JP4152704B2

JP4152704B2 - Stent

Info

Publication number: JP4152704B2
Application number: JP2002271327A
Authority: JP
Inventors: 健池内; 浩二森; 博夫岩田; 和明光藤; 弘章野見山; 吉治吉川; 正年渡辺
Original assignee: Kawasumi Laboratories Inc; Japan Stent Technology Co Ltd
Current assignee: Japan Stent Technology Co Ltd; SB Kawasumi Laboratories Inc
Priority date: 2000-04-20
Filing date: 2002-09-18
Publication date: 2008-09-17
Anticipated expiration: 2020-08-04
Also published as: JP2003117005A

Description

【０００１】
【発明の属する技術分野】
本発明は血管等の生体内に生じた狭窄部の改善に使用されるステントの改良に関する。
【０００２】
【従来の技術及び発明が解決しようとする課題】
図１１、図１２は現在使用されているステント２０１、２４１の平面図である（図１１、図１２で（Ａ）は拡張前、（Ｂ）は拡張後の平面図）。各ステント２０１、２４１には次の課題があった。
図１１のステント２０１は、環状ユニット２０４を構成するセル２０６は３本の直線部２０７を平行に接続し、各セル２０６間の湾曲部２０６Ａが他の環状ユニット２０４を構成するセル２０６近傍の空間２０６Ｂに対向して配置されている構造である。このため適度の放射支持力（ステントを拡張して血管壁に固定した時に、血管壁方向からの外圧に対抗してステントの拡張状態を維持しようとする力）と柔軟性に優れていることが知られているが、Ａの部分において拡張時やデリバリー時に血管の屈曲部で曲線を描きながら挿入されるのでセル２０６の一部が外側突出し引っ掛かり、デリバリーが困難となる場合があった。（以下、これをフレアー現象と称する）。
図１２のステント２４１は環状ユニット２４４を構成するセル２４６は、略＜形状ストラット２４７が連結部２４５により連結されている構造である。このため放射支持力が強く、拡張時や血管の屈曲部通過時に略＜形状ストラット２４７が外側に反ることがない等の利点を持つが、柔軟性に欠けるという課題があった。これは連結部２４５に屈曲部が１つであり連結部２４５の長さも短いことが原因であった。
そこで本発明者らは以上の課題を解決し柔軟性と放射支持力を有するステントを提供するために鋭意検討を重ねた結果次の発明に到達した。
【０００３】
【課題を解決するための手段】
［１］本発明は、略管状体に形成されかつ管状体の内部より半径方向に伸張可能なステント（１）であって、
複数のセル（６）を上下に連結し、当該複数のセル（６）をステント（１）の中心軸（Ｃ１）を取り囲むように複数配列することにより環状ユニット（４）を構成し、
複数の前記環状ユニット（４）がステント（１）の軸方向に配置され、前記隣り合う環状ユニット（４）同士は少なくとも一箇所が連結部（５）により連結され、
前記連結部（５）は、少なくとも２個以上の屈曲部（８）と、当該屈曲部（８）を構成する弧と、当該屈曲部（８）と連続する略直線部（７）から形成され、前記屈曲部（８）の端部は、前記セル（６）の左ないし右端部と接続され、
前記複数のセル（６）は、それぞれステント軸方向の中心線（Ｃ２）を有し、それぞれ当該軸方向の中心線（Ｃ２）に対して略平行に配置された略直線部（１１）と、当該中心線（Ｃ２）に対して鋭角（Ｘ）に配置された曲線部（１３）とを屈曲部（１２）を介して接続するものであって、
前記曲線部（１３）は、その一部を構成しかつ前記屈曲部（１２）と隣接する略直線部（１５）を、前記屈曲部（１２）を介してステント軸方向の中心線（Ｃ２）に対して略平行に配置された略直線部（１１）と接続しており、
前記セル（６）は、ステント軸方向の中心線（Ｃ２）で上下に区画した場合、中心線（Ｃ２）に対して上下非対称に形成され、
前記ステント（１）は、少なくともφ２．５ｍｍに拡張しうるものであって、
前記屈曲部（１２）に隣接する前記略直線部（１５）と前記略直線部（１１）の拡張後の角度θを３０°〜１４０°であるように形成し、
生理活性物質または抗血栓薬剤を被覆したステント（１）を提供する。
［２］本発明は、略管状体に形成されかつ管状体の内部より半径方向に伸張可能なステント（１Ａ）であって、
複数のセル（６Ａ）を上下に連結し、当該複数のセル（６Ａ）をステント（１Ａ）の中心軸（Ｃ１）を取り囲むように複数配列することにより環状ユニット（４Ａ）を構成し、
複数の前記環状ユニット（４Ａ）がステント（１Ａ）の軸方向に配置され、前記隣り合う環状ユニット（４Ａ）同士は少なくとも一箇所が連結部（５Ａ）により連結され、
前記連結部（５Ａ）は、少なくとも２個以上の屈曲部（８Ａ）と、当該屈曲部（８Ａ）を構成する弧と、当該屈曲部（８Ａ）と連続する略直線部（７Ａ）から形成され、前記屈曲部（８Ａ）の端部は、前記セル（６Ａ）の左ないし右端部と接続され、
前記複数のセル（６Ａ）は、それぞれステント軸方向の中心線（Ｃ２）を有し、それぞれ当該軸方向の中心線（Ｃ２）に対して鋭角（Ｘ）に配置された略直線部（１１Ａ）と、当該軸方向の中心線（Ｃ２）に対して略平行に配置された曲線部（１３Ａ）とを屈曲部（１２Ａ）を介して接続するものであって、
前記曲線部（１３Ａ）は、その一部を構成しかつ前記屈曲部（１２Ａ）と隣接する略直線部（１５Ａ）を、前記屈曲部（１２Ａ）を介してステント軸方向の中心線（Ｃ２）に対して鋭角（Ｘ）に配置された略直線部（１１Ａ）と接続しており、
前記セル（６Ａ）は、ステント軸方向の中心線（Ｃ２）で上下に区画した場合、中心線（Ｃ２）に対して上下非対称に形成され、
前記ステント（１Ａ）は、少なくともφ２．５ｍｍに拡張しうるものであって、
