title: A comparative study of heparin responses in arterial and venous thromboembolism using molecular markers for thrombosis.
abstract: BACKGROUND
  Compared with the therapy of venous thromboembolism, there is little consensus regarding guidelines for heparin anticoagulation of patients with arterial thrombosis. This study aimed to identify the quantitative differences in the activation of the coagulation cascade and platelets in these two syndromes and to characterize their specific biological responses to heparin therapy.
  
  
  RESULTS
  Eighteen patients receiving intravenous heparin to treat venous (n = 9) or arterial (n = 9) thromboembolism were prospectively studied for an average of 4 days each. Clinical responses to treatment, activated partial thromboplastin time (aPTT), and molecular markers for thrombosis were measured regularly. Although both groups received equivalent doses of heparin (approximately 1100 units/h), the resulting aPTTs and plasma heparin activity were significantly lower in the arterial patients (P < .05 and P < .01, respectively). The plasma levels of beta-thromboglobulin (a marker for platelet activation and granule release) were significantly higher in the arterial patients (109 +/- 9.5 versus 79 +/- 7.1 ng/mL, mean +/- SEM, P < .05). In vivo fibrin formation, as evidenced by plasma levels of fibrinopeptide A, was less effectively suppressed in the patients with arterial versus venous thrombosis (18.5 +/- 3.2 versus 10.4 +/- 2 ng/mL, P < .05). Prothrombin fragments 1 + 2, a marker for prothrombinase complex activity, was nearly normal in both heparinized groups.
  
  
  CONCLUSIONS
  The anticoagulant response to heparin is blunted in patients with arterial thrombosis, at least in part by the antagonistic actions of increased platelet activation. Comparing arterial with venous thrombosis, higher doses of heparin on the average may be required to achieve comparable aPTTs, plasma heparin activity, and comparable suppression of fibrin formation.
authors.affiliation: Division of Vascular Surgery, Medical College of Virginia, Virginia Commonwealth University, Richmond.
authors.forename: M
authors.initials: M
authors.lastname: Sobel
authors.forename: W C
authors.initials: WC
authors.lastname: Sternbergh
authors.forename: D
authors.initials: D
authors.lastname: Marques
authors.forename: A S
authors.initials: AS
authors.lastname: Grimsdale
mesh_terms: D000368:Aged; D004797:Enzyme-Linked Immunosorbent Assay; D005344:Fibrinopeptide A / Q000032:analysis; D006493:Heparin / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010314:Partial Thromboplastin Time; D010446:Peptide Fragments / Q000032:analysis; D011446:Prospective Studies; D011498:Protein Precursors / Q000032:analysis; D011516:Prothrombin / Q000032:analysis; D011655:Pulmonary Embolism / Q000188:drug therapy* / Q000453:epidemiology; D013927:Thrombosis / Q000188:drug therapy* / Q000453:epidemiology; D001620:beta-Thromboglobulin / Q000032:analysis
chemical_list: D010446:Peptide Fragments; D011498:Protein Precursors; D001620:beta-Thromboglobulin; D005344:Fibrinopeptide A; C029733:prothrombin fragment 1; C044183:prothrombin fragment 2; D011516:Prothrombin; D006493:Heparin