Flow cytometric evaluation of platelet activation by ionic or nonionic contrast media and modulation by heparin and recombinant hirudin.

ABSTRACT

RATIONALE AND OBJECTIVES: The purpose of this study was to investigate the platelet activation properties of ionic and nonionic contrast media in native heparinized or hirudinized human blood using flow cytometric analysis techniques. MATERIALS AND METHODS: Freshly drawn human blood samples were incubated at 37 degrees C with ionic (Hexabrix and Angiovist) and non-ionic (Isovue and Omnipaque) contrast media for varying periods of time. Using fluorescent monoclonal antibodies to platelet surface receptors glycoprotein IIIa and with granule membrane protein-140, platelet activation was measured in whole blood using flow cytometry. Platelet factor 4 and thromboxane B2 levels also were measured. RESULTS: Dose- and time-dependent platelet activation was observed in nonionic, but not in ionic, contrast media (P < 0.05). Whole blood drawn into heparin or hirudin showed reduced platelet activation in the presence of contrast media compared with nonanticoagulated whole blood. Platelet factor 4 and thromboxane B2 levels showed similar results. Significant platelet activation was seen by flow cytometry in high (2000 mOsmol/kg), but not in lower osmolality (800 mOsmol/kg) controls for ionic and nonionic contrast media, respectively (P < 0.001). CONCLUSION: This study suggests that nonionic contrast media use is associated with significant levels of platelet activation, and that heparin or recombinant hirudin (where heparin is contraindicated) is preferable for use with nonionic contrast media, as these anticoagulants reduce contrast media induced platelet activation.