A Computational Analysis of the Influence of Anastomosis Angle on Stenosis-Prone Locations during Radio-Cephalic Arteriovenous Fistula Maturation

In dialysis treatment, the radio-cephalic arteriovenous fistula (RCAVF) is a commonly used fistula, yet its low maturation rate remains a challenge. To enhance surgical outcomes, the relationship between stenosis-prone locations and RCAVF anastomosis angle is studied during maturation by developing two sets of RCAVF models for early (non-mature) and mature RCAVFs at five anastomosis angles. The impact of hemodynamics and wall shear stress (WSS) is examined to determine optimal anastomotic angles. Results indicate that acute angles produce more physiological WSS distributions and fewer disturbed regions, with early stenosis-prone regions located near the anastomosis that shift to the bending venous segment during remodeling. A pilot study comparing clinical and numerical results is conducted for validation.

Optimization of Maturation of Radio-Cephalic Arteriovenous Fistula Using a Model Relating Energy Loss Rate and Vascular Geometric Parameters

The main reason for the early failure of radio-cephalic arteriovenous fistula (RCAVF) is non-maturity, which means that the blood flow rate in the fistula cannot increase to the expected value for dialysis. From a mechanical perspective, the vascular resistance at the artificially designed anastomosis causes an energy loss that affects blood flow rate growth and leads to early failure. This research studied how to maximize the RCAVF maturity and primary patency by controlling the energy loss rate. We theoretically analyzed and derived a model that evaluates the energy loss rate Eavf in RCAVF as a function of its blood vessel geometric parameters (GPs) for given flow rates. There was an aggregate of five controllable GPs in RCAVF: radial artery diameter (Dra), cephalic vein diameter (Dcv), blood vessel distance between artery and vein (h), anastomotic diameter (Da), and anastomotic angle (θ). Through this analysis, it was found that Eavf was inversely proportional to Dra, Dcv, Da, and θ, whereas proportional to h. Therefore, we recommended surgeons choose the vessels with large diameters, close distance, and increase the diameter and angle of the anastomosis to decrease the early failure of RCAVF. Simultaneously, we could explain the results of many clinical empiricisms with our formula. We found that increasing Dcv and θ was more significant in reducing Eavf than increasing Dra and Da. Based on our model, we could define two critical energy loss rates (CELa, CELb) to help surgeons evaluate the blood vessels and choose the ideal range of θ, and help them design the preoperative RCAVF plan for each patient to increase the maturity and the primary patency of RCAVF.

腕部自体动静脉内瘘术前血管超声检查的临床应用价值

目的探讨腕部桡动脉-头静脉内瘘(radiocephalic arteriovenous fistula,RCAVF)术前血管超声检查的临床应用价值。方法选自2016年08月~2019年01月于包头市中心医院血液透析中心首次行腕部RCAVF的患者135例,术前进行彩色多普勒超声检查。RCAVF通畅定义为可满足双针穿刺、泵控血流量>200 ml/min维持连续血液透析治疗6次以上者,并根据腕部RCAVF结局分组进行对比分析。结果腕部RCAVF通畅组99例,失功组24例,死亡或肾移植共12例。12个月时RCAVF通畅率为81%,24个月和32个月均为77%。二元Logistic回归分析,术前超声检查头静脉内径是RCAVF通畅的独立危险因素(OR=4.05,95%CI:1.49~11.01,P=0.006)。ROC曲线分析示头静脉内径的曲线下面积为0.707,最佳临界值为2.075mm。结论术前头静脉内径是预测腕部RCAVF内瘘日后通畅的最佳指标。

年龄是影响桡动脉⁃头静脉内瘘成熟的危险因素

目的:既往研究发现老年患者腕部桡动脉⁃头静脉内瘘(RCAVF)成熟率较低,本文旨在分析年龄与内瘘成熟的相关性。方法:回顾性队列研究265例RCAVF手术患者。术前超声测量血管内径,术后至少随访3个月。多变量Logistic回归分析影响RCAVF成熟的危险因素。将患者按年龄分为四组(≤29岁、30~49岁、50~69岁和70~89岁),经过多模型校正及P趋势检验,分析年龄增长与RCAVF不成熟风险的关系。结果:术后4~6周按照腕部RCAVF是否达到成熟标准,将患者分成熟组218例,不成熟组47例。随年龄升高与成熟相关的OR值降低,多模型校正P趋势均<0.05。经多因素模型校正,年龄每增加20岁,不成熟的风险显著增加,所得的OR值均>1.6。结论:腕部RCAVF的不成熟风险随着年龄的增加而显著增加。年龄与RCAVF功能成熟降低存在线性趋势。年龄每增加20岁,不成熟风险增加60%以上。

静脉扩张性与动静脉内瘘成熟的相关性分析

目的探讨应用超声评估束臂前、后头静脉直径和静脉扩张性与腕部桡动脉-头静脉内瘘(radiocephalic arteriovenous fistula,RC-AVF)成熟的关系。方法91例接受RC-AVF手术患者,术前行超声检查,评估止血带束臂前、后头静脉直径和头静脉扩张性,观察术后6周RC-AVF成熟情况,并根据RC-AVF成熟情况分为成熟组70例及未成熟组21例,比较2组患者一般资料及束臂前、后头静脉直径和头静脉扩张性,采用多因素logistic回归分析预测RC-AVF成熟的影响因素;绘制ROC曲线,评估束臂后头静脉直径和头静脉扩张性预测RC-AVF成熟的价值。结果成熟组年龄、性别比例、慢性肾衰竭病因和中心静脉置管史与未成熟组比较差异均无统计学意义(P>0.05);成熟组束臂前、后头静脉直径[(2.14±0.58)、(2.86±0.61)mm]和头静脉扩张性[(0.71±0.27)mm]均大于未成熟组[(1.81±0.30)、(2.20±0.34)、(0.38±0.16)mm](P<0.05);束臂后头静脉直径(OR=3.463,95%CI:1.935~6.198,P<0.001)和头静脉扩张性(OR=3.887,95%CI:2.074~7.284,P<0.001)是预测RC-AVF成熟的影响因素;束臂后头静脉直径最佳截断值>2.4 mm时,预测RC-AVF成熟的AUC为0.837(95%CI:0.745~0.906,P<0.001),灵敏度为72.86%,特异度为84.29%;头静脉扩张性最佳值断值>0.4 mm时,预测RC-AVF成熟的AUC为0.894(95%CI:0.812~0.949,P<0.001),灵敏度为88.57%,特异度为85.71%。结论束臂后头静脉直径>2.4 mm和头静脉扩张性>0.4 mm是预测腕部RC-AVF成熟的独立危险因素。