JP2016105749A - Galvanic corrosion stent - Google Patents

Galvanic corrosion stent Download PDF

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JP2016105749A
JP2016105749A JP2013079323A JP2013079323A JP2016105749A JP 2016105749 A JP2016105749 A JP 2016105749A JP 2013079323 A JP2013079323 A JP 2013079323A JP 2013079323 A JP2013079323 A JP 2013079323A JP 2016105749 A JP2016105749 A JP 2016105749A
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stent
metal material
metal
galvanic corrosion
galvanic
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猛士 馬場
Takeshi Baba
猛士 馬場
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Terumo Corp
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Terumo Corp
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Priority to JP2013079323A priority Critical patent/JP2016105749A/en
Priority to PCT/JP2014/057905 priority patent/WO2014162902A1/en
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82—Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
    • A61F2/91—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
    • A61F2/915—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
    • A61L31/02—Inorganic materials
    • A61L31/022—Metals or alloys
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
    • A61L31/12—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material
    • A61L31/121—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material having an inorganic matrix
    • A61L31/124—Composite materials, i.e. containing one material dispersed in a matrix of the same or different material having an inorganic matrix of other specific inorganic materials not covered by A61L31/122 or A61L31/123
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
    • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
    • A61L31/14—Materials characterised by their function or physical properties, e.g. injectable or lubricating compositions, shape-memory materials, surface modified materials
    • A61L31/148—Materials at least partially resorbable by the body
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82—Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
    • A61F2/91—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
    • A61F2/915—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other
    • A61F2002/91533—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other characterised by the phase between adjacent bands
    • A61F2002/91541—Adjacent bands are arranged out of phase
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82—Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
    • A61F2/91—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
    • A61F2/915—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other
    • A61F2002/9155—Adjacent bands being connected to each other
    • A61F2002/91558—Adjacent bands being connected to each other connected peak to peak
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/82—Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
    • A61F2/86—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure
    • A61F2/90—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure
    • A61F2/91—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes
    • A61F2/915—Stents in a form characterised by the wire-like elements; Stents in the form characterised by a net-like or mesh-like structure characterised by a net-like or mesh-like structure made from perforated sheet material or tubes, e.g. perforated by laser cuts or etched holes with bands having a meander structure, adjacent bands being connected to each other
    • A61F2002/9155—Adjacent bands being connected to each other
    • A61F2002/91566—Adjacent bands being connected to each other connected trough to trough
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2210/00—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2210/0004—Particular material properties of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof bioabsorbable
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F2250/00—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
    • A61F2250/0014—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis
    • A61F2250/0043—Special features of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof having different values of a given property or geometrical feature, e.g. mechanical property or material property, at different locations within the same prosthesis differing in electric properties, e.g. in electrical conductivity, in galvanic properties

Abstract

PROBLEM TO BE SOLVED: To provide a stent being thinned, being over-expandable and degradable in a living body.SOLUTION: The galvanic corrosion stent comprises a base material formed of a first metal material, and a sintered body with second metal materials dispersed in the base material. The second metal materials are more noble than the first metal material. Once the stent is placed in the body, the second metal materials are degraded by galvanic corrosion.SELECTED DRAWING: None

Description

本発明は、ステント、特に生体内に留置された後、ガルバニック腐食によって分解される、ガルバニック腐食ステントに関する。   The present invention relates to a stent, and more particularly to a galvanic erosion stent that is placed in vivo and then degraded by galvanic erosion.

従来より、患者への侵襲が低いため、狭心症や心筋梗塞などの虚血性心疾患は、冠動脈の狭窄部に対する経皮経管的冠動脈形成術（ＰＴＣＡ）等により、大腿動脈や頚動脈の虚血性疾患などは狭窄部に対する経皮経管的血管形成術（ＰＴＡ）等により治療が行われている。これらの治療法はいずれも、先端に小さく折りたたまれたバルーンを装着したカテーテルを用いて、狭窄または閉塞してしまった血管を拡張することにより、血液の流れを確保、再開させる手技である。また、拡張した血管が再狭窄または閉塞するのを防止するため、金属製のステントを留置して血管の開存性を確保する治療が行われている。ステントは、一般的には１本の金属パイプから切り出されたものや、金属線からなるメッシュ状、コイル状等のものがあるが、いずれも縮径可能な管状構造を有し、縮径状態でカテーテルにより血管内に挿入され、狭窄部において血管内腔を機械的に支持するよう拡径され留置されるものである。また、Ｘ線透視下でステントの位置を良好に確認できるように、ステント端部にＸ線不透過性金属材料がマーカーとして設置されているものもある。   Conventionally, ischemic heart disease such as angina pectoris and myocardial infarction is less likely to occur in patients due to percutaneous transluminal coronary angioplasty (PTCA) for stenosis of coronary arteries. Hematologic diseases and the like are treated by percutaneous transluminal angioplasty (PTA) or the like for the stenosis. Each of these treatment methods is a technique for securing and resuming blood flow by dilating a blood vessel that has been narrowed or occluded by using a catheter equipped with a balloon folded at the tip. Further, in order to prevent the dilated blood vessel from restenosis or occlusion, a treatment for securing the patency of the blood vessel by placing a metal stent is performed. Stents are generally cut out from a single metal pipe, or meshed or coiled of metal wire, but all have a tubular structure that can be reduced in diameter and are in a reduced diameter state. The catheter is inserted into the blood vessel by the catheter, and the diameter is expanded and placed so as to mechanically support the blood vessel lumen in the stenosis. In some cases, a radiopaque metallic material is provided as a marker at the end of the stent so that the position of the stent can be confirmed well under fluoroscopy.

血管拡張後、一定期間は血管のリモデリングを防ぐラジアルフォースがステントには必要であるが、その後、ラジアルフォースは必要なくなる。むしろ、この時期にはそのリジッドな特性が血管への余計なストレスを生じさせるおそれすらある。したがって、中長期的に役目を終えたステントは徐々に分解していく方が望ましい。   After vasodilation, the stent needs a radial force that prevents remodeling of the blood vessel for a certain period of time, but then no radial force is needed. Rather, the rigid properties may even cause extra stress on the blood vessels at this time. Therefore, it is desirable to gradually disassemble a stent that has finished its role in the medium to long term.

一般に、生体内で分解する生分解性ステントといえば、特許文献１に示されるような、ポリ乳酸といった生分解ポリマーや、特許文献２に示されるような、Ｍｇといった腐食しやすい金属を用いている。   In general, a biodegradable stent that degrades in vivo uses a biodegradable polymer such as polylactic acid as shown in Patent Document 1 or a corrosive metal such as Mg as shown in Patent Document 2. .

国際公開第２００１／０６７９９０号International Publication No. 2001/067990 特開２００４−１６０２３６号公報JP 2004-160236 A

しかしながら、特許文献１に示されるような、生分解性ポリマーは、金属に比べて強度が低いためステントの肉厚を厚くせざるを得ず、伸びもあまりないため過拡張ができない。また、Ｍｇについても生分解性ポリマーと程度の差こそあれ、同様の問題点を持つ。   However, a biodegradable polymer as shown in Patent Document 1 has a lower strength than a metal, so the thickness of the stent has to be increased, and since there is not much elongation, it cannot be overexpanded. In addition, Mg has similar problems to some extent with biodegradable polymers.

本発明はこのような実情に鑑みてなされたものであり、その目的とするところは、薄肉にすることができ、過拡張可能な、生体内において分解するステントを提供することである。   The present invention has been made in view of such circumstances, and an object of the present invention is to provide a stent that can be thinned and can be over-expanded and decomposes in vivo.

本発明者は、上記の問題を解決すべく、鋭意研究を行った。その結果、金属材料から形成された基材に、その基材よりも貴な電位を持つ金属が分散されてなる焼結体により構成されるステントを提供することによって、上記課題を解決することができることを見出した。   The present inventor has intensively studied to solve the above problems. As a result, the above problem can be solved by providing a stent composed of a sintered body in which a metal having a noble potential is dispersed in a base material formed from a metal material. I found out that I can do it.

すなわち、上記課題は、第１の金属材料から形成された基材と、前記基材に分散された第２の金属材料との焼結体からなる、ガルバニック腐食ステントであって、前記第２の金属材料が、前記第１の金属材料より貴な金属であり、生体内に留置された後、ガルバニック腐食によって分解される、ガルバニック腐食ステントを提供することによって解決する。   That is, the said subject is a galvanic corrosion stent which consists of a sintered compact of the base material formed from the 1st metal material, and the 2nd metal material disperse | distributed to the said base material, Comprising: The solution is to provide a galvanic erosion stent in which the metal material is a noble metal than the first metal material and is degraded by galvanic erosion after placement in vivo.