前記屈曲部（１２Ａ）に隣接する前記略直線部（１５Ａ）と前記略直線部（１１Ａ）の拡張後の角度θを３０°〜１４０°であるように形成し、
生理活性物質または抗血栓薬剤を被覆したステント（１Ａ）を提供する。
［３］本発明は、略管状体に形成されかつ管状体の内部より半径方向に伸張可能なステント（１Ｂ）であって、
複数のセル（６Ｂ）を上下に連結し、当該複数のセル（６Ｂ）をステント（１Ｂ）の中心軸（Ｃ１）を取り囲むように複数配列することにより環状ユニット（４Ｂ）を構成し、
複数の前記環状ユニット（４Ｂ）がステント（１Ｂ）の軸方向に配置され、前記隣り合う環状ユニット（４Ｂ）同士は少なくとも一箇所が連結部（５Ｂ）により連結され、
前記連結部（５Ｂ）は、少なくとも２個以上の屈曲部（８Ｂ）と、当該屈曲部（８Ｂ）を構成する弧と、当該屈曲部（８Ｂ）と連続する略直線部（７Ｂ）から形成され、前記屈曲部（８Ｂ）の端部は、前記セル（６Ｂ）の左ないし右端部と接続され、
前記複数のセル（６Ｂ）は、それぞれステント軸方向の中心線（Ｃ２）を有し、それぞれ当該軸方向の中心線（Ｃ２）に対して鋭角（Ｘ）を有する略直線部（１１Ｂ）と、当該軸方向の中心線（Ｃ２）に対して略平行に配置された略直線部（１３Ｂ）とを屈曲部（１２Ｂ）を介して接続することにより形成しており、
前記セル（６Ｂ）は、ステント軸方向の中心線（Ｃ２）で上下に区画した場合、中心線（Ｃ２）に対して上下非対称に形成され、
前記ステント（１Ｂ）は、少なくともφ２．５ｍｍに拡張しうるものであって、
前記屈曲部（１２Ｂ）に隣接する前記略直線部（１３Ｂ）と前記略直線部（１１Ｂ）の拡張後の角度θを３０°〜１４０°であるように形成し、
生理活性物質または抗血栓薬剤を被覆したステント（１Ｂ）を提供する。
【０００４】
【発明の実施の形態】
図１は本発明のステントの平面図（図２は図１の拡大図、図３は拡張後の本発明のステントの状態を示す拡大図、図４はセルを構成するストラットの概念図）である。
ステント１は略管状体に形成されかつ管状体の内部より半径方向に伸張可能であって、複数のセル６を上下に連結し、これらをステント１の中心軸Ｃ１を取り囲むように複数配列することにより環状ユニット４を構成し、複数の前記環状ユニット４がステント１の軸方向に延設され、前記環状ユニット４同士は少なくとも一箇所が連結部５により連結されている。
【０００５】
本発明で前記セル６とは、ステント１の表面を構成する模様の一つの構成単位を意味し、図２のように少なくとも一つ以上の鋭角Ｘを有する屈曲部１２を有し、これを介して略直線部１１と曲線部１３を接続して構成される全ての形態を含む。さらに前記セル６はステント軸方向の中心線Ｃ２で上下に区画した場合、中心線Ｃ２に対して上下非対称に形成され、屈曲部１２の拡張後の角度θを図３のように３０°以上となるように形成している。
屈曲部１２の拡張後の角度θとは図３のように屈曲部１２上の点Ｏと略直線部１１及び曲線部１３の点Ｏ側に近い略直線部１５との間に形成される角度を意味する。
セル６は屈曲部１２を介して略直線部１１と曲線部１３を連結することにより構成され、曲線部１３は鈍角Ｙを有する小屈曲部１４を２箇所以上形成するのが良い。
【０００６】
セル６を構成する略直線部１１及び屈曲部１２、小屈曲部１４からなる曲線部１３（略Ｓ形状部ともいう）は、ステントの拡張後において中心軸Ｃ１に対し垂直に近くなるほうが、ステントの放射支持力が大きくなる。これにより屈曲部１２の拡張後の角度θは１８０°に近づくほどステントの放射支持力が大きくなることを見出した。すなわちステントの設計においては、少なくともφ２．５ｍｍに拡張した時において、屈曲部１２の拡張後の角度θは、少なくとも３０°以上に設計するのが良い。
また、これらはセル６の配置数にも関係するため、セル６の半径方向の配置数は、４個以上が好ましい。さらに拡張後の径としてφ３．０ｍｍ以上となる場合においては６個以上、好ましくは６個から１２個配置するのが良い。またステント軸方向においては１０ｍｍあたり３個以上好ましくは４個から８個配置し、ステント拡張の目標径（規格径、例えばφ３．０、φ４．０）となった時点において、例えば先に述べたように屈曲部１２の拡張後の角度θが、少なくとも３０°以上、好ましくは４５°から１４０°、より好ましくは４５°から１２０°の間に設計するのが良い。
目標径において１４０°を越えるように設計することは、ステントの放射支持力には有効であるが、屈曲部１２の変形量が大きくなり強度に問題が出ること、拡張に伴うステントの全長短縮（フォーショートニング）が大きくなり、ステント留置時の位置決めが困難となる等の問題が起こり好ましくない。
【０００７】
またセル６のストラットの形状はステント軸方向の中心線Ｃ２に対して図４（ａ）のように対称に形成するよりも図４（ｂ）のように非対称に形成するほうがストラット全体の相対的な長さが大きくなり（例えば図４（ａ）と（ｂ）を比較すると必ず２ａ＜ｃ＋ｄとなる）、ステント自体の拡張性を高めるとともにフォーショートニングの抑制効果を高めることができる。
【０００８】
前記連結部５は、少なくとも２個以上の屈曲部を有し、例えばステント１では中央の略直線部７の両側に屈曲部８を接続することにより構成され、屈曲部８の端部は接続部９を介してそれぞれ異なる環状ユニット４を構成する前記セル６の端部と接続されている。
前記連結部５は前記セル６の両端に左右非対称に接続されている。
連結部５は略直線部７と屈曲部８を合わせた全体の長さが１ｍｍ以上で長いほど柔軟性は向上すると考えられ良いが、長くすると比例して略Ｓ形状の連結部５が大きくなり、該ステントをバルーンカテーテルにマウントする時（バルーンカテーテル上で若干ステントの径を縮小することがある）や、血管の屈曲部通過時にステントは血管に沿って湾曲した時に、上下の連結部５が干渉しあい、逆に柔軟性を損なうこととなる。そのため、全体の長さが１ｍｍ以上、好ましくは１ｍｍから２ｍｍが良い。さらに屈曲部８を構成する弧のＲ（半径）も上述の理由により、Ｒ＝０．０５ｍｍ以上、好ましくは０．０５ｍｍから０．２ｍｍに形成するのが良い。
