Introduction: Lymph flows along the lymphatics due to spontaneous contraction. However, injury and inflammation may deteriorate lymphatic' s endothelial and muscle cells and valves. In consequence, lymphatic vessels (LVs) become insufficient. Their contraction strength and rate slow down, and then lymph flow stops. Our study aimed to investigate the changes in lymph flow in early lymphedema cases. Methods and Results: In 36 patients with unilateral lymphedema stages 0 and I, we performed indocyanine green (ICG) lymphography, lymphoscintigraphy, skin water concentration, and stiffness measurement. We compared lymph flow velocity, LVs' appearance, contraction pattern, and rate between swollen and healthy limbs. ICG lymphography revealed (1) slower lymph flow after 3 minutes of foot movement; in lower calf level, lymphatics are seen in 22 (61.1%) swollen limbs compared with 36 (100%) healthy limbs (p < 0.0001); (2) dye spots in the foot (47.1%) and calves (13.9%) in swollen limbs; (3) dilated foot (41.7%) and calves' lymphatics (52.8%); (4) different patterns of lymphatics contractility with slower contractions rate and (5) higher fluorescent intensity in edema limbs. There was higher skin water concentration at foot and ankle level and higher skin stiffness in the foot. Conclusions: Our studies have shown the distortion in lymphatic function as dilatation, slower lymph flow, slower contraction rate, presence of areas with occluded lymphatics (dermal backflow in foot and calves-focal edema), and higher skin water concentration in these regions in limbs with early lymphedema. ICG lymphography can be used for the early detection of LV insufficiency, which allows early prophylactic implementation.
Keywords: early lymphedema; focal edema; indocyanine green lymphography; lymphangion contraction; lymphatic insufficiency.