Immunological and histopathological changes in the atrial tissue during and after cardiopulmonary bypass.

Background: Ischemia and reperfusion injury occur in cardiac operations using cardiopulmonary bypass (CPB). Little is known about the immunological and histopathological changes in the atrial tissue under these conditions.

Objectives: To investigate and compare multiple right atrial biopsy specimens by means of a self-developed pathological and immunohistochemistry panel.

Patients And Methods: Thirty-six nonselected adult patients (mean age 59+/-11.6 years, range 34 to 75) who had undergone different types of heart surgery (26 with and 10 without the use of CPB).

Results: Circumscribed necrosis was not found in any of the samples. Contractile bundle necrosis deteriorated only moderately with CPB. The share of hibernated myocardium seemed to increase during CPB, reaching 30% regardless of the basic disease. From the subepicardial toward the subendocardial surface, the amount of contractile proteins decreased continuously. Features similar to those seen with the phenomenon of 'stunning', which develops due to acute ischemia, were also noted. The apoptosis index did not exceed 1%. Apoptotic cells were generally randomly spread. It was very characteristic that with the use of CPB neither pro- nor antiapoptotic peptides (Bax, Bcl-2) were seen. In samples taken from patients who underwent surgery performed without the use of CPB both proteins were detected. The occurrence of cellular stress (heat shock protein 70 reaction) was rather variable in the samples.

Conclusions: These investigations should be continued on homogeneous patient populations with the inclusion of proinflammatory cytokine determination.