Hypercoagulability and the hypercoagulability syndromes.

Hypercoagulability is a state in which an alteration of the blood shifts the hemostatic balance toward excessive platelet/fibrin deposition leading to arterial and/or venous thrombosis [1]. Although the concept of hypercoagulability has been recognized clinically for more than a century, in recent years a number of specific disorders have been define, diagnostic tests developed, and treatment regimens improved. The currently recognized disorders are generally classified as primary or secondary states, although some of the primary conditions may develop as a result of other disorders (Table 1). The primary disorders generally result from abnormalities of proteins in the coagulation or fibrinolytic systems. Although the number of secondary conditions is much greater, generally these syndromes are not as precisely defined on a molecular basis. Secondary hypercoagulability syndromes are subclassified into abnormalities of platelets, coagulation and fibrinolysis, and blood vessels and rheology (Table 1). While the prevalence and clinical significance of hypercoagulability are becoming increasingly apparent to physicians in general, this pathologic state is an especially practical concern to vascular interventionalists, as hypercoagulability is an important cause of early thrombosis after otherwise uncomplicated arterial interventional procedures. The purpose of this review is to describe the clinical presentation, diagnosis, and treatment of the hypercoagulability syndromes most likely to be encountered by the interventional radiologist.