角田 聖, 小田 洋平, 光本 保英, 山田 千尋

Sei TSUNODA, Yohei ODA, Yasuhide MITSUMOTO, Chihiro YAMADA

京都鞍馬口医療センター内科循環器科

Division of Cardiology, Department of Internal Medicine, Kyoto Kuramaguchi Medical Center

キーワード : inferior vena cava aneurysm, Doppler ultrasound, three-dimensional ultrasonography, Fly Thru, virtual vascular endoscopy

症例は20年来の反復するめまい発作で近医にて内服治療を受けている70歳，女性．持続するめまいと嘔吐を主訴に当院救急外来を独歩で受診した．身体所見は特に異常なく耳鳴りや眼振は認めず，頭部MRI検査でも急性の脳血管障害は指摘されなかったが，めまい症状が強いため観察入院となった．めまいは炭酸水素ナトリウム点滴などで改善し，嘔吐も自然に軽快したが，原因検索目的に施行した腹部超音波検査で，下大静脈（inferior vena cava: IVC）と血流の交通がある長径45 mm，短径25 mmの静脈瘤を認めた．造影CT所見ではIVCの閉塞は伴わない肝後面／腎静脈頭側の嚢状瘤であり，内部に血栓を認めず，肺動脈血栓塞栓症も認めなかった．IVC造影では瘤内造影剤のwash out遅延を認め，内部に一部隔壁を伴っていた．3次元エコーにて仮想血管内視鏡画像を作成し，IVC内および瘤内の視点で立体的に連続性を確認した．3次元エコーは2次元で得られた画質に依存することに留意し，血管壁の質感や細部の構造が実際に則しているか他の画像診断と比較検討する必要はあるが，血管内異常構造物の直観的な把握に有用な手法であると思われた．血栓塞栓症の既往がないため，抗血小板薬内服で経過観察の方針とした．

We report the case of a 70-year-old woman presenting with chronic vertigo and vomiting due to Meniere-like symptoms. Abdominal ultrasonography was performed, revealing an anechoic mass connected to the retrohepatic/suprarenal inferior vena cava (IVC); color Doppler imaging showed venous flow from the IVC into the mass-like space. Enhanced computed tomography (CT) demonstrated a saccular aneurysm without IVC interruption. The maximal diameter was 25 mm and the length was 45 mm. CT showed neither mural thrombus in the IVC aneurysm nor thrombus of the pulmonary artery. IVC angiography showed several compartments divided by partition walls and delayed washout of contrast agent in the aneurysm. Endoluminal observation was performed, perspectively and consecutively, with virtual vascular endoscopy (VVE) using three-dimensional ultrasonography, from inside the IVC into the intra-aneurysmal space. VVE imaging indicated the direct opening of the aneurysm orifice from the IVC and delineated the intra-aneurysmal structure, including the compartments of the inner wall of the aneurysm. In lieu of anti-coagulation therapy or surgical removal, she was started on oral anti-platelet therapy because of a lack of history of thrombosis.