Contractility patterns of human leg lymphatics in various stages of obstructive lymphedema.

In healthy human leg, lymphatics contract spontaneously, rhythmically propelling lymph. The pressures generated by lymphatic contractions constitute the main force for lymph flow. This mechanism is of utmost importance during night rest, anesthesia, and immobilization, as well as in those with damaged peripheral motor neurons. Under physiological conditions, limb muscular activity and position only slightly change lymph flow. In obstructive lymphedema, lymphatic wall muscular fibers become damaged and the spontaneous contractility becomes ineffective in lymph transport because of low generated pressures and lymphatic valve insufficiency. The lymph-propelling task is taken over by leg muscle contractions. Measuring intralymphatic pressures and flow gives some insight into the mechanism of lymph flow in healthy limbs and loss of this function in lymphedema. This knowledge will be useful in the derivation of rational treatments for lymphedema.