of the base material to the expanded stent is obtained. Works. For this reason, the conventional balloon expandable stent undergoes a reduced diameter deformation at a relatively large recoil rate.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a method for manufacturing a stent with a reduced recoil rate.

A stent manufacturing method according to the present invention that achieves the above object includes a stent base formed by forming struts on a base material, and is transferred to a target site in a living body in contact with the expansion member. A method of manufacturing a stent that is expanded and deformed only by expansion, wherein the base material is processed to form the stent base body having an overall outer shape of a cylindrical shape, and after the forming step And a diameter expanding step for expanding the diameter of the stent base before being held by the expansion member.

According to the stent manufacturing method of the present invention, a forming step of forming a stent base having struts and having an overall outer shape of a cylindrical shape, and after the forming step and before being held by the expansion member (balloon) The diameter of the stent base is increased, and the plastic deformation is generated with a relatively low stress compared to the case where the diameter of the stent base is not expanded before being held by the expansion member. be able to. Therefore, the stent can relatively reduce the return of elastic deformation at the time of unloading, and can reduce the recoil rate.

It is a flowchart which shows the manufacturing method of a stent. It is a schematic diagram which shows the formation process which processes a base material and forms a stent base | substrate. It is a schematic diagram which shows the chemical polishing process which performs a chemical polishing to a stent base | substrate following a formation process. It is a schematic diagram which shows the electrolytic polishing process of performing electrolytic polishing to a stent base | substrate following a chemical polishing process. It is a schematic diagram which shows the diameter expansion process which expands the diameter of a stent base | substrate following an electropolishing process. It is a schematic diagram which shows the heating process which heats a stent base | substrate following a diameter expansion process. It is a schematic diagram which shows the connection process which connects the adjacent struts of a stent base | substrate following a heating process. It is a schematic diagram which shows the chemical | medical agent application process which applies a chemical | medical agent to a stent base | substrate and forms a stent following a connection process. It is a schematic diagram which shows the crimping process which crimps a stent to a balloon following a chemical | medical agent application process. It is a figure which shows the stent which concerns on embodiment, Comprising: (A) is an expanded view of a stent, (B) is a figure which expands and shows the part shown with the broken-line part 10B in FIG. 10 (A). 1A and 1B are diagrams showing a stent according to an embodiment, in which FIG. 1A is a schematic perspective view of the stent, and FIG. 1B is an axial orthogonal sectional view taken along line 11B-11B shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, the following description does not limit the meaning of the technical scope and terms described in the claims. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may differ from actual ratios.

FIG. 1 is a flowchart showing overall steps of a method for manufacturing a stent according to the embodiment, and FIGS. 2 to 9 are diagrams for explaining each step of the manufacturing method according to the embodiment. FIG. 1 is a view showing a stent according to an embodiment. In the description of the specification, the longitudinal direction of the stent (the left-right direction in FIG. 10A) is referred to as the axial direction.

As shown in FIG. 10, the stent 10 according to the present embodiment includes a stent base 30 on which coil-shaped struts (linear constituent elements) 41 that are integrally connected are formed, and as a whole, the stent 10 is predetermined in the axial direction. (See FIG. 11). The stent 10 is placed in a lumen (eg, blood vessel, bile duct, trachea, esophagus, other gastrointestinal tract, urethra, etc.) in a living body, and treats a stenosis or occlusion site by expanding the lumen lumen. Used for illustration. The stent 10 is a so-called balloon expandable stent (balloon expandable stent) in which the diameter of the stent is expanded and indwelled by a balloon (corresponding to an “expansion member”) 91 provided in the balloon catheter.

Next, a method for manufacturing the stent 10 will be described with reference to FIGS.

Referring to FIG. 1, the method for manufacturing the stent 10 will be outlined. FIG. 1 is a flowchart showing a method for manufacturing the stent 10.

