Effects of contrast media on the hemostatic and thrombotic mechanisms.

The hemostatic and thrombotic mechanisms represent complex biologic systems. When a vessel is severed, a platelet plug begins to form, followed by activation of the coagulation mechanism to form thrombin, which converts fibrinogen to fibrin. The formation of thrombin also requires platelet coagulant activities, which help keep fibrin formation localized at the site of vessel wall damage. The thrombo-hemorrhagic balance represents a complicated homeostatic biologic system; this system has many control mechanisms, but its balance is rather fragile. Our studies show that the new nonionic contrast media induce far fewer changes in the thrombo-hemorrhagic balance than the ionic media.