Vascularized lymph node flaps can survive on venous blood without an arterial inflow:an experimental model describing the dynamics of venous flow using indocyanine green angiography(With video)

Background:Several surgeons have described studies of free-tissue transfers using veins instead of arteries.These innovative microsurgical techniques can offer several advantages,such as an easier dissection during flap harvesting,and represent an alternative during an accidental surgical mistake or development of new surgical procedures.The purpose of this study was to describe and explore different constructs of vascularized lymph node transfer(VLNT)only based on venous blood flow in a mouse model,evaluate their blood flow microcirculation through indocyanine green(ICG)angiography and investigate the lymphatic drainage function and the lymph nodes’structures.Methods:Five types of venous lymph node flaps(LNF)were created and investigated:Types IA,IB,IC,IIA and IIB were developed by ICG intraoperatively(with videos in the article).Seven weeks later,by applying methylene blue,the recanalization of the lymphatic vessels between the LNF and the recipient site was detected.Lymph nodes were collected at the same time and their structures were analyzed by hematoxylin and eosin staining analysis.Results:All of the venous LNFs developed except Type IC.Seven weeks later,methylene blue flowed into Types IA,IB,IIA and IIB from recipient sites.When comparing with arteriovenous lymph node,the medullary sinus was diffusely distributed in venous lymph nodes.The proportion of cells was significantly reduced(p<0.05).The artery diameters were significantly smaller(p<0.05).The veins diameters and lymphatic vessels output in Types IA,IB,IIA and IIB were more dilated(p<0.05).Conclusions:This research demonstrated that Type IA,IB,IIA and IIB venous LNFs can retrogradely receive venous blood supply;they can survive,produce a lymphatic recanalization and integrate with the surrounding tissue,despite lymph node structural changes.Our results will improve the understanding of the survival mechanism of venous LNFs and will help researchers to design new studies or lymphatic models and eventually find an alternative procedure for the surgical treatment of lymphedema.