In the formation step S110, the base material 20 is processed to form the stent substrate 30. Next, in the chemical polishing step S120, the stent substrate 30 is chemically polished. Next, in the electrolytic polishing step S130, the stent base 30 is subjected to electrolytic polishing. Next, in the diameter expanding step S140, the diameter of the stent substrate 30 is expanded (expanded). Next, in the heating step S150, the stent substrate 30 is heated. Next, in the connection step S160, adjacent struts 41 of the stent base 30 are connected. Next, in the medicine application step S <b> 170, the medicine is applied to the stent substrate 30 to form the stent 10. Next, in the crimping step S180, the stent 10 is crimped to the balloon 91.

The formation step S110 will be described with reference to FIG. FIG. 2 is a schematic view showing a forming step S110 for forming the stent base 30 by processing the base material 20. As shown in FIG.

In the forming step S110, the thin cylindrical substrate 20 is subjected to laser processing to form the stent base body 30 having the struts 41 and having an overall outer shape of a cylindrical shape. The forming step S110 may be performed by mechanical polishing, electric discharge machining, chemical etching, or the like.

The outer diameter of the base material 20 to be processed in the forming step S110 is the outer diameter of the stent substrate 30 in the axial orthogonal cross section when the diameter is increased by a pressure lower than the recommended expansion pressure by the diameter expansion device 142 in the diameter expansion step S140 described later. Use one that is less than the diameter. As a constituent material of the base material 20, a known material that can constitute a balloon expandable stent can be appropriately selected. For example, a metal other than a superelastic alloy used for a self-expandable stent is used. can do. "Metal other than superelastic alloy" here refers to JIS Z 2241, when a tensile test was performed in which a tensile stress was applied and unloaded until the total elongation reached 3% in a temperature environment of 35 ° C. , Can be defined as a metal having a permanent elongation of 2% or more. As an example of such a metal, stainless steel, a cobalt-based alloy such as a cobalt-chromium alloy (for example, CoCrWNi alloy), or a platinum-chromium alloy (for example, PtFeCrNi alloy), which is a non-biodegradable metal material, can be used. .

Here, FIG. 2A shows a state before the base material 20 is subjected to laser processing, and FIG. 2B shows a state in the middle of forming the stent substrate 30 by applying laser processing to the base material 20. ing. The support member 111 inserts the base material 20 in the horizontal direction with respect to the rotating portion 111a and supports the base member 20 in a rotatable manner. The laser oscillator 112 is disposed above the base material 20 so as to be movable along the axial direction of the long base material 20.

The base material 20 is rotated along the circumferential direction by the rotating portion 111a of the support member 111, and is penetrated from the outer peripheral surface toward the inner peripheral surface by the laser light L1 derived from the laser oscillator 112 moving in the axial direction. A plurality of struts 41 are formed. The outer peripheral surface of the base material 20 is linearly irradiated with the laser light L1 while regularly changing the irradiation position. Accordingly, the plurality of struts 41 are spirally connected along the L1 axis direction and configured in a coil shape. For example, a YAG laser or an excimer laser is used as the light source of the laser oscillator 112, but it is arbitrarily selected according to the material of the substrate 20. The details of the struts 41 formed in the forming step S110 will be described later (see FIGS. 10A and 10B).

The chemical polishing step S120 will be described with reference to FIG. FIG. 3 is a schematic view showing a chemical polishing step S120 for chemically polishing the stent substrate 30 subsequent to the forming step S110.

In the chemical polishing step S120, the struts 41 of the stent substrate 30 formed in the forming step S110 are dissolved and polished. The stent substrate 30 is immersed in the chemical polishing liquid 122 filled in the container 121, and the surface of the strut 41 is dissolved by a chemical reaction of the chemical polishing liquid. The struts 41 have the surface burrs peeled off by the chemical polishing liquid 122, the cross section is changed from a rectangular shape to a circular shape, and the surface irregularities are reduced. Therefore, when the strut 41 is expanded radially outward in the post-expansion step S140, it can be prevented from cracking or breaking.

In addition, impurities such as spatter attached to the surface of the strut 41 are removed by the chemical polishing liquid 122 by the laser oscillator 112 used in the formation step S110. When the strut 41 is immersed in the chemical polishing liquid 122, it can be uniformly polished without unevenness in the degree of polishing. The chemical polishing liquid 122 is arbitrarily selected according to the material of the substrate 20.