本発明によれば、薄肉にすることができ、過拡張可能な、生体内において分解するステントを提供することができる。   ADVANTAGE OF THE INVENTION According to this invention, the stent which can be thinned and can be overexpanded and decomposes | disassembles in the living body can be provided.

本発明の実施形態に係るガルバニック腐食ステントを示す図である。It is a figure which shows the galvanic corrosion stent which concerns on embodiment of this invention. 図１に示されるガルバニック腐食ステントにおける点線で囲まれた部分３の部分拡大図である。It is the elements on larger scale of the part 3 enclosed with the dotted line in the galvanic corrosion stent shown by FIG. ガルバニック電流を測定するための装置を示す図である。It is a figure which shows the apparatus for measuring a galvanic current. 参考例２におけるガルバニック電流の測定結果を示す図である。It is a figure which shows the measurement result of the galvanic current in the reference example 2.

以下、本発明の実施の形態を説明する。なお、本発明は、以下の実施の形態のみには限定されない。また、図面の寸法比率は、説明の都合上誇張されており、実際の比率とは異なる場合がある。また、本明細書において、範囲を示す「Ｘ〜Ｙ」は「Ｘ以上Ｙ以下」を意味し、「重量」と「質量」、「重量％」と「質量％」および「重量部」と「質量部」は同義語として扱う。また、特記しない限り、操作および物性等の測定は室温（２０〜２５℃）／相対湿度４０〜５０％の条件で測定する。   Embodiments of the present invention will be described below. In addition, this invention is not limited only to the following embodiment. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios. In the present specification, “X to Y” indicating a range means “X or more and Y or less”, and “weight” and “mass”, “wt%” and “mass%”, “part by weight” and “ “Part by mass” is treated as a synonym. Unless otherwise specified, measurement of operation and physical properties is performed under conditions of room temperature (20 to 25 ° C.) / Relative humidity 40 to 50%.

本発明は、第１の金属材料から形成された基材と、前記基材に分散された第２の金属材料との焼結体からなる、ガルバニック腐食ステントであって、前記第２の金属材料が、前記第１の金属材料より貴な金属であり、生体内に留置された後、ガルバニック腐食によって分解される、ガルバニック腐食ステントである。なお、本明細書において「ガルバニック腐食ステント」を単に「ステント」とも称する。   The present invention is a galvanic corrosion stent comprising a sintered body of a base material formed from a first metal material and a second metal material dispersed in the base material, wherein the second metal material Is a galvanic corrosion stent which is a noble metal than the first metal material and is decomposed by galvanic corrosion after being placed in the living body. In the present specification, the “galvanic corrosion stent” is also simply referred to as “stent”.

上記述べたように、血管拡張後、一定期間は血管のリモデリングを防ぐラジアルフォースがステントには必要であるが、その後、ラジアルフォースは必要なくなる。むしろ、この時期にはそのリジッドな特性が血管への余計なストレスを生じさせるおそれすらある。したがって、中長期的に役目を終えたステントは徐々に分解していく方が望ましい。本発明においては、この分解を、ガルバニック腐食を使って行う。   As described above, a radial force that prevents remodeling of blood vessels for a certain period after vasodilation is necessary for the stent, but thereafter, the radial force is not necessary. Rather, the rigid properties may even cause extra stress on the blood vessels at this time. Therefore, it is desirable to gradually disassemble a stent that has finished its role in the medium to long term. In the present invention, this decomposition is performed using galvanic corrosion.

より詳しく説明すると、金属はそれぞれ固有の電位を持つ。種類の異なる金属を接触させて、電解質溶液に浸漬すると、両者の電位が異なるため、卑な金属（イオン化傾向の大きい金属）と貴な金属（イオン化傾向の小さい金属）との間に電位差（ガルバニック電位）が生じ電池（局部電池、ガルバニック電池）が形成され、電流が流れ（局部電流）、腐食が生じる。このような異種金属を電極とした局部電池の形成による電気化学的反応で生じる腐食を、ガルバニック腐食（異種金属接触腐食または局部電流腐食と呼ばれることもある）と呼ぶ。本発明のガルバニック腐食ステントでは、このガルバニック腐食を利用して中長期的に役目を終えたステントを徐々に分解させそのリジッドな特性による血管への余計なストレスを解放する。なお、本明細書における「中長期」の具体的な期間としては、１〜数ヶ月程度であることが好ましく、例えば、１〜６ヶ月、２〜５ヶ月、あるいは３〜４ヶ月程度を想定している。これ以上の期間をかけて分解させてもよいが、ただ１年、２年以上になると血管への余計なストレスが必要以上に続いてしまうため好ましくない場合がある。なお上記期間は一般的なものであり、患者の重篤度、年齢などによって必ずしも上記とはならない場合があることは言うまでもない。   More specifically, each metal has a unique potential. When different types of metals are brought into contact and immersed in an electrolyte solution, the potentials of the two differ, so there is a potential difference (galvanic) between a base metal (a metal with a high ionization tendency) and a noble metal (a metal with a low ionization tendency). Potential) occurs to form a battery (local battery, galvanic battery), current flows (local current), and corrosion occurs. Corrosion caused by an electrochemical reaction due to formation of a local battery using such a foreign metal as an electrode is called galvanic corrosion (sometimes called foreign metal contact corrosion or local current corrosion). In the galvanic erosion stent of the present invention, the galvanic erosion is used to gradually disassemble the stent that has finished its role in the medium to long term, thereby releasing extra stress on the blood vessel due to its rigid characteristics. The specific period of “medium-long term” in the present specification is preferably about 1 to several months, for example, assuming 1 to 6 months, 2 to 5 months, or about 3 to 4 months. ing. Although it may be decomposed over a longer period, it may not be preferable if it is only 1 year or 2 years or more because excessive stress on the blood vessel continues more than necessary. Needless to say, the above period is general, and may not always be the above depending on the severity and age of the patient.

本発明のステントにおいては、このガルバニック電位を生じさせるため、第１の金属材料と、第２の金属材料とを含んで構成される。そして、第１の金属材料と、第２の金属材料とに自然浸漬電位の差が存在することによって局部電流が発生しガルバニック腐食が起こり、生体内において分解が生じる。電位差が大きいほど、流れる局部電流が増大して、腐食も促進されることになる。この際の自然浸漬電位の差にも特に制限はないが、中長期的に役目を終えたステントが徐々に分解していくような自然浸漬電位の差が好ましく、例えば、第１の金属材料と、第２の金属材料の自然浸漬電位の差が２００ｍＶを超えて１０００ｍＶ以下であると好ましく、２１０〜８００ｍＶ程度であるとより好ましい。２００ｍＶ以下であると電流が流れにくくガルバニック腐食が起こりにくい場合がある。１０００ｍＶを超えると、腐食が早く進みすぎてラジアルフォースが必要な時期に分解が進む場合がある。   The stent according to the present invention includes a first metal material and a second metal material in order to generate the galvanic potential. And when a difference in natural immersion potential exists between the first metal material and the second metal material, a local current is generated, galvanic corrosion occurs, and decomposition occurs in the living body. The greater the potential difference, the greater the local current that flows and the more corrosion is promoted. Although there is no particular limitation on the difference in natural immersion potential at this time, a difference in natural immersion potential is preferable in which the stent that has finished its role in the medium to long term is gradually decomposed, for example, the first metal material and The difference in natural immersion potential of the second metal material is preferably more than 200 mV and not more than 1000 mV, more preferably about 210 to 800 mV. If it is 200 mV or less, current may hardly flow and galvanic corrosion may not easily occur. If it exceeds 1000 mV, the corrosion proceeds too quickly, and decomposition may proceed at a time when radial force is required.