さらに本発明では前記セル６のステント軸方向の長さ６Ｌと前記連結部５のステント軸方向５の長さ方向５Ｌの比率を、６Ｌを１００とすると５Ｌを５０から１００に形成するのが好ましいが設計の都合上、５０から９０に形成するのが良い。これによりステントの拡張後やデリバリー時のフレアー現象を抑制するとともにステント自体に柔軟性を付与することができる。
【０００９】
本発明のステント１のパターンの特徴は次のとおりである。
セル６は連結部５を介してステント軸方向に非対称に配置されているがステント軸方向に同じ向きで同じ高さに配置されている。ステント軸方向のセル６は仮にｎ列目から（ｎ＋１）列目にステント軸方向に移動させて見た時、相互に重なり合うように配置されている。また同じ列のセル６も同列の上または下にスライドさせて見た時、相互に重なり合うようにステント半径方向に同じ向きに配置されている。ここで略直線部１１は、中心線Ｃ２に対し略水平（略平行）であるが、屈曲部１２の拡張後の角度θが３０゜未満とならない範囲で若干角度をつけ斜めにしても良い。
【００１０】
連結部５もセル６を介してステント軸方向に非対称に配置されているが、ステント軸方向に同じ向きでかつ同じ高さに配置されている。ステント軸方向の連結部５は仮にｎ列目から（ｎ＋１）列目にステント軸方向に移動させて見た時、相互に重なり合うように配置されている。また同じ列の連結部５も同列の上または下にスライドさせて見た時、相互に重なり合うようにステント半径方向に同じ向きに配置されている。
また、セル６を構成するストラットの幅は連結部５を構成するストラットの幅よりも大きく形成され、ステント軸方向のセル６と連結部５の高さは連結部５かセル６よりも高い位置にずらして配置されている。
【００１１】
以上のように本発明のステント1は前記屈曲部１２の拡張後の角度θ、セル６のステント軸方向の長さ６Ｌとステント軸方向の長さ５Ｌの比率、前記連結部５とセル６の形態、連結部５とセル６のステントの半径方向並びに軸方向の配置（パターン）により、血管へのデリバリー時に、図５に示すようにステント１の径を縮小させた時に、セル６と連結部５がそれぞれお互いにステントの半径方向に立体的に重なることがなく、相互間のステントの半径方向の空間Ｓ内に納まるように形成されている。
【００１２】
図６及び図８は本発明のステントのその他の実施例を示す平面図（図７及び図９は図６及び図８の一部拡大平面図）である。
図６（図７）のステント１Ａは、図１のステント１と比較して、（ａ）セル６Ａがステント１Ａの軸方向の中心線Ｃ２に対して鋭角Ｘを有する略直線部１１Ａを屈曲部１２Ａを介して曲線部１３Ａと接続することにより構成されている（ステント１は、セル６がステント１の軸方向の中心線Ｃ２に対して略水平（略平行）に配置された略直線部１１を屈曲部１２を介して曲線部１３と接続することにより構成されている）点、（ｂ）セル６Ａが連結部５Ａを介してステント１Ａの軸方向に左右対称に配置されている点、（ｃ）ステント１Ａ軸方向のセル６Ａは仮にｎ列目から（ｎ＋２）列目に一列置きにステント１Ａの軸方向に見た場合、相互に重なり合うように配置されている点等が異なるのみで、その他の各構成部材及びこれらの定義等はステント１と実質的に同じであるから詳細な説明は省略する。
【００１３】
また図８（図９）のステントは１Ｂは、図１、図６（図７）のステント１、１Ａと比較して、（ａ）セル６Ｂがステント１Ｂの軸方向の中心線Ｃ２に対して鋭角Ｘを有する略直線部１１Ｂを屈曲部１２Ｂを介してステント１の軸方向の中心線Ｃ２に対して略水平（略平行）に配置された略直線部１３Ｂと接続することにより構成されている（ステント１、１Ａは、セル６、６Ａが略直線部１１、１１Ａを屈曲部１２を介して曲線部１３、１３Ａと接続することにより構成されている）点等がステント１、１Ａと異なるのみで、（ｂ）セル６Ｂが連結部５Ｂを介してステント１Ｂの軸方向に左右対称に配置されている点及び（ｃ）ステント１Ｂ軸方向のセル６Ｂは仮にｎ列目から（ｎ＋２）列目に一列置きにステント１Ｂの軸方向に見た場合、相互に重なり合うように配置されている点等はステント１と異なり、ステント１Ａと実質的に同じである。その他の各構成部材及びこれらの定義等はステント１、１Ａ実質的に同じであるから詳細な説明は省略する。
【００１４】
また本発明の前記図１、６、８に例示したステント１、１Ａ、１Ｂでは、各環状ユニット４、４Ａ、４Ｂを構成するセル６、６Ａ、６Ｂの連結部５、５Ａ、５Ｂは、ステント１、１Ａ、１Ｂの半径方向に隙間無く連続して配置されているが、半径方向に少なくとも一個以上の空間を空けて配置（一個置きあるいは一個または二個置きに空間を空けて配置する）ことにより、ステント１、１Ａ、１Ｂ全体がより柔軟となり、分岐した血管へのデリバリー性が向上することが期待される。
【００１５】
本発明のステント１（１Ａ、１Ｂ）はＳＵＳ３１６Ｌ等のステンレス鋼、Ｔｉ−Ｎｉ合金、Ｃｕ−Ａｌ−Ｍｎ合金等の形状記憶合金、チタン合金、タンタル等からなる金属パイプから例えばレーザー加工法等により形成される。
またこれらの金属より形成されたステントにウレタン等の高分子材料やヘパリン、ウロキナーゼ等の生理活性物質、アルガトロバン等の抗血栓薬剤を被覆させるのも良い。
【００１６】
実施例１
図１０に示す略＜形状のセル１７と略Ｓ形状の接続部１８からなる構成部１９により構成されるステントＡ（Ｂ）において、拡張後の角度の違いによる放射支持力の差を評価するため、円周方向に構成部１９の配置数が異なるステントＡ、Ｂを製作し放射支持力を評価した。
ステントＡ：構成部１９の配置数８
セル１７のストラット幅０．１２ｍｍ
３ｍｍ拡張後の１θ角度６０゜
ステントＢ：構成部１９の配置数６
セル１７のストラット幅０．１２ｍｍ
３ｍｍ拡張後の１θ角度８１゜
評価は、ステントをチャンバー内に配置したシリコンチューブ内にφ３ｍｍまで拡張して留置した後、チャンバー内に空気にて圧力をかけステントの外径変化を測定することにより評価した。
【００１７】
【表１】

