Department of Engineering and Applied Sciences, University of Bergamo, Italy.
Department of Biomedical Engineering - Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy.
J Vasc Access. 2024 Jan;25(1):60-70. doi: 10.1177/11297298221087160. Epub 2022 Apr 22.
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 (VasQ) has been designed. The aim of this study was to provide preliminary evidence of VasQ impact on AVF hemodynamics as compared to AVFs created with conventional surgery.
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.
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 VasQ 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.
This study demonstrated the feasibility of characterizing the morphological and hemodynamic changes occurring over time in AVFs created using the VasQ device and provided preliminary evidence of the potential hemodynamic benefits of its use.
动静脉瘘（AVF）是血液透析的首选血管通路，但由于狭窄的发展，其仍然受到高未成熟和早期失败率的影响。越来越多的证据表明，湍流样流的存在可能起着关键作用，因此，为了稳定静脉段的血流，设计了一种外部支撑装置（VasQ）。本研究的目的是提供与传统手术相比，VasQ 对 AVF 血液动力学影响的初步证据。
在这项单中心前瞻性随机研究中，共纳入 6 名患者，其中 VasQ 组 3 例，对照组 3 例。在动静脉瘘手术后 3 天、3 个月和 1 年，分别进行无对比磁共振成像（MRI）扫描，并用于生成 3D 患者特异性模型。使用 pimpleFoam 进行计算流体动力学（CFD）模拟，在近端和远端动脉入口处施加来自超声（US）检查的患者特异性流量波形，并在静脉流出处施加无拉力条件。在 VasQ 和对照组 AVF 之间比较随时间发生的形态和血液动力学变化。
我们的 MRI 方案提供了高质量的图像，适用于在所有三个时间点对 6 名患者中的 4 名患者的 AVF 进行可靠的分割和重建。VasQ 装置随时间几乎保持了动脉和静脉之间的角度不变，在装置支撑下的 AVF 中具有更稳定的血流。相比之下，对照组的一个 AVF 发展为静脉极度扩张和高度紊乱的血流，而另一个则在吻合口附近区域发展为狭窄。
本研究证明了使用 VasQ 装置创建的 AVF 中随时间发生的形态和血液动力学变化的特征化的可行性，并提供了其使用的潜在血液动力学益处的初步证据。
