Wang Tianqi, Zhou Zunqiang, Liang Fuyou
State Key Laboratory of Ocean Engineering, School of Naval Architecture, Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, China.
Department of Surgery, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China.
Front Physiol. 2021 Apr 12;12:661030. doi: 10.3389/fphys.2021.661030. eCollection 2021.
Splenectomy, as an effective surgery for relieving complications caused by portal hypertension, is often accompanied by a significantly increased incidence of postoperative thrombosis in the portal venous system (PVS). While the underlying mechanisms remain insufficiently understood, the marked changes in hemodynamic conditions in the PVS following splenectomy have been suggested to be a potential contributing factor. The aim of this study was to investigate the influences of the anatomorphological features of the PVS on hemodynamic characteristics before and after splenectomy, with emphasis on identifying the specific anatomorphological features that make postoperative hemodynamic conditions more clot-promoting. For this purpose, idealized computational hemodynamics models of the PVS were constructed based on general anatomical structures and population-averaged geometrical parameters of the PVS. In the models, we incorporated various anatomorphological variations to represent inter-patient variability. The analyses of hemodynamic data were focused on the spatial distribution of wall shear stress (WSS) and the area ratio of wall regions exposed to low WSS (ALS). Obtained results showed that preoperative hemodynamic conditions were comparable among different models in terms of space-averaged WSS and ALS (all were small) irrespective of the considerable differences in spatial distribution of WSS, whereas, the inter-model differences in ALS were significantly augmented after splenectomy, with the value of ALS reaching up to over 30% in some models, while being smaller than 15% in some other models. Postoperative ALS was mainly determined by the anatomical structure of the PVS, followed by some morphogeometrical parameters, such as the diameter and curvature of the splenic vein, and the distance between the inferior mesenteric vein and splenoportal junction. Relatively, the angles between tributary veins and trunk veins only had mild influences on ALS. In addition, a marked increase in blood viscosity was predicted after splenectomy, especially in regions with low WSS, which may play an additive role to low WSS in initiating thrombosis. These findings suggest that the anatomical structure and some morphogeometrical features of the PVS are important determinants of hemodynamic conditions following splenectomy, which may provide useful clues to assessing the risk of postsplenectomy thrombosis based on medical imaging data.
脾切除术作为缓解门静脉高压症所致并发症的一种有效手术，术后门静脉系统（PVS）血栓形成的发生率常显著增加。虽然其潜在机制仍未完全明了，但脾切除术后PVS血流动力学状况的显著变化被认为是一个潜在的促成因素。本研究的目的是探讨PVS的解剖形态学特征对脾切除术前、后血流动力学特性的影响，重点是确定使术后血流动力学状况更易促进血栓形成的具体解剖形态学特征。为此，基于PVS的一般解剖结构和人群平均几何参数构建了理想化的PVS计算血流动力学模型。在模型中，我们纳入了各种解剖形态学变异以代表患者间的变异性。血流动力学数据分析集中于壁面切应力（WSS）的空间分布以及低WSS暴露壁区面积比（ALS）。所得结果表明，术前不同模型间的血流动力学状况在空间平均WSS和ALS方面具有可比性（均较小），尽管WSS的空间分布存在显著差异；然而，脾切除术后模型间ALS的差异显著增大，在某些模型中ALS值高达30%以上，而在其他一些模型中则小于15%。术后ALS主要由PVS的解剖结构决定，其次由一些形态几何参数决定，如脾静脉的直径和曲率以及肠系膜下静脉与脾门静脉汇合处之间的距离。相对而言，分支静脉与主干静脉之间的夹角对ALS的影响较小。此外，预计脾切除术后血液黏度会显著增加，尤其是在低WSS区域，这可能在引发血栓形成方面对低WSS起叠加作用。这些发现表明，PVS的解剖结构和一些形态几何特征是脾切除术后血流动力学状况的重要决定因素，这可能为基于医学影像数据评估脾切除术后血栓形成风险提供有用线索。
