Normalization of local blood flow regulation in the ischemic forefoot after arterial reconstruction.

Two local blood flow regulating mechanisms were studied before and after arterial reconstruction in 30 limbs suffering from occlusive arterial disease. Changes in forefoot blood flow were measured from the washout of a subcutaneous 133xenon depot. Arterial and venous pressures were changed by passive lowering and elevation of the foot. In 14 limbs suffering from severe ischemia, the local vasoconstrictor response to increased venous pressure was abolished as blood flow increased 37% when the limbs were lowered 40 cm. Autoregulation of blood flow was abolished also as flow decreased 51% when the limbs were elevated 20 cm. The estimated vascular resistance was constant during lowering and elevation, indicating paralysis of the arterioles. The vasoconstrictor response had returned at the tenth postoperative day as blood flow decreased 32% during lowering. Autoregulation had also returned as blood flow remained almost constant during elevation to 40 cm. In 16 limbs with less severe ischemia, vasoconstrictor response as well as autoregulation was preserved before operation, and no disturbances occurred after operation. Despite the early normalization of local blood flow regulation, postoperative hyperemia developed in most limbs. Post-reconstruction edema developed after all but one of the 13 femorodistal bypass operations and after only one of the 17 aortoiliac reconstructions. This suggests that post-reconstruction hyperemia and post-reconstruction edema are not caused by arteriolar insufficiency.