Computational Investigation of Lymphatic Valves and Vessels
Wolf, Ki Tae
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The lymphatic system transports macromolecules and fluids throughout the body via contractions of lymphatic vessels. This flow from vessel contractions is regulated by unidirectional lymphatic valves, which allow lymphatic pumping against adverse pressure gradient. Despite the importance of the lymphatic system, understanding of lymphatic operation, especially the role of lymphatic valves, is still limited. By using a fully coupled three-dimensional fluid-structure interaction model created using lattice Boltzmann method and lattice spring model, we computationally investigate the role of lymphatic valve and vessel properties on lymphatic pumping. First, the effect of lymphatic valve properties such as valve aspect ratio and bending stiffness on pumping performance is investigated with a rigid lymphatic vessel. This study found that shorter and more flexible valves generally reduce flow resistance but valves that are too short cannot block backflow properly. Then, the effect of lymphatic valve and vessel properties on pumping performance under vessel contraction is studied. This study showed that lymphatic valve and vessel properties have complex relationship with lymphatic pumping, and all parameters investigated have optimal conditions with maximum pumping efficiencies. Finally, a model of lymphatic filarial worm is created and introduced to the model of lymphatic valve and vessel to investigate the worm’s behavior when navigating through the lymphatic system. Overall, this work highlights many important parameters of lymphatic valve and vessel that affect lymphatic operation and provides insights into conditions that may cause lymphatic disorders.