なお、本明細書において、「自然浸漬電位」は、ＪＩＳ Ｔ０３０２：２０００に記載される方法によって測定され、具体的には、下記方法によって測定された値（ｍＶ）である。すなわち、まず、試料（第１の金属材料および第２の金属材料）をそれぞれ適当なサイズに切断する。切断時の影響を除去するため、試料を耐水研磨紙を用いて流水下で研磨する。この際、研磨紙は、目の粗いもの（１５０番）から始め、最終的に６００番まで使用する。研磨後、試料を蒸留水中で５分間超音波洗浄する。洗浄後、試料に導線を接続する。なお、試料と導線の接続方法は、試料の形状により、半田付け、ドータイト、クリップ、ネジ止めなどから適宜選択する。次に、試料が１平方ｃｍのみ露出するように、導線との接続部を含めてシール剤で被覆する。被覆後、２４時間以内に、以下の評価に供する。ＰＢＳ溶液（組成：８．０ｇ／Ｌ ＮａＣｌ、０．２ｇ／Ｌ ＫＣｌ、１．１５ｇ／Ｌ Ｎａ２ＨＰＯ４、０．２ｇ／Ｌ ＫＨ２ＰＯ４、ｐＨ ７．２〜７．６）を入れた電解セルを恒温浴槽内に入れ、ＰＢＳ溶液の温度を３７℃に保持する。ＰＢＳ溶液に高純度窒素ガスを３０分以上バブリングする。その後、上記で調製した試料をＰＢＳ溶液に浸漬させる。試料に生じる電位をエレクトロメーター（北斗電工株式会社製、商品名：ＨＥ−１０４）で測定する。なお、測定は、３７℃で１時間浸漬した状態で行い、１時間後の値を自然浸漬電位（ｍＶ）とする。 In the present specification, the “natural immersion potential” is measured by the method described in JIS T0302: 2000, and specifically, is a value (mV) measured by the following method. That is, first, the sample (first metal material and second metal material) is cut into appropriate sizes. In order to remove the influence at the time of cutting, the sample is polished under running water using water-resistant abrasive paper. At this time, the abrasive paper starts from the coarse one (No. 150) and finally uses up to No. 600. After polishing, the sample is ultrasonically cleaned in distilled water for 5 minutes. After cleaning, connect the conductor to the sample. In addition, the connection method of a sample and a conducting wire is appropriately selected from soldering, dotite, clip, screwing, and the like depending on the shape of the sample. Next, it coat | covers with a sealing compound including a connection part with conducting wire so that a sample may expose only 1 square cm. The following evaluation is performed within 24 hours after coating. PBS solution (composition: 8.0 g / L NaCl, 0.2 g / L KCl, 1.15 g / L Na 2 HPO 4 , 0.2 g / L KH 2 PO 4 , pH 7.2 to 7.6) The electrolysis cell is placed in a thermostatic bath, and the temperature of the PBS solution is maintained at 37 ° C. A high purity nitrogen gas is bubbled through the PBS solution for 30 minutes or longer. Thereafter, the sample prepared above is immersed in a PBS solution. The potential generated in the sample is measured with an electrometer (Hokuto Denko Co., Ltd., trade name: HE-104). In addition, a measurement is performed in the state immersed at 37 degreeC for 1 hour, and let the value after 1 hour be a natural immersion potential (mV).

また、一般に生分解性ステントといえば、上記も述べたように、ポリ乳酸といった生分解ポリマーや、Ｍｇといった腐食しやすい金属を用いる。しかし、生分解性ポリマーは金属に比べて強度が低いためステントの肉厚を厚くせざるを得ず、伸びもあまりないため過拡張ができない。また、Ｍｇについても生分解性ポリマーと程度の差こそあれ、同様の問題点を持つ。これに対し、本発明のガルバニック腐食ステントは、基材である第１の金属材料として、それ自体に生分解作用がなくても（あるいは生分解作用が殆どなく長い時間に亘っても生分解しない場合でも）、それより貴な第２の金属材料を併合させて用いるので、当該第１の金属材料として高強度・高延性の材料を選択して、狭窄部に留置するために必要なラジアルフォースを有させながら分解もさせることができるため、材料選択の幅が大きく向上し、結果として、薄肉かつ過拡張可能なステントを提供することができる。   In general, a biodegradable stent uses a biodegradable polymer such as polylactic acid or a corrosive metal such as Mg as described above. However, since biodegradable polymers have lower strength than metals, it is necessary to increase the thickness of the stent, and because there is not much elongation, it cannot be overexpanded. In addition, Mg has similar problems to some extent with biodegradable polymers. On the other hand, the galvanic corrosion stent of the present invention does not biodegrade as a first metal material as a base material even if it has no biodegradation action (or hardly has biodegradation action over a long period of time). However, since the second metal material that is noble is used together, the radial force required to select a high-strength / high-ductility material as the first metal material and place it in the constriction. Therefore, the range of material selection is greatly improved, and as a result, a thin and overexpandable stent can be provided.

ここで、本発明のガルバニック腐食ステントの厚みは、従来の一般的な生分解性ステントの厚みより薄くすることができ、例えば、５〜３００μｍ程度にできたり、あるいは２０〜２００μｍ程度にできたり、５０〜１００μｍ程度にできたりする。また、この程度の厚みであれば、血流を阻善せず好適と言える。   Here, the thickness of the galvanic corrosion stent of the present invention can be made thinner than the thickness of a conventional general biodegradable stent, for example, about 5 to 300 μm, or about 20 to 200 μm, Or about 50-100 μm. Moreover, if it is this thickness, it can be said that it does not obstruct blood flow and is suitable.

また、本発明のガルバニック腐食ステントは、従来使用されるステントと同様に、バルーンエクスパンダブルステント(balloon-expandable stent)（バルーン拡張型ステント）またはセルフエクスパンダブルステント(self-expandable stent)（自己拡張型ステント）のいずれであってもよい。   In addition, the galvanic erosion stent of the present invention is similar to a conventionally used stent in that a balloon-expandable stent (balloon expandable stent) or a self-expandable stent (self-expandable stent). Any of expandable stents may be used.

そして、本発明のガルバニック腐食ステントの形状は、特に制限されないが、血管等の生体管腔内に安定して留置するに足る強度を有することが必要である。この点、本発明は上記のような特有の構成を有しているので、生分解性ステントとして従来知られている生分解性ポリマーのようなものと比較しても強度が高く、またＭｇからなるステントと比較してもやはり強度が高く、血管等の生体管腔内に安定して留置することができる。ステントの具体的な形状としては、例えば、繊維を編み上げて円筒状に形成したものや、パイプ（管状体）に開口部を設けたもの等が挙げられる。   The shape of the galvanic erosion stent of the present invention is not particularly limited, but it is necessary to have sufficient strength to be stably placed in a living body lumen such as a blood vessel. In this respect, since the present invention has the above-described unique configuration, the strength is higher than that of a biodegradable polymer conventionally known as a biodegradable stent. Compared to a stent, the strength is high, and it can be stably placed in a living body lumen such as a blood vessel. Specific examples of the stent include those in which fibers are knitted into a cylindrical shape and those in which an opening is provided in a pipe (tubular body).

以下では、本発明のガルバニック腐食ステントの一実施形態として、バルーン拡張型ステントの例を挙げて、図１に示されるステントを説明する。図１に示されるように、ステント１において、ステント本体（基材）２は、両末端部が開口し、該両末端部の間を長手方向に延在する円筒体である。円筒体の側面は、その外側面と内側面とを連通する多数の切欠部を有し、この切欠部が変形することによって、円筒体の径方向に拡縮可能な構造になっており、血管等の生体管腔内に留置され、その形状を維持する。図１に示す形態において、ステント本体（基材）２は、内部に切欠部を有する略菱形の要素Ａを基本単位とする。複数の略菱形の要素Ａが、略菱形の形状がその短軸方向に連続して配置され結合することで環状ユニットＢをなしている。環状ユニットＢは、隣接する環状ユニットと線状の連結部材Ｃ（これも本明細書では「基材」の概念に含まれる）を介して接続されている。これにより複数の環状ユニットＢが一部結合した状態でその軸方向に連続して配置される。ステント本体（基材）２は、このような構成により、両末端部が開口し、該両末端部の間を長手方向に延在する円筒体をなしている。そして円筒体の側面は、略菱形の切欠部を有しており、この切欠部が変形することによって、円筒体の径方向に拡縮可能な構造になっている。   Hereinafter, as an embodiment of the galvanic erosion stent of the present invention, an example of a balloon expandable stent will be described and the stent shown in FIG. 1 will be described. As shown in FIG. 1, in the stent 1, the stent body (base material) 2 is a cylindrical body that is open at both end portions and extends in the longitudinal direction between the both end portions. The side surface of the cylindrical body has a large number of notches communicating with the outer side surface and the inner side surface, and the notched portions are deformed to have a structure that can be expanded and contracted in the radial direction of the cylindrical body. It is placed in the body lumen and maintains its shape. In the form shown in FIG. 1, the stent main body (base material) 2 has a substantially rhombic element A having a notch inside as a basic unit. A plurality of substantially rhombic elements A form an annular unit B by arranging and combining substantially rhombus shapes continuously in the minor axis direction. The annular unit B is connected to an adjacent annular unit via a linear connecting member C (also included in the concept of “base material” in this specification). As a result, the plurality of annular units B are continuously arranged in the axial direction in a partially coupled state. With such a configuration, the stent body (base material) 2 forms a cylindrical body having both ends opened and extending between the ends in the longitudinal direction. The side surface of the cylindrical body has a substantially diamond-shaped notch, and the notch is deformed so that the cylindrical body can be expanded or contracted in the radial direction.

