Departament d'Enginyeria Informàtica i Matemàtiques, Universitat Rovira i Virgili, Tarragona, Catalunya, Spain.
Departament d'Enginyeria Química, Universitat Rovira i Virgili, Tarragona, Catalunya, Spain.
Int J Numer Method Biomed Eng. 2020 Jul;36(7):e3343. doi: 10.1002/cnm.3343. Epub 2020 May 19.
The alteration of blood flow around an OPTEASE inferior vena cava filter with one or two blood clots attached was investigated by means of computational fluid dynamics. We used a patient-specific vein wall geometry, and we generated different clot models with shapes adapted to the filter and vein wall geometries. A total of eight geometries, with one or two clots and a total clot volume of 0.5 or 1 cm , were considered. A non-Newtonian model for blood viscosity was adopted and the possible development of turbulence was accounted for by means of a three-equation model. Two blood flow rates were considered for each case, representative for rest and exercise conditions. In exercise conditions, flow unsteadiness and even turbulence was detected in some cases. Pressure and wall shear stress (WSS) distributions were modified in all cases. Clots attached to the filter downstream basket considerably increased averaged WSS values by up to almost 50%. In all the cases a flow recirculation region appeared downstream of the clot. The degree of flow stagnation in these regions, an indicator of propensity to thrombogenesis, was estimated in terms of mean residence times and mean blood viscosity. High levels of flow stagnation were detected in rest conditions in the wake of those clots that were placed upstream from the filter. Our results suggest that one downstream placed big clot, showing a higher tendency to induce flow instabilities and turbulence, might be more harmful than two small clots placed in tandem.
通过计算流体动力学研究了附着有一个或两个血块的 OPTEASE 下腔静脉滤器周围血流的变化。我们使用了患者特定的静脉壁几何形状，并生成了与滤器和静脉壁几何形状相适应的不同血块模型。总共考虑了八种几何形状，其中一个或两个血块，总血块体积为 0.5 或 1 厘米。采用了血液粘度的非牛顿模型，并通过三方程模型考虑了可能发生的湍流发展。对于每种情况，都考虑了两种血流速度，分别代表休息和运动条件。在运动条件下，在某些情况下检测到了流动不稳定性甚至湍流。在所有情况下，压力和壁面剪切应力 (WSS) 分布都发生了变化。附着在滤器下游篮上的血块大大增加了平均 WSS 值，最高可达近 50%。在所有情况下，血块下游都出现了回流区域。这些区域的流动停滞程度（血栓形成倾向的指标）是根据平均停留时间和平均血液粘度来估计的。在那些放置在滤器上游的血块后面，在休息状态下检测到了高水平的流动停滞。我们的结果表明，一个放置在下游的大血块比两个串联放置的小血块更有可能引起流动不稳定和湍流，因此可能更具危害性。
