title: Heparinase-modified thrombelastometry: inactivation of heparin in plasma samples.
abstract: 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).
authors.affiliation: Institute of Physiological Chemistry, Medical University of Graz, Austria. gerhard.cvirn@medunigraz.at
authors.forename: Gerhard
authors.initials: G
authors.lastname: Cvirn
authors.forename: Erwin
authors.initials: E
authors.lastname: Tafeit
authors.forename: Gerd
authors.initials: G
authors.lastname: Hoerl
authors.forename: Michaela
authors.initials: M
authors.lastname: Janschitz
authors.forename: Thomas
authors.initials: T
authors.lastname: Wagner
authors.forename: Guenther
authors.initials: G
authors.lastname: Juergens
authors.forename: Martin
authors.initials: M
authors.lastname: Koestenberger
mesh_terms: D000328:Adult; D001780:Blood Coagulation Tests / Q000379:methods*; D016903:Drug Monitoring / Q000379:methods; D005260:Female; D006493:Heparin / Q000097:blood* / Q000493:pharmacokinetics / Q000627:therapeutic use; D019763:Heparin Lyase / Q000737:chemistry*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D013916:Thrombelastography / Q000379:methods*; D013927:Thrombosis / Q000097:blood / Q000188:drug therapy / Q000517:prevention & control; D055815:Young Adult
chemical_list: D006493:Heparin; D019763:Heparin Lyase