本実施形態におけるステントは、ステント本体（基材）２（連結部材Ｃも含む）が第１の金属材料から形成され、それに第２の金属材料が分散された形態で焼結されてなる焼結体である（図１には、第２の金属材料を図示していない）。この分散形態にも特に制限はないが、ステント本体（基材）２（連結部材Ｃも含む）の表面上に点在するようにして分散されてもよいし、ステント本体（基材）２（連結部材Ｃも含む）の表面だけではなく、内部にも存在するように海島状に分散されてもよい。このように、第２の金属材料が、第１の金属材料に分散されていると、それらの間に存在する自然浸漬電位の差に起因して局部電流が流れてガルバニック腐食が起こり、生体内において分解が生じ、そのリジッドな特性による血管への余計なストレスを解放する。   In the stent according to the present embodiment, the stent body (base material) 2 (including the connecting member C) is formed from the first metal material, and the second metal material is dispersed in the sintered body. (The second metal material is not shown in FIG. 1). Although there is no restriction | limiting in particular also in this dispersion | distribution form, you may disperse | distribute so that it may be scattered on the surface of the stent main body (base material) 2 (a connection member C is also included), or the stent main body (base material) 2 ( It may be dispersed in a sea-island shape so as to exist not only on the surface of the connection member C) but also inside. As described above, when the second metal material is dispersed in the first metal material, a local current flows due to a difference in natural immersion potential existing between them, and galvanic corrosion occurs. Decomposition occurs in the tube, releasing extra stress on the blood vessels due to its rigid properties.

図２は、図１に示されるガルバニック腐食ステントにおける点線で囲まれた部分３の部分拡大図である。図２に示されるように、図１に示されるガルバニック腐食ステントにおけるステント本体（基材）２の表面および内部に、第２の金属材料４が海島状に分散されている。またこのように、ステント本体（基材）２（連結部材Ｃも含む）の表面だけではなく、内部にも存在するように海島状に分散されることによって、ステント全体から見て局部的にのみガルバニック腐食を起こすことを抑制することができ、ステント全体が均一にガルバニック腐食によって分解していくので、自然浸漬電位の差が小さくても分解を促進することができる。また、第２の金属材料が第１の金属材料よりも比重が重く、Ｘ線不透過性が高い場合、このように海島状に分散されることによって、Ｘ線透視下でステントの位置を良好に確認できるという効果がある。つまり、通常のステントには、Ｘ線透視下でステントの位置を良好に確認できるように、ステント端部にＸ線不透過性金属材料がマーカーとして特別に設置されていることがある。しかし、端部のみにＸ不透過性マーカーが設けられているステントでは、ステント全体の形状までは把握できず、例えば、複数のステントを長さ方向に端部を重なり合わせながら留置するオーバーラップ法や、ステント同士を接触させた状態で血管の本管と側枝双方にステントを留置する２ステント法などを行う場合に困難を伴うことがある。また、再狭窄が生じて、ステントを留置した病院と別の病院へ搬送された場合、ステント全体の形状が正確に把握し難いことにより、的確な処置が行えない恐れもある。一方、生分解性ステントからなるステントやＭｇからなるステントもＸ線不透過性に乏しいといった欠点がある。これに対し本実施形態においては、第２の金属材料に第１の金属材料よりも比重が重く、Ｘ線不透過性が高い金属を使用することにより、ガルバニック腐食させるための作用の他に、ステントの位置を良好に確認させるためのマーカーとしての作用を有させることもでき、別途のマーカーを設けることなくステントの位置の視認性に優れるという効果を有する。また、海島状に分散されることによって、ステント全体の形状も簡便に確認することができるため、生体管腔内により安全に留置させることができる。また、第２の金属材料４をステント本体（基材）２（連結部材Ｃも含む）の表面だけではなく内部にも存在するように海島状に分散されることによって、ステントの単位体積あたりの比重を高めることができるため、第２の金属材料を表面のみに点在させる形態と比較し、Ｘ線透視下での視認性の観点で優れている。   FIG. 2 is a partially enlarged view of a portion 3 surrounded by a dotted line in the galvanic corrosion stent shown in FIG. As shown in FIG. 2, the second metal material 4 is dispersed in the shape of a sea island on the surface and inside of the stent body (base material) 2 in the galvanic erosion stent shown in FIG. Further, as described above, by being dispersed in a sea-island shape so as to exist not only on the surface of the stent body (base material) 2 (including the connecting member C), but only locally as viewed from the whole stent. The occurrence of galvanic corrosion can be suppressed, and the entire stent is uniformly decomposed by galvanic corrosion, so that the decomposition can be promoted even if the difference in natural immersion potential is small. In addition, when the second metal material has a higher specific gravity than the first metal material and has a high radiopacity, it is dispersed in a sea-island like this, so that the position of the stent is excellent under X-ray fluoroscopy. There is an effect that can be confirmed. That is, in a normal stent, a radiopaque metallic material may be specially installed as a marker at the end of the stent so that the position of the stent can be confirmed well under fluoroscopy. However, in a stent in which an X-opaque marker is provided only at the end, the shape of the entire stent cannot be grasped. For example, an overlap method in which a plurality of stents are placed while overlapping the end in the length direction. In addition, it may be difficult to perform a two-stent method in which a stent is placed in both the main and side branches of a blood vessel while the stents are in contact with each other. In addition, when restenosis occurs and the stent is transported to a hospital other than the hospital where the stent is placed, it is difficult to accurately grasp the shape of the entire stent, and there is a possibility that accurate treatment cannot be performed. On the other hand, a stent made of a biodegradable stent and a stent made of Mg also have a drawback of poor radiopacity. On the other hand, in this embodiment, in addition to the action for causing galvanic corrosion by using a metal having a higher specific gravity than the first metal material and a high radiopacity for the second metal material, It can also have an effect as a marker for confirming the position of the stent satisfactorily, and has an effect of excellent visibility of the position of the stent without providing a separate marker. In addition, since the shape of the entire stent can be easily confirmed by being dispersed in a sea-island shape, it can be safely placed in a living body lumen. Further, the second metal material 4 is dispersed in a sea-island shape so as to exist not only on the surface of the stent body (base material) 2 (including the connecting member C) but also on the inside of the stent body volume. Since the specific gravity can be increased, it is superior in terms of visibility under X-ray fluoroscopy, compared to a mode in which the second metal material is scattered only on the surface.

ここで、ステント作製における、原料としての第１の金属材料・第２の金属材料の形状にも特に制限はないが、粉末として取り扱えることが、ステント作製の観点から好ましく、具体的には、球状、繊維状、棒状、略球状、偏平状、不定形状などが挙げられ、中でも球状、略球状であることが好ましい。ステントして作製された後の、第１の金属材料・第２の金属材料の形状も、特に制限されず、その焼結条件等を適宜調整することで変更できる。   Here, the shape of the first metal material and the second metal material as raw materials in the production of the stent is not particularly limited, but it is preferable that it can be handled as a powder from the viewpoint of the production of the stent. , Fiber shape, rod shape, substantially spherical shape, flat shape, irregular shape, and the like. Among them, spherical shape and substantially spherical shape are preferable. The shapes of the first metal material and the second metal material after the stent is manufactured are not particularly limited, and can be changed by appropriately adjusting the sintering conditions and the like.

また、原料としての第１の金属材料・第２の金属材料の融点としては、第１の金属材料は、ステント作製の容易さの観点から好ましくは５００〜３，０００℃程度で、より好ましくは８００〜２，０００℃程度であり、第２の金属材料は、ステント作製の容易さの観点から好ましくは５００〜３，０００℃程度で、より好ましくは８００〜２，０００℃程度である。   Moreover, as melting | fusing point of the 1st metal material and 2nd metal material as a raw material, from a viewpoint of the ease of stent production, the 1st metal material becomes like this. Preferably it is about 500-3,000 degreeC, More preferably The second metal material is preferably about 500 to 3,000 ° C, more preferably about 800 to 2,000 ° C, from the viewpoint of ease of manufacturing the stent.

また、原料としての第１の金属材料・第２の金属材料の大きさにも特に制限はない。ただし、第１の金属材料の大きさは、ステント作製の観点や、ステントしての拡張性の観点から、好ましくは、０．０１〜２００μｍ、より好ましくは０．１〜５０μｍである。また、第２の金属材料の大きさは、ステント作製の観点や、ステントしての拡張性の観点から、好ましくは、０．０１〜２００μｍ、より好ましくは０．１〜５０μｍである。このような所定の範囲の粒径の金属材料を準備するためには篩などによって分級すればよい。なお、本明細書中において、「粒径」とは、粒子の輪郭線上の任意の２点間の距離のうち、最大の距離を意味するものとし、「平均粒子径」の値としては、走査型電子顕微鏡（ＳＥＭ）や透過型電子顕微鏡（ＴＥＭ）などの観察手段を用い、数〜数十視野中に観察される粒子の粒子径の平均値として算出される値を採用するものとする。   Moreover, there is no restriction | limiting in particular also in the magnitude | size of the 1st metal material and 2nd metal material as a raw material. However, the size of the first metal material is preferably 0.01 to 200 μm, more preferably 0.1 to 50 μm, from the viewpoint of stent fabrication and the viewpoint of expandability as a stent. The size of the second metal material is preferably 0.01 to 200 μm, more preferably 0.1 to 50 μm, from the viewpoint of stent fabrication and the viewpoint of expandability as a stent. In order to prepare a metal material having a particle diameter in such a predetermined range, it may be classified by a sieve or the like. In this specification, “particle diameter” means the maximum distance among any two points on the particle outline, and the value of “average particle diameter” is a scan. A value calculated as an average value of particle diameters of particles observed in several to several tens of fields using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM) is adopted.

