Abstract
This paper evaluates the effect of iodinated X-ray contrast media on plasma clotting time, plasma thrombin generation and thrombin activity. Investigated materials consisted of diatrizoate, iothalamate and ioxaglate as ionic contrast media (ICM), and iopamidol, iohexol, ioversol and iotrolan as nonionic contrast media (NICM). Both the prothrombin time and the activated partial thromboplastin time of normal pooled plasma were markedly prolonged in the presence of contrast media in a dose-dependent manner. All the contrast media also inhibited thrombin generation in plasma, as assessed in the def ibrinated plasma with a chromogenic substrate, S-2238. Although these contrast media did not affect the thrombin amidolytic activity, they interfered with thrombin-clotting of fibrinogen by affecting either thrombin-fibrinogen interaction or fibrin polymerization, or both. The anticoagulant activities of the contrast media were more evident in 3 ICM than in 4 NICM used in this study. These results suggested that NICM could not sufficiently suppress the thrombin generation in the catheter-syringe system because of this lesser degree of anticoagulant activity than that of ICM. In a separate set of experiment, heparin cofactor activity of antithrombin III was not impaired in the presence of these contrast media, suggesting that heparin would be an effective agent to prevent the thromboembolic complications during angiography using NICM.
