Page 10 - Read Online

Page 4 of 13 Liang et al. Plast Aesthet Res 2023;10:71 https://dx.doi.org/10.20517/2347-9264.2023.81

Lymphatic vessels
Using ultrasonography, the radio-opaque superficial fascia was first identified at a depth of approximately 1
cm from the skin surface. Lymphatic vessels are often found at the highest density just deep to this fascia.
Patent lymphatics appear as round, elliptical, or flat and spiculated hypo-echoic structures, representing the
[23]
fluid-filled lumen [22,23] . These are surrounded by a hyper-echoic vessel wall of variable thickness . Repeated
squeezing and releasing the limb distally to promote lymphatic flow helps distend the vessels for better
visualization. While their appearance may be similar to subcutaneous veins to the casual eye, several
features distinguish them from veins. For instance, unlike veins, lymphatics are typically non-compressible
due to their relatively high intraluminal pressure in patients with lymphedema. Doppler flow in lymphatics
is also usually imperceptible at rest, although flow signal may be elicited during sequential squeeze and
release of the limb distal to the probe [Figure 1]. Lymphatics may appear more irregular and specular,
unlike the smoother, circular veins [Figure 2]. Turbulent flow [Figure 3] can be detected in large lymphatics.
When traced proximally, lymphatics often run parallel to each other without joining, and also run across
[24]
the path of veins, which, in contrast, usually merge and increase in size as they travel proximally . Finally,
after identifying and tracing the lymphatic vessels, patent, non-sclerosed lymphatics with lumens denoted
by a clearly hypoechoic center were deemed suitable for use in LVA and their locations were marked.

Subcutaneous veins
Subcutaneous veins can be easily detected using ultrasonography. Veins appear as round or elliptical
structures with a hyperechoic rim and a hypoechoic center. Compressibility is a hallmark of these vessels,
which expediently and easily differentiates them from lymphatics. With the flow detection set at an
appropriately low value of 3-4 cm/s, a flow signal is typically observable within the lumen.

Subcutaneous veins and venules are ubiquitous and found easily after incising the skin, making preoperative
mapping appear redundant. However, herein lies the main rationale for performing ultrasonography.
Rather than just identifying and locating any vein, it is important to check if there is a reflux flow in that
vein. The presence of venous reflux flow can retard the antegrade flow of lymph after completion of LVA or
may even cause backflow of blood into the lymphatic vessel [25,26] . Under ultrasonography, reflux can be
detected by squeezing the limb distally to promote venous flow, and observing if there is any alteration in
the color Doppler signal upon the release of the pressure. A color change shows the reverse flow of blood
within the vein, indicating reflux. The veins are traced proximally; if a smaller branch joins a significantly
larger vein, this usually denotes the presence of a valve at the junction preventing backflow [Video 1]. The
detected anti-reflux veins were marked for use in the subsequent LVA surgery.

Lymphaticovenular anastomosis
All LVA procedures were performed by the senior author of this paper. The surgeries were performed
under general anesthesia for patient comfort. With the patient in the supine position, the affected arm was
placed in an abducted position. Local anesthesia with epinephrine was administered subdermally prior to
skin incision. The superficial subcutaneous fat was gently spread and teased apart through a combination of
blunt and sharp dissection. Anti-reflux subcutaneous veins were identified corresponding to their
preoperative markings and preserved. The superficial fascia was carefully entered and separated. Lymphatics
were detected by direct visual identification and confirmed with both correlation to skin markings and
intraoperative ICG lymphography using a Leica FL800® microscope. Anastomoses were performed with
either 11-0 or 12-0 nylon (Keisei, 50 μ needle, 5R23, 11/12-0N®), by the Intravascular Stenting (IVaS)
method with 4/0 nylon as first described by Narushima . After completion of LVA, patency was confirmed
[27]
with intraoperative ICG lymphography [Figure 4] [Video 2].