Mosayyebi Ali, Vijayakumar Aravinthan, Mosayebi Maryam, Lange Dirk, Somani Bhaskar K, Manes Costantino, Carugo Dario
Department of Mechanical Engineering, Faculty of Engineering and Physical Sciences, University of Southampton, Southampton SO17 1BJ, United Kingdom.
Department of Urologic Sciences, Faculty of Medicine, University of British Columbia, Vancouver V6H 3Y8, Canada.
APL Bioeng. 2022 May 5;6(2):026102. doi: 10.1063/5.0083260. eCollection 2022 Jun.
Ureteric stents are clinically deployed to restore urinary drainage in the presence of ureteric occlusions. They consist of a hollow tube with multiple side-holes that enhance urinary drainage. The stent surface is often subject to encrustation (induced by crystals-forming bacteria such as ) or particle accumulation, which may compromise stent's drainage performance. Limited research has, however, been conducted to evaluate the relationship between flow dynamics and accumulation of crystals in stents. Here, we employed a full-scale architecture of the urinary system to computationally investigate the flow performance of a ureteric stent and experimentally determine the level of particle accumulation over the stent surface. Particular attention was given to side-holes, as they play a pivotal role in enhancing urinary drainage. Results demonstrated that there exists an inverse correlation between wall shear stress (WSS) and crystal accumulation at side-holes. Specifically, side-holes with greater WSS levels were those characterized by inter-compartmental fluid exchange between the stent and ureter. These "active" side-holes were located either nearby ureteric obstructions or at regions characterized by a physiological constriction of the ureter. Results also revealed that the majority of side-holes (>60%) suffer from low WSS levels and are, thus, prone to crystals accumulation. Moreover, side-holes located toward the proximal region of the ureter presented lower WSS levels compared to more distal ones, thus suffering from greater particle accumulation. Overall, findings corroborate the role of WSS in modulating the localization and extent of particle accumulation in ureteric stents.
输尿管支架在临床上用于在输尿管梗阻时恢复尿液引流。它们由带有多个侧孔的中空管组成，这些侧孔可增强尿液引流。支架表面经常会出现结垢（由形成晶体的细菌如……引起）或颗粒堆积，这可能会损害支架的引流性能。然而，关于评估流动动力学与支架中晶体堆积之间关系的研究有限。在此，我们采用泌尿系统的全尺寸模型进行计算，以研究输尿管支架的流动性能，并通过实验确定支架表面的颗粒堆积水平。特别关注了侧孔，因为它们在增强尿液引流方面起着关键作用。结果表明，壁面剪应力（WSS）与侧孔处的晶体堆积之间存在负相关。具体而言，WSS水平较高的侧孔其特点是支架与输尿管之间存在隔室间的液体交换。这些“活跃”侧孔位于输尿管梗阻附近或输尿管生理性狭窄区域。结果还显示，大多数侧孔（>60%）的WSS水平较低，因此容易出现晶体堆积。此外，与更远端的侧孔相比，位于输尿管近端区域的侧孔WSS水平较低，因此颗粒堆积更多。总体而言，研究结果证实了WSS在调节输尿管支架中颗粒堆积的位置和程度方面的作用。
