Fibrinolytic and Hemorheologic Alterations During and After Elective Aortic Graft Surgery

The hemorheologic and fibrinolytic variables of 15 patients undergoing elective aortic graft surgery were investigated before, during, and after surgery. During the operation, a relative hemodilution was induced intentionally by an infusion of crystalloids and albumin. This led to a decrease in hematocrit (35.5 +/- 6.3-->31.8 +/- 5.6%, P < 0.01), fibrinogen, and platelets, as well as a decrease in fibrinolysis (Euglobulin Clot Lysis Time increases 246 +/- 52-->300 +/- 46 min and fast-acting plasminogen activator inhibitor 1 [PAI-1] activity increases 10.5 +/- 6.9-->15.1 +/- 9 IU/mL, P < 0.01). There was also specific rheologic impairment with a dissociation of erythro-aggregates (primary aggregation time 3.37 +/- 2.63-->7.18 +/- 7.2 s). Tissue-type plasminogen activator (t-PA) antigen was only increased just after surgery (8.3-->14.5 ng/mL, P < 0.01). During the first postoperative week, the acute-phase response subsided. This was accompanied by an increase in fibrinogen, von Willebrand factor antigen, and plasma viscosity (1.33 +/- 0.13-->1.49 +/- 0.13 mPa x s, P < 0.01). Hematocrit and the extrinsic fibrinolytic system (t-PA/PAI) returned to baseline values, whereas intrinsic fibrinolysis remained altered (the Euglobulin Clot Lysis Time, reflecting total activity of plasminogen activators, was still increased). Postoperative management may benefit from a recognition of these two distinct phases induced by surgery. The acute-phase reaction of the first postoperative week is an added vascular risk factor and requires a specific therapeutic approach.