MYOCARDIUM IS A MAJOR SOURCE OF PROINFLAMMATORY CYTOKINES IN PATIENTSUNDERGOING CARDIOPULMONARY BYPASS

Proinflammatory cytokines, such as tumor necrosis factor-alpha, interl eukin-6, and interleukin-8, and antiinflammatory cytokines, such as in terleukin-10, may play an important role in patient responses to cardi opulmonary bypass. We sought to define whether the myocardium and the lungs serve as important sources of these cytokines under conditions o f cardiopulmonary bypass. Ten patients (age 64 +/- 3 years, mean +/- s tandard error of the mean) undergoing elective coronary artery bypass grafting were monitored with an arterial catheter, a coronary sinus ca theter, and a pulmonary artery catheter. Plasma levels of tumor necros is factor-a, interleukin-6, interleukin-8, and interleukin-10 were mea sured simultaneously in peripheral arterial blood, coronary sinus bloo d, and mixed venous blood before heparin administration, 1 minute befo re aortic crossclamping, 5 minutes after aortic declamping, and at 0.5 , 1, 1.5 and 2 hours after aortic declamping. The durations of cardiop ulmonary bypass and aortic crossclamping were 114 +/- 9 and 64 +/- 5 m inutes, respectively. Levels of tumor necrosis factor-alpha and interl eukin-6 were significantly higher in coronary sinus blood than in arte rial blood after aortic declamping. Tumor necrosis factor-a and interl eukin-6 levels were also higher in mixed venous blood than in arterial blood within 1 hour after declamping. There were no significant diffe rences among the three sampling sites with respect to interleukin-8 an d interleukin-10 levels. In one patient who had postoperative myocardi al infarction, however, interleukin-8 levels were three times as high as in coronary sinus blood than in arterial blood. These data indicate that the myocardium is a major source of tumor necrosis factor-a and interleukin-6 in patients undergoing cardiopulmonary bypass. The lungs may consume rather than release proinflammatory cytokines in the earl y phase of reperfusion. The source under these conditions of the antii nflammatory cytokine interleukin-10 remains to be determined.