The Xylum Clot Signature Analyzer (R): A dynamic flow system that simulates vascular injury

The Xylum Clot Signature Analyzer(R) (CSA) is an automated, user-friendly, benchtop analyzer that assesses platelet function and coagulation in nonant icoagulated whole blood under physiological flow and temperature conditions . From blood drawn in a single venipuncture, the CSA measures: a) the time for platelets to occlude holes "punched" in a blood conduit (platelet hemos tasis time or PI-IT); b) collagen-induced thrombus formation (CITF) as bloo d flows in a channel containing a collagen fiber; and c) clotting time (CT) . Micrographs show platelet-rich thrombi in the punched holes and on the co llagen surface after a run. PI-IT and CITF increased at lower shear rate, s uggesting that shear activation of platelets is involved in hole closure an d in collagen-induced thrombus formation. In blood mixed with anti-von Will ebrand's factor (vWF) antibodies, anti-GPIb antibodies, aurin tricarboxylic acid (ATA), or anti-GPIIb-IIIa, PHT and CITF were prolonged, further suppo rting the reflection of platelet function by those parameters. At low shear rate (<1000 sec(-1)), native blood and blood treated with anti-vWF did not have significantly different PHTs or CITFs. At high shear rate (>6000 sec( -1)), the PHT and CITF of the anti-vWF-treated sample were significantly gr eater than those of the untreated sample. This supports the inhibition of s hear-induced activation of platelets by anti-vWF in the CSA. Heparin-treate d blood showed significantly longer CT, indicating that coagulation of bloo d under flow is inhibited by heparin. The CSA thus assess multiple aspects of hemostasis under near-physiological conditions. (C) 1998 Elsevier Scienc e Ltd.