Résumé
Patients with recurrent thrombosis of access arterio-venous fistulae were selected to clarify the cause of their shunt failure. Antithrombin III being the most important physiological normal circulating anticoagulant which causes progressive irreversible destruction of thrombin in plasma, has been estimated in 43 patients and 20 normal controls. Every patient was subjected to determination of Antithrombin III [ATIII] level by functional assay, 2 weeks course of 5 mg Warfarin/day, re-estimation of ATIII level and then to construction of a new A -V fistula under maintenance dose of 2 mg Warfarin/day. The ATIII time in the patients [25.67 +/- 12.05 sec] was significantly lower than in controls [31.27 +/- 7.66 sec]. After warfarin therapy it increased significantly [30.37 +/- 8 sec] as compared to that before therapy. Patients who had reduced ATIII time showed dramatic response to warfarin therapy and ATIII increased to become within normal or even higher, but no significant change was observed in patients with normal or high ATIII. After three months follow up the new fistulae were patent in all the 12 patients who had low ATIII time which was improved by warfarin in contrary to those with normal or high ATIII time only 15 new shunts were patent out of 31 cases