表１に示すように、拡張後の角度の大きいステントＢが−０．０４ｍｍ（外径が０．０４ｍｍ減少した）で変化量が少なく放射支持力が大きいことが確認できた。
【００１８】
実施例２
図１に示すステント１を製作し、放射支持力をステント２０１、２４１と比較し、柔軟性をステント２０１と比較し評価した。放射支持力の評価は実施例１と同じ方法で行い、柔軟性は４点曲げ法にて評価した。
【００１９】
【表２】

【００２０】
【表３】

以上のように、本発明のステント１は表２の結果よりステント２０１、２４１より外径変化量が少なく、表３の結果よりステント２０１より曲げ強度が小さいことが確認できた。したがって本発明のステント１は高い放射支持力と柔軟性を併せ持つステントであることが理解できる。
【００２１】
実施例３
ステント１Ａ、１Ｂも実施例１、２と同様に放射支持力と柔軟性を測定し評価したところステント１と実質的に同様の結果が得られた。
【００２２】
【表４】

【００２３】
【表５】

【００２４】
実施例４
本発明のステント１、１Ａ及び１Ｂについて、φ３．０ｍｍに拡張したときのフォーショートニング値を測定した。測定は、拡張前の各ステント長（Ｌ１とする）を測定し、φ３．０まで拡張した後のステント長（Ｌ２）を計測し、全長の縮小率を算出しフォーショートニング値とした。比較例としてステント２０１、２４１も測定した。
【００２５】
【表６】

表６の結果より、本発明のステント１、１Ａ、１Ｂはステント２０１、２４１よりもフォーショートニング値が小さいことが確認できた。
【００２６】
【発明の作用効果】
本発明のステントは高い柔軟性と放射支持力を充分に確保するとともに、血管拡張性を高めフォーショートニング並びにフレアー現象を抑えることができる。
【図面の簡単な説明】
【図１】本発明のステントの平面図
【図２】図１の拡大図
【図３】拡張後の本発明のステントの状態を示す拡大図
【図４】セルを構成するストラットの概念図
【図５】血管へのデリバリー時に、ステント１の径を縮小させた時の拡大図
【図６】本発明のステントのその他の実施例を示す平面図
【図７】図６の一部拡大平面図
【図８】本発明のステントのその他の実施例を示す平面図
【図９】図８の一部拡大平面図
【図１０】本発明のステントの参考例の拡大図
【図１１】従来のステントの平面図
【図１２】従来のステントの平面図
【符号の説明】
１、１Ａ、１Ｂステント
４、４Ａ、４Ｂ環状ユニット
５、５Ａ、５Ｂ連結部
６、６Ａ、６Ｂセル
７略直線部
８、８Ａ、８Ｂ屈曲部
９接続部
１１、１１Ａ、１１Ｂ、１３Ｂ略直線部
１２、１２Ａ、１２Ｂ屈曲部
１３、１３Ａ曲線部
１４、１４Ａ小屈曲部
１５略直線部
１７略＜形状のセル
１８略Ｓ形状の接続部
１９ステントＡ、Ｂにおける構成部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in a stent used to improve a stenosis that occurs in a living body such as a blood vessel.
[0002]
[Prior art and problems to be solved by the invention]
11 and 12 are plan views of the

stents

201 and 241 that are currently used (in FIGS. 11 and 12, (A) is a plan view before expansion, and (B) is a plan view after expansion). Each of the

