Thrombus formation at the surface of guide-wire models: effects of heparin-releasing or heparin-exposing surface coatings.
OBJECTIVE
This study was conducted to investigate whether thrombus formation at the surface of guide wires occurs, and--if so--whether this can be suppressed or prevented through incorporation of heparin in the surface coating.


METHODS
Five guide wire models were examined; three had a polymeric hydrophilic surface coating (90/10 guide wire), which was either heparin-free, impregnated with sodium-heparin (Na-hep), or impregnated with benzalkonium heparin (BAK-hep). The other two guide wires had a coating of polytetrafluoroethylene (PTFE), either without heparin, or impregnated with BAK-hep. Release of heparin, exposure of heparin at the surface of the guide wires, thrombogenicity (under static and flow conditions) and their propensity to attract blood platelets were investigated.


RESULTS
The guide wire 90/10 Na-hep releases approximately 150-200 mU active heparin per cm coil within the first few minutes after incubation in buffer. The PTFE BAK-hep shows a relatively slow release of 60-70 mU active heparin per cm coil. The 90/10 BAK-hep showed no released heparin but the most exposed heparin. In a static experiment with human full blood excessive thrombus formation occurred at the heparin-free models, whereas the others remained essentially clean. In a thrombin-generation assay under flow the authors observed strong retardation of thrombin formation in the case of the 90/10 Na-hep guide wire.


CONCLUSIONS
The static and dynamic in vitro assays, taken together, show that the 90/10 Na-hep provides a coating with an extremely low level of surface thrombogenicity. Use of a guide wire with a hydrophilic distal coating that releases and exposes sodium heparin may contribute to the safety of diagnostic and therapeutic interventional procedures.
Aldenhoff
Yvette B J
YB
Centre for Biomaterials Research, Faculty of Medicine, University of Maastricht, Universiteitssingel 50, 6229 ER Maastricht, The Netherlands. y.aldenhoff@bioch.unimaas.nl
Hanssen
Johannes H L
JH
Knetsch
Menno L W
ML
Koole
Leo H
LH
D000925:Anticoagulants / Q000008:administration & dosage; D001777:Blood Coagulation / Q000187:drug effects*; D002404:Catheterization / Q000009:adverse effects*; D020099:Coated Materials, Biocompatible / Q000008:administration & dosage*; D003692:Delayed-Action Preparations / Q000008:administration & dosage*; D006493:Heparin / Q000008:administration & dosage*; D006801:Humans; D013499:Surface Properties; D013927:Thrombosis / Q000209:etiology* / Q000517:prevention & control*
D000925:Anticoagulants; D020099:Coated Materials, Biocompatible; D003692:Delayed-Action Preparations; D006493:Heparin