Summary
Thrombotic complications are frequent with indwelling central venous catheters and
result in catheter dysfunction, vascular obstruction and may also contribute to catheter-associated
infections. The pathogenesis of catheter thrombosis is not well characterized but
may involve vessel damage, local stasis and catheter-associated thrombin formation.
We have, therefore, measured the thrombin activity associated with central venous
catheters removed from patients and have also determined the ability of hirudin to
inactivate catheter-associated thrombin. We obtained 48 catheters from 46 patients
and removed 1 cm portions for study. These were taken from the distal end, 5 cm proximal,
and 15 cm proximal from the end. Following washing, thrombin activity was measured
with a chromogenic assay. Thrombin was associated with 40 of 48 catheters and with
100 of 144 segments with a mean activity of 132 ± 27 μU/cm with a range of 0 to 2,160
μU/cm. Incubation in hirudin reduced the activity from a mean of 122 ± 33 μU/cm to
18 ± 6 μU/cm (p <.001). Scanning electron microscopy of selected catheters showed
that some had areas of fibrin deposition which was not apparent visually. The findings
indicate that indwelling central venous catheters frequently have associated thrombin
activity which can be inhibited by a direct-acting thrombin inhibitor such as hirudin.