stents

201 and 241 has the following problems.
In the stent 201 of FIG. 11, the cells 206 constituting the annular unit 204 connect three straight portions 207 in parallel, and a curved portion 206 A between the cells 206 is a space in the vicinity of the cell 206 constituting the other annular unit 204. This is a structure arranged to face 206B. For this reason, it should be excellent in moderate radiation support force (force to maintain the expanded state of the stent against the external pressure from the blood vessel wall direction when the stent is expanded and fixed to the blood vessel wall) and flexibility. As is known, since the portion A is inserted while drawing a curve at the bent portion of the blood vessel at the time of expansion or delivery, a part of the cell 206 protrudes outwardly and may be difficult to deliver. (Hereinafter, this is called a flare phenomenon).
The stent 241 in FIG. 12 has a structure in which the cells 246 constituting the annular unit 244 are substantially <shaped struts 247 are connected by a connecting portion 245. For this reason, the radiation supporting force is strong, and there is an advantage that the shape strut 247 does not warp outward when dilating or passing through the bent portion of the blood vessel, but there is a problem that it lacks flexibility. This is because the connecting portion 245 has one bent portion and the length of the connecting portion 245 is short.
Accordingly, the present inventors have intensively studied to solve the above problems and provide a stent having flexibility and radiation support force, and as a result, have reached the following invention.
[0003]
[Means for Solving the Problems]
[1] The present invention provides a stent (1) that is formed in a substantially tubular body and is radially expandable from the inside of the tubular body,
A plurality of cells (6) are connected vertically, and a plurality of the cells (6) are arranged so as to surround the central axis (C1) of the stent (1), thereby forming an annular unit (4).
A plurality of the annular units (4) are disposed in the axial direction of the stent (1), and the adjacent annular units (4) are connected to each other by at least one connection part (5),
The connecting portion (5) is formed of at least two or more bent portions (8), an arc constituting the bent portion (8), and a substantially straight portion (7) continuous with the bent portion (8). The end of the bent portion (8) is connected to the left or right end of the cell (6),
Each of the plurality of cells (6) has a center line (C2) in the stent axial direction, and a substantially straight line portion (11) disposed substantially parallel to the axial center line (C2), A curved portion (13) disposed at an acute angle (X) with respect to the center line (C2) is connected via a bent portion (12),
The curved portion (13) constitutes a part thereof and a substantially straight portion (15) adjacent to the bent portion (12) passes through the bent portion (12), and the center line (C2) in the stent axial direction. Connected to a substantially straight line portion (11) disposed substantially parallel to
The cell (6) is vertically asymmetric with respect to the center line (C2) when the cell (6) is vertically divided by the center line (C2) in the stent axial direction,
The stent (1) is expandable to at least φ2.5 mm,
Forming an angle θ after expansion of the substantially linear portion (15) adjacent to the bent portion (12) and the substantially linear portion (11) to be 30 ° to 140 °;
A stent (1) coated with a physiologically active substance or an antithrombotic agent is provided.
[2] The present invention provides a stent (1A) that is formed in a substantially tubular body and is radially expandable from the inside of the tubular body,
A plurality of cells (6A) are vertically connected, and a plurality of the cells (6A) are arranged so as to surround the central axis (C1) of the stent (1A) to constitute the annular unit (4A).
A plurality of the annular units (4A) are arranged in the axial direction of the stent (1A), and the adjacent annular units (4A) are connected to each other by at least one connection portion (5A),
The connecting portion (5A) is formed of at least two or more bent portions (8A), an arc constituting the bent portion (8A), and a substantially straight portion (7A) continuous with the bent portion (8A). The end of the bent portion (8A) is connected to the left or right end of the cell (6A),
Each of the plurality of cells (6A) has a center line (C2) in the axial direction of the stent, and is substantially linear (11A) arranged at an acute angle (X) with respect to the central line (C2) in the axial direction. And a curved portion (13A) arranged substantially parallel to the axial center line (C2) via a bent portion (12A),
The curved portion (13A) constitutes a part thereof and a substantially straight portion (15A) adjacent to the bent portion (12A) passes through the bent portion (12A) in the stent axial direction center line (C2). Connected to a substantially straight line portion (11A) disposed at an acute angle (X),
The cell (6A) is vertically asymmetric with respect to the center line (C2) when the cell (6A) is partitioned vertically by the center line (C2) in the stent axial direction,
The stent (1A) is expandable to at least φ2.5 mm,
Forming the angle θ after expansion of the substantially linear portion (15A) adjacent to the bent portion (12A) and the substantially linear portion (11A) to be 30 ° to 140 °;
Providing a physiologically active substance or antithrombotic drugs coated stents (1A).
[3] The present invention provides a stent (1B) that is formed in a substantially tubular body and is radially expandable from the inside of the tubular body,
A plurality of cells (6B) are vertically connected, and the plurality of cells (6B) are arranged so as to surround the central axis (C1) of the stent (1B) to constitute an annular unit (4B).
A plurality of the annular units (4B) are arranged in the axial direction of the stent (1B), and the adjacent annular units (4B) are connected to each other by at least one connection portion (5B),
The connecting portion (5B) is formed of at least two or more bent portions (8B), an arc constituting the bent portion (8B), and a substantially straight portion (7B) continuous with the bent portion (8B). The end of the bent portion (8B) is connected to the left or right end of the cell (6B),
The plurality of cells (6B) each have a center line (C2) in the stent axial direction, and a substantially straight portion (11B) having an acute angle (X) with respect to the axial center line (C2), respectively. It is formed by connecting a substantially straight part (13B) arranged substantially parallel to the axial center line (C2) via a bent part (12B),
The cell (6B) is vertically asymmetric with respect to the center line (C2) when the cell (6B) is partitioned vertically by the center line (C2) in the stent axial direction,
The stent (1B) is expandable to at least φ2.5 mm,
Forming the angle θ after expansion of the substantially linear portion (13B) and the substantially linear portion (11B) adjacent to the bent portion (12B) to be 30 ° to 140 °;
A stent (1B) coated with a physiologically active substance or an antithrombotic agent is provided.
[0004]
DETAILED DESCRIPTION OF THE INVENTION
1 is a plan view of a stent of the present invention (FIG. 2 is an enlarged view of FIG. 1, FIG. 3 is an enlarged view showing a state of the stent of the present invention after expansion, and FIG. 4 is a conceptual view of struts constituting a cell). is there.
The stent 1 is formed in a substantially tubular body and is radially expandable from the inside of the tubular body, and a plurality of cells 6 are connected vertically, and a plurality of these cells are arranged so as to surround the central axis C1 of the stent 1. To form an annular unit 4, a plurality of the annular units 4 are extended in the axial direction of the stent 1, and at least one of the annular units 4 is connected by a connecting portion 5.
[0005]
In the present invention, the cell 6 means one structural unit of a pattern constituting the surface of the stent 1, and has at least one bent portion 12 having an acute angle X as shown in FIG. All forms configured by connecting the substantially linear portion 11 and the curved portion 13 are included. Further, when the cell 6 is vertically divided by the center line C2 in the stent axial direction, it is formed vertically asymmetric with respect to the center line C2, and the angle θ after expansion of the bent portion 12 is 30 ° or more as shown in FIG. It is formed to become.
