根本 芳広¹, 石川 浩史², 川瀧 元良³

Yoshihiro NEMOTO¹, Hiroshi ISHIKAWA², Motoyoshi KAWATAKI³

¹海老名総合病院マタニティーセンター, ²神奈川県立こども医療センター産婦人科, ³神奈川県立こども医療センター新生児科

¹Ebina General Hospital Maternity Center, ²Department of Obstetrics & Gynecology, Kanagawa Children's Medical Center, ³Department of Neonatology, Kanagawa Children's Medical Center

キーワード : premature closure of ductus arteriosus, premature constriction of ductus arteriosus, persistent pulmonary hypertension of the newborn, ultrasonography

動脈管早期収縮（premature constriction of ductus arteriosus: PCDA）は，早期に胎児診断し適切に対処されれば比較的予後が良い疾患である．しかし，完全閉鎖例で対応の時期を誤ると胎児の肺血流が増加し，肺動脈平滑筋層を肥厚させるようになり，胎児右心不全や胎児水腫，新生児遷延性肺高血圧症（persistent pulmonary hypertension of the newborn: PPHN）などを合併して死に至ることもある．今回我々は，胎児診断により救命し得たPPHN合併の重篤で非典型的なPCDAを経験したのでここに報告する．症例は27歳の1回経妊1回経産婦で，過去の妊娠分娩歴に特に異常はなく，在胎36週からnon-stress test（NST）で軽度変動一過性徐脈を認めていた．胎児心エコー検査では，three vessel view（3VV）～three vessel trachea view（3VTV）にかけて，大動脈に比較して拡大した動脈管を認めたが，動脈管内の血流は描出できず在胎38週4日に高次医療施設に転院となった．本症例では，通常のPCDAと同様に右室内腔は拡大，右室駆出率の低下（24％），右室面積変化率は低下（3.6％）し，Tei indexは1.16と高値を示したが，逆に右室壁の菲薄化と低い右室圧が特徴でPCDAとしては非典型的であった．動脈管が完全閉鎖していなかった本症例においてこのような状態になったことは，いわゆる右室の「後負荷不適合」だけでは説明できず右室への冠潅流障害などの可能性などを考慮する必要があるが，直接説明できるだけの所見はみられず不明な点が多い．ただ，逆にPCDAとして非典型的な右室心筋の菲薄化，低い右室圧という所見は，PCDA症例における重症化の指標となり得るかもしれないと思われた．

Premature constriction of the ductus arteriosus (PCDA) has a comparatively good prognosis if diagnosed early in utero and appropriately treated. If patients whose ductus arteriosus has closed completely are treated at the incorrect time, however, blood flow to the fetal lungs increases and thickening the smooth muscle layer of the pulmonary artery occurs, as well as potentially fatal complications such as fetal right heart failure, fetal hydrops, and persistent pulmonary hypertension of the newborn (PPHN). We report a case of serious atypical PCDA complicated by PPHN in which fetal diagnosis proved lifesaving. A 27-year-old gravida 1, para 1, who had not experienced any complications during her previous pregnancy and delivery underwent a non-stress test at 36 weeks gestation that revealed mild variable deceleration. Fetal echocardiography showed that on three-vessel view and three-vessel trachea view, compared to the aorta, the ductus arteriosus was dilated and blood flow was absent; therefore, the patient was transferred to a tertiary care facility at 38 weeks 4 days of gestation. This case resembled a regular PCDA in that the right ventricular lumen was dilated and the right ventricular ejection fraction (24%) and the right ventricular fractional area change (3.6%) were both low; in addition, the Tei index was high at 1.16, but was atypical in terms of the thinning of the ventricular wall and low right ventricular pressure. The development of this state, despite the fact that the ductus arteriosus had not completely closed, cannot be explained solely in terms of “afterload mismatch” of the right ventricle; although other possibilities such as impaired coronary perfusion must be considered, there were no findings that directly explained the condition, and many points remain unclear. It is conceivable, however, that atypical thinning of the right ventricular myocardium and low right ventricular pressure may be indicative of increased severity of PCDA.