The electrolytic polishing step S130 will be described with reference to FIG. FIG. 4 is a schematic diagram showing an electrolytic polishing step S130 in which the stent base 30 is subjected to electrolytic polishing following the chemical polishing step S120.

In the electrolytic polishing step S130, the struts 41 of the stent substrate 30 already polished in the chemical polishing step S120 are further dissolved and polished. The stent substrate 30 inserted on the outer peripheral surface of the electrode rod 133 is immersed in the electropolishing liquid 132 filled in the container 131. The electrode rod 133 corresponds to an electrode on the anode side. The container 131 is made of metal and functions as a cathode-side electrode. The electrode bar 133 is attached with an anode-side wiring 135 connected to the power supply device 134. A cathode-side wiring 136 connected to the power supply device 134 is connected to the outer peripheral edge of the container 131. When the strut 41 is energized between the electrode bar 133 and the container 131 by the power supply device 134, the surface dissolves and the minute irregularities are eliminated, so that it is difficult for foreign matter to adhere.

Furthermore, since the strut 41 is formed with a strong passive film on the surface when energized, the corrosion resistance is improved. Therefore, the strut 41 on which the passive film is formed can be prevented from cracking or breaking when it is expanded radially outward in the subsequent diameter expansion step S140. When the strut 41 is immersed in the electrolytic polishing liquid 132, it can be uniformly polished without unevenness in the degree of polishing. The electropolishing liquid 132 is arbitrarily selected according to the material of the substrate 20.

The diameter expansion step S140 will be described with reference to FIG. FIG. 5 is a schematic diagram showing a diameter expansion step S140 for expanding the diameter of the stent base body 30 following the electrolytic polishing step S130.

In the diameter expanding step S140, the diameter of the stent substrate 30 is expanded after the stent substrate 30 is formed at least by the forming step S110 and before the stent 10 is held by the balloon 91 by the crimping step S180. The diameter expansion step S140 is desirably performed after the unevenness on the surface of the strut 41 is sufficiently reduced by at least the chemical polishing step S120 in order to avoid cracks and fractures when the stent substrate 30 is expanded in diameter.

A diameter-enlarging device 142 through which the stent base 30 is inserted is attached to the discharge portion 141a of the compressor 141 that discharges compressed air. The diameter expanding device 142 is constituted by a balloon that can be expanded and contracted. The diameter expanding device 142 has a total length along the axial direction longer than the total length of the stent base 30 and an outer diameter slightly smaller than the inner diameter of the stent base 30. When compressed air is introduced from the compressor 141 to the diameter expanding device 142 and the diameter expanding device 142 is expanded radially outward, the stent base 30 is expanded radially outward.

The pressure at the time of expanding the diameter of the stent substrate 30 is, for example, 9 atm, which is about the same as or slightly lower than the recommended expansion pressure (Nominal Pressure) of the stent 10 that is expanded by the balloon 91 in a state of being introduced into the living body. It is set. For example, the stent base 30 is expanded in the range of 80% to 120% of the outer diameter when the balloon 91 is expanded at the recommended expansion pressure. After the diameter of the stent substrate 30 is sufficiently expanded, air is discharged from the diameter expansion device 142 to reduce the diameter expansion device 142 and the stent substrate 30 is removed from the diameter expansion device 142. Here, the case where the pressure when expanding the diameter of the stent base 30 is set to 9 atm has been described. However, the present invention is not limited to this, and there is no particular limitation as long as the balloon is finally expanded to the diameter at the recommended expansion pressure. . Further, the expansion at this time may not be performed with a balloon, and the pressure may not be the recommended expansion pressure.

If the diameter of the stent substrate 30 is once expanded in the manufacturing process of the stent 10, the recoil rate when the diameter of the stent 10 is expanded in vivo can be reduced. That is, after the stent substrate 30 is once expanded in the diameter expanding step S140, the diameter of the stent substrate 30 is reduced in the crimping step S180, which will be described later. Occurs at a relatively low stress. Therefore, the stent 10 can relatively reduce the return of elastic deformation at the time of unloading, and can reduce the recoil rate.

The heating step S150 will be described with reference to FIG. FIG. 6 is a schematic diagram showing a heating step S150 for heating the stent base 30 subsequent to the diameter expansion step S140.

