Increasing Perfusion Pressure Does Not Distend Perforators or Anastomoses but Reveals Arteriovenous Shuntings

BACKGROUND: It has been proposed that hyperperfusion of perforators and distension of anastomotic vessels may be a mechanism by which large perforator flaps are perfused. This study investigates whether increasing perfusion pressure of radiographic contrast in cadaveric studies altered the radiographic appearance of vessels, particularly by distending their anastomotic connections. METHODS: From 10 fresh cadavers, bilateral upper limbs above the elbow were removed. Three cadavers were excluded. Seven pairs of limbs were injected with lead oxide solutions via the brachial artery while distally monitoring intravascular pressure in the radial artery using a pressure transducer. One limb was injected slowly (0.5 mL/s) and the other rapidly (1.5 mL/s) to produce low and high perfusion pressures, respectively. Skin and subcutaneous tissue were then removed and radiographed. RESULTS: The filling of perforators and their larger caliber branches appeared unchanged between low- and high-pressure injections, with no significant increase in true anastomoses (P = 0.32) and no association between maximum perfusion pressure and number (P = 0.94) or caliber (P = 0.10). However, high-pressure injections revealed arteriovenous shunting with filling of the tributaries of the major veins. CONCLUSIONS: This study demonstrated that increased perfusion pressure of the cutaneous arteries (1) did not change the caliber of vessels; (2) did not convert choke to true anastomoses; and (3) revealed arteriovenous shunting between major vessels with retrograde filling of venous tributaries as pressure increased. This suggests that it is not possible to distend anastomotic connections between vascular territories by increasing perfusion alone.