title: Analysis of Microvascular Free Flap Failure Focusing on the Microscopic Findings of the Anastomosed Vessels.
abstract: Microvascular flap reconstruction is known as successful technique, although vascular thrombosis can cause free flap failure. To analyze the histologic characteristics and causes of free flap failure, this clinical study examined failed free flaps, including the microanastomosed sites. This study included a total of 5 failed flaps, including 3 radial forearm free flaps, 1 latissimus dorsi free flap, and 1 fibular free flap, all performed with microvascular reconstruction surgery from 2009 to 2011 at Seoul National University Dental Hospital. At the resection surgeries of the failed nonviable flaps, histologic specimens including the microanastomosed vessels were acquired. For light microscope observation, the slides were stained with hematoxylin and eosin (HE), and also with Masson trichrome. Selected portions of graft tissue were also observed under transmission electron microscope (TEM). It was found that the cause of flap failure was the occlusion of vessels because of thrombi formation. During the microanastomosis, damage to the vessel endothelium occurred, followed by intimal hyperplasia and medial necrosis at the anastomosed site. In the TEM findings, some smooth muscle cells beneath endothelium were atrophied and degenerated. The formation of thrombi and the degeneration of the smooth muscle cells were coincident with vascular dysfunction of graft vessel. The damaged endothelium and the exposed connective tissue elements might initiate the extrinsic pathway of thrombosis at the microanastomotic site. Therefore, it is suggested that accurate surgical planning, adequate postoperative monitoring, and skillful technique for minimizing vascular injury are required for successful microvascular transfer.
authors.affiliation: *Department of Oral and Maxillofacial Surgery, Oral Cancer Center, Dental Research Institute, School of Dentistry, Seoul National University, Seoul †Department of Oral Pathology, College of Dentistry, Gangneung-Wonju National University, Gangneung, South Korea.
authors.forename: Mi Hyun
authors.initials: MH
authors.lastname: Seo
authors.forename: Soung Min
authors.initials: SM
authors.lastname: Kim
authors.forename: Fan
authors.initials: F
authors.lastname: Huan
authors.forename: Hoon
authors.initials: H
authors.lastname: Myoung
authors.forename: Jong Ho
authors.initials: JH
authors.lastname: Lee
authors.forename: Suk Keun
authors.initials: SK
authors.lastname: Lee
mesh_terms: D000368:Aged; D000714:Anastomosis, Surgical / Q000009:adverse effects; D001284:Atrophy; D004730:Endothelium, Vascular / Q000473:pathology; D005260:Female; D058752:Free Tissue Flaps / Q000098:blood supply / Q000637:transplantation*; D006085:Graft Survival; D006801:Humans; D006965:Hyperplasia; D008297:Male; D046529:Microscopy, Electron, Transmission; D008866:Microsurgery / Q000009:adverse effects; D055806:Microvessels / Q000473:pathology*; D008875:Middle Aged; D009131:Muscle, Smooth, Vascular / Q000473:pathology; D009336:Necrosis; D011183:Postoperative Complications; D019651:Plastic Surgery Procedures / Q000009:adverse effects*; D013927:Thrombosis / Q000209:etiology*; D017539:Tunica Intima / Q000473:pathology; D017540:Tunica Media / Q000469:parasitology