title: Sustained heparin effect contributes to reduced plasma thrombin generation capacity early after cardiac surgery.
abstract: BACKGROUND
  Thrombin is a key component in the coagulation cascade, and impaired thrombin generation has been linked to increased bleeding after surgical procedures. The aim was to evaluate postoperative thrombin generation capacity in plasma after cardiac surgery, and its potential associations to activity of individual coagulation factors and heparin.
  
  
  METHODS
  Forty-eight coronary artery bypass grafting patients were included in a prospective observational cohort study. Thrombin generation capacity was analysed in plasma with calibrated automated thrombogram with tissue factor as activator before (baseline), and 2 h and 24 h after surgery. In addition, plasma activity of coagulation factors II, V, VII, VIII, IX, X, XI, XIII, were determined. Heparin effect was assessed by anti-Xa activity, APTT and thrombin time.
  
  
  RESULTS
  Thrombin generation was markedly reduced 2h after surgery compared to baseline. Peak levels decreased with median 74% (interquartile range 52-90), p<0.001, and endogenous thrombin generation potential decreased with 65% (43-86), p<0.001. Postoperative changes in endogenous thrombin generation potential correlated inversely to changes in anti-Xa activity (r=-0.51, p=0.010) and to changes in thrombin time (r=-0.51, p=0.009), but there were no correlations to changes in individual coagulation factor activity.
  
  
  CONCLUSIONS
  A marked reduction in thrombin generation potential was observed in the early postoperative phase after cardiac surgery. The decrease was independent of reductions in individual coagulation factor activity but correlated to heparin effects. The results indicate that a sustained heparin effect contributes to the postoperative reduction in thrombin generation capacity.
authors.affiliation: Department of Medicine/Haematology and Coagulation Disorders, Sahlgrenska University Hospital, Gothenburg, Sweden.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Radulovic
authors.forename: Monica
authors.initials: M
authors.lastname: Hyllner
authors.forename: Lisa
authors.initials: L
authors.lastname: Ternström
authors.forename: Martin
authors.initials: M
authors.lastname: Karlsson
authors.forename: Anders
authors.initials: A
authors.lastname: Bylock
authors.forename: Kenny M
authors.initials: KM
authors.lastname: Hansson
authors.forename: Fariba
authors.initials: F
authors.lastname: Baghaei
authors.forename: Anders
authors.initials: A
authors.lastname: Jeppsson
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage; D001779:Blood Coagulation Factors / Q000378:metabolism; D015331:Cohort Studies; D001026:Coronary Artery Bypass / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006493:Heparin / Q000008:administration & dosage*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013917:Thrombin / Q000096:biosynthesis*
chemical_list: D000925:Anticoagulants; D001779:Blood Coagulation Factors; D006493:Heparin; D013917:Thrombin