ROLE OF ISCHEMIC GRADIENT IN NEOVASCULARIZATION OF INTERPOLATED SKIN FLAPS

Objectives: To investigate the significance of the ischemic gradient b etween interpolated skin flaps and the recipient bed and to determine its role in flap viability. Design: Bilateral interpolated skin flaps were elevated in 10 pigs and intravenous fluorescein was used to defin e a border of pedicle perfusion. Flaps were assigned to 1 of 2 groups: proximal flaps, which were contained within the fluorescein border, o r distal flaps, which extended 3 cm beyond the fluorescein border. Fla ps were then transferred to an adjacent cutaneous defect and pedicles were divided after 2 weeks. The flap and pedicle portions were evaluat ed separately and viability was quantified. Subjects: Ten adolescent p igs with bilateral flaps. None were withdrawn. Intervention: Intraveno us fluorescein (20 mg/kg) to determine extent of perfusion in the flap s. Results: Proximal flaps (n=10) maintained excellent viability with the pedicles attached. After pedicle division, however, partial flap a nd pedicle necrosis developed. Distal flaps (n=10) promptly showed sig ns of ischemia and congestion but soon showed improved vascularity. A statistically significant improvement was seen in mean percent viabili ty of the distal group compared with the proximal group (P<.05) (Stude nt t test). Conclusion: The more ischemic flap-pedicle complex resulte d in greater viability after pedicle division. The ischemic gradient s eemed to represent a potent angiogenic stimulus to the recipient bed.