Okayama University Medical School Acta Medica Okayama 0386-300X 66 6 2012 Evaluating the Need for and Effect of Percutaneous Transluminal Angioplasty on Arteriovenous Fistulas by Using Total Recirculation Rate per Dialysis Session (�gClearance Gap�h) 443 447 EN Toyomu Ugawa Kazufumi Sakurama Takashi Yorifuji Munenori Takaoka Yasuhiro Fujiwara Narutoshi Kabashima Daisuke Azuma Takahiro Hirayama Kohei Tsukahara Sunao Morisada Atsuyoshi Iida Keitaro Tada Naoki Shiba Nobuo Sato Shingo Ichiba Koichi Kino Masaki Fukushima Yoshihito Ujike Original Article 10.18926/AMO/49040 The functioning of an arteriovenous fistula (AVF) used for vascular access during hemodialysis has been assessed mainly by dilution methods. Although these techniques indicate the immediate recirculation rate, the results obtained may not correlate with Kt/V. In contrast, the clearance gap (CL-Gap) method provides the total recirculation rate per dialysis session and correlates well with Kt/V. We assessed the correlation between Kt/V and CL-Gap as well as the change in radial artery (RA) blood flow speed in the fistula before percutaneous transluminal angioplasty (PTA) in 45 patients undergoing continuous hemodialysis. The dialysis dose during the determination of CL-Gap was 1.2 to 1.4 Kt/V. Patients with a 10% elevation or more than a 10% relative increase in CL-Gap underwent PTA (n��45), and the values obtained for Kt/V and CL-Gap before PTA were compared with those obtained immediately afterward. The mean RA blood flow speed improved significantly (from 52.9 to 97.5cm/sec) after PTA, as did Kt/V (1.07 to 1.30) and CL-Gap (14.1% to �|0.2%). A significant correlation between these differences was apparent (r���|0.436 and p��0.003). These findings suggest that calculating CL-Gap may be useful for determining when PTA is required and for assessing the effectiveness of PTA, toward obtaining better dialysis. No potential conflict of interest relevant to this article was reported.