Catecholamine sensitivity in the rat femoral artery after microvascular anastomosis

Tissue can demonstrate vasospastic instability after microvascular anastomosis. This study investigates the in vitro effect of increasing concentrations of phenylephrine on the rat femoral artery after microvascular anastomosis. Bilateral groin flaps based on the inferior epigastric artery were raised on 55 Wistar male rats. On the test side, a microvascular anastomosis was performed, but not on the control side. On days 2-12 postoperatively, the rats were sacrificed and the femoral arteries harvested and suspended in increasing concentrations of phenylephrine. The vascular tone on the test and control sides were recorded and compared. Increased sensitivity was found on the test side as compared with the control side (P = 0.000). This supersensitivity to phenylephrine was blocked by the addition of phentolamine and it is believed to be the result of sympathetic denervation, which occurs when the sympathetic fibers are cut during the harvesting of the flap. The resulting vascular instability is believed to contribute to flap failure.