川端 一美, 矢田 豊, 高田 さゆり, 田中 恒行, 池尾 光一, 宮本 勇人, 中川 泰樹, 中嶋 紀元, 宮崎 純一, 阿部 孝

Kazumi KAWABATA, Yutaka YATA, Sayuri TAKADA, Tsuneyuki TANAKA, Kouichi IKEO, Hayato MIYAMOTO, Yasuki NAKAGAWA, Noriyuki NAKAJIMA, Junichi MIYAZAKI, Takashi ABE

阪和記念病院消化器内科

Department of Gastroenterology, Hanwa Memorial Hospital

キーワード : SMA syndrome, RFCA, atrial fibrillation, positional changing observation

症例は58歳男性．心房細動に対するカテーテルアブレーション（radiofrequency catheter ablation：RFCA）後から食欲不振，体重減少（10 kg/2か月），繰り返す嘔吐を認め当科受診．CTで著明な胃拡張と十二指腸水平脚の部分的拡張および虚脱を認めた．十二指腸水平脚は上腸間膜動脈（superior mesenteric artery：SMA）と大動脈（aorta：Ao）により圧迫され，SMA症候群と診断した．体位変換を活用した超音波検査でSMA-Ao間の距離は，大きく変化し，十二指腸の圧迫は左側臥位で最も軽減された．入院の上，モサプリドクエン酸塩投与，分割食，食後左側臥位の指導により嘔吐は消失し，食事も全量摂取可能となり退院した．近年，SMA症候群の一因に，心房細動に対するRFCAが指摘されている．RFCAによる焼灼エネルギーが心臓外に放射され，胃周囲迷走神経叢の損傷により胃の蠕動機能障害が起こり，食思不振から体重減少ひいてはSMA症候群を生ずるとされる．本例では体位変換による超音波検査でSMA周囲腸管を観察したところ，左側臥位でSMAが大きく偏位するに伴い，十二指腸狭窄部が開放される状態をリアルタイムに観察できた．体位変換を活用した超音波検査は，SMA症候群の診断および最適な発症予防体位の同定に有用である．

The patient was a 58-year-old male. He was admitted to our hospital with anorexia, weight loss (-10 kg/2 months), and repeated vomiting after radiofrequency catheter ablation (RFCA) for atrial fibrillation. Abdominal CT showed marked gastric dilatation and partial dilatation and collapse of the third portion of the duodenum. Since a part of the third portion of the duodenum was compressed by the superior mesenteric artery (SMA) and the aorta (Ao), we diagnosed SMA syndrome. Ultrasonography utilizing positional changes revealed that the distance between the SMA and Ao varied from 6.0 mm in the supine position, 40.1 mm in the left lateral recumbent position, 30.8 mm in the right lateral recumbent position, and 7.7 mm in the sitting position, with duodenal compression being reduced most in the left lateral recumbent position. After hospitalization and instruction in mosapride citrate administration, divided meals, and left-side supine position after meals, his symptoms including vomiting resolved.The patient was discharged from the hospital without any symptoms. Recently, RFCA for atrial fibrillation has been pointed out as a cause of SMA syndrome, in which the ablation energy from RFCA is radiated outside the heart and damages the perigastric vagal plexus, resulting in gastric peristalsis, anorexia, and weight loss, which causes SMA syndrome. In the present case, the peri-SMA intestinal tract was observed with positional ultrasonography, which allowed real-time observation of the opening of the duodenal stenosis as the SMA was greatly displaced in the left lateral recumbent position. Ultrasonography utilizing positional changes is useful for diagnosis of SMA syndrome and identification of the optimal position for prevention of the onset of this syndrome.