Lymphatic pumping: mechanics, mechanisms and malfunction

Abstract

A combination of extrinsic (passive) and intrinsic (active) forces move lymph against a hydrostatic pressure gradient in most regions of the body. The effectiveness of the lymph pump system impacts not only interstitial fluid balance but other aspects of overall homeostasis. This review focuses on the mechanisms that regulate the intrinsic, active contractions of collecting lymphatic vessels in relation to their ability to actively transport lymph. Lymph propulsion requires not only robust contractions of lymphatic muscle cells, but contraction waves that are synchronized over the length of a lymphangion as well as properly functioning intraluminal valves. Normal lymphatic pump function is determined by the intrinsic properties of lymphatic muscle and the regulation of pumping by lymphatic preload, afterload, spontaneous contraction rate, contractility and neural influences. Lymphatic contractile dysfunction, barrier dysfunction and valve defects are common themes among pathologies that directly involve the lymphatic system, such as inherited and acquired forms of lymphoedema, and pathologies that indirectly involve the lymphatic system, such as inflammation, obesity and metabolic syndrome, and inflammatory bowel disease.

Edema and pain reduction using transcutaneous electrical nerve stimulation treatment

“…Edema refers to an increased fluid volume in the body when the distribution of water, which is normally well distributed, becomes unbalanced. That is, when fat accumulates in blood vessels, leading to poor blood circulation, or there is an obstacle preventing the flow of lymph fluid, the homeostasis of the moisture content of cells is broken, leading to the development of edema3 ) .…”

“…Primary lymphedema is secondarily caused by lymphatic vessel aplasia, hypoplasia, or atresia, which can occur at any time. In addition, primary lymphedema occurs more frequently in females than in males, and in particular, it frequently occurs in the lower extremities, below the knees3 ) .…”

The Lymphatic System: Integral Roles in Immunity

“…Therefore, the main function of lymphatic muscle is to generate the pressure needed to pump lymph along the vessel length against gradually increasing pressure. A recent review discusses lymphatic contractile function in exquisite detail (78). …”

Photoacoustic imaging of lymphatic pumping

“…Many pathologies directly or indirectly involve the lymphatic system and its pumping mechanisms, often presenting as lymphatic contractile dysfunction, barrier dysfunction, and valve defects. 2 Common clinical procedures, including lymph node resection for cancer diagnostics, sometimes result in morbid complications to the lymphatic system. 2,3 As many as 30% to 50% of breast cancer patients undergoing lymph node or sentinel lymph node dissection develop lymphedema.…”

“…2 Common clinical procedures, including lymph node resection for cancer diagnostics, sometimes result in morbid complications to the lymphatic system. 2,3 As many as 30% to 50% of breast cancer patients undergoing lymph node or sentinel lymph node dissection develop lymphedema. 4,5 Despite its critical role, the lymphatic system and many of its mechanisms are poorly understood, partly due to the poor contrast of the lymphatic vessels (LVs) and structures.…”