Effect of CTI on the prothrombotic activity of PCI catheter segments. Catheter segments were incubated with plasma for 10 minutes at 37°C in wells containing increasing concentrations of CTI. Clotting was initiated by the addition of CaCl2 to 20mM. Time to clot was determined as the time to reach one-half maximal absorbance. The bars represent the mean of ≥ 3 separate experiments, and the lines above the bars reflect the SD.