Extrinsic Vascular Pathway Preservation Improves Survival in a Rat Three-Territory Flap Model Based on the Deep Circumflex Iliac Artery.

Abstract

Extended flaps are commonly applied for large defects. However, a postoperative flap necrosis incidence of 11% to 44% remains a major complication. Previous clinical studies have shown that maintaining the extrinsic vascular pathway (EVP) can increase the survival area of extended flaps. The authors hypothesized that preserving the EVP would improve flap survival by reducing blood resistance within the vascular territory. Twenty-four adult male Sprague-Dawley rats were used. Tissue samples were obtained from eight untreated rats as a baseline control. Three-territory flaps were elevated in the remaining 16 rats. The EVP was preserved or ligated. Flap perfusion was assessed immediately using indocyanine green angiography. Rats were euthanized on day 7. The flap survival area was measured using Adobe Photoshop. Hematoxylin and eosin staining, CD31 immunostaining, and Western blot analysis of vascular endothelial growth factor protein expression were used to quantitatively assess vasodilation and angiogenesis in choke zones. Indocyanine green angiography revealed that blood could flow through the preserved EVP and perfuse the third vascular territory of the flap. EVP preservation significantly increased flap survival area (86.3%, 19.3% difference; P < 0.001), promoted vasodilation (5.0/choke zone, 3.0/choke zone difference; P = 0.013) and angiogenesis (29.3/mm 2 , 14.3/mm 2 difference; P = 0.002), and increased vascular endothelial growth factor expression (0.6, 0.2 difference; P = 0.067) in the second choke zone. EVP preservation improves flap survival in this rat three-territory flap model. Further investigation in large-animal models is required for clinical translation. Although further validation in large animal models and prospective clinical trials are necessary to verify the efficacy of the authors' hypothesis, their findings suggest that the EVP preservation procedure could provide an alternative for surgeons to create an extended flap in defect reconstruction.