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Seki et al. Plast Aesthet Res 2021;8:58 https://dx.doi.org/10.20517/2347-9264.2021.80 Page 3 of 11

power creates continuous lymphatic flow at the site of LVA. In other words, this new LVA itself acts as a
perpetual motion, preventing its own obstruction and efficiently draining lymph into the anastomosed
veins; therefore, we describe this new LVA concept as “functional LVA”.

In the functional LVA concept, the method of maximizing muscle pumping is different between the upper
limb and lower limbs, because the anatomical and physiological characteristics of lymphatic and venous
dynamics differ between them. The lymphatic function in the arm works more longitudinal with low gravity
effect on the veins. In contrast, the lymphatic function in the leg works more transversal with high gravity
[9]
effect on the veins . These differences in lymphatic function and gravity effect on the vein between upper
and lower extremities are important for making LVA strategy.

The current functional LVA methods we have developed are the dynamic LVA method for upper extremity
lymphedema (UEL) and the superior-edge-of-the-knee incision method for lower extremity lymphedema
(LEL).

The dynamic LVA method for upper extremity lymphedema
To keep continuous lymphatic flow at the lymph-to-venous anastomosis in upper extremity, the muscle
pumping power by patient’s natural hand motions can be utilized as functional LVA.

The dynamic LVA method is a reliable LVA technique at the forearm for UEL, which the senior author
[21]
developed in November 2016, and we reported a case-control study in January 2019 . After the detection
of the lymphatic vessels at the arm by other modalities, preoperative dynamic ultrasonography (US) is
performed to determine the best incision point on each lymphatic vessel on each patient forearm where
muscle pumping by hand movements works maximally.

Because the patient’s dominant hand, lifestyle, work, and other activities affect muscle development and
tissue structure in the arm, the anatomical and physiological function of lymphatic and venous systems are
not uniform in UEL patients. That is why the best incision sites for LVA in patients with UEL must be
determined individually.

The clinical effect of the dynamic LVA is obtained at the whole upper extremity because LVA at the arm
can be seen at a longitudinally far distal or far proximal region [9,23] . Preoperative determination of incision
points using traditional US technology is the essence of this method. An important point in the dynamic
LVA method is that US is utilized not to detect lymphatic vessels but to evaluate muscle pumping and
subcutaneous veins over 1.0 mm in diameter. Thus, no special US techniques are needed to perform
dynamic LVA.

As preparation of the method, the lymphatic vessels’ pathways are identified first. Although our preferred
way to detect lymphatic vessels for dynamic LVA is utilizing ICG lymphography findings at affected and
non-affected arms [9,23,24] , any modalities to visualize the lymphatic vessels can be used to identify lymphatic
pathways in this method. Several modalities, including ICG lymphography, MRI, high-frequency US, and
photoacoustic imaging, can be combined to identify lymphatic pathways for dynamic LVA [3-14,25] .

Once a lymphatic vessel is detected at the patient’s arm, dynamic US is performed along the detected vessel
to determine the incision point with maximum muscle pumping function. Throughout dynamic US
examination, patients are instructed to move the lymphedematous hand continuously to evaluate muscle
and venous pumping in the subcutaneous tissue at the forearm. If the large subcutaneous vein (> 1.0 mm) is