Over the last 9 yr approximately 4000 infants have had physiologic monitoring with UAC at Vanderbilt University Medical Center. A larger number of them had minor ischemic complications prompting removal of the catheter, but 41 patients had major thromboembolic problems requiring varying degrees of surgical management. The place of surgery is clear in patients with catheter emboli or bleeding due to vascular avulsion related to catheter removal. Patients with arterial occlusion distal to the femoral artery may be treated expectantly although significant skin loss may occur. Occlusions at the femoral level allow limb survival, but the long-term outlook is not known; perhaps these patients may better be subjected to femoral thrombectomy in the future. Peripheral pulses are not normal early and Doppler studies suggest that collateral circulation is responsible for limb survival. Whether this will be sufficient to support adequate limb growth and function remains to be seen. Patients with signs of aortoiliac or mesenteric occlusion should be rapidly investigated and operated upon if survival is to be obtained. This study suggests that an aggressive surgical approach is in order. Computer-assisted radionuclide flow studies are helpful in diagnosing major aortic occlusion, as well as for followup.