Stimulation of neutrophil activation during coronary artery bypass grafting: Comparison of crystalloid and blood cardioplegia

Background. During myocardial ischemia, activation of polymorphonuclear neu trophils (PMNs) results in the production of free oxygen radicals, which in crease myocardial injury. It has been shown that PMNs also produce nitric o xide. It is not clear whether PMNs become activated as a result of their di rect contact with ischemic/ reperfused myocardium or if PMN activation and free oxygen radical production are effects of specific stimuli released dur ing coronary artery bypass grafting (CABG). The aim of the current study wa s to evaluate plasma-mediated neutrophil stimulation and production of supe roxide anion (O-2(-)) and nitric oxide in patients undergoing CABG, and to verify whether crystalloid and blood cardioplegia can modify such stimulati on. Methods. Coronary sinus, peripheral arterial, and venous plasma samples wer e collected from 50 patients who underwent CABG and were divided into 2 equ al groups which received either crystalloid or blood cardioplegia: directly before myocardial ischemia and aortic cross-clamping; at the beginning of reperfusion after aortic clamp release; and 30 minutes after reperfusion. O -2(-), and nitric oxide production by PMN was evaluated by standard methods . Results. There was a significant (p < 0.05) increase in O-2 production by P MN incubated with plasma obtained from the coronary sinus immediately after reperfusion in patients receiving crystalloid cardioplegia compared to blo od cardioplegia. No difference was observed in plasma stimulation of nitric oxide production by FMN in the 2 groups of patients at different times dur ing the procedure. Conclusions. Cardioplegia may affect release of neutrophil-oriented stimuli from ischemic myocardium and modify neutrophil activation during coronary artery bypass grafting. (C) 2001 by The Society of Thoracic Surgeons.