Plastic Surgery Research Council
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PSRC 60th Annual Meeting
Program and Abstracts

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Is More Better? The Number of Lymph Nodes in the Vascularized Lymph Node Transfer Influences its Lymphaticovenous Drainage
Grzegorz Kwiecien, MD, Bahar Bassiri Gharb, MD, PhD, Kashyap Tadisina, BA, Maria Madajka, PhD, James E. Zins, MD, Graham S. Schwarz, MD.
Cleveland Clinic, Cleveland, OH, USA.

PURPOSE: Vascularized lymph node (VLN) transfer is a new and promising treatment option for patients suffering from lymphedema. Despite reported good outcomes and recent growth in popularity, several questions remain unanswered including mechanism of action and optimal flap design. Finding answers to these questions would aid in the surgical planning and execution of this novel technique. The purpose of this study was: 1) to evaluate the mechanism of lymph drainage through the VLN flap, and 2) to investigate if the number of VLNs impacts on the kinetics of lymph transit through the flap.
METHODS: Twenty-four lymph node containing flaps were elevated in the axillary region in 12 male Sprague-Dawley rats (450-500g) based on the axillary artery and vein (Figure 1). Flaps were divided into 3 experimental groups (n=8 each) based on the number of lymph nodes present: Group 1 (0 VLN), Group 2 (2 VLN), and Group 3 (4 VLN). Excessive lymph nodes were gently excised from the distal edge of the flaps with attention paid to prevent injury to the adjacent lymphatic vessels. Indocyanine green (ICG) was injected into the edge of each flap and latency period between injection and fluorescence in the axillary vein was recorded (Figure 2). Pearson correlation coefficient was used to evaluate the relationship between the number of lymph nodes in the flap and the lymphatic fluid transit. Analysis of variance (ANOVA) was used to compare flap weights between the groups.
RESULTS: Fluorescence was detected in the axillary vein after the mean latency period of 197 ± 188, 109 ± 97, and 73 ± 57 seconds in the Group 1, 2, and 3, respectively. There was a negative correlation between the number of VLN in the flap and the latency period (r = -0.39; p = 0.03). Mean flap weight was comparable in the Groups 1, 2, and 3 (275 ± 54, 298 ± 74 mg, 309 ± 60 mg, p = 0.54).
CONCLUSIONS: Lymphatic fluid in VLN flaps drains into the venous system mainly by passing through the vascularized lymph nodes. A secondary mechanism is the diffusion of the fluid directly into the venous system via flap capillary lymphatics. This is shown by comparatively delayed presence of fluorescence in the pedicle vein in flaps without VLN. Negative correlation between the number of VLN and fluorescence latency period in the pedicle vein indicates that increasing the number of lymph nodes in the flap directly improves flap lymphatic drainage capacity.

Figure 1. Elevated axillary flap based on the axillary artery and vein: arrowheads, VLN; arrow, fluorescent dye injection site.

Figure 2. Visible presence of the fluorescence in the pedicle vein after injection of ICG dye into the edge of the axillary VLN flap.

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