[Experimental study of mechanism of survival of venous flaps]

The mechanism of survival of venous flaps was studied by observations employed in the study of microcirculation and blood vessel perfusion in rabbits. Initially, the flap was nourished by venous blood (within 72 hours): venous blood flowed slowly from the principal vein to its tributary veins, and then through the venous anastomoses (including small venous anastomoses, venular anastomoses and terminal venule anastomoses), reaching other tributary veins. No backflow from venules into capillaries was seen. The second stage was arterial nourishing and vessel reconstructive period (72 hours to 6 weeks): new vessels began to grow into the flaps at 72 hours postoperatively. 4 days postoperation, arterial flow with low velocity appeared in the primary flap arteries and the backflow of venous blood disappeared. 7 days postoperation, the abnormal, flow in 'unphysiologic' channels was replaced by the normal flow in 'physiologic' channels completely. 6 weeks postoperation, the vessel structure of venous flaps was the same as that of normal skin. These results suggested that rich venous network in venous flaps and early invasion of new blood vessels are the mainstay of venous flaps survival.