Initial single-center experience with a new external support device for the creation of the forearm native arteriovenous fistula for hemodialysis

Efficacy and safety of implantable vascular support in the treatment of arteriovenous fistula: A single-arm meta-analyses

BACKGROUND AND OBJECTIVES

VasQ (Laminate Medical Technologies, Israel) is an external support device for autologous arteriovenous fistula (AVF) designed to improve anastomotic blood flow and reduce neointimal hyperplasia. However, different studies have shown that the efficacy of the VasQ device in improving AVF is inconsistent. The purpose of this study was to conduct a meta-analysis to further evaluate the efficacy and safety of the VasQ device.

DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS

Two reviewers independently searched studies published in PubMed, EMBASE, Cochrane, Web of Science, CNKI, and Wan Fang databases from inception to 2023. The Cochrane Systematic Evaluation Bias Risk Tool Version 1 was used to assess the risk of RCTS bias. The ROBINS-I tool was used to assess the risk of bias in non-randomized studies. A Single-arm meta-analysis was performed, and a random effects model was used for all analyses.

RESULTS

We identified six trials involving 146 patients and conducted a meta-analysis. The results showed that after 6 months of VasQ device treatment, the primary patency rate of AVF was [76.4% (95%CI: 0.608-0.920), p < 0.01] while the secondary patency rate was [76.5% (95%CI: 0.572-0.958), p < 0.01]. The maturity rate of AVF 1 month after surgery was [88.5% (95%CI: 0.818-0.952), p = 0.46]. The incidence of anastomotic stenosis was [8.9% (95%CI: 0.015-0.163), p = 0.23], and the incidence of anastomotic venous thrombosis was [10% (95%CI: 0.035-0.179), p = 0.38].

CONCLUSIONS

Meta-analysis data of this study show that the VasQ device has a good effect in improving the patency rate of AVF and does not increase the occurrence of adverse events. However, due to the limitation of the number and quality of included studies, more high-quality studies are needed to confirm this in the future.

Arteriovenous fistula creation with VasQTM device: A feasibility study to reveal hemodynamic implications

BACKGROUND

Arteriovenous fistula (AVF) is the preferred vascular access (VA) for hemodialysis, but it is still affected by high non-maturation and early failure rates due to stenosis development. Increasing evidence suggests that the presence of turbulent-like flow may play a key role, therefore, to stabilize the flow in the venous segment, an external support device (VasQTM) has been designed. The aim of this study was to provide preliminary evidence of VasQTM impact on AVF hemodynamics as compared to AVFs created with conventional surgery.

METHODS

In this pilot single-center prospective randomized study six patients were enrolled, three in the VasQ group and three in the control group. Contrast-free magnetic resonance imaging (MRI) scans were acquired at 3 days, 3 months and 1 year after AVF surgery and were used to generate 3D patient-specific models. Computational fluid dynamic (CFD) simulations were performed using pimpleFoam, imposing patient-specific flow waveforms derived from ultrasound (US) examinations at the inlet of the proximal and distal artery, and a traction-free condition at the venous outflow. Morphologic and hemodynamic changes occurring over time were compared between VasQ and control AVFs.

RESULTS

Our MRI protocol provided high-quality images suitable for reliable segmentation and reconstruction of patient-specific 3D models of AVFs at all three timepoints in four out of six patients. The VasQTM device maintained the angle between the artery and the vein almost unchanged over time, with a more stable flow in the AVFs supported by the device. In contrast, one of the AVFs of the control group evolved to an extreme dilatation of the vein and highly disturbed flow, while the other developed a stenosis in the juxta-anastomotic region.

CONCLUSIONS

This study demonstrated the feasibility of characterizing the morphological and hemodynamic changes occurring over time in AVFs created using the VasQTM device and provided preliminary evidence of the potential hemodynamic benefits of its use.

Intimal Hyperplasia and Arteriovenous Fistula Failure: Looking Beyond Size Differences

The development of venous intimal hyperplasia (IH) has been historically associated with failure of arteriovenous fistulas (AVF) used for hemodialysis. This long-standing assumption, based on histological observations, has been recently challenged by clinical studies indicating that the size of the intima by itself is not enough to explain stenosis or AVF maturation failure. Irrespective of this lack of association, IH is present in most native veins and fistulas, is prominent in many cases, and suggests a role in the vein that may not be reflected by its dimensions. Therefore, the contribution of IH to AVF dysfunction remains controversial. Using only clinical data and avoiding extrapolations from animal models, we critically discuss the biological significance of IH in vein remodeling, vascular access function, and the response of the venous wall to repeated trauma in hemodialysis patients. We address questions and pose new ones such as: What are the factors that contribute to IH in pre-access veins and AVFs? Do cellular phenotypes and composition of the intima influence AVF function? Are there protective roles of the venous intima? This review explores these possibilities, with hopes of rekindling a critical discussion about venous IH that goes beyond thickness and AVF outcomes.