Effects of Heparin-coating of Cardiopulmonary Bypass Circuits on Leukocytes During Simulated Extracorporeal Circulation

Heparin-coated circuits used during extracorporeal circulation reduce many postoperative complications occurring after heart surgery. Such complications are partly related to leukocyte activation with subsequent release of active substances, e.g. oxygen free radicals, myeloperoxidase and lactoferrin. This experiment was performed to elucidate a possible influence of heparin-coating on leukocytes. A 2-h-long simulated extracorporeal circulation was performed on two groups of five extracorporeal circulation circuits, primed with heparinized, fresh whole human blood and Ringer's solution. Heparin-coated circuits (HC group) were compared with uncoated circuits (NC group). Oxygen free radical production was estimated by determination of malonyldialdehyde in plasma and erythrocyte suspension. Granulocyte activation was measured in terms of myeloperoxidase and lactoferrin release. Time-related changes in leukocyte subset counts were analysed. Heparin-coating diminished myeloperoxidase and lactoferrin release. There were significant inter-group differences after 90 and 120 min of extracorporeal circulation for myeloperoxidase (101 (12) microg/l and 107(12) microg/l in the HC group versus 154(20) microg/l and 174(23) microg/l in the NC group), and after 120 min of extracorporeal circulation for lactoferrin (78(5) microg/l in the HC group versus 212(49) microg/l in the NC group). No significant changes of MDA concentration were observed in plasma or erythrocytes; however, a tendency towards lower MDA levels was seen after 90 and 120 min of extracorporeal circulation in the NC group. Neutrophil, monocyte and eosinophil numbers decreased significantly in the NC group but were unchanged in the HC group, as were lymphocyte counts. Heparin-coated extracorporeal circulation circuits significantly reduce granulocyte activation and better preserve the number of circulating neutrophils, eosinophils and monocytes, but do not change oxygen free radical production during simulated extracorporeal circulation.