また、第２の金属材料のステント全体積の存在割合に関しても特に制限はないが、本発明の効果を効率よく奏させるという観点や、ステントしての拡張性の観点から、ステント全体積の１〜８０％の割合で海島状に分散され、さらに好ましくは３０〜７０％の割合で海島状に分散される。   Further, the existing ratio of the total stent volume of the second metal material is not particularly limited, but from the viewpoint of efficiently achieving the effects of the present invention and from the viewpoint of expandability as a stent, 1% of the total stent volume is obtained. It is dispersed in the form of sea islands at a rate of ˜80%, more preferably in the form of sea islands at a rate of 30-70%.

また、仕込みの際の、第１の金属材料と、第２の金属材料との質量比についても特に制限されないが、本発明の効果を効率よく奏させるという観点や、ステントしての拡張性の観点から、1５：８５〜７０：３０程度が好ましい。   Further, the mass ratio between the first metal material and the second metal material at the time of preparation is not particularly limited, but the viewpoint of efficiently exhibiting the effects of the present invention, and the expandability as a stent. From the viewpoint, about 15:85 to 70:30 is preferable.

続いて、第１の金属材料や第２の金属材料などの本発明のステントを構成する成分の具体例について説明する。   Then, the specific example of the component which comprises the stent of this invention, such as a 1st metal material and a 2nd metal material, is demonstrated.

［第１の金属材料］
第１の金属材料は、ステントの基材としての役割を果たす。図１では、ステント本体２や連結部材Ｃは、第１の金属材料から形成されている。第１の金属材料は、通常医療分野においてステントとして使用されるものと同様の金属が使用でき、具体的には、ステンレス鋼、コバルト系合金、ニッケル−チタン系合金、マグネシウム系合金、モリブデン系合金、タンタル系合金などが挙げられる。上記のうち、ステンレス鋼、コバルト系合金、ニッケル−チタン系合金が好ましい。ここで、ステンレス鋼としては、通常医療分野において使用できるステンレス鋼が同様にして使用できるが、例えば、ＳＳ３０４、ＳＳ３１６Ｌ、ＳＳ４２０Ｊ２、ＳＳ６３０などが挙げられる。これらのうち、生体内での使用実績の観点から、ＳＳ３１６Ｌ（組成：炭素 ０．０３５重量％以下、リン ０．０４重量％以下、硫黄 ０．０３重量％以下、マンガン ２．００重量％以下、ケイ素 ０．７５重量％以下、クロム １６．００〜１８．００重量％、ニッケル １２．００〜１５．００重量％、モリブデン ２．００〜３．００重量％、残部 鉄）が好ましい。また、コバルト系合金としても、通常医療分野において使用できるコバルト系合金が同様にして使用できるが、例えば、Ｌ６０５等のコバルト−クロム合金（Ｃｏ−Ｃｒ合金）、コバルト−ニッケル−クロム合金、ＭＰ３５Ｎ等のコバルト−ニッケル−クロム−モリブデン合金、コバルト−クロム−モリブデン合金などが挙げられる。これらのうち、強度、生体内での使用実績の観点から、Ｌ６０５（組成：クロム １９．００〜２１．００重量％、ニッケル ９．００〜１１．００重量％、タングステン １４．００〜１６．００重量％、鉄 最大３．００重量％、マンガン １．００〜２．００重量％、炭素 ０．０５〜０．１５重量％、ケイ素 最大０．４０重量％、リン 最大０．０４０重量％、硫黄 最大０．０３０重量％、残部 コバルト）、ＭＰ３５Ｎ（組成：炭素 最大０．０２５重量％、リン 最大０．０１５重量％、硫黄 最大０．０１０重量％、マンガン 最大０．１５重量％、ケイ素 最大０．１５重量％、クロム １９．００〜２１．００重量％、ニッケル ３３．００〜３７．００％重量、モリブデン ９．００〜１０．５０％重量、チタン 最大１．００重量％、ホウ素 最大０．０１重量％、鉄 最大１．００重量％、残部 コバルト）が好ましく、特に、Ｌ６０５等のＣｏ−Ｃｒ合金は、高強度・高延性を有するため薄肉かつ過拡張が容易に可能となり非常に好ましい。また、ニッケル−チタン系合金としても、通常医療分野において使用できるニッケル−チタン系合金が同様にして使用できるが、例えば、約５０重量％〜約６０重量％のニッケルを含有し、残部がチタンであるニッケル−チタン合金、ニッケル−チタン合金に銅を添加したニッケル−チタン−銅合金などが挙げられる。これらのうち、生体内での使用実績、超弾性特性の観点から、上記約５０重量％〜約６０重量％のニッケルを含有し残部がチタンであるニッケル−チタン合金（ニチノール）が好ましい。なお、本発明で使用されうる第１の金属材料（第１の金属材料からなる粉末）は市販のものを買ってきてもよいし、自己で作製してもよい。自己で作製する場合でも従来公知の知見を参照し、あるいは組み合わせて行えばよく、例えば、金属または合金の溶湯をるつぼ底部の小孔から流出させて細流とし、これに高速の空気、窒素、アルゴン、水などを吹き付けて、溶湯を飛散・急冷凝固させるアトマイズ法などを用いればよい。 [First metal material]
The first metallic material serves as a stent substrate. In FIG. 1, the stent body 2 and the connecting member C are made of a first metal material. As the first metal material, the same metal as that usually used as a stent in the medical field can be used. Specifically, stainless steel, cobalt alloy, nickel-titanium alloy, magnesium alloy, molybdenum alloy And tantalum alloys. Of the above, stainless steel, cobalt-based alloy, and nickel-titanium-based alloy are preferable. Here, as the stainless steel, stainless steel that can be used in a normal medical field can be used in the same manner, and examples thereof include SS304, SS316L, SS420J2, and SS630. Of these, SS316L (composition: carbon 0.035% by weight or less, phosphorus 0.04% by weight or less, sulfur 0.03% by weight or less, manganese 2.00% by weight or less, Preferred is silicon (0.75% by weight or less), chromium (16.00 to 18.00% by weight), nickel (12.00 to 15.00% by weight), molybdenum (2.00 to 3.00% by weight, balance iron). Further, as the cobalt-based alloy, a cobalt-based alloy that can be used in the normal medical field can be used in the same manner. For example, a cobalt-chromium alloy (Co-Cr alloy) such as L605, a cobalt-nickel-chromium alloy, MP35N, and the like. And cobalt-nickel-chromium-molybdenum alloy and cobalt-chromium-molybdenum alloy. Among these, L605 (composition: chromium 19.00 to 21.00% by weight, nickel 9.00 to 11.00% by weight, tungsten 14.00 to 16.00 from the viewpoint of strength and use in vivo. Wt%, iron up to 3.00 wt%, manganese 1.00-2.00 wt%, carbon 0.05-0.15 wt%, silicon up to 0.40 wt%, phosphorus up to 0.040 wt%, sulfur 0.030 wt% maximum, cobalt remaining), MP35N (composition: carbon max 0.025 wt%, phosphorus max 0.015 wt%, sulfur max 0.010 wt%, manganese max 0.15 wt%, silicon max 0 .15 wt%, chromium 19.00 to 21.00 wt%, nickel 33.00 to 37.00 wt%, molybdenum 9.00 to 10.50 wt%, titanium up to 1.00 wt%, boron (Up to 0.01 wt%, iron up to 1.00 wt%, balance cobalt) is preferable. Especially, Co-Cr alloys such as L605 have high strength and high ductility, so they can be easily thinned and overexpanded. Is preferable. Also, as the nickel-titanium alloy, a nickel-titanium alloy that can be used in the medical field can be used in the same manner. For example, the nickel-titanium alloy contains about 50 wt% to about 60 wt% nickel and the balance is titanium. Examples thereof include a nickel-titanium alloy and a nickel-titanium-copper alloy obtained by adding copper to a nickel-titanium alloy. Of these, nickel-titanium alloys (Nitinol) containing about 50 wt% to about 60 wt% of nickel and the balance being titanium are preferable from the viewpoint of in-vivo use results and superelastic characteristics. In addition, the 1st metal material (powder which consists of 1st metal material) which can be used by this invention may purchase the commercially available thing, and may produce it self. Even in the case of self-manufacturing, it is only necessary to refer to known knowledge or to combine them. For example, a molten metal or alloy is made to flow out of a small hole at the bottom of the crucible to form a trickle, and high-speed air, nitrogen, argon An atomizing method that sprays water or the like to scatter and rapidly solidify the molten metal may be used.

