Comparative rheology of low- and iso-osmolarity contrast agents at different temperatures.

Background: Several contrast media (CM) are used for diagnostic angiography and coronary percutaneous interventions. Catheter miniaturization allows performance of most diagnostic studies using 4-5 F catheters and interventions using 5-6 F catheters. As a result of catheter lumen downsizing and viscosity of CM, the operators are sometimes required to forcefully inject to produce adequate images.

Methods And Results: The aim of the study is to perform a comparative rheology analysis between three different commonly used CM: iso-osmolar, nonionic iodixanol, Visipaque, (GE Healthcare); low-osmolar, nonionic ioversol, Optiray; and low-osmolar, ionic ioxaglate, Hexabrix, (Tyco Healthcare, US). The viscosity was experimentally assessed for temperature varying from 14 to 40 degrees C. To reproduce clinical use, an experimental set-up was used and the pressure developed to inject CM was evaluated at different temperatures and compared between the three CM. All three agents demonstrated a nonlinear inverse relationship between temperature and viscosity. At 14 degrees C iodixanol showed a twofold increase in viscosity compared with ioversol and ioxaglate. At 40 degrees C, the difference was reduced to 27%. At room temperature (20 degrees C), the difference in pressure needed to inject CM was 10% between iodixanol and ioxaglate and 6% between iodixanol and ioversol. As the temperatures increased, the differences in pressure became less important, becoming negligible (1%) at 37 degrees C.

Conclusion: The viscosity of the iso-osmolar nonionic contrast agent iodixanol showed a stronger dependence on temperature compared with ioversol and ioxaglate. The impact of differences in viscosity and pressure to inject between CM were minimized at 37 degrees C. This emphasizes the importance of temperature control when using current low-osmolar CM and iso-osmolar CM with smaller sized catheters.