A demonstration of vascular proliferation in response to arteriovenous reversal in the ischemic canine hind limb.

Patients with diffuse peripheral vascular disease, resulting in inadequate arteriographic runoff, and/or multiple failed bypasses almost inevitably face amputation. We have previously used an arteriovenous reversal (AVR) procedure at the popliteal level to salvage severely ischemic canine hind limbs. This procedure is followed by the development of an intense network of new vessels in the proximity of the arteriovenous anastomosis. The present study was designed to define the nature of these vessels and their role in providing nutrient perfusion to the limb. Using an established model to create severe limb ischemia. AVR was performed in 24 dogs. Tissue perfusion and neovascularization were assessed by angiography, transcutaneous oximetry (TcpO2), tritiated thymidine uptake combined with autoradiography, and histologic capillary density measurements. Angiography revealed the intense vascular network in the region of the anastomosis by postoperative Day 22 in all dogs. TcpO2 on Day 1 was indicative of severe ischemia in the operated calf compared to controls (12 vs 80 mm Hg, P less than 0.01) but returned to normal by Day 22 (81 vs 76 mm Hg). A progressive, significant increase in tritiated thymidine uptake was seen by Day 22 (0.36 vs 0.27 microCi/g, P = 0.005); on autoradiography 95% of these labeled nuclei in the operated limbs were in endothelial cells compared to only 5% in the control limbs. Finally, capillary density studies of the calf muscles showed a substantial increase in the operated limbs (mean, 1011 vs 605 cap/mm2, P = 0.0004). These studies suggest that the dramatic increase in vascularity observed angiographically following AVR in a severely ischemic limb consists primarily of a rapidly expanding capillary network.(ABSTRACT TRUNCATED AT 250 WORDS)