Methods: Thirty-six patients (19 males, 17 females; mean age 61.2±16.1 years; range 47 to 85 years) who underwent surgery in our clinic between January 2005 and April 2006 were enrolled in this study. The patients were divided into two groups. Group 1 consisted of 20 patients who underwent surgery for the first time whereas group 2 consisted of 16 patients who had previously undergone at least one cardiac surgery. Two biopsies were obtained in both groups one immediately after opening the pericardium and the other 60 minutes after the first biopsy. A portion of the biopsies that were obtained was fixed in neutral formalin by the TUNEL method for uPAR (urokinase plasminogen activator receptor) and FGF-2 (fibroblast growth factor-2) immunostaining, and it was also used to detect cells with DNA fragmentation. The other tissue samples were examined by the transient electromagnetic (TEM) method and stained with toluidine blue.

Results: No statistically significant differences were found between the groups either in the preoperative risk factors or the demographic characteristics of the patients. However, there were marked differences in the tissues between the first and second biopsies in group 1 regarding the uPAR and FGF-2 levels. Moreover, at the ultrastructural level, superficial microvilli and deep basal interdigitations of cells were identified in the first biopsy, while microvilli disappeared and basal interdigitations smoothed out in the second biopsy, and in both biopsies of group 2. No important differences were found between the first and second biopsies in group 2. There was no statistically significant difference between the groups with respect to apoptosis.

Conclusion: In conclusion, the fact that the reactions seen in the pericardium of patients undergoing cardiac surgery for the first time are absent in patients undergoing cardiac surgery for the second time suggests that the structure of the pericardium deteriorates as a whole.