渡邉 学¹, 塩澤 一恵¹, 金山 政洋¹, 向津 隆規¹, 八鍬 恒芳², 丸山 憲一², 本田 善子³, 島田 長人³, 住野 泰清¹

Manabu WATANABE¹, Kazue SHIOZAWA¹, Masahiro KANAYAMA¹, Takanori MUKOUZU¹, Tsuneyoshi YAKUWA², Kenichi MARUYAMA², Yoshiko HONDA³, Nagato SHIMADA³, Yasukiyo SUMINO¹

¹東邦大学医療センター大森病院消化器内科, ²東邦大学医療センター大森病院臨床生理機能検査部, ³東邦大学医療センター大森病院総合診療外科

¹Department of Hepatology and Gastroenterology, Toho University Medical Center Omori Hospital, ²Department of Clinical Functional Physiology, Toho University Medical Center Omori Hospital, ³Department of General Medicine and Emergency Care, Toho University Medical Center Omori Hospital

キーワード : Isolated superior mesenteric artery dissection, intestinal ischemia, contrast-enhanced ultrasonography, sonazoid, intimal flap

65歳，男性．前日ゴルフのラウンド中に上腹部痛が出現し入院となった．腹部超音波検査（US）にてintimal flapの描出は認めなかったが上腸間膜動脈（SMA）近位部の軽度拡張とカラードプラ法にて背側の順行性シグナルと反転するように腹側の逆行性シグナルを確認した．腹部multi-detector-row computed tomography（MDCT）でSMA根部の解離と限局性空腸壁肥厚を認めたため虚血性空腸を合併した孤立性上腸間膜動脈解離（ISMAD）と診断し抗凝固剤を開始した．SMA解離部及び虚血空腸についてUSとMDCTにて血流動態を追跡観察した．SMA解離は根部より約2 cm末梢側まで真腔・偽腔ともに血流を有していたが，偽腔拡張による真腔の狭小化をUSにて経時的に確認した．一方，MDCTや造影超音波（CEUS）で染影が低下していた空腸壁肥厚部の一部は，第19病日のCEUSにて血流の改善を認めた．その後，腹痛はなく第26病日より食事を開始したが，第38病日に食後の左側腹部痛が出現した．小腸造影で空腸に狭窄部位を認めたため，第59病日に開腹術を施行した．Treitz靭帯から20 cm肛門側の部位から約30 cmの範囲で空腸の狭窄を認めたため切除した．病理組織学的検査にて虚血に伴う遅延性狭窄と診断した．本症例では，保存的治療中のSMAの解離状態や腸管viabilityの判定にUSはきわめて有用であった．

The patient was a 65-year-old man who had experienced upper abdominal pain during a round of golf on the previous day and was admitted to the hospital. Although the intimal flap was not delineated on abdominal ultrasonography (US), we noted mild dilation in the proximal part of the superior mesenteric artery (SMA), and antegrade signals on the dorsal side and flapping retrograde signals on the ventral side were observed on color Doppler ultrasonography. Because abdominal multi-detector row CT (MDCT) revealed dissection at the root of the SMA and localized thickening of the jejunal wall, a diagnosis of isolated superior mesenteric artery dissection (ISMAD) complicated by jejunal ischemia was made and anticoagulation therapy was initiated. The hemodynamics of the dissected part of the SMA and ischemic jejunum was monitored by US and MDCT. Both the true and the false lumen of the dissected SMA showed blood flow to about 2 cm distally from the root, but progressive narrowing of the true lumen resulting from dilation of the false lumen was confirmed by follow-up US. The thickened part of the jejunal wall, in which the contrast was attenuated on MDCT and contrast-enhanced US (CEUS), showed improvement in blood flow by CEUS on the 19th hospital day. Thereafter, the patient stopped complaining about abdominal pain, and oral intake of meals resumed on the 26th hospital day. However, pain in the left flank appeared postprandially on the 38th hospital day. Since a narrowed part was noted in the jejunum on barium radiography of the small intestine, open surgery was carried out on the 59th hospital day. Because the jejunum was narrowed over 30 cm from a point 20 cm anally to the ligament of Treitz, this segment was resected and, based on histopathological examination of the resected specimen, a diagnosis of delayed stenosis associated with ischemia was made. US proved extremely useful in evaluating the state of dissection of the SMA and the viability of the intestine during conservative treatment.