New approaches in the measurement of coagulation

In this session contributors present recent developments in laboratory tools for investigation of haemorrhagic disorders as well as their relative utility in clinical research. In an overview of B. Sørensen the present knowledge is summarized on the dynamic properties of whole blood fibrin formation as studied by changes in whole blood elasticity on a thrombelastometry system. Additionally, fibrin formation dynamics using simple APTT methods are presented. G. Castaman reviews the pathophysiology of von Willebrand's disease (VWD) and explains which tests are best used in diagnosis and subclassification of VWD accounting for recent developments. This presentation also describes the treatment technologies available today and their implications in clinical management of bleeding episodes in VWD. J. Lloyd addresses the assay discrepancy phenomenon that is found in some of our patients suffering from mild haemophilia A. Assay discrepancy most often means a much lower factor VIII:C value by a two-stage or chromogenic assay for factor VIII:C compared to the activity recorded by the one-stage clotting system for factor VIII:C. In rare cases, the opposite phenomenon exist. The presentation includes data from 16 Australian families with discrepant results. D. Varon reports on an assay for study of platelet function in whole blood under flow conditions. The equipment is described as a cone-and-plate(let) analyser in which the adhesion and aggregation of platelets onto a polystyrene surface is studied under arterial flow conditions. Basically, it is anticipated that proteins such as VWF and fibrinogen of flowing blood is attached to the polystyrene surface where they build up a thrombogenic surface. In the study of the author platelets were pre-activated with agonists and platelet deposits were determined after passage of whole blood for a pre-set time interval. Data presented suggest that the assay is sensitive to platelet numbers as well as qualitative changes in platelets themselves, and several examples of disorders characterized by enhanced as well as reduced platelet aggregating activities illustrates the sensitivity of the method.