Purpose: An arteriovenous fistula (AVF) is the first choice vascular access for hemodialysis. The AVF pathway can be seen as consisting of seven segments: proximal artery, distal artery, arterial collaterals, proximal vein, distal vein, venous collaterals, and the anastomosis. While most studies describe access complications without considering the impact of the anastomosis (7th segment), the present mathematical study investigated the hemodynamic impact of anastomosis size and angle on pressure drop and flow distribution.Methods: A side-to-end AVF model was developed, consisting of an anastomosis with a given cross-sectional area (substudy 1) and angle (substudy 2). Starting from two reference cases (one for each substudy) with fixed flow distribution, pressure drop over the anastomosis was calculated for an arterial inflow in the range 600 to 1200 mL/min. The same reference cases, subsequently with fixed pressure boundary conditions, were further used to assess flow distribution over the proximal vein and distal artery.Results: Pressure drop decreased with a larger anastomosis cross-sectional area and an angle wider than 43, while it was almost stable for smaller angles. Although proximal arterial inflow increased for larger anastomosis areas, the overall flow distribution shifted almost totally to the proximal vein. When the anastomosis angle exceeded 58, the proximal arterial inflow was not sufficient to deliver enough flow, leading to distal arterial flow reversal.Conclusion: Despite the underestimation of the hemodynamic impact of the anastomosis size and angle in the literature, this study showed major influences on the pressure drop over the anastomosis and, with it, on flow distribution towards the arterial and venous outflow. (J Vasc Access 2010; 11: 52-8)
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机译:目的:动静脉瘘(AVF)是血液透析的首选血管通路。可以将AVF通路视为由七个部分组成:近端动脉,远端动脉,动脉侧支,近端静脉,远端静脉,静脉侧支和吻合。虽然大多数研究都在不考虑吻合术影响的情况下描述了进入并发症(第7节),但本数学研究调查了吻合术的大小和角度对压降和血流分布的血流动力学影响。方法:建立了端到端AVF模型,由具有给定截面积(子研究1)和角度(子研究2)的吻合术组成。从具有固定流量分布的两个参考案例(每个子研究一个)开始,针对动脉流入量在600至1200 mL / min范围内的吻合口计算压降。相同的参考案例,随后在固定的压力边界条件下,进一步用于评估近端静脉和远端动脉的血流分布。结果:压降降低,吻合截面积更大,角度大于43,而对于较小的角度几乎稳定。尽管较大的吻合区域近端动脉血流增加,但总体血流分布几乎全部转移至近端静脉。当吻合角度超过58°时,近端动脉血流不足以提供足够的流量,导致远端动脉血流逆转。结论:尽管文献中低估了吻合口大小和角度对血流动力学的影响,但这项研究显示出主要影响吻合口的压力下降,以及随之而来的流向动脉和静脉流出的压力。 (J Vasc Access 2010; 11:52-8)
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