Influence of radiographic contrast media viscosity to flow through coronary angiographic catheters.

To assess the influence of viscosity on flow resistance, 4 clinically available contrast media were injected through 12 angiographic catheters of varying dimensions at 20 degrees and 37 degrees C. Seven cc of contrast was injected at a pressure of 200 PSI at 3cc/sec by Medrad Mark IV power injector. The pressure of injection through the manifold was recorded with an electronic pressure transducer. The lowest injection pressure at 37 degrees C occurred with Hexabrix. Differences in contrast media viscosity were apparent with catheters less than 6 French diameter. There were minimal differences in injection pressures with regard to the coronary curve tip configurations for any of the contrast agents. At 20 degrees C, Isovue had lower injection pressures than the other contrast agents. Injection through 5 French catheters demonstrated a greater than 1.5 atmosphere difference, especially between Omnipaque and Hexabrix. The difference in contrast media injection pressure was greater than 2 atmospheres between 8 French guiding and 8 French diagnostic catheters and between 5 French and 6 French diagnostic catheters and less than 2 atmospheres between 8 French and 6 French diagnostic catheters. Injection pressure differences greater than 1 atmosphere were not observed for catheters of the same French size at body or room temperature contrast injection. These data indicate that important temperature related viscosity differences between agents are present and confirm that the largest differences in contrast media are most apparent for the smallest diameter catheters. Given equivalent image opacification and hemodynamic and adverse effects, selection of a low viscosity contrast media theoretically provides an advantage during procedures using small diameter catheters or interventional procedures requiring contrast media visualization through reduced channels.