Thromb Haemost 1993; 70(02): 259-262
DOI: 10.1055/s-0038-1649561
Original Articles
Clinical Studies
Schattauer GmbH Stuttgart

Thrombin Generation during Cardiac Surgery: Is Heparin the Ideal Anticoagulant?

S J Brister
1   The Department of Surgery, Hamilton, Ontario, Canada
,
F A Ofosu
2   The Department of Pathology, McMaster University, Hamilton, Ontario, Canada
3   The Canadian Red Cross Society Blood Services, Hamilton, Ontario, Canada
,
M R Buchanan
1   The Department of Surgery, Hamilton, Ontario, Canada
2   The Department of Pathology, McMaster University, Hamilton, Ontario, Canada
› Author Affiliations
Further Information

Publication History

Received 03 December 1992

Accepted after revision 22 February 1993

Publication Date:
04 July 2018 (online)

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Summary

Blood samples were collected from 43 patients undergoing elective cardiac surgery to determine the extent of thrombin generation and inhibition in patients when receiving heparin while undergoing cardiopulmonary bypass (CPB). Plasma prothrombin fragment F1 + 2 and thrombin-antithrombin III (TAT) levels were measured as markers of thrombin generation and inhibition, respectively. Both F1 + 2 and TAT levels increased significantly during the course of CPB despite the heparin causing significant systemic anticoagulation, i.e. the activated coagulation time (ACT) was prolonged to greater than 400 s throughout the entire surgical procedure. The extent of thrombin generation increased with time on CPB but did not differ between patients receiving normothermic and hypothermic cardioplegia during CPB. Furthermore, thrombin generation increased following the neutralization of the heparin with protamine sulphate, and continued to be elevated significantly 24 h post surgery. The observation that high dose heparin did not prevent thrombin generation during CPB, is consistent with previous experimental studies demonstrating that thrombin bound to fibrin or other surfaces (e.g. the CPB conduit) is resistant to antithrombin III/heparin inhibition, and thus able to facilitate further thrombin generation. The observation that thrombin generation continued to be elevated post surgery i.e. 24 h after neutralizing the heparin with protamine sulphate, suggests that the high dose heparin did not inhibit effectively all of the thrombin that had been generated. Thus, CPB patients may be at risk not only of bleeding and other side-effects associated with the acute use of high dose heparin, but may also be at risk of further thrombosis-related events either acutely or chronically.