Effects of platelet and phospholipids on clot formation activated by a small amount of tissue factor.

INTRODUCTION: Physiological coagulation is considered to activate coagulation factor IX (FIX) by a small amount of tissue factor (TF) and activated coagulation factor VII (FVIIa) with the presence of platelets. A Clot waveform analysis (CWA) may be useful for evaluating physiological coagulation.

MATERIAL AND METHODS: A CWA using a small amount of TF (CWA/sTF) was performed in platelet-rich plasma (PRP), platelet-poor plasma (PPP), several phospholipids (PLs) and patients with lupus anticoagulant (LA), idiopathic thrombocytopenic purpura (ITP) or inhibitor for FVIII.

RESULTS: The CWA/sTF without PLs showed a shorter peak time and higher peak height in PRP than in PPP. The effect of PRP on the CWA/sTF depended on the platelet count, and PLs showed a similar effect on the CWA/sTF results in PPP. The peak time of the CWA/sTF in PRP was prolonged in patient with ITP. The CWA/sTF in PRP showed a prolonged peak time and decreased peak height of the second derivative in patient with LA. Both a shortened peak time and elevated peak height were observed in the CWA/sTF of patient with inhibitor after treatment with activated recombinant human FVII.

CONCLUSION: A CWA can be conducted using a small amount of TF and platelets or PL without contact activation and may be able to detect not only hemostatic abnormalities but also changes in platelet counts.