The angle θ after expansion of the bent portion 12 is an angle formed between the point O on the bent portion 12 and the substantially straight portion 15 close to the point O side of the substantially straight portion 11 and the curved portion 13 as shown in FIG. Means.
The cell 6 is configured by connecting the substantially straight line portion 11 and the curved portion 13 via the bent portion 12, and the curved portion 13 is preferably formed with two or more small bent portions 14 having an obtuse angle Y.
[0006]
The curved portion 13 (also referred to as a substantially S-shaped portion) composed of the substantially straight portion 11, the bent portion 12, and the small bent portion 14 constituting the cell 6 is closer to being perpendicular to the central axis C1 after the stent is expanded. Increases the radiation support force. As a result, it has been found that the radiation support force of the stent increases as the angle θ after expansion of the bent portion 12 approaches 180 °. That is, in the design of the stent, the angle θ after expansion of the bent portion 12 is preferably designed to be at least 30 ° or more when expanded to at least φ2.5 mm.
Moreover, since these relate to the number of cells 6 arranged, the number of cells 6 arranged in the radial direction is preferably four or more. Further, when the diameter after expansion is φ3.0 mm or more, 6 or more, preferably 6 to 12 are arranged. Further, in the stent axial direction, 3 or more, preferably 4 to 8 are arranged per 10 mm, and when the target diameter of the stent expansion (standard diameter, for example, φ3.0, φ4.0) is reached, for example, as described above Thus, the angle θ after expansion of the bent portion 12 should be designed to be at least 30 ° or more, preferably 45 ° to 140 °, more preferably 45 ° to 120 °.
Designing the target diameter to exceed 140 ° is effective for the radial support force of the stent, but the amount of deformation of the bent portion 12 increases, causing a problem in strength, and shortening the total length of the stent accompanying expansion ( For shortening) becomes large, and problems such as difficulty in positioning during stent placement occur, which is not preferable.
[0007]
The strut shape of the cell 6 is relatively asymmetrical as shown in FIG. 4 (b) rather than symmetrically as shown in FIG. 4 (a) with respect to the center line C2 in the stent axial direction. (E.g., 2a <c + d when comparing FIGS. 4 (a) and 4 (b)), the expandability of the stent itself can be enhanced and the foreshortening suppressing effect can be enhanced.
[0008]
The connecting part 5 has at least two or more bent parts. For example, in the stent 1, the connecting part 5 is configured by connecting the bent parts 8 to both sides of the substantially straight part 7 at the center, and the end of the bent part 8 is a connecting part. 9 are connected to the end portions of the cells 6 constituting different annular units 4.
The connecting portion 5 is connected to both ends of the cell 6 asymmetrically.
The connecting portion 5 may be considered to be improved in flexibility as the total length of the substantially straight portion 7 and the bent portion 8 is longer than 1 mm. However, as the connecting portion 5 becomes longer, the substantially S-shaped connecting portion 5 becomes proportionally larger. When the stent is mounted on a balloon catheter (the diameter of the stent may be slightly reduced on the balloon catheter) or when the stent is bent along the blood vessel when passing through the bent portion of the blood vessel, the upper and lower connecting portions 5 are Interference, and conversely, flexibility is lost. Therefore, the total length is 1 mm or more, preferably 1 mm to 2 mm. Furthermore, the R (radius) of the arc constituting the bent portion 8 is also preferably set to R = 0.05 mm or more, preferably 0.05 mm to 0.2 mm, for the reason described above.
Further, in the present invention, it is preferable that the ratio of the length 6L of the cell 6 in the stent axial direction and the length direction 5L of the connecting portion 5 in the stent axial direction 5 is 5L from 50 to 100, where 6L is 100. However, it is preferable to form 50 to 90 for convenience of design. As a result, it is possible to suppress the flare phenomenon after expansion of the stent or during delivery and to impart flexibility to the stent itself.
[0009]
The features of the pattern of the stent 1 of the present invention are as follows.
The cells 6 are arranged asymmetrically in the stent axial direction via the connecting portion 5 but are arranged in the same direction and at the same height in the stent axial direction. The cells 6 in the stent axis direction are arranged so as to overlap each other when viewed from the nth column to the (n + 1) th column in the stent axis direction. The cells 6 in the same row are also arranged in the same direction in the radial direction of the stent so as to overlap each other when viewed by sliding up or down in the same row. Here, the substantially straight portion 11 is substantially horizontal (substantially parallel) with respect to the center line C2, but may be slightly inclined with an angle within a range where the angle θ of the bent portion 12 after expansion is not less than 30 °.
[0010]
The connecting portions 5 are also arranged asymmetrically in the stent axial direction via the cells 6, but are arranged in the same direction and at the same height in the stent axial direction. The connecting portions 5 in the stent axial direction are arranged so as to overlap each other when viewed from the nth row to the (n + 1) th row in the stent axial direction. Further, the connecting portions 5 in the same row are also arranged in the same direction in the radial direction of the stent so as to overlap each other when viewed in sliding up or down in the same row.
In addition, the width of the struts constituting the cell 6 is formed larger than the width of the struts constituting the connecting part 5, and the height of the cell 6 and the connecting part 5 in the stent axial direction is higher than the connecting part 5 or the cell 6. It is arranged to shift to.
[0011]
As described above, the stent 1 of the present invention has an angle θ after expansion of the bent portion 12, a ratio of the length 6L of the cell 6 in the stent axial direction to the length 5L in the stent axial direction, and the connection portion 5 and the cell 6. When the diameter of the stent 1 is reduced as shown in FIG. 5 at the time of delivery to the blood vessel due to the configuration, the radial arrangement and the axial arrangement (pattern) of the stent of the connection portion 5 and the cell 6, the cell 6 and the connection portion 5 are formed so as not to overlap each other in the radial direction of the stent and to fit within the space S in the radial direction of the stent.
[0012]
6 and 8 are plan views showing other embodiments of the stent of the present invention (FIGS. 7 and 9 are partially enlarged plan views of FIGS. 6 and 8).
The stent 1A of FIG. 6 (FIG. 7) is compared with the stent 1 of FIG. 1 in that (a) the cell 6A bends a substantially straight portion 11A having an acute angle X with respect to the axial center line C2 of the stent 1A. (Stent 1 has a substantially straight portion 11 in which cells 6 are arranged substantially horizontally (substantially parallel) with respect to the axial center line C2 of the stent 1). (B) the cell 6A is arranged symmetrically in the axial direction of the stent 1A via the connecting portion 5A, and (b) c) The cells 6A in the axial direction of the stent 1A differ only in that they are arranged so as to overlap each other when viewed in the axial direction of the stent 1A every other row from the nth row to the (n + 2) th row. Other components and their definitions The stent 1 substantially detailed description because it is the same will be omitted.
[0013]
In addition, the stent 1B of FIG. 8 (FIG. 9) is compared with the stents 1 and 1A of FIGS. 1 and 6 (FIG. 7). (A) The cell 6B is in relation to the axial center line C2 of the stent 1B. It is configured by connecting a substantially straight portion 11B having an acute angle X to a substantially straight portion 13B disposed substantially horizontally (substantially parallel) with respect to the axial center line C2 of the stent 1 via a bent portion 12B. (Stents 1 and 1A are formed by connecting cells 6 and 6A to substantially

