Post-perfusion syndrome and disturbed microcirculation after cardiac surgery: the role of angiotensin-converting-enzyme inhibitors

Background: The sympathoadrenal and the renin-angiotensin system (RAS) are involved in blood pressure regulation. They are known to be activated durin g cardiac surgery. We investigated the influence of preoperative RAS-blocka de using angiotensin-converting-enzyme inhibitors (ACEI) on hemodynamic var iables and on the perioperative need for exogenous catecholamines. Methods: 240 patients undergoing coronary artery bypass grafting (CABG) or valve su rgery were divided into three matched groups (group A: pre- and postoperati ve ACEI; group B: ACEI only pre-, not postoperatively: group C: no ACEI). I n these three groups we analyzed hemodynamic variables, the need for catech olamines and the incidence of a "post-perfusion syndrome" or systemic infla mmatory response syndrome (SIRS) with impaired microcirculation. Results: T here were significant differences in the intra- and postoperative need for catecholamines in groups A and B compared to C (intraop. A: 35%, B: 35%, C: 15%; postop. A: 21.2%, B: 15.2%, C: 10%) (p < 0.05). In the ACEI groups (A and B) there were 9 patients with a postoperative SIRS, only 2 cases in gr oup C. Furthermore 4 patients of group B suffered from disturbances of the intestinal microcirculation postoperatively. Conclusions: Long-term ACEI tr eatment before cardiac surgery raises the perioperative need for catecholam ines. Patients with preoperative long-term use of ACEI who do not receive A CEI postoperatively face an increased risk of impaired microcirculation. Th e inhibition of angiotensin-ll (AT II) generation causes the vasodilatatory effects of ACEI, and could be one reason for a post-perfusion syndrome or a SIRS.