Effect of vascular delay on viability, vasculature, and perfusion of muscle flaps in the rabbit

The delay procedure is known to augment pedicled skin or muscle flap surviv al. In this study, we set out to investigate the effectiveness of vascular delay in two rabbit muscle flap models. In each of the muscle flap models, a delay procedure was carried out on one side of each rabbit (n = 20),and t he contralateral muscle was the control. In the latissimus dorsi flap model , two perforators of the posterior intercostal Vessels were ligated. In the biceps femoris flap model, a dominant vascular pedicle from the popliteal artery was ligated. After the 7-day delay period, the bilateral latissimus dorsi naps (based on the thoracodorsal vessels) and the bilateral biceps fe moris flaps (based on the sciatic vessels) were elevated. Animals were divi ded into three groups: part A, assessment of muscle flap viability at 7 day s using the tetrazolium dye staining technique (n = 7); part B, assessment of vascular anatomy using lead oxide injection technique (n = 7); and part C, assessment of total and regional capillary blood flow using the radioact ive microsphere technique (n = 6). The results in part A show that the aver age viable area of the latissimus dorsi flap was 96 +/- 0.4 percent (mean /- SEM) in the delayed group and 84 +/- 0.7 percent (mean +/- SEM) in the c ontrol group (p < 0.05, n = 7), and the mean viable area of the biceps femo ris flap was 95 +/- 2 percent in the delayed group and 78 +/- 5 percent in the control group (p < 0.05, n = 7). In part B, it was found that the line of necrosis in the latissimus dorsi flap usually appeared at the junction b etween the second and third vascular territory in the flap. Necrosis of the biceps femoris flap usually occurred in the third territory, and occasiona lly in both the second and the third territories. In Part C, total capillar y blood flow in delayed flaps (both the latissimus dorsi and biceps femoris ) was significantly higher than that in the control flaps (p < 0.05). Incre ased regional capillary blood flow was found in the middle and distal regio ns, compared with the control (p < 0.05, n = 6). In conclusion, ligation of either the dominant Vascular pedicle in the biceps femoris muscle flap or the nondominant pedicle in the latissimus dorsi muscle flap in a delay proc edure 1 week before flap elevation improves capillary blood flow and muscle viability. Vascular delay prevents distal flap necrosis in two rabbit musc le nap models.