15. 中心肺動脈高度低形成・欠損を伴う肺動脈閉鎖・心室中隔欠損症と周術期管理

Surgical Strategy for Pulmonary Atresia with Ventricular Septal Defect with Major Aortopulmonary Collateral Artery

肺動脈閉鎖・心室中隔欠損（pulmonary atresia with ventricular septal defect）は，心室中隔欠損を介した静脈血と動脈血の混合によるチアノーゼを呈する疾患であり，第一の治療目的は心室中隔欠損を閉鎖しチアノーゼをなくすことである．ただし中心肺動脈が高度低形成ないしは欠損し，主要体肺側副血行路（MAPCA）により肺血流が確保されている症例では，右室と肺動脈の連続性を確立するために，まず発生学上縦隔構造に対して不規則的に走行するMAPCAと中心肺動脈を吻合する，ないしは中心肺動脈を作成する肺動脈統合術（unifocalization）を行う必要がある．また中心肺動脈が存在し，統合するMAPCAの本数が少ない場合は，体肺動脈短絡術を行い中心肺動脈の成長を促す（rehabilitation）治療方針を選択する1，2）．いずれにせよ，得られた肺区域の数と肺血管抵抗，ならびに吻合部狭窄の程度により，心室中隔欠損（VSD）閉鎖後の右室圧が決定される．このため長期的に良好な血行動態を得るための治療目標は，中心から末梢にいたるまでより抵抗の少ない肺動脈の連続性を確立し，VSD閉鎖後に，より低圧の右室で肺循環を成立させることである．

Although the characteristics and pathophysiology of major aortopulmonary collateral artery （MAPCA） have been better understood, treatment of pulmonary atresia and ventricular septal defect with MAPCA remains challenging. The difficulty in treating this disease is the lack of availability of pulmonary homografts required for pulmonary angioplasty in Japan and the need for manipulation of the posterior mediastinum region, which is not performed in normal cardiac surgery. It is important to build an appropriate surgical strategy by means of preoperative computed tomography （CT） and selective angiography.

For treatment, unifocalization or rehabilitation is selected depending on the condition of MAPCA and central pulmonary artery. Because unifocalization is highly invasive, it would be performed at 6 months of age and weigh 5 kg.

As a procedure, extensive dissection is performed, and anastomoses between tissue to tissue are basically performed, and reconstruction of the right ventricular outflow tract is performed using a valved conduit that can secure anterograde pulmonary blood flow that is not affected by the condition of the lung.

It is effective to confirm postoperative lung perfusion scan and CT, perform a cardiac catheterization test approximately 6 months after surgery, and maintain the pulmonary vessels with catheter intervention if necessary.

The ultimate goal of treating this disease is not only to improve cyanosis, but also to maintain pulmonary circulation at lower right ventricular pressure.