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Lymphedema microsurgery gaining momentum


 

EXPERT ANALYSIS AT THE NORTHWESTERN VASCULAR SYMPOSIUM

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CHICAGO – Microsurgery does not cure lymphedema, in most cases. But, in most cases, it does improve the severity of lymphedema and reduce the complications of this chronic and debilitating disease. And “it certainly improves patients’ quality of life,” lymphedema treatment pioneer Dr. David W. Chang said at the 40th annual Northwestern Vascular Symposium.

Surgical treatment for limb lymphedema has come into its own since a lymphovenous shunt was first used in a dog model in 1962, with Dr. Chang and others now anastomosing subdermal lymphatics to subdermal venules less than 0.8 mm in diameter. The rationale behind “super-microsurgery” is that venous pressure is low in the subdermal venules and has minimal back flow, he said.

Dr. David W. Chang Patrice Wendling/Frontline Medical News

Dr. David W. Chang

One of the big problems early on was knowing exactly where the lymphatic vessels were, but newer technology like indocyanine green (ICG) lymphangiography helps visualize functioning lymphatic channels for potential bypass and determine the severity of the disease. Understanding the disease stage is key to selecting the appropriate surgical procedure.

Lymphovenous bypass (LVB) is best in patients with stage 1 or 2 upper extremity lymphedema, while lymph node transfer (LNT) works for patients who are poor candidates for LVB or require combined breast reconstruction, said Dr. Chang, a plastic surgeon with the University of Chicago.

More recently, Dr. Chang has begun combining LVB and LNT, particularly for the more severe cases with stage 3 or 4 upper or lower extremity disease.

In Dr. Chang’s first 100 consecutive LVB cases while at the M.D. Anderson Cancer Center in Houston, quantitative improvement occurred in 74% of patients, symptom improvement in 96%, and the average volume differential reduction was 42% at 12 months (Plast Reconstr Surg. 2013 Nov;132:1305-14). The reduction was significantly larger in patients with earlier stage 1 or 2 vs. later stage 3 or 4 disease (61% vs. 17%).

Images courtesy of Dr. David W. Chang

During lymphovenous bypass, ICG is injected into the dermis of the web space and the superficial lymphatics evaluated with near-infrared fluorescence. It is easy to identify discrete functioning lymphatic channels in early-stage disease, but in late-stage disease significant dermal back flow is present, Dr. Chang said.

Dissection is performed under the microscope in the superficial subcutaneous plane to locate a good venule and lymph channel. Lymphatics are confirmed with isosulfan blue and ICG, and once the bypass site is determined, the lymphatic is anastomosed to the venule using 11-0 or 12-0 nylon, preferably in an end-to-side fashion. It’s thought this creates a more favorable flow pattern for the lymph to empty into the venule than an end-to-end anastomosis, he observed.

After the anastomosis is complete, patency is confirmed with isosulfan blue and ICG and the incision is closed under the microscope to ensure that the delicate anastomosis isn’t damaged. To avoid shear injury to the anastomosis, the limb is wrapped postoperatively for about a month without use of compression garments, he said.

Lymph node transfer (LNT) is increasingly being offered at centers to provide relief from lymphedema, although the mechanism by which it works is yet unclear; either the healthy lymph nodes act as a sponge to absorb lymphatic fluid or they induce lymphangiogenesis. Experience has shown, however, that rather than just grafting the lymph nodes, they need to be harvested with a vascular pedicle before transfer and anastomosed to the recipient artery and vein, although reconnecting the actual lymphatics may not be necessary, Dr. Chang observed.

Despite its popularity as a donor site, Dr. Chang said he is reluctant to use the groin because of the potential for iatrogenic lymphedema and prefers to harvest the supraclavicular nodes based off the transverse cervical artery. The external jugular vein can be harvested with the nodes if adequate venae comitantes are not present with the artery. Dissection of this flap can be difficult and care should be taken not to injure the lymphatic ducts, he noted.

It is also important to excise all scar tissue in the recipient site as this can impair lymphatic flow and inhibits lymphangiogenesis. If it is difficult to access or remove the scar, the vascularized lymph nodes are best placed just distal on the limb to the site of lymphatic obstruction, he added.

A recent meta-analysis (Plast Reconstr Surg. 2014 Apr;133:905-13) in five LNT studies reported that 91% of patients had a quantitative improvement, 78% discontinued compression garments, and complications were infection (8%), lymphorrhea (15%), and need for additional procedures (36%). There was great heterogeneity between studies, so the results should be interpreted with caution, Dr. Chang advised.

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