Valve Elasticity for Optimal Lymphatic Pumping

The lymphatic system transports interstitial fluid, fatty acid, and immune cells and maintains this vital function by pumping the lymphatic fluid via networks of contracting lymphatic vessels and elastic valves. The interplay of peristaltic motion of the lymphatic vessels and valves achieve unidirectional flow against adverse pressure gradient while minimizing any backflow. Despite the significance, research into the lymphatic system has been limited, especially regarding the function of lymphatic valves. We use fully coupled, three-dimensional fluid-structure interaction model to study the performance of compliant lymphatic valves in the lymphatic vessel that undergoes peristaltic motion. Parameters such as adverse pressure gradient, contraction frequency, contraction amplitude, and elasticity of the lymphatic valves are varied to investigate their effects on the flow rate and pumping efficiency, which are compared against their valve-less counterparts. The results suggest that lymphatic valves significantly extend the range of operational adverse pressure gradients. Furthermore, the simulations reveal the optimum valve elasticity enhancing pumping performance.