In the heating step S150, the stent base 30 expanded in the diameter expansion step S140 is heated. Here, the heating step S150 is in a state in which the diameter expanded by the diameter expansion step S140 is maintained, or is slightly reduced by recoil after the diameter expansion step S140 but before being expanded by the diameter expansion step S140. The stent base 30 is heated in a state where the diameter is larger than the diameter.

The holding member 151 holds the stent base 30 inserted in the holding shaft 151a along the horizontal direction. The holding shaft 151 a has a total length along the axial direction that is longer than the total length of the stent base 30 and an outer diameter that is slightly smaller than the inner diameter of the stent base 30. The heater 152 is disposed adjacent to the holding shaft 151 a and heats the stent base 30. The heat shielding box 153 is openable and closable, and houses the holding member 151 and the heater 152. The heat shield box 153 is opened, the holding member 151 is taken out from the inside, the stent base 30 is attached, and after returning to the heat shield box 153, the heat shield box 153 is closed. After the heating of the stent base 30 is completed, the holding member 151 holding the stent base 30 is taken out, and the stent base 30 is recovered.

Here, for example, the stent base 30 is heated at a temperature equal to or higher than 1/3 of the melting point of the material. Desirably, the stent substrate 30 is heated at a temperature that is at least half the melting point of the material. The heating time is, for example, about 1 to 10 minutes. In the heating step S150, the residual strain is removed by heating the stent substrate 30, and the energy of defects such as vacancies and dislocations in the stent substrate 30 in the state of the diameter at the time of heating is stabilized. The recoil rate when the diameter is increased can be greatly reduced. In the heating step S150, the heated stent substrate 30 is rapidly cooled, for example.

The connection step S160 will be described with reference to FIG. FIG. 7 is a schematic diagram showing a connection step S160 for connecting adjacent struts 41 of the stent base body 30 subsequent to the heating step S150.

In connection process S160, the connection part 60 which connects the some strut 41 adjacent in the axial direction of the stent base | substrate 30 mutually is formed. The connection part 60 reduces the connection force which connects the struts 41 after progress in a predetermined period in the state which detained the stent 10 in the living body. Here, in the connecting step S160, FIG. 7A shows a state in which the stent base 30 is subjected to laser processing in advance, and FIG. 7B shows a state in which the connecting portion 60 is formed on the stent base 30.

In the connection step S160, as shown in FIG. 7A, the support member 161 rotatably supports the stent base 30 by inserting the stent base 30 along the horizontal axis 161a. The laser oscillator 162 is disposed above the stent substrate 30 so as to be movable along the axial direction of the long stent substrate 30. Before forming the connection portion 60, the laser oscillator 162 forms a hook-like connection structure portion 61 (see FIG. 10B) that connects adjacent struts 41 to each other. Thereafter, spatter generated by laser irradiation is removed by cleaning.

Further, in the connecting step S160, as shown in FIG. 7B, the coating device 163 is disposed above the stent base 30 and movably along the axial direction of the long stent base 30. Yes. The stent base 30 is rotated in the circumferential direction by the rotation shaft 161a of the support member 161 and is connected to the connecting member 71 made of a biodegradable material discharged from the coating device 163 moving in the axial direction (FIG. 10B). Is applied to the connection portions 60 of the plurality of struts 41, and the connection members 71 are interposed in the connection portions 60. The coating device 163 continuously applies the connection member 71 to the plurality of struts 41 connected in a coil shape. The details of the connection unit 60 will be described later (see FIG. 10B).

The connection member 71 is formed of a biodegradable material such as a biodegradable polymer material or a biodegradable metal material. Examples of biodegradable polymer materials include polylactic acid, polyglycolic acid, lactic acid-glycolic acid copolymer, polycaprolactone, lactic acid-caprolactone copolymer, glycolic acid-caprolactone copolymer, and poly-γ-glutamic acid. It is preferable to use a biodegradable synthetic polymer material or a biodegradable natural polymer material such as cellulose or collagen. Moreover, as a biodegradable metal material, it is preferable to use magnesium, zinc, etc., for example.

