Probing the effect of morphology on lymphatic valve dynamic function
Probing the effect of morphology on lymphatic valve dynamic function
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DOI：
10.1007/s10237-018-1030-y
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发表时间：
2018-10-01
影响因子：
3.5
通讯作者：
Alexeev, Alexander
中科院分区：
文献类型：
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作者：
Ballard, Matthew;Wolf, Ki T.;Alexeev, Alexander
淋巴系统对循环系统和免疫系统至关重要，执行一系列重要功能，如间质液，脂肪酸和免疫细胞的运输。淋巴管由可收缩的管壁和淋巴管瓣组成，使它们能够泵送淋巴液以抵抗不利的压力梯度并防止回流。尽管淋巴系统的重要性，淋巴阀和血管的机械和几何变化在淋巴功能障碍的病理学中的作用，如水肿，还没有很好地理解。我们开发了一个完全耦合的流体-固体三维计算模型，以询问被认为影响瓣膜行为的各种参数以及这些变化对整体淋巴功能的后果。格子玻尔兹曼模型用于模拟淋巴，而格子弹簧模型用于模拟淋巴阀的力学。研究了淋巴管瓣膜的功能，如在不同的淋巴管瓣膜几何形状和机械性能下使淋巴液流动和防止回流，以提供对淋巴管和瓣膜功能的理解。模拟结果表明，当瓣膜具有低纵横比和弯曲刚度时，淋巴瓣膜功能得到优化，只要这些参数保持在足够高的值以允许适当的瓣膜关闭。这表明瓣膜硬化可能对整体淋巴泵送性能产生深远影响。此外，动态瓣膜模拟表明，该模型捕获了淋巴瓣膜对动态流动条件的延迟响应，这是瓣膜操作的基本特征。因此，我们的模型增强了我们对淋巴病理学的理解，特别是那些表现出异常瓣膜形态的病理学，如已被认为发生在原发性水肿的情况下，可以导致淋巴功能障碍。
The lymphatic system is vital to the circulatory and immune systems, performing a range of important functions such as transport of interstitial fluid, fatty acid, and immune cells. Lymphatic vessels are composed of contractile walls and lymphatic valves, allowing them to pump lymph against adverse pressure gradients and to prevent backflow. Despite the importance of the lymphatic system, the contribution of mechanical and geometric changes of lymphatic valves and vessels in pathologies of lymphatic dysfunction, such as lymphedema, is not well understood. We develop a fully coupled fluid-solid, three-dimensional computational model to interrogate the various parameters thought to influence valve behavior and the consequences of these changes to overall lymphatic function. A lattice Boltzmann model is used to simulate the lymph, while a lattice spring model is used to model the mechanics of lymphatic valves. Lymphatic valve functions such as enabling lymph flow and preventing backflow under varied lymphatic valve geometries and mechanical properties are investigated to provide an understanding of the function of lymphatic vessels and valves. The simulations indicate that lymphatic valve function is optimized when valves are of low aspect ratio and bending stiffness, so long as these parameters are maintained at high enough values to allow for proper valve closing. This suggests that valve stiffening could have a profound effect on overall lymphatic pumping performance. Furthermore, dynamic valve simulations showed that this model captures the delayed response of lymphatic valves to dynamic flow conditions, which is an essential feature of valve operation. Thus, our model enhances our understanding of how lymphatic pathologies, specifically those exhibiting abnormal valve morphologies such as has been suggested to occur in cases of primary lymphedema, can lead to lymphatic dysfunctions.