Abstract
Patients with heparin-induced platelet activation who are reexposed to heparin may have recurrent thrombocytopenia, intravascular thrombosis, arterial emboli, or sudden death. To permit carotid endarterectomy in two patients with confirmed heparin-induced platelet activation, we compared the efficacies of aspirin and iloprost, a stable analogue of prostacyclin, in preventing heparin-induced platelet activation. In the first patient, although aspirin prevented both in vitro heparin-induced platelet aggregation (70% without and 7.5% with aspirin) and 14C serotonin release (48% without and 0% with aspirin), intraoperative administration of heparin resulted in an increase in plasma levels of platelet factor 4 from 8 to 260 ng/ml and beta-thromboglobulin levels from 29 to 39 ng/ml. In addition, the circulating platelet count decreased from 221,000 to 174,000 μl, and 15% spontaneous platelet aggregation was observed. Fortunately, fibrinopeptide A levels remained less than 10 ng/ml intraoperatively, and no thrombotic complications occurred. In the second patient, aspirin did not prevent heparin-induced platelet aggregation in vitro (65% without and 41% with aspirin); however, iloprost (0.01 μmol/L) prevented both in vitro heparin-induced platelet aggregation (59.5% without and 0.0% with iloprost) and 14C serotonin release (56.7% without and 0.0% with iloprost). Therefore, a continuous infusion of iloprost was begun before administration of heparin and was continued until 20 minutes after reversal of heparin with protamine. After intraoperative administration of heparin, plasma levels of platelet factor 4 increased from 19 to 200 ng/ml, and beta-thromboglobulin levels increased from 56 to 76 ng/ml. However, most importantly, the circulating platelet count (254,000/μl) did not change, and no spontaneous platelet aggregation was observed. Fibrinopeptide A levels were also less than 10 ng/ml intraoperatively. Thus, in one patient aspirin did not prevent heparin-induced platelet activation in vitro and in another patient its efficacy in vitro was not reliably predictive of its clinical efficacy. In contrast, iloprost completely prevented heparin-induced platelet activation both in vitro and clinically, thereby safely permitting carotid endarterectomy.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.