心房中隔欠損症に伴う二次性肺動脈性肺高血圧症に対するsildenafilの効果―高齢者心房中隔欠損症の1手術例

The Effects of Sildenafil on Atrial Septal Defect with Secondary Pulmonary Hypertension：A case report

患者は76歳，女性．呼吸苦を主訴に当科入院した．現症では血圧92/62mmHg，心雑音第2肋間胸骨左縁2/6度の収縮期雑音，II音の固定性分裂(＋)あり，胸部単純X線写真では著明な心拡大，肺うっ血，肺動脈の拡大，心電図は完全右脚ブロック，心エコー検査では径29mmの心房中隔の欠損孔，右室拡大，推定肺動脈圧88.8mmHgより心房中隔欠損症に伴う肺高血圧症，心不全と診断した．心臓カテーテル検査では心房レベルでの左右シャント，血中酸素飽和度の上昇を認めた．肺動脈の拡張能をみる試験には純酸素，一酸化窒素(NO)吸入試験がある．また，sildenafilにもNOと同様の肺血管拡張作用を認めていることから，肺血管の拡張効果，有用性の比較検討のため酸素吸入(O₂)とsildenafil(Si)負荷試験を施行した．その結果，PVRはO₂後68.6%，Si後51.8%低下し，PVR/SVR ratioはO₂後66.6%，Si後55.5%低下した．sildenafilの内服は酸素吸入とほぼ同等に肺高血圧を低下させた．高齢者ASD，PH患者においても肺血管の拡張能の評価に用うることが示唆された．

In a case of a 76-year-old female with atrial septal defect complicated by pulmonary hypertension, the effects of oxygen inhalation (O₂) and sildenafil on pulmonary vessel compliance were compared. Pulmonary vessel compliance can be assessed by conducting an inhalation test using pure O₂ or nitric oxide(NO). Since sildenafil dilates pulmonary vessels in a manner similar to dilation induced by NO, we investigated the effects of sildenafil on pulmonary hypertension. The results confirmed that O₂ and sildenafil lowered pulmonary vascular resistance (PVR) by 68.6 and 51.8%, respectively, and decreased the PVR/systemic vascular resistance (SVR) ratio by 66.6 and 55.5%, respectively. Because the results of the present study showed that sildenafil lowered pulmonary hypertension to a degree comparable to that induced by oxygen inhalation, it can be used to assess pulmonary vessel compliance even in elderly patients with pulmonary hypertension.