NEUTROPHIL DEGRANULATION RELATED TO THE REPERFUSION OF ISCHEMIC HUMANHEART DURING CARDIOPULMONARY BYPASS

Activation of polymorphonuclear neutrophils (PMNs) during cardiopulmon ary bypass (CPB) is a well-known phenomenon, This study aimed to deter mine if activated PMNs are sequestered and degranulated within the myo cardium at reperfusion in patients undergoing coronary artery bypass g rafting (CABG). Nineteen patients undergoing elective CABG were includ ed in a prospective randomized study. Blood samples were obtained simu ltaneously from the radial artery (RA) and the coronary sinus (CS) at the following times: T0 (5 min after onset of CPB), T1 (2 min after ao rtic unclamping), and T2 (10 min after aortic unclamping). Neutrophil function was evaluated by PMN count and by elastase and lactoferrin co ncentrations. All patients survived. Neutrophils increased significant ly from T0 to T1 and T2 in both RA and CS (p < 0.001 between T0 and T1 or T2). Pre-ischemia and reperfusion were associated with a significa ntly lower neutrophil count in CS compared with RA blood (p < 0.001), suggesting that PMNs were trapped within the myocardium at the onset o f the CPB, Elastase and lactoferrin concentrations increased significa ntly from TO to T1 and from T1 to T2 for each site, with greater conce ntrations (p < 0.001) in the CS compared with the RA, suggesting that activated neutrophils released their granular content into the plasma milieu only after reperfusion of the ischemic heart. This study establ ishes that neutrophil sequestration seems to be secondary to PMN activ ation by CPB but that the ischemia-reperfusion sequence induces specif ic degranulation of the PMNs trapped within the ischemic myocardium.