The drug application step S170 will be described with reference to FIG. FIG. 8 is a schematic diagram showing a drug application step S170 in which a drug is applied to the stent substrate 30 to form the stent 10 following the connection step S160.

In the drug application step S170, for example, a drug that prevents intimal thickening due to migration or proliferation of vascular smooth muscle cells, which is a main cause of restenosis, is applied to the outer peripheral surface of the strut 41 of the stent base 30. The drug applied to the stent substrate 30 is once dried and fixed, and then continues to elute from the stent substrate 30 in the blood vessel to prevent restenosis of the blood vessel. In the drug application step S170, an antithrombotic drug may be applied to the stent substrate 30.

The support member 171 is rotatably supported by inserting the stent base body 30 along the horizontal direction on the rotation shaft 171a. The drug application device 172 is disposed above the stent substrate 30 and is movable along the axial direction of the long stent substrate 30. The stent base 30 is rotated along the circumferential direction by the rotation shaft 171 a of the support member 171, and the medicine discharged from the medicine application device 172 moving in the axial direction is applied to the plurality of struts 41. The drug application device 172 continuously applies the drug to the plurality of struts 41 connected in a coil shape.

The drug can be arbitrarily selected according to the material of the base material 20. For example, the drugs include anticancer agents, immunosuppressive agents, antibiotics, anti-rheumatic agents, antithrombotic agents, HMG-CoA reductase inhibitors, insulin resistance improving agents, ACE inhibitors, calcium antagonists, antihyperlipidemic agents Drugs, integrin inhibitors, antiallergic agents, antioxidants, GP IIb / IIIa antagonists, retinoids, flavonoids, carotenoids, lipid improvers, DNA synthesis inhibitors, tyrosine kinase inhibitors, antiplatelet drugs, anti-inflammatory drugs, Biological materials, interferons, and nitric oxide production promoters can be used.

The crimping process S180 will be described with reference to FIG. FIG. 9 is a schematic diagram showing a crimping step S180 for crimping the stent 10 to the balloon 91 of the balloon catheter following the drug application step S170.

In the crimping step S180, the stent 10 is held on the outer peripheral surface of the balloon 91 provided on the distal end side of the shaft member 92 while reducing the diameter. The crimp device 181 includes a plurality of bars 181a provided in an arc shape. The distal ends of the plurality of bars 181a are opened outward in the radial direction, and the balloon 91 into which the stent 10 is inserted is inserted into the openings. Thereafter, the stent 10 is compressed radially inward and reduced in diameter while closing the distal ends of the plurality of bars 181a squeezed radially inward. After the diameter of the stent 10 is reduced, the distal ends of the plurality of bars 181a are opened outward in the radial direction, and the balloon 91 crimped with the stent 10 is taken out. In addition, as a balloon catheter for delivering the stent 10 in the living body, for example, a known balloon catheter such as a rapid exchange type or an over-the-wire type can be used.

Next, the stent 10 manufactured by the manufacturing method described above will be described.

As shown in FIGS. 10 and 11, the stent 10 includes a stent base body 30 on which coil-shaped struts (linear components) 41 that are integrally connected are formed, and as a whole, the stent 10 has a predetermined length in the axial direction. It is formed with a substantially cylindrical outer shape having a thickness.

As shown in FIG. 10A, the strut 41 extends in a spiral shape around the axial direction (circumferential direction) of the stent substrate 30 while being folded back in a wave shape in the axial direction (longitudinal direction) of the stent substrate 30. And a plurality of spiral portions 43 and endless

annular portions

51 and 52 disposed at both axial end portions of the stent substrate 30.

The spiral portion 43 and the

annular portions

51 and 52 are integrally formed with the stent base 30 so as to constitute a part of the stent base 30. The adjacent spiral portions 43 are connected to each other through the connection portion 60. Each

annular part

51, 52 is connected to an adjacent spiral part 43 via a link part 53. The link portion 53 is integrally formed with the stent base 30 together with the spiral portion 43 and the

annular portions

51 and 52.

