Immunological aspects of cardiopulmonary bypass

E XTRACORPOREAL circulation (ECC) using the heart-lung machine has been known to contribute to the morbidity and mortality of cardiac surgery since the first operations were performed.‘V2 Cardiopulmonary bypass (CPB) can never be truly physiological, primarily because of the artificial environment of the extracorporeal circuit. Interaction among the patient’s blood, the artificial surfaces, and the pump results in generation of various mediators in plasma and direct cellular injury, leading to a systemic inflammatory response.3 Although the immune system normally serves to protect the host from offenders, overreacting ongoing immunological responses may be detrimental and result in the postperfusion syndrome. In the most severe cases, pulmonary and renal dysfunction, a bleeding tendency, neurological disorders, and fevers of noninfectious origin may develop. Closed cardiac surgery without the use of CPB and other major procedures have fewer sequelae.4-7 The present review updates the most important theories concerning the systemic inflammatory response initiated by CPB in patients undergoing cardiac surgery, and discusses possible therapeutic interventions.