A Novel Approach to Subcutaneous Collecting Lymph Ducts Using a Small Diameter Wire in Animal Experiments and Clinical Trials.

While performing microsurgery, including lymphaticovenous anastomosis (LVA) for chronic limb lymphedema, it is a common procedure to identify the subcutaneous collecting lymph ducts with near-infrared fluorescence lymphangiography (NIR) using indocyanine green. However, due to limitations such as minimum observable depth, only a few lymphatic ducts can be identified with this procedure. Hence, we developed a new smaller-diameter "lymphatic wire" (LW) that could be inserted directly into lymphatic collecting ducts of the limbs, enabling accurate identification and localization. First, used the LW on the hind limbs of 6 swine, and 36 porcine lymphatic collecting ducts were identified, the outer diameter of which varied from 0.3-0.7 mm (mean 0.41 ± 0.11 mm). We could insert the LW after creating a side opening in 30 of these ducts. We encountered no difficulties during the procedure. In the pathological examination, adverse events such as valve dysfunction and perforation were not identified. Based on the results, a clinical evaluation of the LW was performed in two patients with lower extremity lymphedema, and the LW helped us identify lymphatic ducts in the subcutaneous layer, even at the sites where the NIR had proved ineffective. Based on our results, we suggest that the procedure for identifying lymphatic vessels using the newly developed LW is a useful technique that can be utilized before performing a LVA for lymphedema. However, further clinical study is required to develop this device and technique, for wider clinical application in the future.