As shown in FIG. 10B, the spiral portion 43 provided in the strut 41 includes a pair of

linear portions

45a and 45b extending at a predetermined angle with respect to the axial direction of the stent base 30 and a pair of A curved portion (folded portion) 48 provided between the

linear portions

45a and 45b is formed. The

straight portions

45a and 45b and the curved portion 48 are formed so as to repeat over a predetermined length, thereby forming one spiral portion 43. The spiral portion 43 is the axis of the stent substrate 30. By providing a plurality in series in the direction, the entire stent 10 forms one spiral. In addition, the number of the helical parts 43, the number of the curved parts 48, etc. are not specifically limited.

As shown in FIG. 10B, the connection portion 60 has a connection structure portion 61 formed integrally with the spiral portion 43 of the strut 41, and a connection member 71 made of a biodegradable material. is doing.

The connection structure portion 61 is formed by adding a predetermined shape to a pair of

spiral portions

43a and 43b arranged adjacent to each other so as to face each other in the axial direction. In the illustrated example, the first engaging portion 63 formed in one adjacent spiral portion (hereinafter referred to as “first spiral portion”) 43a and the other spiral portion (hereinafter referred to as “second spiral shape”). The connection structure part 61 is comprised by the 2nd engaging part 66 formed in 43b. The first engaging portion 63 and the second engaging portion 66 have a function of mechanically connecting the

spiral portions

43a and 43b by engaging (hooking) with each other.

The first engaging portion 63 is formed by projecting from the curved portion 48 to the second spiral portion 43b side, and by forming a recess between the first projecting portion 63a and the curved portion 48 in a concave shape. 1st accommodating part 63b. The second engaging portion 66 has a second protruding portion 66a formed to protrude from the curved portion 48 toward the first spiral portion 43a, and a recess between the second protruding portion 66a and the curved portion 48. And the formed second accommodating portion 66b.

The first protrusion 63a included in the first engagement portion 63 is formed with a curved tip, and the second storage portion 66b included in the second engagement portion 66 stores the first protrusion 63a. It is made possible. The second protrusion 66a included in the second engagement portion 66 is formed with a curved tip, and the first storage portion 63b included in the first engagement portion 63 stores the second protrusion 66a. It is made possible. When the first protruding portion 63a is accommodated in the second accommodating portion 66b and the second protruding portion 66a is accommodated in the first accommodating portion 63b, the first engaging portion 63 and the second engaging portion 66 are interposed. The adjacent first spiral portion 43a and second spiral portion 43b are connected.

The

protrusions

63a and 66a can be arranged so as to form a gap g between the

accommodating parts

63b and 66b, and are arranged so as to partially contact the

accommodating parts

63b and 66b. Is also possible. Further, as shown in the drawing, the engaging

portions

63 and 66 can be arranged so that a part or all of them overlap each other in a region along the circumferential direction or the axial direction of the stent 10. By arranging in this way, the engagement between the engaging

portions

63 and 66 can be strengthened, and the connection state of the first engaging portion 63 and the second engaging portion 66 can be stably maintained. It becomes possible. Further, as shown in the drawing, the

protrusions

63a and 66a can be arranged so as to face each other in a direction inclined with respect to the axial direction. When arranged in this way, when a tensile force in a direction to be separated from the first spiral portion 43a and the second spiral portion 43b is applied along the axial direction, for example, between the

protrusions

63a and 66a. The distance is reduced, and the

protrusions

63a and 66a come into contact with each other. Thereby, since the catch between the 1st engaging part 63 and the 2nd engaging part 66 becomes firm, it becomes possible to maintain the connection state of

spiral part

43a, 43b more reliably.

The connection member 71 is provided so as to cover the surface of the connection structure 61 and to be filled between the

protrusions

63a and 66a and the

storage portions

63b and 66b. In addition, it forms so that a recessed part may be formed on the surface of each

engaging part

63 and 66, and the through-hole penetrated in both front and back may be filled with the connection member 71 in these recessed part and through-hole. It is also possible to do. By configuring in this way, it becomes possible to improve the adhesion (adhesive force) of the connection member 71 to the connection structure portion 61.

