15. 体外設置型補助人工心臓後の植込み型補助人工心臓装着術

Conversion Surgery from Extra-corporeal to Implantable Ventricular Assist Devices

2011年に植込み型補助人工心臓（iVAD）の「心臓移植への橋渡し」（BTT）使用が保険適用となるまで，わが国では体外式左室補助人工心臓（LVAD）であるNipro VAD（ニプロ社，大阪）［図1］が長らくBTT目的に使用されていた．2011年以降，BTTでは原則としてiVADが使用されるようになっているが，移植適応外ないし移植未登録の急性心原性ショックに対しては，今もなお「移植適応をめざした装着」（BTC）などの適応により，体外式VADが使用されている．体外式VAD装着後に移植登録の諸検査をすすめ，移植適応と判断されればBTTとしてiVADへの植え替え（コンバージョン）手術を施行できる．本稿では，Nipro VADからiVADへのコンバージョン手術における注意点・ポイントをまとめた．

Extra-corporeal ventricular assist device （VAD）, or Nipro VAD in Japan, is still one of the indispensable treatment options for patients with acute cardiogenic shock or post-cardiotomy shock, who are not eligible for heart transplantation. Once they were stabilized and enrolled to heart transplantation, or indicated to destination therapy in the future, a conversion surgery from Nipro VAD to implantable VAD （iVAD） as bridge-to-transplant is essential for them to return to social life. Three tips for successful conversion surgery are summarized in the current manuscript. Firstly, we surgeons should be deliberate considering a conversion surgery when we conduct the first Nipro VAD implantation. For example, we cover mediastinal structure with a 0.1 mm Gore-Tex and avoid an extensive anatomical dissection, which could make the next surgery more complicated. Secondly, conversion surgery should be performed after the patient completely recovers from Nipro VAD surgery. And thirdly, we should pay a specific attention to prevent a future infection of iVAD, which is caused by an existing infection of Nipro VAD exit sites. Conversion surgery from Nipro VAD to iVAD was originated in Japan and its case numbers are limited. Experienced institutions should keep their efforts to disseminate its pitfalls to other institutions.