Title: Haemodynamic optimisation of a dialysis graft design using a global optimisation approach.
Abstract: Disturbed flow and the resulting non-physiological wall shear stress (WSS) at the graft-vein anastomosis play an important role in arteriovenous graft (AVG) patency loss. Modifying graft geometry with helical features is a popular approach to minimise the occurrence of detrimental haemodynamics and to potentially increase graft longevity. Haemodynamic optimisation of AVGs typically requires many computationally expensive computational fluid dynamics (CFD) simulations to evaluate haemodynamic performance of different graft designs. In this study, we aimed to develop a haemodynamically optimised AVG by using an efficient meta-modelling approach. A training dataset containing CFD evaluations of 103 graft designs with helical features was used to develop computationally low-cost meta-models for haemodynamic metrics related to graft dysfunction. During optimisation, the meta-models replaced CFD simulations that were otherwise needed to evaluate the haemodynamic performance of possible graft designs. After optimisation, haemodynamic performance of the optimised graft design was verified using a CFD simulation. The obtained optimised graft design contained both a helical graft centreline and helical ridge. Using the optimised design, the magnitude of flow disturbances and the size of the anastomotic areas exposed to non-physiological WSS was successfully reduced compared to a regular straight graft. Our meta-modelling approach allowed to reduce the total number of CFD model evaluations required for our design optimisation by approximately a factor 2000. The applied efficient meta-modelling technique was successful in identifying an optimal, helical graft design at relatively low computational costs. Future studies should evaluate the in vivo benefits of the developed graft design.
Source： Quicken S, Delhaas T, Mees B, et al. Haemodynamic optimisation of a dialysis graft design using a global optimisation approach[J]. Int J Numer Method Biomed Eng, 2021, 37(2):e3423. DOI: 10.1002/cnm.3423.
摘要：在移植物-静脉吻合处的扰动流动和由此产生的非生理性壁切应力(WSS)在动静脉移植物(AVG)通畅性丧失中起着重要作用。用螺旋特征改变移植物的几何形状是一种流行的方法，可以最大限度地减少有害血流动力学的发生，并有可能延长移植物的寿命。AVG的血流动力学优化通常需要许多计算量大的计算流体动力学（CFD）仿真，以评估不同移植物设计的血流动力学性能。在这项研究中，我们旨在通过使用有效的元建模方法来开发血液动力学优化的AVG。训练数据集包含对具有螺旋特征的103个移植物设计的CFD评估，用于开发与移植物功能障碍相关的血液动力学指标的低成本计算元模型。在优化过程中，元模型取代了计算流体力学模拟，否则需要评估可能的移植物设计的血液动力学性能。优化后，使用计算流体力学模拟验证优化移植物设计的血液动力学性能。获得的优化移植物设计包含螺旋移植物中心线和螺旋脊。使用优化的设计，与常规的直移植物相比，成功地减少了血流扰动的幅度和暴露于非生理WSS的吻合区域的大小。我们的元建模方法使我们设计优化所需的计算流体动力学模型评估总数减少了大约2000倍。应用有效的元建模技术成功地以相对较低的计算成本确定了最佳的螺旋移植物设计。未来的研究应该评估移植设计的体内益处。
启发：良好的血流动力学可以大大减少内瘘失功，但如何改进内瘘血流动力学，我们一直还在探索中。该文从血流动力学方面解析了螺旋形AVG设计的优势，也为该方面研究提供了一些分析及建模工具。（原文理论需要花时间消化）
