[Position of venous outflow: a crucial aspect in flaps with 2 opposed pedicles. Application to the cutaneous delay phenomenon. Experimental study with rats]

In the present study, the authors decided to focus on the effect of the venous outflow location in the survival of a flap with a choke vessels barrier by means of a rat bipedicled ventral island flap. In a first experiment, the extent of flap necrosis was examined in three experimental groups: group 1, alternate vein and artery ligation (n = 5); group 2, unilateral artery ligation (n = 5); group 3, unilateral pedicle ligation (n = 5). Less than 10% necrosis occurred in group 1; 28% in group 2 and 33% in group 3. In a second experiment we applied the first results to the delay phenomenon. 10 rats were divided into 2 groups: group 4, primary ligation of a complete pedicle on one side; group 5, primary alternate vein and artery ligation and the flaps were raised 21 days later. We observed 20% necrosis in group 4 and only 4% in group 5. The data of the first experiment indicate that a vein remaining near the artery can be a dramatic obstacle to the efficiency of choke vessels. The second experimental study shows the superiority of primary selective ligation in the delay phenomenon.