Clot formation in angiographic catheters--an in vitro comparative study. Effects of heparin and protein coating of the catheter.

Clot formation was compared in 6 brands of angiographic catheters, each of which was tested in 3 states: untreated, heparinized, and albumin-coated. Forty-six samples of each brand in each state (in total 828) were filled with blood from 23 donors and incubated at +37 degrees C for 5 or 15 min. Physiologic saline was then injected through the catheters at a flow rate of 5 and 50 ml/s, respectively, and any expelled clots identified on a filter. Heparinization reduced the number of clotted catheters at 5 min, but not at 15 min. The only significant difference related to catheter brands was found between the heparinized nylon and polyurethane catheters at 5-min incubation with fewer clotted polyurethane catheters. This difference was not found between the same materials made by two other manufacturers. Albumin coating had no effect on clot formation, but clots were more easily expelled by low-flow injections in albumin-coated and, to a lesser degree, in heparinized than in untreated catheters.