Validation and efficacy of 'pure' venous lymph node flap in a rat lymphoedema model

The venous lymph node flap (vLNF) is regarded as an arterialized or 'pure' venous flap, subject to which type of vessel provides blood supply to the flap. However, whether the vLNF drainage function is maintainable or sufficient for the treatment of lymphoedema is yet to be elucidated. In this study, the venous flow-through lymph node flaps or 'pure' vLNF was investigated in a rat's tail (lymphoedema model), and the therapeutic effect was analysed to clarify its potential value for the treatment of lymphoedema. The subjects (rats) were divided into three groups, the experimental group ('pure' vLNF group), the control group (lymphoedema group), and the baseline group. The tail circumference and diameter were recorded for 5 weeks after the operation. Five weeks after surgery, the lymphatic drainage function was evaluated using indocyanine green (ICG) lymphography, while the skin thickness and collagen layer were assessed by histological analysis. The average diameter and circumference of the experimental group were significantly shorter than the control group (p < 0.01). When comparing ICG lymphography within the three groups, the baseline group showed that the ICG entered the inguinal lymph node and appeared in the liver while the ICG still accumulated in the oedematous tail with no fluorescence emerging in other parts of the rat's body, in the control group. In the experimental group, the ICG entered the vLNF via the flap junction with the rat's tail and fluorescence emerging in the rat's liver. When comparing the three groups above with the control group, the experimental group's skin and collagen layer thickness were significantly improved (p < 0.01). Lymphatic recanalization was shown to appear between 'pure' vLNF and the recipient area. Moreover, vLNF was shown to drain lymph fluid via the venous system, thus relieved swelling and fibrosis of the lymphoedematous tissue. Consequently, this could represent a new potential surgical approach for the treatment of lymphoedema.