山口 祐美, 河野 靖, 白澤 邦征, 田口 晴之

Yumi YAMAGUCHI, Yasushi KONO, Kuniyuki SHIRASAWA, Haruyuki TAGUCHI

一般社団法人日本海員掖済会大阪掖済会病院循環器内科

Department of Cardiology, Osaka Hospital of Japan Seafarers Relief Association

キーワード : hypoxemia, myocardial infarction, atrial septal defect, shunt

症例は84歳，女性．2007年より複数の欠損孔を有する心房中隔欠損を指摘されており，2015年3月にうっ血性心不全のため入院となった．その際，肺体血流比が1.8であり，心不全を併発していたことから外科的治療を勧められたが，高齢を理由に希望しなかった．同年8月に急性下壁梗塞の診断で緊急入院となり，冠動脈造影検査で右冠動脈の近位部に完全閉塞を認めた．同部位に対して経皮的冠動脈インターベンションを施行され，入院後の第1病日にはバイタルサインは安定していた．しかし，第2病日に急激に呼吸状態が悪化した．経胸壁心エコー図検査にて心房中隔欠損孔を通して新たに右左シャントが生じており，これに伴う低酸素血症と考えられた．再度外科的治療を勧められたが，ご家族は希望されなかった．内科的治療を継続したが，治療の甲斐なく他界した．右室梗塞の経過中に卵円孔開存や心房中隔欠損を介した右左シャントを生じた例はこれまでにも報告されているが，本症例では解剖学的な要因も関与していた可能性がある．たとえば，心房中隔の伸展とそれに伴う下大静脈の血流方向の変化，ペースメーカーリードによる三尖弁逆流ジェットの偏位である．これらのことを踏まえた上で，考察も交えて報告する．

An 84-year-old woman was diagnosed with atrial septal defect (ASD) accompanied by multiple holes in 2007. In March 2015, she was admitted with congestive heart failure due to ASD. Surgical closure was recommended because her pulmonary to systemic flow ratio was 1.8, but she declined due to her advanced age. In August 2015, she developed acute inferior myocardial infarction, and coronary angiography showed an occluded proximal right coronary artery. Direct percutaneous coronary angioplasty was successfully performed. After the operation, her condition was stable, but she suddenly fell into refractory hypoxemia on the day after admission. Transthoracic echocardiogram showed acute right-to-left shunting through ASD. Although surgical closure was again recommended, her family asked for conservative medical treatment, not surgical treatment. She ultimately died in spite of medical treatment. Some case reports documented that right ventricular infarctions were complicated by refractory hypoxemia with right-to-left shunting through patent foramen ovale (PFO) or ASD. In the present case, various causes for the right-to-left shunting were considered, e.g., a shift in inferior vena cava flow associated with a stretched atrial septum or a shift in tricuspid regurgitation flow associated with a pacemaker lead. We report this case with a review of some of the literature on right-to-left shunting through PFO or ASD in inferior myocardial infraction.