The stent 10 according to the present embodiment is provided with a spiral portion 43, thereby providing flexibility. For this reason, the followability to the deformation of the lumen is improved. In addition, since the connection member 71 made of a biodegradable material having relatively strong physical properties is provided at a portion where the spiral portions 43 are connected to each other, an appropriate rigidity can be imparted to the stent base 30, and the lumen It is possible to increase the expansion holding force when the stent 10 is indwelled in the lumen while ensuring high followability to the deformation. Furthermore, when the indwelling connection member 71 is disassembled after a lapse of a predetermined period and the connection force of the connection portion 60 is weakened, the flexibility of the stent 10 is further increased, and the followability to the deformation of the lumen is further improved. Increased further. For this reason, in the initial stage of the indwelling period, a desired expansion holding force is exhibited, and after a predetermined period of time has elapsed after the indwelling, it exhibits high flexibility. The stent 10 is excellent. In addition, the

annular portions

51 and 52 provided at both ends of the stent base body 30 maintain a predetermined expansion holding force regardless of the disassembly of the connection member 71. Therefore, even after the connection member 71 is disassembled, a sufficient expansion holding force can be applied to the lumen from both ends of the stent base 30, so that the displacement of the stent 10 after placement is caused. It can prevent suitably.

It is preferable that one or more connecting portions 60 are provided for each spiral portion (one unit spiral portion in the circumferential direction) 43, but the number of installations is not particularly limited. Moreover, the structure of the connection part 60 and the form of the connection structure part 61 and the connection member 71 with which the connection part 60 is provided are not limited to the structure mentioned above, and can be changed suitably. For example, the shapes of the engaging

portions

63 and 66 included in the connection structure portion 61 can be changed as long as mechanical connection is possible, and the connection force changes without the connection member 71 interposed. It is also possible to configure the connection unit 60 as described above. As an example of such a form, a weak part that is easier to break than other parts is formed in a part of the connection structure part 61, and after a predetermined period of time has passed in place, the weak part is broken. Thus, it is possible to employ a structure in which the connection structure portion 61 can swing (movable).

Here, the Example which measured the recoil rate of the stent 10 which concerns on embodiment is demonstrated.

First, a conventional stent that is not subjected to special treatment as a comparative example has a diameter reduced by 6.4% when the balloon 91 is removed after the diameter has been expanded using the balloon 91. On the other hand, when the stent 10 is subjected to a process of expanding once in the state of the stent base 30 in the diameter expanding step S140, the diameter of the stent 10 is 6 even if the balloon 91 is extracted after being expanded using the balloon 91. Only 2% reduction and recoil could be reduced. Furthermore, in addition to the diameter expansion step S140, the stent 10 is subjected to a process of heating the expanded stent base 30 in the heating step S150. Even when 91 was removed, the diameter remained at a reduction of 4.5%, and the recoil could be greatly reduced.

As mentioned above, according to the manufacturing method of the stent 10 which concerns on this embodiment, after forming process S110 and forming process S110 which form the stent base | substrate 30 which has the strut 41 and the external shape exhibits a cylindrical shape as a whole, it is an expansion member. With the configuration including the diameter expanding step S140 for expanding the diameter of the stent base body 30 before being held by the (balloon 91), plastic deformation when the diameter is expanded can be generated with relatively low stress. Therefore, the stent 10 can relatively reduce the return of elastic deformation at the time of unloading, and can reduce the recoil rate.

Further, the structure including the heating step S150 that heats the stent base body 30 that has been expanded in the diameter expansion step S140 eliminates residual strain, such as vacancies and dislocations in the stent base body 30 in the diameter state at the time of heating. Since the energy of the defect is stabilized, the recoil rate when the diameter is expanded in the living body can be greatly reduced.

Further, after the diameter expansion step S140, a connection step S160 is formed in which the connection portions are connected to each other in the axial direction of the stent base 30 and the connection force decreases after a predetermined period of time in a state where the stent 10 is left in the living body. With the configuration having the above, it becomes possible to provide a stent with improved flexibility following deformation of the lumen by increasing flexibility after placement.