［第２の金属材料］
第２の金属材料は、前記第１の金属材料より貴な金属であり、前記第１の金属材料から形成された基材に分散される。第２の金属材料は、第１の金属材料と同様に、通常医療分野においてステントとして使用されるものと同様の金属が使用でき、具体的には、金属材料が、金、白金、銀、パラジウムおよびそれらを主成分とする合金のいずれかであることが好ましい。なお、本明細書において「主成分」とは全成分のうち質量％が最も多いものを意味する。特に上記で第１の金属材料として列挙したものは、ステント用材料として優れた強度延性バランスを有し、拡張した血管が再狭窄または閉塞するのを防止し、血管の開存性を確保する治療を確実に行うことができる好ましい材料と言える。しかしながら、上記のように、そのリジッドな特性が血管への余計なストレスを生じさせる恐れという問題をも内在していた。それは中長期的には体内において分解されることが好ましいのであるが、第１の金属材料として列挙したものは基本的に耐腐食性という特性を有しており、それを実現できないでいた。本発明によれば、第２の金属材料を併用して用いるため、上記で説明したような機構で、このような課題を解決できる。また、第１の金属材料に第２の金属材料が分散されており、上記で列挙した第２の金属材料は第１の金属材料よりも比重が有意に重いため、高いＸ線不透過性を実現でき、Ｘ線透視下で良好に視認できるため、生体管腔内に安全に留置できることができる。本発明において、第２の金属材料の好ましい比重としては、通常の医療現場におけるＸ線透視下でのマーカーの視認性の観点から、好ましくは、１０以上であり、より好ましくは１２以上である。 [Second metal material]
The second metal material is a noble metal than the first metal material, and is dispersed in a base material formed from the first metal material. Similar to the first metal material, the second metal material can be the same metal as that normally used as a stent in the medical field. Specifically, the metal material is gold, platinum, silver, palladium. And any of alloys containing them as a main component. In the present specification, “main component” means a component having the largest mass% of all components. In particular, those listed above as the first metal material are treatments that have an excellent balance of strength and ductility as a stent material, prevent restenosis or occlusion of dilated blood vessels, and ensure patency of blood vessels It can be said that it is a preferable material that can be reliably performed. However, as described above, there is a problem that the rigid characteristics may cause extra stress on the blood vessels. It is preferable that it is decomposed in the body in the medium to long term, but those listed as the first metal material basically have the property of corrosion resistance, and this cannot be realized. According to the present invention, since the second metal material is used in combination, such a problem can be solved by the mechanism described above. In addition, the second metal material is dispersed in the first metal material, and the specific gravity of the second metal material listed above is significantly higher than that of the first metal material. Since it can be realized and can be seen well under X-ray fluoroscopy, it can be safely placed in a living body lumen. In the present invention, the preferred specific gravity of the second metal material is preferably 10 or more, more preferably 12 or more, from the viewpoint of the visibility of the marker under fluoroscopy in a normal medical field.

なお、第２の金属材料は、第１の金属材料より貴な金属であるように選択されればよいが、両者の関係は相対的なものであるので、例えば、上記で列挙した第２の金属材料から、異なる二種の金属材料を選択し、そのうち相対的に卑な金属材料であるものを第１の金属材料として使い、貴な金属材料であるものを第２の金属材料として使ってもよい。ただし比重が重いような金属材料をステント基材として使うと硬くて脆い場合もあり、その観点においては上記の第１の金属材料で列挙したような金属材料を基材として用いることが好ましい。   The second metal material may be selected to be a noble metal than the first metal material. However, since the relationship between the two metal materials is relative, for example, the second metal material listed above is used. Two different kinds of metal materials are selected from the metal materials, and a relatively base metal material is used as the first metal material, and a noble metal material is used as the second metal material. Also good. However, when a metal material having a heavy specific gravity is used as the stent base material, it may be hard and brittle. From this viewpoint, it is preferable to use the metal materials listed as the first metal material as the base material.

なお、従来にも２種以上の金属からなる合金で形成されるステントも存在するが、合金は通常は均一な状態であるため、仮にその合金からなるステントが体液により腐食されることがあってもそれは本発明のガルバニック腐食とは異なり、第２の金属材料が第１の金属材料に「分散」している点も相違する。また、その合金が仮にミクロ的に見たときに部分的に組成の違いがあり、それぞれの相が接触した部分でガルバニック腐食がミクロ的に起こっていても、それも本発明の第１の金属材料から形成された基材に第２の金属材料が「分散」されてなる構成とは明らかに異なる。   Conventionally, there are stents made of an alloy made of two or more metals, but the alloy is usually in a uniform state, so that the stent made of the alloy may be corroded by body fluids. However, it differs from the galvanic corrosion of the present invention in that the second metal material is “dispersed” in the first metal material. In addition, when the alloy is viewed microscopically, there is a partial difference in composition, and even if galvanic corrosion occurs microscopically at the portion where each phase contacts, this is also the first metal of the present invention. This is clearly different from the configuration in which the second metal material is “dispersed” in the base material formed from the material.

［バインダ］
本発明の焼結体から形成されるステントは、第１の金属材料と第２の金属材料とをより密着させて強度を上げたり、空隙を少なくするという観点や、作業性の観点からバインダを含んでもよい。本発明のステントに用いられうるバインダの種類としては、効率よく接合できるようなものであり、焼結後に消失し、生体内に留置される際に安全性の問題がないものであれば特に制限されないが、例えば、アクリル系ポリマーが挙げられる。また、このバインダの含有量にも特に制限はないが、第１の金属材料および第２の金属材料の合計重量に対して、好ましくは５〜２０重量％程度である。 [Binder]
In the stent formed from the sintered body of the present invention, the first metal material and the second metal material are more closely adhered to increase the strength, the void is reduced, and the binder is used from the viewpoint of workability. May be included. The kind of binder that can be used in the stent of the present invention is particularly limited as long as it can be efficiently joined, disappears after sintering, and has no safety problem when placed in vivo. Although not, for example, an acrylic polymer may be mentioned. Moreover, there is no restriction | limiting in particular also in content of this binder, Preferably it is about 5 to 20 weight% with respect to the total weight of a 1st metal material and a 2nd metal material.

ところで、本発明におけるステントの構造は、図１で示された形態に限定されず、コイル形状もまた本発明の概念に含まれる。また、ステント（本体）を構成する線材（すなわち、基材）の断面形状についても、矩形、円形、楕円形、其の他の多角形等が挙げられるが、他の形状であってもよい。上記に加えて、ステント１の他の好ましい例としては、格子状の構造のステントがある。これらの形態以外にも、例えば、特開２００２−２６３１９５号公報（特に図９、図１０）、特開２００４−１２１３４２号公報（特に図６）、特開２００４−２９０２７９号公報（特に図６、図７）、特開２００５−２７８９９３号公報、米国特許第６，４０２，７７７号明細書（特に図１）等に記載のステントが同様にしてあるいは適宜修飾して適用できる。   By the way, the structure of the stent in the present invention is not limited to the form shown in FIG. 1, and the coil shape is also included in the concept of the present invention. Further, the cross-sectional shape of the wire (that is, the base material) constituting the stent (main body) may be a rectangle, a circle, an ellipse, other polygons, or the like, but may be another shape. In addition to the above, another preferred example of the stent 1 is a stent having a lattice structure. In addition to these forms, for example, Japanese Patent Application Laid-Open No. 2002-263195 (particularly FIGS. 9 and 10), Japanese Patent Application Laid-Open No. 2004-121342 (particularly FIG. 6), Japanese Patent Application Laid-Open No. 2004-290279 (particularly FIG. The stent described in FIG. 7), Japanese Patent Application Laid-Open No. 2005-278993, US Pat. No. 6,402,777 (particularly FIG. 1) and the like can be applied in the same manner or appropriately modified.

