Original Article

The Course of D-dimers as Fibrinolytic Products Generated During Cardiopulmonary Bypass

Division of Cardiothoracic Surgery, Department of Pathology and Laboratory Medicine, (Section of Transfusion Services), Department of Extracorporeal Circulation Technology, College of Health Related Professions, Medical University of South Carolina, Charleston, SC

^* Address correspondence to: Tim Moretz, Duke University Medical Center, Box 3237, Durham, NC 27707

Abstract

D-dimers are the expressed degradation products of the lysis of fibrin. Fibrin monomers may normally occur during routine cardiopulmonary bypass (CPB); therefore, fibrinolysis could play a protective role. Serum D-dimer levels were observed at six events associated with routine CPB. An expected patient D-dimer level while heparinized would be <0.5 ug/ml showing that fibrin is not being formed.

The majority of elevated D-dimer levels came at the termination of CPB when only one of twenty patients investigated showed a minimal DD level of <0.5. The other patients ranged from 0.5 to >8.0 ug/ml at termination of CPB.

The last three event D-dimer levels were significantly greater than the D-dimer from the first three events (p<0.01) demonstrating that fibrinolysis may be a normal occurrence during CPB. The weak correlation in the rise in D-dimers during CPB versus the minimal CPB ACT data (n=20, r=.114) although not statistically significant, suggests that ACTs should be maintained above 480 seconds throughout CPB to minimize fibrin formation and therefore minimize fibrinolysis.