PERIOPERATIVE HISTOLOGIC AND ULTRASTRUCTURAL-CHANGES IN THE PERICARDIUM AND ADHESIONS

The presence of pericardial adhesions prolongs the operation time and increases the risk of serious damage to the heart and other major vasc ular structures during resternotomy. The reported incidence of such da mage is 2% to 6%. Pericardial mesothelial cells exhibit fibrinolytic a ctivity, and therefore have an actual or potential role in the breakdo wn of the fibrinous adhesions that serve as the initial scaffolding fo r the firm collagenous adhesions seen at reoperation. Ten patients und ergoing primary cardiac procedures were studied to assess the morpholo gic changes that take place within the pericardium and to relate these to accompanying changes in the pericardial plasminogen activating act ivity. Samples were taken at 0, 75, and 135 minutes after pericardioto my. Compared with samples obtained at the time of pericardiotomy, thos e taken at 75 and 135 minutes demonstrated a significant progression i n the mesothelial cell damage (p < 0.01), together with increasing evi dence of pericardial inflammation (p < 0.01). The findings from electr on microscope studies confirmed and supplemented these findings. Furth ermore, compared with its initial levels (median, 2.06 IU/cm(2); range , 1.28 to 6.48 IU/cm(2)), the plasminogen activating activity of peric ardial biopsy specimens was significantly reduced at 75 minutes (media n, 0.64 IU/cm(2); range, 0.12 to 2.44 IU/cm(2); p < 0.05), with some r ecovery at 135 minutes (median, 1.45 IU/cm(2); range, 0.12 to 4.39 IU/ cm(2); p = 0.059). This study has revealed that, during cardiac proced ures, the pericardium undergoes inflammatory changes with concomitant damage to its mesothelium, together with a reduction in the pericardia l mesothelial fibrinolytic potential. These changes may be important f actors contributing to the early development of pericardial adhesions.