A three-dimensional finite-element fluid/structure interaction model of an intravascular lymphatic valve was constructed, and its properties were investigated under both favourable and adverse pressure differences, simulating valve opening and valve closure, respectively. The shear modulus of the neo-Hookean material of both vascular wall and valve leaflet was varied, as was the degree of valve opening at rest. Also investigated was how the valve characteristics were affected by prior application of pressure inflating the whole valve. The characteristics were parameterised by the volume flow rate through the valve, the hydraulic resistance to flow, and the maximum sinus radius and inter-leaflet-tip gap on the plane of symmetry bisecting the leaflet, all as functions of the applied pressure difference. Maximum sinus radius on the leaflet-bisection plane increased with increasing pressure applied to either end of the valve segment, but also reflected the non-circular deformation of the sinus cross section caused by the leaflet, such that it passed through a minimum at small favourable pressure differences. When the wall was stiff, the inter-leaflet gap increased sigmoidally during valve opening; when it was as flexible as the leaflet, the gap increased more linearly. Less pressure difference was required both to open and to close the valve when either the wall or the leaflet material was more flexible. The degree of bias of the valve characteristics to the open position increased with the inter-leaflet gap in the resting position and with valve inflation pressure. The characteristics of the simulated valve were compared with those specified in an existing lumped-parameter model of one or more collecting lymphangions and used to estimate a revised value for the constant in that model which controls the rate of valve opening/closure with variation in applied pressure difference. The effects of the revised value on the lymph pumping efficacy predicted by the lumped-parameter model were evaluated.

中文翻译：

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对具有柔性血管壁的次级淋巴瓣进行建模：几何和材料特性如何结合以提供功能。

构建了血管内淋巴瓣的三维有限元流体/结构相互作用模型，并分别在有利和不利的压力差下研究了其特性，分别模拟了瓣膜打开和瓣膜关闭。血管壁和瓣叶的新胡克材料的剪切模量是变化的，静息时瓣膜的打开程度也是如此。还研究了阀门特性如何受到预先施加的压力对整个阀门的影响。这些特性由通过阀门的体积流量、流动的液压阻力、最大窦半径和平分小叶的对称平面上的小叶尖端间隙参数化，所有这些都是所施加压力差的函数。瓣叶对分平面上的最大窦半径随着施加在瓣膜段两端的压力的增加而增加，但也反映了瓣叶引起的窦横截面的非圆形变形，使得它在较小的有利条件下通过了最小值压力差异。当壁较硬时，瓣叶间间隙在阀门打开时呈S形增加；当它像传单一样灵活时，间隙增加得更线性。当壁或小叶材料更灵活时，打开和关闭瓣膜所需的压差较小。阀门特性对打开位置的偏差程度随着静止位置的小叶间隙和阀门充气压力而增加。将模拟瓣膜的特征与一个或多个收集淋巴管的现有集总参数模型中指定的特征进行比较，并用于估计该模型中常数的修正值，该模型控制瓣膜打开/关闭的速率，并随着应用的变化而变化。压差。评估了修正值对集总参数模型预测的淋巴泵送功效的影响。