また、上記で説明した、ステント本体の大きさは、特に制限されず、適用箇所に応じて適宜選択すればよい。拡張前におけるステントの外径は、０．３〜５ｍｍ程度が好ましく、０．４〜４．５ｍｍ程度がより好ましく、０．５〜１．６ｍｍ程度が特に好ましい。また、ステントの長さもまた、特に制限されず、処置すべき疾患によって適宜選択できる。例えば、ステントの長さは、５〜１００ｍｍ程度が好ましく、６〜５０ｍｍ程度がより好ましい。または、ステントの長さは、１．５〜４ｍｍ程度が好ましく、２〜３ｍｍ程度がより好ましい場合もある。   Further, the size of the stent body described above is not particularly limited, and may be appropriately selected depending on the application location. The outer diameter of the stent before expansion is preferably about 0.3 to 5 mm, more preferably about 0.4 to 4.5 mm, and particularly preferably about 0.5 to 1.6 mm. Further, the length of the stent is not particularly limited and can be appropriately selected depending on the disease to be treated. For example, the length of the stent is preferably about 5 to 100 mm, and more preferably about 6 to 50 mm. Alternatively, the length of the stent is preferably about 1.5 to 4 mm, and more preferably about 2 to 3 mm.

続いて、本発明のステントの製造方法の好ましい実施形態を説明する。まず、第１の金属材料と、第２の金属材料と、必要に応じバインダとを準備する。第２の金属材料は、第１の金属材料より貴な金属である。第１の金属材料と、第２の金属材料は、それぞれ独立して、単一金属であってもよいし、合金であってもよい。例えば、第１の金属材料として合金粉末を準備して、第２の金属材料として単一金属の粉末を準備してもよいし、あるいは、その合金を構成する単一金属の粉末をそれぞれ準備し、他の単一金属の粉末と混合してもよい。この際の質量比も、上記で説明した、第１の金属材料と、第２の金属材料との質量比を参考にして適宜設定すればよい。準備された材料を、均一となるようによく混合する。混合方法としては、混粉機などによって行うことが好ましい。その均一に混合された混合物をステントの型に入れ、温間プレスを行う。その際の条件としては、圧力：１０〜３０ＭＰａ程度、温度：２００〜３００℃程度、時間：１〜５分程度である。その後、７００〜９００℃程度、Ａｒガスなどの不活性ガス雰囲気もしくは真空下で、１〜２時間程度焼結を行う。その後、密度をさらに高めるために（さらに間隙をなくすために）、熱間等方圧延（熱間等方圧加圧法）（ＨＩＰ；Ｈｏｔ Ｉｓｏｓｔａｔｉｃ Ｐｒｅｓｓ）を行う。その際の条件は、圧力：５０〜３００ＭＰａ程度、温度：８００〜１２００℃程度、時間：１〜２時間程度である。このＨＩＰによって密度を、好ましくは理論密度の９５体積％以上、より好ましくは９８体積％以上にする。このようにして本発明の焼結体（ロッド）を作製する。温間プレス、焼結及びＨＩＰは必要であれば１回または繰り返し行ってもよい。ここで説明した焼結等の条件は上記の範囲に限定されず、金属材料の融点や、拡散速度を考慮して、適宜設計変更して焼結体を作製することができる。ある程度低い温度で行う場合、その分長時間行えばし、あるいは高圧にすればよい。また、高い温度で行うのであれば時間を短くしたりすればよい。このような条件は当業者であれば適宜設定することができる。また例えば、第２の金属材料として融点の高いものを選択し、焼結あるいはＨＩＰにおいて、第１の金属材料の融点温度以上であって、第２の金属材料の融点以下である温度条件を設定すれば、第２の金属材料は熔けないで、仕込みの際の形状を大体そのまま保ちながら焼結することができるし、あるいは第１の金属材料、第２の金属材料の両方が溶融しないような温度条件を設定すれば、仕込みの、第１の金属材料・第２の金属材料の形状を大体そのまま保ちながら焼結することで金属材料の表面が固相接合された焼結体（ロッド）を作製することもできる。このようにして作製したロッドを切削加工により中心部を繰り抜き、パイプ形状にする。これをレーザー加工によりステントのパターンにカットし、さらに化学研磨、電解研磨を施しステントを作製することができる。   Subsequently, a preferred embodiment of the method for producing a stent of the present invention will be described. First, a first metal material, a second metal material, and a binder as needed are prepared. The second metal material is a noble metal than the first metal material. The first metal material and the second metal material may be independently a single metal or an alloy. For example, an alloy powder may be prepared as the first metal material, and a single metal powder may be prepared as the second metal material, or a single metal powder constituting the alloy may be prepared. It may also be mixed with other single metal powders. The mass ratio at this time may also be appropriately set with reference to the mass ratio between the first metal material and the second metal material described above. The prepared materials are mixed well so as to be uniform. As a mixing method, it is preferable to carry out by a powder mixer or the like. The uniformly mixed mixture is placed in a stent mold and warm pressed. The conditions at that time are: pressure: about 10-30 MPa, temperature: about 200-300 ° C., time: about 1-5 minutes. Thereafter, sintering is performed at about 700 to 900 ° C. in an inert gas atmosphere such as Ar gas or under vacuum for about 1 to 2 hours. Thereafter, in order to further increase the density (to further eliminate gaps), hot isostatic rolling (hot isostatic pressing) (HIP: Hot Isostatic Press) is performed. The conditions at that time are: pressure: about 50 to 300 MPa, temperature: about 800 to 1200 ° C., time: about 1 to 2 hours. With this HIP, the density is preferably 95% by volume or more, more preferably 98% by volume or more of the theoretical density. In this way, the sintered body (rod) of the present invention is produced. Warm pressing, sintering and HIP may be performed once or repeatedly if necessary. The conditions such as sintering described here are not limited to the above range, and the sintered body can be manufactured by changing the design as appropriate in consideration of the melting point of the metal material and the diffusion rate. When it is performed at a certain low temperature, it may be performed for a longer time or at a higher pressure. In addition, if it is performed at a high temperature, the time may be shortened. Such conditions can be appropriately set by those skilled in the art. Further, for example, a material having a high melting point is selected as the second metal material, and a temperature condition that is higher than the melting point temperature of the first metal material and lower than the melting point of the second metal material is set in sintering or HIP. Then, the second metal material does not melt and can be sintered while maintaining the shape at the time of preparation as it is, or both the first metal material and the second metal material do not melt. If the temperature conditions are set, a sintered body (rod) in which the surface of the metal material is solid-phase bonded by sintering while maintaining the shape of the first metal material and the second metal material as they are as they are. It can also be produced. The rod thus produced is cut out at the center to form a pipe. This can be cut into a stent pattern by laser processing, and further subjected to chemical polishing and electrolytic polishing to produce a stent.

本発明の効果を、以下の参考例・実施例を用いて説明する。   The effect of this invention is demonstrated using the following reference examples and examples.

＜参考例１＞
市販のステント（Ｎｏｂｏｒｉ（登録商標）、テルモ株式会社製）を構成する金属であるＳＳ３１６Ｌ、市販のステント（Ｋａｎａｍｅ（商標）、テルモ株式会社製）を構成する金属であるＬ６０５（Ｃｏ−Ｃｒ合金）および金について、自然浸漬電位を測定した。その結果を下記表１に示す。この場合、ＳＳ３１６Ｌ及びＬ６０５が、第１の金属材料に相当し、金が第２の金属材料に相当する。結果を表１に示す。 <Reference Example 1>
SS316L which is a metal constituting a commercially available stent (Nobori (registered trademark), manufactured by Terumo Corporation), L605 (Co-Cr alloy) which is a metal which constitutes a commercially available stent (Kaname (trademark), manufactured by Terumo Corporation) The natural immersion potential was measured for gold and gold. The results are shown in Table 1 below. In this case, SS316L and L605 correspond to the first metal material, and gold corresponds to the second metal material. The results are shown in Table 1.

上記表１より、金（Ａｕ）の、ＳＳ３１６ＬまたはＬ６０５に対する自然浸漬電位の差は有意に大きく、ガルバニック腐食を起こして、本発明のステントを分解することが期待される。   From Table 1 above, the difference in the natural immersion potential of gold (Au) with respect to SS316L or L605 is significantly large, and it is expected to cause galvanic corrosion and decompose the stent of the present invention.

