Immunologic reaction after endovascular versus conventional therapy of aortic aneurysm

Background: Endovascular repair (ER) of aortic aneurysm, though being consi dered minimally invasive, may be associated with a nonspecific inflammatory reaction known as "post-implantation syndrome". The aim of the study was t o compare the immunologic responses to ER and conventional repair (CR). Methods: A prospective, non-randomized study included 8 patients each with ER and CR. Blood samples were taken pre-, intra- and postoperatively. The f ollowing parameters were analyzed quantitatively using ELISA: tumor necrosi s factor (TNF)-alpha, interleukin (IL)-6, IL-10, IL-1 receptor antagonist ( IL-1 RA), cortisol, procalcitonin (PCT), soluble IL-2 receptor (sIL-2R) and polymorphonuclear leucocyte elastase (PMN-E). To test the in vitro secreto ry capacity of monocytes, TNF-alpha and IL-1 beta were measured in whole bl ood cultures after stimulation with LPS. Secretory capacity of PMN leucocyt es was measured after stimulation with PMA. Statistical analysis was perfor med using the Mann-Whitney test for comparison of ER and CR groups and Wilc oxon's test for comparison of values within each group. Results: There were significant elevations of PCT, IL-6, and TNF-alpha afte r ER and CR with significantly higher values of IL-6 (intraop.) and TNF-alp ha (7 d postop.) in CR as compared to ER. SIL-2R was significantly elevated (intraop.-4 h postop., 7 d postop.) in CR versus ER despite an intraoperat ive decrease in both ER and CR. Though anti-inflammatory cytokines IL-10 an d IL-1RA showed significant intra- and postoperative increases in ER and in CR, both IL-1RA. and IL-10 as well as cortisol demonstrated lower plasma c oncentrations in ER as compared to CR. Accordingly, in CR but not in ER, th ere was a marked suppression of in vitro secretion capacity of monocytes wi th significantly lower concentrations of TNF-alpha (1 h post clamp., 4 h an d 3 d postop.) and IL-1 beta (1 h post clamp., 4 h postop.). Plasma (4 h-3 d postop.) and PMA-stimulated (intra-, postop.) PMN-E were significantly hi gher with EA. Conclusion: Moderate inflammation and lacking immunodepression with minimal ly invasive ER might fail to induce a relevant anti-inflammatory response. This might explain the presence of clinical symptoms associated with the "p ost-implantation syndrome" in ER.