和田 直樹, 柿崎 秀宏

Naoki WADA, Hidehiro KAKIZAKI

旭川医科大学腎泌尿器外科

Department of Renal and Urologic Surgery, Asahikawa Medical University

キーワード : bladder blood flow, Doppler, ultrasonography, overactive bladder, bladder outlet obstruction

最近，ドプラ超音波法を用いた臨床研究により，下部尿路閉塞（bladder outlet obstruction: BOO）によって引き起こされる膀胱虚血が膀胱機能や下部尿路症状（lower urinary tract symptoms: LUTS）に与える影響について報告されつつある．Belenkyらは，BOOでは内腸骨動脈領域の血管抵抗（resistive index: RI）が高値であることを報告した．また，前立腺肥大症（benign prostatic hyperplasia: BPH）に対するα1遮断薬や経尿道的前立腺切除術（transurethral resection of the prostate: TURP）によって膀胱RIが改善し，さらにTURP後の排尿筋過活動の残存群においてRIが高値であることが報告されている．造影超音波検査を用いて行った我々の臨床研究では，(1)膀胱RIが前立腺腫大やBOOと相関すること，(2)TURPや5α還元酵素阻害薬投与によって膀胱RIは改善するが，これらの治療後の過活動膀胱の残存群では膀胱RIの改善が乏しいこと，(3)これらの治療後の膀胱RIの改善が乏しい群ではBOOの改善が乏しく，高血圧などの動脈硬化のリスクとなる全身疾患の罹患率が高いこと，が示されている．超音波技術の進歩に伴い簡便かつ正確な膀胱虚血の測定が可能になれば，膀胱虚血がLUTSに与える長期的な影響や，薬物治療もしくは外科的治療介入による膀胱虚血と膀胱機能障害の可逆性について解明されることが期待される．

Recent clinical studies using color Doppler ultrasonography (CDUS) have revealed the influence of bladder ischemia caused by bladder outlet obstruction (BOO) on lower urinary tract function and lower urinary tract symptoms (LUTS). In 2003, Belenky et al. reported the increased vascular resistance of the internal iliac artery represented as the resistive index (RI) in patients with severe BOO. In 2007 and 2008, there were consecutive reports about bladder ischemia in patients with benign prostatic hyperplasia (BPH). Bladder RI was improved overall after medical therapy with alpha-blockers and surgical treatment of BPH (transurethral resection of the prostate: TURP). However, persistent detrusor overactivity after surgery was associated with persistently high bladder RI with subsequent reduced perfusion. We also studied bladder ischemia using CDUS in patients with BPH. Our studies showed that 1) bladder RI correlated with BOO grade and prostatic volume; 2) bladder RI was improved after relieving BOO by TURP or 5-alpha reductase inhibitor, but bladder RI after medical or surgical therapy was less improved in patients with persistent overactive bladder (OAB); and 3) less improvement of bladder RI after medical or surgical therapy was associated with remaining BOO or higher incidence of hypertension (an arterial sclerosis risk factor). Simple and more accurate measurement of bladder blood flow using ultrasonography would reveal the long-term impact of bladder ischemia on LUTS and the reversibility of lower urinary tract dysfunction and bladder ischemia after medical or surgical treatment.