ABSTRACT
Hypercoagulable states as a cause of unexplained vascular thrombosis present a difficult clinical problem. Most graft failures in the perioperative period are presumed to occur because of technical errors in the construction of the anastomosis, problems with the conduit, or poor patient selection. The diagnosis of an abnormal hypercoagulable state is often made only after all of these other factors have been excluded. Although failure of heparin to prevent clotting in the operative field or immediate thrombosis of a vascular repair suggests abnormal coagulation, the diagnosis can be confirmed only by the blood coagulation laboratory. The clotting disorder must be detected early in the course of the disease to obtain a favorable outcome. Abnormal thrombosis falls into five general categories: (a) heparin-induced platelet aggregation, (b) abnormalities in the antithrombin system, (c) abnormalities of the fibrinolytic system, (d) thrombosis caused by lupus-like anticoagulant, and (e) a miscellaneous category consisting primarily of abnormal platelet aggregation and protein C and protein S deficiency.
