THE MICROCIRCULATION AND SURVIVAL OF EXPERIMENTAL FLOW-THROUGH VENOUSFLAPS

The subject of venous flaps is controversial. The purpose of this stud y was to investigate the haemodynamic changes and the survival process of venous flow-through flaps. Venous flaps and composite grafts were elevated along the axis of the thoracoepigastric veins in rabbits. The microcirculation was studied by capillaroscopy and injection studies. For the first 72 h, the flaps were nourished by venous blood; venous blood flowed slowly from the principal vein to its tributary veins and then through venous anastomoses to reach other tributary veins. No ba ckflow from venules into capillaries was seen. New vessels began to gr ow into the flaps from 72 h postoperatively. Four days postoperatively , arterial flow with low velocity was seen in the primary flap arterie s and the backflow of venous blood disappeared. Seven days postoperati vely, the abnormal flow in ''unphysiological'' channels was replaced b y normal flow in ''physiological'' channels. Six weeks postoperatively , the vessel structure of venous flaps was the same as that of normal skin. These results suggest that the profuse venous network in venous flaps and early invasion of new blood vessels are the mainstays of ven ous flap survival.