Study On Revascularization Of Flap In Hemifacial Composite Tissue Allotransplantation (CTA)

Objective:To develop an experimental model of composite hemifacial allograft in rabbit in order to study dynamic vascular changes during the flap revascularization postoperatively.Methods:1.Anatomic study: Ten healthy livid blue rabbits and ten healthy Japanese white rabbits were used for anatomical dissection of arteriovenous system of head and neck. 2.Autologous transplantation(n=4): In order to obtain reliable blood supply and confirm vascular territory. The hemifacial autologous transplantation were performed in four rabbits. 3.Allograft transplantation(n=10): Allotransplantation was performed with the livid blue rabbits as recipient while Japanese white rabbits as donor, the hemifacial composite tissue flap was based in the common carotid artery with the branch of the external mandibular artery and auricularis magna artery. To prevent allograft rejection, Cyclosporin A(CsA) and Methylprednisolone(MP) or Prednisone(PS) were combined as immunosuppressive protocol. Postoperative, to observe the survive ratio of animal and composite tissue flap, verified the practicability of model further. 4. Dynamic vascular changes were investigated by microangiography, microscopy and computerized image analysis at regular intervals after operation. Results:1. (n=25)Unilateral or bilateral common carotid arteries were ligated simultaneously during operation, all the animals were alive. 2. All composite allografts suvived based in the Common carotid artery with the branch of the external mandibular artery afford good blood supply to composite hemifacial allografts. 3. Ten allograft transplantation were performed, two of them died because of anaesthetic thunderbolt, one of them was die 2 hours after operation, and one of them was die of hematoma at 2th day postoperation, the other 6 of them survived 19-30 days (average 24 days). 4. The micrangium density was increased gradually early after operation at the crossing area and the donor area of the flap. The micrangium density of skin flaps and the crossing area of flap had increasing after operation of 5 days and reached summit at 7-10 days, which was also proved by the optical icroscopy.Conclusions:1. Common carotid artery with the branch of the external mandibular artery afford good blood supply to composite hemifacial allografts. This is a successful model of composite face flap transplantation. 2. The micrangium density of skin flaps reached summit at 10th day after operation, which is slower than normal flap.