凍結保存同種心臓弁を用いた大動脈基部置換術

Aortic Root Replacement with Cryopreserved Allograft Aortic Valve

同種心臓弁・血管を用いた大動脈置換術は，歴史的には人工弁や人工血管が開発される前の1950年台まで遡る1）が，希少性と長期保存が困難であったため当時の使用は限定的であった．欧米では1975年にO’Brienらにより凍結保存技術が開発され，凍結保存同種心臓弁（以下，ホモグラフト）の利点を維持した状態で長期保存が可能となり，一般的な治療法として行われるようになった2）．弁置換術全体の約2％にホモグラフ

Aortic root replacement with a cryopreserved allograft aortic valve is effective for active infectious endocarditis and prosthetic valve endocarditis, especially with a perivalvular abscess, since an allograft seems to be resistant to infection by maintaining viable cells under the process of programmed freezing. From December 1998 to March 2017, aortic root replacement with allograft aortic valves were performed in 38 patients in the University of Tokyo. The in-hospital mortality was 18％, the 5-year survival rate was 68％, and the 5-year freedom rate of reoperation was 75％. Although the clinical outcome was improved as institutional experiences increased recently, pseudoaneurysm during the long-term follow-up period needs special attention. The health-insurance system was applied to this allograft treatment in April 2016 by the Ministry of Health, Labour and Welfare. There are still some hurdles for obtaining institutional certification and financial resources, and enough number of donor allografts, so as to use them more commonly.