Radiographic contrast agents and platelet function: A quenched-flow study

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Abstract
Radiographic contrast media (RCM) may alter platelet behavior at concentrations achieved during cardiac angiography. We used quenched‐flow aggregometry coupled to single‐particle counting to study the influence of RCM on the kinetics of platelet aggregation (< 5.0 sec) induced by adenosine diphosphate (ADP, 2.86 μM). At a concentration in platelet‐rich plasma (PRP) of 5 per cent RCM by volume, platelet aggregation was inhibited by diatrizoate, iopamidol and ioxaglate either directly or following incubation of each contrast agent with PRP for 20 minutes. Diatrizoate inhibited more than did iopamidol or ioxaglate (56 ± 6, versus 39 ± 3 and 40 ± 9 per cent respectively; PPPP = 0.04). Our data therefore show that early platelet aggregation was inhibited by 3 commonly‐used ionic and nonionic contrast agents. Inhibition was apparently caused by the iodinated contrast molecule, began within seconds of platelet‐RCM contact and was independent of vehicle composition. Since diatrizoate inhibited aggregation more than iopamidol or ioxaglate, its use may be of additional value during angi‐ographic procedures in clinical situations involving enhanced platelet activation.