Objective: Heart surgery with extracorporeal circulation has a marked effect on platelet function and coagulation accounting for abnormal blood loss and allegedly a low incidence of thromboembolic complications. Little is known about platelet function at the time of hospital discharge of routine patients.
Methods: Blood samples from 91 patients undergoing elective heart surgery were drawn before surgery and prior to discharge. Thirty-seven patients underwent coronary artery surgery and 54 an aortic valve implantation. The mean age of patients was 69+/-9 years. Fifty patients were male and 41 female. Platelet function was evaluated using plasma beta-thromboglobulin quantification in enzyme-linked immunosorbent assay. In addition, flow cytometric analysis of platelet-monocyte conjugates and platelet-neutrophil conjugates was performed.
Results: The platelet count before discharge was significantly increased (265+/-86 vs. 212+/-61 x 10(9)/l preoperatively). beta-Thromboglobulin was significantly increased (176+/-127 vs. 79+/-70 ng/ml preoperatively) and flow cytometry proved a significant increase in monocyte-platelet aggregates (8.3+/-5.4% vs. 5.3+/-2.6% preoperatively) indicating platelet activation at the time of hospital discharge. There were no significant differences among the three subgroups coronary surgery, mechanical valve insertion and biological valve insertion.
Conclusions: Heart surgery with extracorporeal circulation leads to significant platelet activation and a reactive increase in platelet count before discharge. This is in contrast to the reduced platelet function immediately postoperatively.