curved portions

13 and 13A through substantially straight portions 11 and 11A via bent portions 12). (B) The cells 6B are arranged symmetrically in the axial direction of the stent 1B via the connecting portion 5B, and (c) the cells 6B in the axial direction of the stent 1B are temporarily arranged from the n-th column to the (n + 2) -th column. When viewed in the axial direction of the stent 1B every other row, The points or the like are disposed so as each other overlap Unlike stent 1, a stent 1A substantially the same. Since the other constituent members and their definitions are substantially the same as those of the stent 1, 1A, detailed description thereof is omitted.
[0014]
In the

stents

1, 1A and 1B illustrated in FIGS. 1, 6 and 8 of the present invention, the connecting

portions

5, 5A and 5B of the cells 6, 6A and 6B constituting the

annular units

4, 4A and 4B are stents. 1, 1A, 1B are arranged continuously in the radial direction with no gaps, but at least one space or more is arranged in the radial direction (place one or two or every other space). Thus, the

stents

1, 1A, and 1B as a whole are more flexible, and delivery to a branched blood vessel is expected to be improved.
[0015]
The stent 1 (1A, 1B) of the present invention is formed from a metal pipe made of stainless steel such as SUS316L, shape memory alloy such as Ti—Ni alloy, Cu—Al—Mn alloy, titanium alloy, tantalum, etc. by, for example, laser processing. It is formed.
A stent formed from these metals may be coated with a polymer material such as urethane, a physiologically active substance such as heparin or urokinase, or an antithrombotic drug such as argatroban.
[0016]
Example 1
In order to evaluate the difference in the radiation support force due to the difference in angle after expansion in the stent A (B) constituted by the constituent part 19 including the substantially <shaped cell 17 and the substantially S-shaped connecting part 18 shown in FIG. Stents A and B having different arrangement numbers of the constituent portions 19 in the circumferential direction were manufactured, and the radiation supporting force was evaluated.
Stent A: Number of components 19 arranged 8
Strut width of cell 17 0.12 mm
1θ angle after 3 mm expansion 60 ° Stent B: Number of components 19 arranged 6
Strut width of cell 17 0.12 mm
1θ angle after 3 mm expansion 81 ° evaluation is performed by expanding the stent to φ3 mm in a silicon tube placed in the chamber and then measuring the change in the outer diameter of the stent by applying pressure in the chamber with air. evaluated.
[0017]
[Table 1]

As shown in Table 1, it was confirmed that the stent B having a large angle after expansion was −0.04 mm (the outer diameter was decreased by 0.04 mm), and the amount of change was small and the radiation supporting force was large.
[0018]
Example 2
The stent 1 shown in FIG. 1 was manufactured, and the radiation support force was compared with the

stents

201 and 241 and the flexibility was compared with the stent 201 for evaluation. Evaluation of the radiation supporting force was performed by the same method as in Example 1, and the flexibility was evaluated by a four-point bending method.
[0019]
[Table 2]

[0020]
[Table 3]

As described above, it was confirmed that the stent 1 of the present invention had a smaller outer diameter change amount than the

stents

201 and 241 from the results in Table 2, and a bending strength smaller than the stent 201 from the results in Table 3. Therefore, it can be understood that the stent 1 of the present invention is a stent having both high radiation support force and flexibility.
[0021]
Example 3
Stents 1A and 1B were also measured and evaluated for radiation supporting force and flexibility in the same manner as in Examples 1 and 2, and substantially the same results as stent 1 were obtained.
[0022]
[Table 4]

[0023]
[Table 5]

[0024]
Example 4
For the

stents

1, 1 A and 1 B of the present invention, the for shortening value when expanded to φ3.0 mm was measured. In the measurement, each stent length before expansion (referred to as L1) was measured, the stent length after expansion to φ3.0 (L2) was measured, and the reduction ratio of the total length was calculated to obtain a for shortening value. As comparative examples,

stents

201 and 241 were also measured.
[0025]
[Table 6]

From the results shown in Table 6, it was confirmed that the

stents

1, 1 A, and 1 B of the present invention had smaller foreshortening values than the

stents

201 and 241.
[0026]
[Effects of the invention]
The stent of the present invention can sufficiently secure high flexibility and radiation support force, and can enhance vasodilation and suppress foreshortening and flare phenomenon.
[Brief description of the drawings]
FIG. 1 is a plan view of a stent of the present invention. FIG. 2 is an enlarged view of FIG. 1. FIG. 3 is an enlarged view showing a state of the stent of the present invention after expansion. 5 is an enlarged view when the diameter of the stent 1 is reduced during delivery to a blood vessel. FIG. 6 is a plan view showing another embodiment of the stent of the present invention. FIG. 7 is a partially enlarged plan view of FIG. FIG. 8 is a plan view showing another embodiment of the stent of the present invention. FIG. 9 is a partially enlarged plan view of FIG. 8. FIG. 10 is an enlarged view of a reference example of the stent of the present invention. [Fig. 12] Plan view of a conventional stent [Explanation of symbols]
1, 1A,

