Role of ischemic gradient in neovascularization of interpolated skin flaps

S. S. Park, G. T. Rodeheaver and P. A. Levine
Department of Otolaryngology-Head and Neck Surgery, University of Virginia Medical Center, Charlottesville, USA.

OBJECTIVES: To investigate the significance of the ischemic gradient between 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 define a border of pedicle perfusion. Flaps were assigned to 1 of 2 groups: proximal flaps, which were contained within the fluorescein border, or distal flaps, which extended 3 cm beyond the fluorescein border. Flaps were then transferred to an adjacent cutaneous defect and pedicles were divided after 2 weeks. The flap and pedicle portions were evaluated separately and viability was quantified. SUBJECTS: Ten adolescent pigs with bilateral flaps. None were withdrawn. INTERVENTION: Intravenous fluorescein (20 mg/kg) to determine extent of perfusion in the flaps. RESULTS: Proximal flaps (n = 10) maintained excellent viability with the pedicles attached. After pedicle division, however, partial flap and pedicle necrosis developed. Distal flaps (n = 10) promptly showed signs of ischemia and congestion but soon showed improved vascularity. A statistically significant improvement was seen in mean percent viability of the distal group compared with the proximal group (P < .05) (Student t test). CONCLUSION: The more ischemic flap-pedicle complex resulted in greater viability after pedicle division. The ischemic gradient seemed to represent a potent angiogenic stimulus to the recipient bed.