Zheng Shaokai, Obrist Dominik, Burkhard Fiona, Clavica Francesco
ARTORG Center for Biomedical Engineering Research, Faculty of Medicine University of Bern Bern Switzerland.
Department of Urology Inselspital, Bern University Hospital, University of Bern Bern Switzerland.
Bioeng Transl Med. 2022 Sep 13;8(2):e10407. doi: 10.1002/btm2.10407. eCollection 2023 Mar.
Ureteral stents are indispensable devices in urological practice to maintain and reinstate the drainage of urine in the upper urinary tract. Most ureteral stents feature openings in the stent wall, referred to as side holes (SHs), which are designed to facilitate urine flux in and out of the stent lumen. However, systematic discussions on the role of SH and stent lumen size in regulating flux and shear stress levels are still lacking. In this study, we leveraged both experimental and numerical methods, using microscopic-Particle Image Velocimetry and Computational Fluid Dynamic models, respectively, to explore the influence of varying SH and lumen diameters. Our results showed that by reducing the SH diameter from to the median wall shear stress levels of the SHs near the ureteropelvic junction and ureterovesical junction increased by over , even though the flux magnitudes through these SH decreased by about . All other SHs were associated with low flux and low shear stress levels. Reducing the stent lumen diameter significantly impeded the luminal flow and the flux through SHs. By means of zero-dimensional models and scaling relations, we summarized previous findings on the subject and argued that the design of stent inlet/outlet is key in regulating the flow characteristics described above. Finally, we offered some clinically relevant input in terms of choosing the right stent for the right patient.
输尿管支架是泌尿外科实践中不可或缺的器械，用于维持和恢复上尿路的尿液引流。大多数输尿管支架在支架壁上有开口，称为侧孔（SHs），其设计目的是促进尿液进出支架内腔。然而，关于侧孔和支架内腔尺寸在调节流量和剪切应力水平方面的作用，仍缺乏系统性的讨论。在本研究中，我们分别利用微观粒子图像测速技术和计算流体动力学模型，通过实验和数值方法，探讨不同侧孔直径和内腔直径的影响。我们的结果表明，将侧孔直径从[具体数值]减小到[具体数值]，输尿管肾盂交界处和输尿管膀胱交界处附近侧孔的平均壁面剪切应力水平增加了超过[具体数值]，尽管通过这些侧孔的流量大小减少了约[具体数值]。所有其他侧孔的流量和剪切应力水平都较低。减小支架内腔直径显著阻碍了腔内流动以及通过侧孔的流量。通过零维模型和比例关系，我们总结了此前关于该主题的研究结果，并认为支架进出口的设计是调节上述流动特性的关键。最后，我们在为合适的患者选择合适的支架方面提供了一些临床相关的建议。
