TITLE: The Effect of Geometric Graft Modification on Arteriovenous Graft Patency in Haemodialysis Patients: A Systematic Review and Meta-Analysis.
OBJECTIVE:Arteriovenous grafts (AVGs) are the second best option for haemodialysis access when native arteriovenous fistulae placement is not possible, because they have a lower patency owing to neointimal hyperplasia at the venous anastomosis. This review aimed to evaluate the effect of geometric graft modification to the graft-vein interface on AVG patency.
DATA SOURCES:The MEDLINE and Embase (OvidSP) databases were systematically searched for relevant studies analysing the effect of geometrically modified AVGs on graft patency and stenosis formation (last search July 2019).
REVIEW METHODS:Data regarding AVG type, patency, and graft outlet stenosis was extracted for further evaluation. Data were pooled in a random effects model to estimate the relative risk of graft occlusion within one year. Follow up, number of patients, and relevant patient characteristics were extracted for the quality assessment of the included studies using Newcastle-Ottawa Scale and Cochrane Risk of Bias Tool. The quality of the evidence was determined according to the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) system.
RESULTS:Search strategies produced 2772 hits, of which eight articles met predetermined inclusion criteria. Overall, the included articles had low to moderate risk of bias. In total, 414 expanded polytetrafluoroethylene AVGs (232 geometrically modified and 182 standard) were analysed, comprising two modified AVG types: a prosthetic cuff design (Venaflo®) and grafts with a Tyrell vein patch. Overall, modified grafts did not show a statistically significantly higher one year primary (relative risk [RR] 0.86, 95% confidence interval [CI] 95% 0.64-1.16; GRADE: "low to very low") or secondary patency (RR 0.57, 95% CI 0.32-1.02; GRADE: "low to very low") when compared with standard AVGs. Analysis of prosthetic cuffed grafts (112 patients) separately demonstrated a statistically significantly higher one year primary (RR 0.75, 95% CI 0.61-0.91) and one year secondary patency (RR 0.47, 95% CI 0.30-0.75) compared with standard grafts (92 patients). The results on stenosis formation were inconclusive and inadmissible to quantitative analyses.
CONCLUSION:The meta-analysis showed that a prosthetic cuff design significantly improves AVG patency, while a venous cuff does not. Although the heterogeneity and low number of available studies limit the strength of the results, this review shows the potential of grafts with geometric modification to the graft-vein anastomosis and should stimulate further clinical and fundamental research on improving graft geometry to improve graft patency.
SOURCE: Sawo P, Moufarrej A, Sloff M, et al. The Effect of Geometric Graft Modification on Arteriovenous Graft Patency in Haemodialysis Patients: A Systematic Review and Meta-Analysis[J]. Eur J Vasc Endovasc Surg, 2020, 60(4):568-577. DOI: 10.1016/j.ejvs.2020.06.023.
目的：当无法放置天然动静脉内瘘时，动静脉移植物（AVG）是进行血液透析的第二个最佳选择，因为由于静脉吻合处的新内膜增生，它们的通畅率较低。这篇综述旨在评估几何修饰的移植物对静脉通路的AVG通畅性的影响。
数据来源：系统搜索MEDLINE和Embase（OvidSP）数据库以进行相关研究，分析几何修饰的AVG对移植物通畅和狭窄形成的影响（最后搜索2019年7月）。
审查方法：提取有关AVG类型，通畅性和移植物出口狭窄的数据用于进一步评估。将数据汇总到随机效应模型中，以估计一年内移植物闭塞的相对风险。使用纽卡斯尔-渥太华量表和Cochrane偏倚风险工具，对随访情况，患者数量和相关患者特征进行了提取，以对纳入研究的质量进行评估。证据的质量是根据“建议，评估，发展和评估等级”（GRADE）系统确定的。
结果：搜索产生了2772个匹配，其中有8条符合预定的纳入标准。总体而言，所包括的文章具有低至中度偏见的风险。总共分析了414种膨胀的聚四氟乙烯AVG（232几何修饰类型和182标准类型），包括两种修饰的AVG类型：假体袖套设计（Venaflo）和带有Tyrell静脉贴片的移植物。总体而言，改良的移植物未显示统计学上显着较高的一年一期（相对风险[RR] 0.86，95％置信区间[CI] 95％0.64-1.16； GRADE：“从低到非常低”）或二期通畅（RR 0.57 ，与标准AVG相比，95％CI 0.32-1.02；等级：“从低到非常低”）。人工袖套移植物（112例患者）的分析分别显示，与标准移植物相比，一年一期的通畅率（RR 0.75，95％CI 0.61-0.91）和一年的二期通畅率（RR 0.47，95％CI 0.30-0.75）在统计学上显着更高（ 92位患者）。狭窄形成的结果尚无定论，不能用于定量分析。
结论：荟萃分析表明，人工袖套设计可显着改善AVG的通畅性，而静脉袖套则不能。尽管异质性和可用研究数量少，限制了结果的强度，但本综述显示了对几何修饰进行移植静脉吻合术的移植物的潜力，并应激发进一步的临床和基础研究，以改善移植物的几何形状以提高移植物的通畅性。
启发：人工血管静脉出口问题一直困扰着通路医生，几何修饰的人工血管改变了部分血流动力学，期望能减少静脉出口内膜增生，提高移植物血管的通畅率！
