The heart produces but the lungs consume proinflammatory cytokines following cardiopulmonary bypass

Objective: Proinflammatory cytokines, such as interleukin-6 (IL-6), and sol uble adhesion molecules, such as E-selectin, may play an important role in patient response to cardiopulmonary bypass (CPB). We sought to define wheth er the heart and the lungs serve as important sources of these inflammatory mediators under clinical conditions of myocardial revascularization using CPB and cardioplegic arrest. Methods: Plasma levels of IL-6 and E-selectin were measured in coronary sinus (CS), arterial, pulmonary arterial (PA) and left atrial (LA) blood samples taken from 12 consecutive patients (68.3 +/ - 11 years; five females) undergoing coronary artery bypass grafting (CABG) . Blood samples were collected preoperatively, after reperfusion, and 1,6, 12 and 18 h following surgery. CS and LA blood was drawn using transcutaneo us catheters. PA artery blood was obtained through a Swan-Ganz catheter. Cy tokine levels were determined by standard enzyme linked immunosorbent assay (ELISA) technique. Results: A mean of 3.8 +/- 1 coronary anastomoses were performed. The CPB time and aortic X-clamp time were 91 +/- 15 and 45 +/- 1 0 min, respectively, IL-6 levels increased significantly after CPB and peak ed 6 h postoperatively. There was also a significant increase of E-selectin levels with an onset at 1 h and a peak at 12 h postoperatively. At all tim e points the IL-6 and E-selectin concentrations were significantly higher i n the CS than in arterial blood. In contrast, the levels of both mediators measured in the LA were significantly lower than those in the PA. Conclusio n: The reperfusion of ischemic myocardium during CABG results in a signific ant increase in plasma levels of IL-6 and E-selectin. Our data indicate tha t the myocardium, but not the lungs, is a predominant source of IL-6 and E- selectin release following CPB. The lungs may consume rather than release t hose mediators during reperfusion. Not the CPB per se, but the myocardial i schemia seems to be crucial in the pathogenesis of the inflammatory respons e observed following open heart surgery. (C) 1999 Elsevier Science B.V. All rights reserved.