Assessment of Lymphovenous Anastomosis Patency: Technical Highlights

INTRODUCTION

Breast cancer survivors account for nearly 3 million in the United States and represent 41% of female cancer survivors.¹ Breast cancer survival has increased over the years, reaching 91% at 5 years after diagnosis.² Lymphedema surgery is rising worldwide, as breast cancer survival rates increase. The lymphatic system is highly complex, and surgical techniques for correction of lymphedema include microsurgical lymphovenous bypass and lymph node transfer.³ Several techniques have been proposed to help the surgeon visualize the lymphovenous bypass anastomosis patency (Table 1). Here, we present 2 videos showing these techniques, to verify the patency of a lymphovenous anastomosis intraoperatively.

Table 1.

Evaluation Methods for Lymphovenous Bypass Anastomosis Patency

Authors	Method	Description	Notes
Ogata et al4,5	ICG-enhanced patency test (see Video 1 [online], which displays ICG-enhanced patency test)	ICG is used as an optical tracer agent. ICG (0.2 mL) is injected into the web space of the limb(s). An ICG fluorescence high-sensitivity near-infrared video camera system (PDE), in which the optical filtering system is optimized, is used to capture the images. PDE is equipped with a CCD camera as a detector with a 760-nm light-emitting diode and a filter cutting light below 820 nm. The fluorescence images are digitalized for real-time display by using a standard personal computer.	Patients with a history of allergic reaction, especially to iodine, must be excluded.
Yap et al9	Blue dye patency test (see Video 2 [online], which displays blue dye patency test)	Blue dye is injected subdermally and is taken up readily by the draining lymphatic channels. The patency of the anastomosis is also demonstrated by the dynamic pumping action of the lymphatics within the vessels.	This technique also helps confirm the success of the lymphovenous anastomosis.

CCD, charge-coupled device.

INDOCYANINE GREEN-ENHANCED PATENCY TEST

Since its introduction by Ogata et al⁴ in 2007, the lymphographic method based on fluorometric sensing using indocyanine green (ICG) dye has become the standard for preoperative and intraoperative evaluation of lymphatic circulation and patency.^4,5 The use of this system enables real-time visualization of dynamic lymph flow. ICG is not only a dye marker but also a fluorescent substance.⁵ An ICG fluorescence high-sensitivity near-infrared video camera system, the Photodynamic Eye (PDE) (Hamamatsu Photonics, Hamamatsu, Japan), is used to enable detection of sentinel lymph nodes or lymphatic vessels located superficially or deep (2 cm) under the surface of the skin. The optical filtering system of the ICG fluorescence-sensitive camera is optimized to capture the near-infrared light (≈800 nm), enabling noninvasive detection of the fluorescence in deep dermal layers.

Ogata et al^4,5 tested this method in rats and humans to detect lymphatic vessels and their damage, even in a latent stage of radiation-induced lymphostasis. In 2010, Mukenge et al⁶ introduced the possibility of using this system to assess the patency of lymphovenous anastomoses at several follow-up visits after lymphovenous microsurgery for treatment of secondary lymphedema in external male genital organs. The authors used PDE lymphography to objectively assess lymphatic structure and progressive improvement of patients’ clinical conditions at 3, 6, and 12 months after surgery.⁶ ICG fluorescence lymphangiography was performed with a bilateral injection of a bolus of fluorescent ICG, and subcutaneous fluorescence images were collected with the PDE system. The images were analyzed on a personal computer.⁶

In 2016, Maegawa et al⁷ sought to determine midterm postoperative patency of lymphovenous side-to-end anastomoses using ICG fluorescence lymphography in human patients. Anastomosis patency was assessed using ICG fluorescence lymphography 6 months or more after surgery. Patency rates were calculated using Kaplan–Meier analysis. They assessed volume reduction on the operated limb and compared this between patients with patent anastomoses and those in whom anastomoses were not clearly patent.

The ICG approach for lymphangiography is efficient and safe method for patency assessment intraoperatively because it is possible to ascertain patency of the anastomosis and assess lymphatic drainage (see Video 1 [online], which displays ICG-enhanced patency test). In this illustrative case, after general anesthesia was induced, 0.05 mL of ICG was injected intradermally using a 30-gauge needle into each web space of the lymphedematous limb. To better visualize the lymphatic vessels during dissection, we also injected intradermally 0.2 mL of isosulfan blue into each web space, as well an additional 0.1 mL 4 minutes before the specific site dissection, 2–3 cm distal to the incision. An end-to-side anastomosis between the previously mapped lymphatic vessel and adjacent vein was conducted under microscopic magnification using 11-0 nylon suture and 50-μm needle. Future applications of ICG are currently being studied. For instance, Najjar et al⁸ assessed the lymphatic drainage pattern to evaluate the reestablishment of lymphatic drainage in the transplanted nodes of rats by injecting fluorescent ICG and detecting the uptake using a PDE infrared camera.

Video 1. VICG enhanced patency test. Video 1 from “Assessment of Lymphovenous Anastomosis Patency: Technical Highlights”.

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BLUE DYE PATENCY TEST

Blue dyes, such as methylene blue and isosulfan blue, can be used to better visualize and assist with microsurgical dissection. Blue dye is a substance readily excreted, and the real-time visualization of the lymph flow improves visualization of functional lymph vessels during surgery.⁹ However, rare allergic adverse reactions (0.2%–2.7%) from rash to anaphylaxis and cardiovascular collapse and death as well as skin necrosis might appear and should be considered at the moment of the procedure.^10–12 Use of the highly lymphotrophic methylene blue staining of the lymphatic vessels for lymphangiography has the advantage of an intense optical visualization of lymph flow and sensitive detection of leakages.¹³ Blue dye staining during lymphovenous anastomosis is a simple and effective method for mapping suitable subdermal lymphatics, allowing for speedier dissection of the lymphatic vessels.⁹

However, if the blue dye is not used during dissection, then the detection of patency of an anastomosis can be readily assessed with its injection, which helps to confirm success of the lymphovenous anastomosis.¹³ Patency is proved directly by observation of blue dye transit through the anastomosis (see Video 2 [online], which displays blue dye patency test). In this case, 0.2 mL of blue dye was injected intradermally 2.5 cm distal to the incision located 1 cm distal to the wrist crease on the volar aspect of the forearm. An end-to-end anastomosis between the lymphatic vessel and adjacent vein was conducted under microscopic magnification using 11-0 nylon suture.

Video 2. Blue dye patency test. Video 2 from “Assessment of Lymphovenous Anastomosis Patency: Technical Highlights”.

Download video file ^{(40.9MB, mp4)}

CONCLUSIONS

Even though blue dye does not depend on a specific video camera system, such as the PDE, to evaluate the lymph flow between vessels, both ICG-enhanced and blue dye patency tests are helpful for evaluating patency of lymphovenous bypass anastomosis due to their simplicity, accuracy, reproducibility, and safety.