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.

Impact of chemotherapy-associated liver injury on tumour regression grade and survival in patients with colorectal liver metastases.

BACKGROUND: An inverse relation between chemotherapy-associated liver injury (CALI) and tumour response to chemotherapy has been reported. The aim was to validate these findings, and further investigate the impact of CALI on survival in patients who underwent partial hepatectomy for colorectal liver metastases (CRLM). METHODS: Patients who received neoadjuvant chemotherapy and underwent partial hepatectomy for CRLM between 2008 and 2014 were included. Liver and tumour specimens were histologically examined for CALI (steatosis, steatohepatitis, sinusoidal dilatation [SD], nodular regeneration) and tumour regression grade (TRG). TRG 1-2 was defined as complete tumour response. RESULTS: 166 consecutive patients were included with a median survival of 30 and 44 months for recurrence-free and overall survival, respectively. Grade 2-3 SD was found in 44 (27%) and TRG 1-2 was observed in 33 (20%) patients. Of studied CALI, only grade 2-3 SD was associated with increased TRG 3-5 (odds ratio 3.99, 95% CI 1.17-13.65, p = 0.027). CALI was not significantly related to survival. TRG 1-2 was associated with prolonged recurrence-free (hazard ratio 0.47, 95% CI 0.25-0.89, p = 0.020) and overall survival (hazard ratio 0.35, 95% CI 0.18-0.68, p = 0.002). CONCLUSION: CALI was not directly related to survival. CALI was, however, associated with diminished complete tumour response, and diminished complete tumour response, in turn, was associated with decreased survival.

Novel electrospun polyurethane grafts for vascular access in rats.

OBJECTIVES: The purpose of this study is to develop a new and improved polyurethane (PU) graft using electrospinning and chemical modifications for hemodialysis patients, which will replace the current standard, polytetrafluoroethylene (PTFE) graft. The chemical modifications aim to improve hemocompatibility and reduce thrombogenicity and neointimal hyperplasia. METHOD: The study population was randomized and divided equally into four groups; one control group received a PTFE graft, and three treatment groups received three different types of polyurethane grafts. Two duplex measurements were performed directly on the graft on the same locations, followed by a histologic examination. RESULTS: In the first few days after the implantation animals lost some weight, it took a week to recover to pre-surgical weight. Throughout the 28 days, there was no significant difference between animals in wound, activity, and the general appearance. PTFE and PU A groups have lower compliance or reduced graft diameter due to neointimal hyperplasia development on Doppler interrogation. The histological analysis showed limited neointimal hyperplasia development and no excessive inflammatory response to any of the grafts. CONCLUSION: This study demonstrates that animals with polyurethane grafts show better blood flow because the developed NIH was inconspicuous, as indicated by the different velocity measure than controls on Duplex and minimal NIH development microscopically.