Weldon School of Biomedical Engineering, Purdue University, West Lafayette, Indiana, USA.
J Appl Physiol (1985). 2013 Jul 15;115(2):285-92. doi: 10.1152/japplphysiol.00264.2013. Epub 2013 May 30.
Stent deployments with geographical miss (GM) are associated with increased risk of target-vessel revascularization and periprocedural myocardial infarction. The aim of the current study was to investigate the underlying biomechanical mechanisms for adverse events with GM. The hypothesis is that stent deployment with GM [longitudinal GM, or LGM (i.e., stent not centered on the lesion); or radial GM, RGM (i.e., stent oversizing)] results in unfavorable fluid wall shear stress (WSS), WSS gradient (WSSG), oscillatory shear index (OSI), and intramural circumferential wall stress (CWS). Three-dimensional computational models of stents and plaque were created using a computer-assisted design package. The models were then solved with validated finite element and computational fluid dynamic packages. The dynamic process of large deformation stent deployment was modeled to expand the stent to the desired vessel size. Stent deployed with GM resulted in a 45% increase in vessel CWS compared with stents that were centered and fully covered the lesion. A 20% oversized stent resulted in 72% higher CWS than a correct sized stent. The linkages between the struts had much higher stress than the main struts (i.e., 180 MPa vs. 80 MPa). Additionally, LGM and RGM reduced endothelial WSS and increased WSSG and OSI. The simulations suggest that both LGM and RGM adversely reduce WSS but increase WSSG, OSI, and CWS. These findings highlight the potential mechanical mechanism of the higher adverse events and underscore the importance of stent positioning and sizing for improved clinical outcome.
支架部署出现地理性错失（GM）与靶血管血运重建和围手术期心肌梗死风险增加相关。本研究旨在探讨 GM 不良事件的潜在生物力学机制。我们的假设是 GM 时支架部署（纵向 GM，即 LGM[支架未位于病变中心]；或径向 GM，RGM[支架过度扩张]）会导致不良的流体壁面剪切应力（WSS）、WSS 梯度（WSSG）、振荡剪切指数（OSI）和管腔周向壁应力（CWS）。使用计算机辅助设计软件包创建了支架和斑块的三维计算模型。然后，使用经过验证的有限元法和计算流体动力学软件包对模型进行求解。模拟了大变形支架扩张的动态过程，以将支架扩张至所需的血管尺寸。与支架位于病变中心且完全覆盖病变的情况相比，GM 时部署的支架会使血管 CWS 增加 45%。支架过度扩张 20%会使 CWS 比正确尺寸的支架高 72%。支架连接的支柱的应力比主要支柱高得多（即 180 MPa 比 80 MPa）。此外，LGM 和 RGM 降低了内皮细胞 WSS，增加了 WSSG 和 OSI。模拟结果表明，LGM 和 RGM 均会降低 WSS，但会增加 WSSG、OSI 和 CWS。这些发现强调了支架定位和尺寸对改善临床结果的重要性，突出了机械机制在较高不良事件中的潜在作用。
