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Heparinase-modified thrombelastometry: inactivation of heparin in plasma samples
Gerhard Cvirn1, Erwin Tafeit, Gerd Hoerl
1Institute of Physiological Chemistry, Medical University of Graz, Austria. gerhard.cvirn@medunigraz.at
Background:
The 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.
Methods:
In the HEPTEM assay, blood or plasma samples become activated via the intrinsic pathway in the presence of a heparin processing enzyme.
Results:
We 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.
Conclusions:
We 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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