title: A novel modification of the Thrombelastograph assay, isolating platelet function, correlates with optical platelet aggregation.
abstract: Flow cytometry, singlet platelet counting, and optical aggregation have been used to monitor clopidogrel and glycoprotein IIb/IIIa (GPIIb/IIIa) platelet antagonists. Optical aggregation is considered the gold standard, but neither it nor flow cytometry is convenient in larger-scale clinical studies or point-of-care systems. Singlet platelet counting, a point-of-care assay correlated with optical platelet aggregation, only provides a measurement of platelet function at a single point in time. The Thrombelastograph is used to assay whole blood for thrombin-generated maximal clot-shear elasticity, referred to as the maximal amplitude (MA). Although platelet dysfunction, thrombocytopenia, and the in vitro effect of strong inhibitors such as IIb/IIIa antagonists can be observed, with thrombin generation milder platelet inhibitors cannot be assessed. We modified the Thromboelastograph assay, using reptilase and factor XIIIa, to form a clot, without thrombin generation, in heparinized whole blood. The resulting clot MA is dependent on added platelet agonists such as ADP or arachidonic acid, is sensitive to platelet antagonists, and provides a continuous measure of platelet function more analogous and better correlated with optical aggregation. This novel modification of the Thromboelastograph assay should prove to be a useful point-of-care whole-blood assay with which to monitor the effects of GPIIb/IIIa, ADP, and thromboxane A(2)-receptor-inhibiting drugs in patients.
authors.affiliation: Department of Anesthesiology and Medicine, University of Tenessee Graduate School of Medicine, Knoxville, TN 37920. USA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Craft
authors.forename: Jack J
authors.initials: JJ
authors.lastname: Chavez
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Bresee
authors.forename: Dale C
authors.initials: DC
authors.lastname: Wortham
authors.forename: Eli
authors.initials: E
authors.lastname: Cohen
authors.forename: Roger C
authors.initials: RC
authors.lastname: Carroll
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D016718:Arachidonic Acid / Q000494:pharmacology; D012103:Batroxobin / Q000494:pharmacology; D001777:Blood Coagulation / Q000187:drug effects / Q000502:physiology*; D001792:Blood Platelets / Q000187:drug effects / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D026122:Factor XIIIa / Q000494:pharmacology; D006490:Hemostatics / Q000494:pharmacology; D006801:Humans; D010974:Platelet Aggregation / Q000502:physiology*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology; D019095:Point-of-Care Systems; D013916:Thrombelastography / Q000379:methods*
chemical_list: D006490:Hemostatics; D010975:Platelet Aggregation Inhibitors; D016718:Arachidonic Acid; D000244:Adenosine Diphosphate; D026122:Factor XIIIa; D012103:Batroxobin