Platelets contain and release a variety of receptor molecules and molecules which influence platelet adhesion and aggregation. They are also a source of coagulation factors as well as regulators of coagulation and fibrinolysis. Via different surface molecules they interact with each other as well as different ligands from the vessel wall and the blood plasma. In the present study, the expression of platelet surface proteins was determined in order to compare the effects of two different heart-lung-machines (HLM) on platelet activation.
The study was performed as prospective, randomized, single-blinded study. Fourty patients were recruited into two groups according to the application of different HLM systems. A standard system (group 1) is compared with a modified HLM which is designed to minimize procoagulatory effects by using a Deltastream pump, surface-modified tubing, and a reduced priming volume (group 2). Blood was collected at different time points before, during, and after surgical intervention (CABG). Platelets were incubated with either CD42b-FITC-/ CD62P-PE- or Factor Va-FITC-/ Tissue Factor-PE-labeled antibodies. Analysis was performed using a FACSCalibur flowcytometric system.
There was no significant change in the CD62P expression during CABG, and no difference among groups. The expression of CD42b decreased significantly at the end of the observation period in group 1 but not in group 2. Factor Va expression was significantly elevated in group 1 between the beginning and 10 min after the end of the surgical intervention, but without differences between groups. Tissue factor expression did not disclose any significant change or difference between groups. In contrast, the expression of Glycoprotein Ib-alpha, a subunit of the von Willebrandt-Receptor-Complex, decreased in group 2 at the end of CABG.
The results exclude a global platelet activation for both HLM systems, but the differences in the expression of Factor Va, CD42b, and Glycoprotein Ib-alpha indicate effects of the HLM modification.
Modifications in extracorporeal circulation setups that are in routine use in cardiac surgery influence platelet activation.
T. Waldow, None.