The In Vitro Analysis of the Coagulation Mechanism of Activated Factor VII Using Thrombelastogram

Abstract

SummaryWe investigated the effects of addition of recombinant activated coagulation factor VII (rFVIIa) to coagulation factor-deficient plasma and whole blood, using thrombelastograms (TEGs). The addition of rFVIIa to factor II-or X-deficient plasma did not correct hemostatic parameters, whereas it produced partial responses in factor V-, VIII-or IX-deficient plasma and good responses in factor VII-, XI-or XII-deficient plasma. Furthermore, the addition of rFVIIa and platelets (30-100 X 103/µl) to platelet-poor plasma produced marked corrections, producing TEGs similar to those of platelet-rich plasma. These results indicate that factors II and X are essential for the hemostatic effects of rFVIIa, and that factors V and VIII promote these effects. We believe that TEGs are, at present, one of the most useful tools for evaluating in vitro hemostatic effects of rFVIIa.