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特集 頸部頸動脈狭窄症の診断と治療
文献概要
はじめに
頸動脈分岐部は動脈硬化性狭窄病変の好発部位であり，肥厚・変性した内膜を中心とする粥腫（プラーク）の破綻や血栓形成によって動脈原性塞栓（artery to artery embolism）や灌流圧低下による虚血（hemodynamic ischemia）をきたし，大脳半球や眼動脈領域の神経症候を生じる。初回発作が大脳半球領域のtransient ischemic attack（TIA）であった場合は，狭窄の程度に関係なく急性期の症状再発が高率であることが知られているが1），一般に症候性病変では狭窄度が高いほど症状の再発が多く2－7），外科治療による再発予防効果も大きい8）。一方，無症候性病変においては，60％以上の狭窄ではその程度と脳卒中発症率との関連は不明瞭で9，10），症候性病変でみられる狭窄度と外科治療の有益性との相関も認められていない10）。
本病変に対する外科的血行再建術として，頸動脈内膜剝離術（carotid endarterectomy：CEA）と頸動脈ステント留置術（carotid artery stenting：CAS）がある。CASは本邦では2008年4月に保険収載されたが，同年には推定で5,000件以上施行され，既にCEA施行件数（約3,000件）より多い11）。これに対しCEAは多くの無作為化比較試験（randomized controlled trial：RCT）から得られた治療エビデンスの蓄積によって，一定の条件では内科的治療を上回る脳卒中予防効果を有することが広く認識されており2－5，9，10），その術式はほぼ確立されている12，13）。
本稿ではCEAに関する代表的なRCT，術前検査，手術の実際，周術期管理，中長期成績，および現時点での手術適応について解説する。
頸動脈分岐部は動脈硬化性狭窄病変の好発部位であり，肥厚・変性した内膜を中心とする粥腫（プラーク）の破綻や血栓形成によって動脈原性塞栓（artery to artery embolism）や灌流圧低下による虚血（hemodynamic ischemia）をきたし，大脳半球や眼動脈領域の神経症候を生じる。初回発作が大脳半球領域のtransient ischemic attack（TIA）であった場合は，狭窄の程度に関係なく急性期の症状再発が高率であることが知られているが1），一般に症候性病変では狭窄度が高いほど症状の再発が多く2－7），外科治療による再発予防効果も大きい8）。一方，無症候性病変においては，60％以上の狭窄ではその程度と脳卒中発症率との関連は不明瞭で9，10），症候性病変でみられる狭窄度と外科治療の有益性との相関も認められていない10）。
本病変に対する外科的血行再建術として，頸動脈内膜剝離術（carotid endarterectomy：CEA）と頸動脈ステント留置術（carotid artery stenting：CAS）がある。CASは本邦では2008年4月に保険収載されたが，同年には推定で5,000件以上施行され，既にCEA施行件数（約3,000件）より多い11）。これに対しCEAは多くの無作為化比較試験（randomized controlled trial：RCT）から得られた治療エビデンスの蓄積によって，一定の条件では内科的治療を上回る脳卒中予防効果を有することが広く認識されており2－5，9，10），その術式はほぼ確立されている12，13）。
本稿ではCEAに関する代表的なRCT，術前検査，手術の実際，周術期管理，中長期成績，および現時点での手術適応について解説する。
参考文献
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