＜参考例２＞
図３の装置を用いて、下記方法によって、ガルバニック電流を測定した。結果を図４に示す。すなわち、第２の金属材料である、試料（金）を適当なサイズ（２ｃｍ×２ｃｍ）に切断した。切断後、試料を耐水研磨紙を用いて流水下で研磨した。この際、研磨紙は、目の粗いもの（１５０番）から始め、最終的に６００番まで使用した。研磨後、試料を蒸留水中で５分間超音波洗浄した。洗浄後、試料に導線をクリップにより接続した。次に、試料が１平方ｃｍのみ露出するように、導線との接続部などを含めてシール剤で被覆した。これを試料極（電極Ｓ２）として使用した。同様にして、市販のステント（Ｋａｎａｍｅ（商標）、テルモ株式会社製）を構成する金属であるＬ６０５（Ｃｏ−Ｃｒ合金）を第１の金属材料として用い、上記と同様にして、導線接続、シール剤での被覆を行い、これを対極（電極Ｓ１）として使用した。被覆後、２４時間以内に、以下の評価に供した。この際、参照極（標準電極）として、Ａｇ／ＡｇＣｌ電極（銀／塩化銀電極）Ｓ３を使用し、参照極Ｓ３と電極Ｓ１、Ｓ２との間にエレクトロメーター（図３中の「Ｅ」）を設置した。ＰＢＳ溶液（組成：８．０ｇ／Ｌ ＮａＣｌ、０．２ｇ／Ｌ ＫＣｌ、１．１５ｇ／Ｌ Ｎａ２ＨＰＯ４、０．２ｇ／Ｌ ＫＨ２ＰＯ４、ｐＨ ７．２〜７．６）を入れたセルＤを恒温浴槽（図示せず）内に入れ、ＰＢＳ溶液の温度を３７℃に保持した。ＰＢＳ溶液に高純度窒素ガスを３０分以上バブリングした。その後、上記で調製した電極Ｓ１、Ｓ２をＰＢＳ溶液中に浸漬させた。対極（電極Ｓ１）及び試料極（電極Ｓ２）間に流れる電流を無抵抗電流計（図３中の「Ｉ」）で測定した。なお、この際の測定温度は、３７℃に調節した。 <Reference Example 2>
The galvanic current was measured by the following method using the apparatus of FIG. The results are shown in FIG. That is, the sample (gold) that is the second metal material was cut into an appropriate size (2 cm × 2 cm). After cutting, the sample was polished under running water using water-resistant abrasive paper. At this time, the abrasive paper started from the coarser one (No. 150) and finally used up to No. 600. After polishing, the sample was ultrasonically cleaned in distilled water for 5 minutes. After washing, the lead wire was connected to the sample by a clip. Next, the sample was covered with a sealing agent including the connecting portion with the conductor so that only 1 cm 2 was exposed. This was used as a sample electrode (electrode S2). Similarly, L605 (Co—Cr alloy), which is a metal constituting a commercially available stent (Kaname (trademark), manufactured by Terumo Corporation), is used as the first metal material. Coating with an agent was performed, and this was used as a counter electrode (electrode S1). The following evaluations were made within 24 hours after coating. At this time, an Ag / AgCl electrode (silver / silver chloride electrode) S3 is used as a reference electrode (standard electrode), and an electrometer ("E" in FIG. 3) is provided between the reference electrode S3 and the electrodes S1 and S2. Was installed. PBS solution (composition: 8.0 g / L NaCl, 0.2 g / L KCl, 1.15 g / L Na 2 HPO 4 , 0.2 g / L KH 2 PO 4 , pH 7.2 to 7.6) The cell D was placed in a thermostatic bath (not shown), and the temperature of the PBS solution was maintained at 37 ° C. High purity nitrogen gas was bubbled into the PBS solution for 30 minutes or more. Thereafter, the electrodes S1 and S2 prepared above were immersed in a PBS solution. The current flowing between the counter electrode (electrode S1) and the sample electrode (electrode S2) was measured with a non-resistance ammeter (“I” in FIG. 3). The measurement temperature at this time was adjusted to 37 ° C.

図４に示されるように、第２の金属材料である金は、第１の金属材料であるＬ６０５に対してガルバニック電流（局部電流）が生じ、腐食していることが分かる。   As shown in FIG. 4, it can be seen that gold, which is the second metal material, corrodes due to a galvanic current (local current) generated with respect to L605, which is the first metal material.

＜実施例１＞
純Ｃｏ、純Ｃｒ、純Ｗ、純Ｎｉ、純Ｍｎ等の各粉末を秤量し、アトマイズ法でＬ６０５粉末を作製する。また、純Ａｕ粉末を準備する。作製したＬ６０５粉末および純Ａｕ両粉末はそれぞれ分級し、Ｌ６０５粉末は５０μｍの篩を通った物、Ａｕ粉末は１０μｍの篩を通った物を使用する。両粉末およびバインダー（重量比で、金属粉末１００重量％に対して、オリコックスＫＣ−１１００を５重量％、テルピネオールを２０重量％）を混粉し（Ｌ６０５粉末とＡｕ粉末の配合重量比率＝７：３）、３０ＭＰａ、３００℃で、３分間温間プレスにより形状を作製した後、８００℃、Ａｒ雰囲気下で１時間焼結を行う。次に８００℃、１５０ＭＰａで１時間、ＨＩＰ（Ｈｏｔ Ｉｓｏｓｔａｔｉｃ Ｐｒｅｓｓ）を行い、密度を９７体積％程度にまで上昇させる。 <Example 1>
Each powder of pure Co, pure Cr, pure W, pure Ni, pure Mn, etc. is weighed, and L605 powder is produced by an atomizing method. Moreover, pure Au powder is prepared. The prepared L605 powder and pure Au both powders are classified, and the L605 powder uses a product that has passed through a 50 μm sieve, and the Au powder uses a product that has passed through a 10 μm sieve. Both powders and binder (5% by weight of Oricox KC-1100 and 20% by weight of terpineol with respect to 100% by weight of metal powder by weight ratio) were mixed (weight ratio of L605 powder and Au powder = 7 : 3) After forming a shape by warm pressing at 30 MPa and 300 ° C. for 3 minutes, sintering is performed in an Ar atmosphere at 800 ° C. for 1 hour. Next, HIP (Hot Isostatic Press) is performed at 800 ° C. and 150 MPa for 1 hour to increase the density to about 97% by volume.

このようにして作製したロッドを切削加工により中心部を繰り抜き、パイプ形状にする。これをレーザー加工によりステントのパターンにカットし、さらに化学研磨、電解研磨を施しステントを作製する。   The rod thus produced is cut out at the center to form a pipe. This is cut into a stent pattern by laser processing, and further subjected to chemical polishing and electrolytic polishing to produce a stent.

１ ステント、
２ ステント本体（基材）、
Ｓ１ 対極、
Ｓ２ 試料極、
Ｓ３ 参照極、
Ｄ セル、
Ｉ 無抵抗電流計、
Ｅ エレクトロメーター。 1 stent,
2 Stent body (base material),
S1 counter electrode,
S2 Sample electrode,
S3 reference electrode,
D cell,
I Non-resistance ammeter,
E Electrometer.

Claims (7)

第１の金属材料から形成された基材と、前記基材に分散された第２の金属材料との焼結体からなる、ガルバニック腐食ステントであって、
前記第２の金属材料が、前記第１の金属材料より貴な金属であり、生体内に留置された後、ガルバニック腐食によって分解される、ガルバニック腐食ステント。 A galvanic corrosion stent comprising a sintered body of a base material formed from a first metal material and a second metal material dispersed in the base material,
The galvanic erosion stent, wherein the second metal material is a noble metal than the first metal material and is decomposed by galvanic corrosion after being placed in a living body. 前記第１の金属材料と、前記第２の金属材料の自然浸漬電位の差が２００ｍＶを超えて１０００ｍＶ以下である、請求項１に記載のガルバニック腐食ステント。   The galvanic corrosion stent according to claim 1, wherein a difference in natural immersion potential between the first metal material and the second metal material is more than 200 mV and 1000 mV or less. 前記第１の金属材料が、Ｃｏ−Ｃｒ合金である、請求項１または２に記載のガルバニック腐食ステント。   The galvanic corrosion stent according to claim 1 or 2, wherein the first metal material is a Co-Cr alloy. 前記第２の金属材料が、金、白金、銀、パラジウムおよびそれらを主成分とする合金のいずれかである、請求項１〜３のいずれか１項に記載のガルバニック腐食ステント。   The galvanic corrosion stent according to any one of claims 1 to 3, wherein the second metal material is any one of gold, platinum, silver, palladium, and an alloy containing them as a main component. 前記ステントの厚みが５〜３００μｍである、請求項１〜４のいずれか１項に記載のガルバニック腐食ステント。   The galvanic corrosion stent according to any one of claims 1 to 4, wherein the stent has a thickness of 5 to 300 µm. 前記第２の金属材料が、前記基材に海島状に分散される、請求項１〜５のいずれか１項に記載のガルバニック腐食ステント。   The galvanic corrosion stent according to any one of claims 1 to 5, wherein the second metal material is dispersed in a sea-island shape on the base material. 前記第２の金属材料が、ステント全体積の１〜８０％の割合で海島状に分散される、請求項６に記載のガルバニック腐食ステント。   The galvanic erosion stent according to claim 6, wherein the second metal material is dispersed in a shape of a sea island at a rate of 1 to 80% of a total volume of the stent.
JP2013079323A 2013-04-05 2013-04-05 Galvanic corrosion stent Pending JP2016105749A (en)

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