Evaluation of platelet and coagulation function in different animal species using the xylum clot signature analyzer.

Platelet and coagulation function were evaluated in four different animal species with a newly developed clot signature analyzer (CSA). CSA is unique in that it simultaneously measures global platelet and coagulation function under flow using whole blood. No anticoagulant, chemical, or immunologic agent is required. Three CSA parameters are measurable: platelet mediated hemostasis time (PHT), collagen induced thrombus formation time (CITF), and clotting time (CT). Bovine, ovine, and canine species were chosen because these are the animal models most frequently used in in vivo testing of cardiovascular implants. These parameters, as well as data from whole blood platelet aggregometry (commonly used for platelet function studies because of the response to exogenous agonists), and platelet counts from these animals, were measured and compared with those in humans. In all three parameters, the canine species showed distinctively shorter time values than other species, including humans, suggesting that the dog is not an ideal animal model for the evaluation of blood-surface interactions. Ovine and human blood showed similar PHT and CT values, but CITF time values were significantly shorter in sheep than in humans. With bovine blood, PHT was most prolonged among the four species compared. CT and CITF times in calves were shorter than those in humans, although the difference in CITF time was not statistically significant. Adenosine diphosphate induced platelet aggregation showed the same order of responsiveness in four species as did CITF. It was noted that the intermeasurement variation was rather high for CSA parameters, especially in PHT, warranting caution when this parameter is used to study time-dependent changes after device implantation.