1B Stent

4, 4A,

4B Annular unit

5, 5A, 5B Connecting portion 6, 6A, 6B Cell 7 Substantially

straight portion

8, 8A, 8B bent portion 9

Connection portion

11, 11A, 11B, 13B Substantially

straight portion

12, 12A,

12B Bent part

13, 13A Curved part 14, 14A Small bent part 15 Substantially straight part 17 Substantially <shaped cell 18 Substantially S-shaped connecting part 19 Constituent part in stents A and B

Claims

A stent (1) formed in a generally tubular body and extensible radially from the inside of the tubular body,
A plurality of cells (6) are connected vertically, and a plurality of the cells (6) are arranged so as to surround the central axis (C1) of the stent (1), thereby forming an annular unit (4).
A plurality of the annular units (4) are disposed in the axial direction of the stent (1), and the adjacent annular units (4) are connected to each other by at least one connection part (5),
[1] The connecting portion (5) includes at least two or more bent portions (8), an arc (R) constituting the bent portion (8), and a substantially straight portion continuous with the bent portion (8). Formed from (7),
Each left or right end portion of the bent portion (8) located at the left end and the right end portion of the two or more bent portions (8) is connected to the respective left or right end portion of the cell (6),
[2] The plurality of cells (6)
(I) each having a center line (C2) in the stent axial direction;
(Ii) a substantially straight line portion (11) disposed substantially parallel to the axial center line (C2),
(Iii) A curved portion (13) composed of a small bent portion (14) and a substantially straight portion (15), wherein the substantially straight portion (15) has an acute angle (X the curved portion disposed) and (13),
(Iv)
a ) constituted by connecting via a bent part (12), and
b) the substantially linear portion (11) with the curved portion connection (13), the curved portion forms a part of (13) and the bent portion (12) and the generally linear portion adjacent (15) has been carried out by connecting to the bent portion and the substantially straight portions arranged substantially parallel to (12) through the stent axis direction of the center line (C2) (11),
(V) the cell (6), when partitioned up and down in the stent axial direction of said center line (C2), is formed vertically asymmetrical with respect to the center line (C2),
[3] The stent (1) is a one which can be extended to at least phi 3 mm,
Forming an angle θ after expansion of the substantially linear portion (15) adjacent to the bent portion (12) and the substantially linear portion (11) to be 30 ° to 140 °; and
[4] A stent (1), which is coated with a physiologically active substance or an antithrombotic agent.

A stent (1A) formed in a substantially tubular body and radially expandable from the inside of the tubular body,
A plurality of cells (6A) are vertically connected, and a plurality of the cells (6A) are arranged so as to surround the central axis (C1) of the stent (1A) to constitute the annular unit (4A).
A plurality of the annular units (4A) are arranged in the axial direction of the stent (1A), and the adjacent annular units (4A) are connected to each other by at least one connection portion (5A),
[1] The connecting portion (5A) includes at least two or more bent portions (8A), an arc constituting the bent portion (8A), and a substantially straight portion (7A) continuous with the bent portion (8A). formed from, respectively left or right end portion of the bent portion (8A) located at the left end and the right end portion of the two or more bent portions (8A) includes a respective left or right end portion of the cell (6A) Connected,
[2] The plurality of cells (6A)
(I) each having a center line (C2) in the stent axial direction;
Substantially straight portion and (11A) disposed at an acute angle (X) with respect to (ii), respectively the axial direction of the center line (C2),
(Iii) A curved portion (13A) disposed substantially parallel to the axial center line (C2) , wherein the curved portion (13A) includes a small bent portion (14A) and a substantially straight portion (15A). ) And the curved portion (13A) composed of
(Iv)
a) It is configured by connecting via a bent portion (12A), and
b) the substantially straight portion (11A) with the curved portion connection (13A), the form part of the curved portion (13A) and the bent portion (12A) and adjacent the substantially straight portion (15A) has been carried out by connecting the substantially straight portions arranged at an acute angle (X) and (11A) relative to the stent axis direction of the center line (C2) through the bent portion (12A),
(V) the cell (6A), when partitioned up and down in the stent axial direction of said center line (C2), is formed on the vertically asymmetric relative to the center line (C2),
[3] The stent (1A) is expandable to at least φ 3 mm,
Forming the angle θ after expansion of the substantially linear portion (15A) adjacent to the bent portion (12A) and the substantially linear portion (11A) to be 30 ° to 140 °, and
[4] A stent (1A) that is coated with a physiologically active substance or an antithrombotic agent.

A stent (1B) formed in a generally tubular body and radially expandable from the inside of the tubular body,
A plurality of cells (6B) are vertically connected, and the plurality of cells (6B) are arranged so as to surround the central axis (C1) of the stent (1B) to constitute an annular unit (4B).
A plurality of the annular units (4B) are arranged in the axial direction of the stent (1B), and the adjacent annular units (4B) are connected to each other by at least one connection portion (5B),
[1] The connecting portion (5B) includes at least two or more bent portions (8B), an arc constituting the bent portion (8B), and a substantially straight portion (7B) continuous with the bent portion (8B). It is formed from the two or more bends left end of (8B) and the bent portion located at the right end respectively left or right end portion of the (8B) of the bent portion (8B), the cells (6B) Each connected to the left or right edge,
[2] The plurality of cells (6B)
(I) each having a center line (C2) in the stent axial direction;
(Ii) a substantially straight portion (11B) having an acute angle (X) with respect to the axial center line (C2),
(Iii) a substantially straight line portion (13B) disposed substantially parallel to the axial center line (C2),
(Iv) It is configured by connecting via a bent portion (12B),
(V) the cell (6B), when partitioned up and down in the stent axial direction of the center line (C2), it is formed vertically asymmetrical with respect to the center line (C2),
[3] The stent (1B) is expandable to at least φ 3 mm, and is expanded after the substantially straight portion (13B) and the substantially straight portion (11B) adjacent to the bent portion (12B). And an angle 閘 of 30 ° to 140 °, and
[4] physiologically active substance or a stent, characterized in that coated with antithrombotic agents (1B).