• Gerhard Cvirn, Erwin Tafeit, Gerd Hoerl, Michaela Janschitz, Thomas Wagner, Guenther Juergens, and Martin Koestenberger.
• Institute of Physiological Chemistry, Medical University of Graz, Austria. gerhard.cvirn@medunigraz.at
• Clin Lab. 2010 Jan 1; 56 (11-12): 585-9.

BackgroundThe heparinase-modified thrombelastometry (HEPTEM) assay is a promising tool to assess the coagulation status of heparinised patients. The aim of our study was to examine the heparin neutralizing capability of the HEPTEM assay in plasma samples.MethodsIn the HEPTEM assay, blood or plasma samples become activated via the intrinsic pathway in the presence of a heparin processing enzyme.ResultsWe examined coagulation times (CTs) in the presence of increasing amounts (0-4 IU/mL) of heparin. We found that up to a concentration of 0.5 IU/mL, heparin is completely neutralized. However, CTs increased linearly in the presence of heparin concentrations higher than 0.5 IU/mL, indicating incomplete heparin neutralization in the standard HEPTEM assay.ConclusionsWe provide herein a mathematical procedure to correct the misleadingly prolonged CTs (for heparin > 0.5 IU/mL) for the HEPTEM assay performed in plasma samples to allow better estimation of the coagulation status in patients requiring intense anticoagulation (e.g., patients undergoing cardiac surgery).

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