Effect of warm ischemia on neovascularization of island flaps

Poor neovascularization in free-flap transfers is considered to be a conseq uence of insufficient hypoxic stimulus in a transferred flap with good axia l-pattern circulation and a short warm ischemia time. The purpose of the st udy was to investigate the effect of warm ischemia time on neovascularizati on of axial-pattern flaps. Oblique adipomusculocutaneous groin island flaps based on the superficial epigastric vessels were raised on the right side of 21 Wistar rats, evaluated in three groups. In Group 1 (n=7), flaps were resutured without creating ischemia; in Groups 2 (n=7) and 3 (n=7), flaps w ere resutured after 90-min and 180-min warm ischemic periods, respectively. At 5 days postoperatively, an intravenous fluorescein test was performed f ollowing pedicle. ligation, and survival was assessed by planimetric techni que 7 days after pedicle. ligation. Histopathologic scoring was performed a ccording to capillary formation, inflammation, and necrosis. The intravenou s fluorescein test revealed significantly higher uptake in the group with t he longest ischemic period, while the mean surviving area was greater in th e groups with ischemic insult, comparing to the non-ischemic group. Similar ly, histopathologic scoring showed significantly higher values in the ische mic groups. The authors demonstrated that neovascularization was enhanced a fter 90- and 180-min warm ischemia times. The authors concluded that short ischemia time in free flaps may be an attributable factor in late flap fail ures, due to pedicle obstruction.