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Managing Venous Hypertension in Vascularized Omentum Lymphatic Transplant: Restoring Bidirectional Venous Drainage.

Managing Venous Hypertension in Vascularized Omentum Lymphatic Transplant: Restoring Bidirectional Venous Drainage Sir: T vascularized omentum lymphatic transplant is a compelling alternative to peripheral lymph nodes for treating lymphedema because there is no risk of donor-site lymphedema.1,2 This flap is based on the right gastroepiploic vessels with a single arterial and venous anastomosis. However, venous hypertension has been observed even with a patent venous anastomosis.1 This may compromise a distal lymph node transplant because a favorable pressure gradient is required for lymph to be effectively shunted into the venous system.3,4 To reduce venous pressure, the authors propose venous anastomosis to both the proximal and distal ends of the right gastroepiploic vein. Venous hypertension in the omentum flap may be related to its unique vascular anatomy, with bidirectional venous drainage through the left and right gastroepiploic veins. In an in vivo study of 20 patients by Kumagai et al., using indocyanine green angiography, 16 patients had contiguous left and right gastroepiploic veins and four had no anastomosis present.5 In summary, most patients have continuous bidirectional venous outflow that may lead to venous hypertension once the left gastroepiploic vein is divided. This is consistent with our observation of high-pressure venous back-bleeding when opening the distal end of the gastroepiploic vein following revascularization of the omentum. Nguyen et al. reported a creative strategy for managing venous hypertension.1 The distal end of the right gastroepiploic artery is anastomosed to the distal end of the right gastroepiploic vein, creating an arteriovenous fistula. This creates a favorable arteriovenous pressure gradient and reduces venous congestion. However, the absolute pressure within the vein will rise in an arteriovenous fistula, potentially compromising the pressure gradient for lymphovenous shunting. An alternative strategy is to restore the natural bidirectional venous physiology of the omentum by performing a venous anastomosis to both the proximal and distal ends of the right gastroepiploic vein. This recreates the normal venous flow-through circuit that reduces the absolute venous pressure in a more favorable direction for lymphovenous shunting. The authors have since performed bidirectional venous anastomoses in the calf using both medial sural veins, in the forearm using radial artery venae comitantes, and in the axilla using the thoracodorsal and circumflex scapular veins (Figs. 1 and 2). A total of 13 flaps in seven patients have been performed: three with lower extremity and four with upper extremity lymphedema. Indocyanine green lymphangiography confirmed bidirectional venous outflow for all flaps. The flaps remained soft in the early postoperative period, and we have observed a more rapid reduction in swelling. In contrast, many of our previous omentum flaps were firm for several months. We now advocate for proximal and distal gastroepiploic vein anastomosis to restore normal physiologic venous pressure. (See Video, Supplemental Digital Content 1, which shows a bidirectional venous anastomosis of the omentum lymphatic transplant, confirmed with indocyanine green angiography, available in the “Related Videos” section of the full-text article on PRSJournal.com or, for Ovid users, available at http://links.lww.com/PRS/C614.) Fig. 1. Vascularized omentum lymphatic flap to the axilla with bidirectional venous outflow through the thoracodorsal vein and circumflex scapular vein.