小林 大樹¹, 末光 浩太郎²

Hiroki KOBAYASHI¹, Kotaro SUEMITSU²

¹関西労災病院中央検査部, ²関西労災病院内科（腎臓）

¹Central Clinical Laboratory, Kansai Rosai Hospital, ²Department of Internal Medicine, Division of Kidney and Dialysis, Kansai Rosai Hospital

キーワード : brachial artery, high bifurcation, ultrasonography, endovascular therapy, artery occlusion

上腕動脈は上腕部を走行する動脈であり，肘関節部より1〜2横指末梢側で橈骨動脈と尺骨動脈に分岐する．しかし，稀に腋窩付近またはその末梢側でそれらが分岐する高位分岐例が存在する．今回，超音波検査で高位分岐を正確に診断できた症例を中心に解説する．68歳，女性，右手第 I ‐IV指に潰瘍が出現し当院受診となった．超音波検査では腋窩付近で橈骨動脈が分岐する上腕動脈高位分岐例であった．上腕部の橈骨および尺骨動脈は血流を認めたが，前腕部の両者は閉塞していた．前腕部の骨間動脈においては微弱ながら血流シグナルを認めた．血管内治療を施行する方針となり，橈骨および尺骨動脈の分岐部をエコーガイド下でマーキングを行った．高位分岐のため，左鼠径部からアプローチしガイドワイヤーを進めた．造影画像とマーキング部から橈骨動脈起始部を同定し，橈骨動脈閉塞部を手関節部まで通過，バルーンカテーテルで拡張し血流を再開通させた．術前の超音波検査で橈骨動脈の起始部を同定したことが，血管内治療の手技において有用な情報になった．超音波検査において上腕動脈を描出する際は，必ず短軸像から描出し動脈が1本か2本かを意識する必要がる．また，術前に高位分岐を診断しておくことで，シースの留置部位が決定でき，必要最小限のデバイスで効率良く治療手技を進めることができる．

The brachial artery is the major artery of the upper arm, and it divides into the radial artery and the ulnar artery at the distal site of the elbow. However, there are rare cases of high brachial artery bifurcation that divides near or below the axillary region. We encountered a case of high brachial artery bifurcation that we could diagnose accurately by ultrasonography. The patient was a 68-year-old female. She had a complaint of ulcers in some fingers of the right hand. Ultrasonography revealed high brachial artery bifurcation that divided near the axillary region. Though the blood flow of the radial and ulnar arteries was maintained in the upper arm, both of these arteries totally occluded in the forearm. A slight blood flow signal in the interosseous artery in the forearm could be confirmed. She underwent endovascular therapy. We marked the bifurcation of the radial and ulnar arteries under ultrasound guidance. The access site was the left femoral artery. We advanced the guidewire to the right subclavian artery and the right axillary artery. We identified the origin of the radial artery by the echo-guided marking and angiography, and the guidewire passed through the radial artery occlusion site. We expanded the balloon catheter into the occlusion site and successfully recanalized the blood flow. The right radial artery was subsequently palpable. Identifying the origin of the radial artery by ultrasonography was useful information for the success of the endovascular therapy. It is important to be aware of the high brachial artery bifurcation. Confirming the high bifurcation by ultrasonography in advance helps to decide the access site for the endovascular therapy, making it possible to proceed with the procedure efficiently with the minimum number of devices.