1 誠馨会新東京病院臨床検査室Department of Clinical Laboratory, New Tokyo Hospital
2 近畿大学奈良病院臨床検査部Faculty of Medicine, Nara Hospital Kinki University
3 誠馨会新東京病院心臓内科Clinical Department of Cardiology, New Tokyo Hospital
はじめに：下腿動脈3分枝の約10%に脛骨動脈の起始異常や低形成などの解剖学的亜型の存在が知られている．特にType IIIは，前脛骨動脈，後脛骨動脈の一方もしくは両方が低形成や無形成であり，血管造影ではこれらと通常解剖の慢性完全閉塞を区別することは困難である．したがって，重症下肢虚血（CLI）の血行再建前に下腿動脈の解剖学的特性を認識することは重要であり，事前に超音波検査で亜型の存在を指摘できれば治療の手助けとなる．
目的：下肢動脈超音波検査において下腿動脈3分枝の亜型であるType IIIについて，CLIとの関連とその特徴について検討すること．
対象と方法：当院で2016年1月～2017年10月までに下肢虚血が疑われ下肢動脈超音波検査を行った353例603肢（男238例，女115例，平均年齢72±11歳）を対象とした．CLI群と非CLI群でのType IIIの割合や，通常解剖群とType III群における超音波所見について後方視的に検討した．
結果：全体のうち26例31肢（5.1%）にType IIIを認め，その内訳はType III-A 14肢（2.3%），Type III-B 15肢（2.4%），Type III-C 2肢（0.3%）であった．CLI 156肢中Type IIIは17肢（10.9%），非CLI 447肢中Type IIIは14肢（3.1%）で，CLIで有意にType IIIを多く認めた（p＜0.001）．通常解剖群における足関節部レベルでの前脛骨動脈と後脛骨動脈の走行角度は176±3.5度，165±7.8度とほぼ水平に近い角度で走行するのに対し，Type III群では腓骨動脈から前脛骨動脈遠位部あるいは後脛骨動脈遠位部に屈曲して合流するため，それぞれ154±13.7度，142±18.5度と通常解剖群に比し走行角度に有意な差を認めた．また，Type III群の低形成前・後脛骨動脈の血管径は通常解剖群に比べ有意に細くdiameter-ratioにも有意な差を認めた．
結語：Type IIIの割合は，非CLIに比べCLIで多かった．また，血管造影では下腿動脈閉塞例において評価が困難な場合が多いが，超音波検査は下腿動脈の通常解剖とType IIIの鑑別に有用であった．下肢動脈超音波検査によるCLIの解剖学的亜型の検出は有用である．
Background: The existence of anatomical variants, including a high division of popliteal artery branching and hypoplastic branching in the tibial artery, are present in ~10% of infrapopliteal arteries. In Type III variants in particular, one or both of the anterior tibial and posterior tibial arteries are hypoplastic or aplastic, and it is difficult for diagnostic angiography to distinguish usual anatomical patterns in a Type III variant with chronic total occlusion (CTO). Therefore, it is important to be aware of anatomical variations in the infrapopliteal artery prior to revascularization in cases of critical limb ischemia (CLI). The ability to identify the presence of variants using duplex ultrasound scanning (DUS) in advance is expected to be useful for revascularization.
Purposes: The present study aimed to investigate ultrasound findings of Type III variants that can be detected by DUS, and the association between Type III variants and CLI.
Subjects and Methods: Between January 2016 and October 2017, a total of 603 limbs in 353 patients (238 men and 115 women, mean age 72±11 years) with suspected lower limb ischemia were enrolled in the present study. The patients were divided into two groups according to the presence or absence of CLI. The rate of Type III variants were compared between these groups. Additionally, the patients were divided into two groups according to the presence of the Type III variant or usual anatomical pattern, excluding cases with lower extremity arterial occlusive/stenosis. The ultrasound findings, including the angle of direction of the distal tibial arteries, vessel diameter, and diameter ratio of the tibial arteries were compared between these groups.
Results: Of the total 603 limbs in 353 patients, the Type III variant was present in 31 limbs of 26 patients (5.1%), which were classified as Type III-A (2.3%; 14/603), Type III-B (2.4%; 15/603), and Type III-C (0.2%; 2/603). The rate of the Type III variant was significantly higher (10.9% vs. 3.1%, p＜0.001) in the CLI group. There were significant differences between the Type III and usual pattern in the angles of the distal tibial arteries, vessel diameter, and diameter ratio of the tibial artery.
Conclusion: The rate of the Type III variant was higher in patients with CLI as compared with those without CLI. With CTO of the lower limb artery, diagnostic angiography is often difficult to evaluate vessels sufficiently; however, DUS is useful for the distinction between usual anatomical patterns and the Type III variant. Lower extremity arterial DUS is useful for the detection of infrapopliteal variants in CLI.
Key words: critical limb ischemia; duplex ultrasound; ultrasonography; variation; variant
© 2019 一般社団法人日本超音波検査学会© 2019 Japanese Society of Sonographers
This page was created on 2019-02-22T16:17:13.853+09:00
This page was last modified on 2019-04-02T10:50:55.000+09:00
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