Rheometer

Assays based on the formation of thrombin and fibrin are frequently used and results are considered exchangeable in research/clinical settings. However, thrombin generation and fibrin formation do not always go hand in hand and flow profoundly influences thrombus formation. We developed and validated an assay to simultaneously measure thrombin generation and fibrin formation under conditions of physiological flow.

Introduction of a fluorometer into a cone and base principle-based rheometer allowed the measurement of thrombin generation (using a thrombin-sensitive substrate) and fibrin formation (changes in viscosity), while applying a linear shear flow (ranging from venous to arterial flow). The device allows the measurement of platelet-poor and -rich plasma, as well as whole blood. Increasing shear rates inversely related with thrombin generation and fibrin formation. Increasing fibrinogen concentrations in defibrinated plasma resulted in increased thrombin generation and fibrin formation. In pre-operative samples of 70 patients undergoing cardiothoracic surgery, fibrin formation and thrombin generation parameters correlated with fibrinogen content, rotational thromboelastometry (ROTEM) and whole blood Calibrated Automated Thrombinography (CAT) parameters, respectively. Interestingly, this test proved to be indicative for the amount of blood loss during/after cardiothoracic surgery.


 

1. Kelchtermans H, Pelkmans L, Bouwhuis A, Schurgers E, Lindhout T, Huskens D, Miszta A, Hemker HC, Lancé MD, de Laat B. Simultaneous measurement of thrombin generation and fibrin formation in whole blood under flow conditions. Thromb Haemost 2016;116(1):134-45. 2. Ninivaggi M, Apitz-Castro R, Dargaud Y, et al. Whole-blood thrombin generation monitored with a calibrated automated thrombogram-based assay. Clin Chem 2012; 58: 1252-9. 3. Evans PA, Hawkins K, Lawrence M, et al. Rheometry and associated techniques for blood coagulation studies. Medical engineering & physics 2008; 30: 671-9. 4. Wolberg AS, Campbell RA. Thrombin generation, fibrin clot formation and hemostasis. Transfus Apher Sci 2008; 38: 15-23. 5. Kremers RM, Wagenvoord RJ, Hemker HC. The effect of fibrin(ogen) on thrombin generation and decay. Thromb Haemost 2014; 112: 486-94. 6. Konings J, Govers-Riemslag JW, Philippou H, et al. Factor XIIa regulates the structure of the fibrin clot independently of thrombin generation through direct interaction with fibrin. Blood 2011; 118: 3942-51. 7. Hathcock JJ. Flow effects on coagulation and thrombosis. Arteriosclerosis, thrombosis, and vascular biology 2006; 26: 1729-37. 8. Campbell RA, Aleman M, Gray LD, et al. Flow profoundly influences fibrin network structure: implications for fibrin formation and clot stability in haemostasis. Thromb Haemost 2010; 104: 1281-4. 9. Gersh KC, Edmondson KE, Weisel JW. Flow rate and fibrin fiber alignment. J Thromb Haemost 2010; 8: 2826-8. 10. Cosemans JM, Angelillo-Scherrer A, Mattheij NJ, et al. The effects of arterial flow on platelet activation, thrombus growth, and stabilization. Cardiovascular research 2013; 99: 342-52. 11. Wagenvoord R, Hemker PW, Hemker HC. The limits of simulation of the clotting system. J Thromb Haemost 2006; 4: 1331-8.