The present study is intended to investigate and compare the hemodynamics in two different sizes of hemodialysis arteriovenous grafts for upper arm hemodialysis vascular access: 8-mm tapered to 6-mm at the arterial side and straight 6 mm. A computational simulation approach is presented for this study, which is validated against the available experimental and numerical pressure measurements in the literature. The imposed boundary conditions at the arterial inlet and venous outlet boundaries of the models are physiological velocity and pressure waveforms, respectively. Blood flow fields and distribution patterns of the hemodynamic indices including wall shear stress (WSS) as one of the major hemodynamic parameters of the cardiovascular system and spatial wall shear stress gradient (SWSSG) as an indicator of disturbed flow patterns and hence susceptible sites of lesion developments are analyzed and compared between the two grafts. The tapered 6- to 8-mm graft seemingly is associated with less disturbed flow patterns within the venous anastomosis (VA) and the vein downstream while benefiting from higher blood flow rates within. Also, it shows a definitive advantage in terms of WSS and SWSSG distribution patterns around the VA and throughout the vein downstream with significantly lower values, which reduce the risk of thrombosis formation and stenotic lesion developments. The only disadvantage encountered in using 6- to 8-mm tapered graft is higher values of hemodynamic parameters at the arterial junction attributable to its significantly higher mean blood flow rate within. The results clearly indicate that the tapered 6- to 8-mm graft entirely outperforms straight 6-mm graft hemodynamically as an upper arm hemodialysis vascular access graft and confirms clinical data in the literature, which suggests advantageous use of tapered 6- to 8-mm grafts in the creation of upper arm brachioaxillary hemodialysis vascular access grafts in selected groups of patients with expectably higher patency rates and lower complications.

.11 (range 16-40) and female was 27.93±11.38 (range 15-60). Patients were divided in two groups. Group 1 included cases ≤25 yrs and consisted of 32 cases. Cases >25 yrs were placed in group 2 (19 cases). From 51 cases included in this study, 43 of them were appropriate for non-surgical treatment. Eight cases underwent surgical treatment. Of 51 cases, 35 cases (68.6%) were male and 31.4% were female. Of 43 cases who treated conservatively, 29 (67.44%) cases were male and 14 (32.56%) were female. There was no significant difference between rate of successful conservative treatment among cases >25 yrs and cases ≤25 yrs. There was no significant different between different duration of manifestation. conclusion. In this study we found successful non-surgical treatment in 90.6% of cases ≤25 yrs and 73.7% of cases >2 yrs. Non-surgical treatment may be appropriate option in uncomplicated cases. Another study is recommended to confirm this method of treatment.

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