Use of antithrombin III concentrates to correct antithrombin III deficiency during vascular surgery.

Congenital deficiency of antithrombin III (AT III) is the only inherited hypercoagulable disorder for which a concentrate of purified protein is available for replacement therapy during periods of increased thrombotic risk. This report describes how such concentrates have been used in a patient with congenital AT-III deficiency undergoing venous surgery. A 40-year-old woman with AT III deficiency was evaluated for bilateral grade 3 chronic venous insufficiency. Noninvasive venous assessment and ascending venography revealed incompetence of the lower leg perforators, a patent deep venous system, and competent greater and lesser saphenous veins. Staged subfascial ligations were performed. Pasteurized AT III was administered 1 hour before surgery and at 30 hours at a dose calculated to increase AT-III activity to at least 120%. Perioperative AT III activity levels were measured. Subcutaneous heparin and oral warfarin were initiated the evening of surgery. An infusion of AT III increased plasma AT III from the baseline activity of 51% to 180%; it was 87% 13 hours later. Two measurements of the initial half-life of AT III were 7 and 14 hours. No perioperative thrombotic complications occurred. The ulcers healed, and the patient remains symptom free. Pasteurized AT III concentrates are now commercially available, easily administered, and provide a useful adjunct to the anticoagulation regimen of patients with AT III deficiency undergoing vascular surgery.