Role of low-osmolality contrast media in thromboembolic complications: scanning electron microscopy study.

Numerous in vitro studies have found that clot formation may occur when blood is mixed directly with nonionic low-osmolality contrast media during angiographic procedures because of activation of hemostasis in the catheter; ionic contrast media, on the other hand, inhibit clot formation. Thirty patients were injected with low-osmolality contrast media--15 with ioxaglate, an ionic dimer, and 15 with iopamidol, a nonionic monomer. The inner wall of the angiographic catheter was studied with electron microscopy after selective catheterization of supraaortic vessels. Clot formation of various extent was observed in nine (60%) of the patients administered iopamidol. No coagulation process was found in the catheters of the patients administered ioxaglate. Results indicate that nonionic, low-osmolality contrast media may play a role in the formation of thromboembolisms.