Furthermore, since the connection step S160 includes a step of interposing the biodegradable material in the connection portion 60, the connection force can be reduced over time according to the decomposition of the biodegradable material, and high follow-up in the lumen. It becomes possible to provide a stent capable of exerting its properties. Further, since the biodegradable material is interposed in the connecting portion after the diameter expanding step S140, the biodegradable material can be interposed in the connecting portion 60 regardless of the presence or absence of the heating step S150.

Furthermore, it is possible to suitably apply the drug to the stent substrate 30 by the configuration having the drug application step S170 for applying the drug to the stent substrate 30 after the diameter expansion process S140.

Further, in the configuration in which the forming step S110 forms the coil-shaped strut 41, the stent 10 having such a coil shape has a larger recoil than a stent having a shape other than the coil shape, but the diameter expanding step S140. The recoil can be reduced by the heating step S150.

Furthermore, when the base material 20 is subjected to a tensile test in which a tensile stress is applied and unloaded until the total elongation reaches 3% in a temperature environment of 35 ° C. according to JIS Z 2241, the permanent elongation is 2%. By using the above metals (metals other than superelastic alloys), a wide range of materials can be selected as materials that can form a balloon expandable stent. Therefore, the stent 10 according to various product specifications can be selected. It becomes possible to provide.

Furthermore, by using a stent base 30 made of a stainless steel, a cobalt-based alloy such as a cobalt-chromium alloy, a platinum-chromium alloy, or the like, the stent 10 whose diameter is expanded by an expansion member (balloon 91) to which the above materials are widely applied. Can be configured.

Furthermore, the irregularity on the surface of the stent substrate 30 is reduced by the configuration including the polishing step (chemical polishing step S120 or the electrolytic polishing step S130) for polishing the stent substrate 30 before the diameter expanding step S140. When expanding the diameter of the stent base 30 in S140, it is possible to prevent cracks from occurring or breaking.

As mentioned above, although the stent which concerns on this invention was demonstrated through embodiment, this invention is not limited only to the structure demonstrated in embodiment, It can change suitably based on description of a claim. .

This application is based on Japanese Patent Application No. 2014-261070 filed on December 24, 2014, the disclosure of which is referenced and incorporated as a whole.

10 stent,
20 substrate,
30 stent substrate,
41 struts,
60 connections,
91 balloon (expansion member),
142 diameter expansion device,
152 heater,
L1 laser light,
S110 forming step,
S120 chemical polishing process,
S130 electrolytic polishing step,
S140 diameter expansion process,
S150 heating step,
S160 connection process,
S170 drug application process,
S180 Crimping process.

Claims

This is a method of manufacturing a stent that includes a stent base formed by forming struts on a base material, is transferred to a target site in a living body in contact with the expansion member, and is expanded and deformed only by expansion of the expansion member. And
Processing the base material to form the stent base body having an overall outer shape of a cylindrical shape; and
A diameter expansion step of expanding the diameter of the stent substrate after the forming step and before being held by the expansion member.
The method for producing a stent according to claim 1, further comprising a heating step of heating the stent substrate expanded in diameter by the diameter expansion step.
After the diameter expansion step,
The connection step of forming a connection portion that is connected to each other in the axial direction of the stent base and in which the connection force decreases after a predetermined period of time when the stent is indwelled in a living body. 3. A method for producing the stent according to 2.
The method for manufacturing a stent according to claim 3, wherein the connecting step includes a step of interposing a biodegradable material in the connecting portion.
After the diameter expansion step,
The stent manufacturing method according to any one of claims 1 to 4, further comprising a drug application step of applying a drug to the stent substrate.
The method for manufacturing a stent according to any one of claims 1 to 5, wherein the forming step forms the coil-shaped struts.
According to JIS Z 2241 as a base material, when a tensile test was performed by applying a tensile stress until the total elongation reached 3% in a temperature environment of 35 ° C., the permanent elongation was 2% or more. The method for manufacturing a stent according to any one of claims 1 to 6, wherein a certain metal is used.
The method for producing a stent according to any one of claims 1 to 7, wherein the base material made of stainless steel, cobalt-based alloy, or platinum-chromium alloy is used.
The method for manufacturing a stent according to any one of claims 1 to 8, further comprising a polishing step of polishing the stent substrate before the diameter expansion step.