Intraoperative sRAGE kinetics. A new age-related outcome predictor of cardiac surgery.

BACKGROUND: Glycated proteins (advanced glycation endproducts, AGE) in tissue are associated with degenerative diseases. This study evaluated the role of sRAGE (soluble receptor for advanced glycation endproducts), a decoy receptor of AGEs in blood, for the outcome of patients after coronary artery bypass grafting (CABG). METHODS: A total of 90 patients undergoing CABG were analysed in two centres. Perioperative blood samples were collected before surgery up to 1 week postoperatively. sRAGE was measured by ELISA. Patients were subdivided regarding age (< 64 versus > 70 years, 14 % versus 35 % female), euroSCORE (< 3 versus > 4, 14 % versus 29 % female) and sRAGE changes between sternotomy and end of the operation (< 30 % versus > 45 %, 33 % versus 33 % female) and subsequently analysed with respect of postoperative outcome parameters. RESULTS: Preoperative sRAGE values did not correlate with the outcome of the patients. sRAGE levels increase within 10 min from 1,539 ± 96 to 5,311 ± 187 pg/ml after sternotomy, then returning to baseline levels within 2 days after surgery. Comparing the analysed possible risk factors age, euroSCORE and sRAGE changes, no difference was observed regarding 30-day mortality. Age and the euroSCORE are superior with respect of tachyarrythmia, whereas sRAGE kinetics seems to be superior with respect of prolonged postoperative respiration time/stay in the intensive care unit or catecholamine support. CONCLUSION: A prolonged, increased intraoperative sRAGE level is a new outcome predictor for patients undergoing CABG surgery, mutually complementary to the euroSCORE.

Inflammatory response in on- versus off-pump myocardial revascularization: is ECC really the culprit?

A review of inflammatory mediators in on- versus off-pump surgery reveals that parameters of systemic inflammation differ quantitatively, not qualitatively between these approaches. Mediator system and cellular activation is observed after surgical trauma and following ischemia/reperfusion. Such activation is also modulated by genetic factors. The available literature does not permit definitive conclusions to be made on the advantages of off-pump surgery with respect to the systemic inflammatory response. The relationship between mediator systems and clinical course needs to be assessed in large patient populations to demonstrate to what extent off-pump surgery is more than just theoretically superior to on-pump surgery.

Advanced glycation end products, diabetes and ageing.

Advanced glycation end products (AGEs) are formed in vivo by a non-enzymatic reaction of proteins with carbohydrates and accumulate in many tissues during ageing. They are discussed as being responsible for many age- and diabetes-related diseases. On the other hand, AGEs are formed by the heating of food and are taken up by the nutrition. The contribution of endogenously formed versus exogenous intake of AGEs to age-related diseases is still under discussion.

Advanced glycation endproducts: a biomarker for age as an outcome predictor after cardiac surgery?

OBJECTIVE: A decline in the function of all organs can be detected during ageing. Although the trend appears to be stable, deviation within the elderly population is much greater in comparison to young controls. The aim of the study was to identify a marker of senescence which correlates to heart function. Advanced glycation endproducts (AGEs) accumulate with age and are associated with degenerative diseases. METHODS: Carboxymethyllysine (CML) concentrations in the pericardial fluid (as a measure of AGEs) were analysed with ELISA technique in 75 patients undergoing cardiac surgery and correlated with clinical parameters and outcome of these patients. RESULTS: CML content of pericardial fluid increases significantly with age. AGEs show an inverse correlation to left ventricular ejection fraction. High CML levels correlate with poor outcome of patients as shown by adverse cardiac events, prolonged ventilation time and prolonged stay within the Intensive Care Unit. Within all parameters, AGE concentration of the pericardial fluid fits better with the outcome of the patients in comparison to age alone. Interestingly, medical treatment with nitrates correlates with increased CML content. CONCLUSION: AGEs, in addition to being a marker of senescence, appear to represent a prognostic factor in cardiac surgery, which can be used as a predictor of patient outcome.

Regulation of cytokine synthesis in cardiac surgery: Role of extracorporeal circuit and humoral mediators in vivo and in vitro.

OBJECTIVE AND DESIGN: Cardiopulmonary bypass (CPB) impairs monocyte and neutrophil proliferation, cytokine synthesis, and antigen presentation. This study compares in vivo data with results from an extracorporeal circulation (ECC) model, distinguishing direct effects on cytokine synthesis from regulatory mechanisms. PATIENTS AND METHODS: Whole blood from 18 patients prior to, during and after CPB was stimulated with lipopolysaccharide (LPS). Tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, and IL-8 levels were measured. Additionally, blood from 4 volunteers was circulated in an ECC model. Cytokine levels were measured before and during mock ECC. RESULTS: LPS-induced cytokine synthesis was reduced after CPB (TNF-alpha: 11 %; IL-6: 29 %; IL-8: 48 % of preoperative values, all p < 0.001). In mock ECC, cytokine production (except IL-8) was suppressed: TNF-alpha production was lowest 60 min after starting ECC, IL-6 synthesis was lowest at 90 min (33 % and 15 % vs. pre-ECC levels; both p < 0.001). Patient sera contained cytokine-inhibitory activity after CPB, an activity not found in mock ECC. CONCLUSIONS: (1) In patients, CPB induces early transient LPS hyporesponsiveness; (2) blood contact with foreign surfaces induces LPS hyporesponsiveness; (3) serum cytokine-inhibitory activities are released after CPB, but not in mock ECC. Impaired leukocyte function may explain increased susceptibility to infections after CPB.

Age-dependent myocardial reinduction of apoptosis inhibitors under VAD in heart failure.

Hemodynamic unloading using the ventricular assist device [VAD] results in partial functional recovery of failing hearts that show increased susceptibility to cardiomyocyte apoptosis. The caspase cascade is the central element of the apoptotic process in cells. We therefore tested expression shifts of left ventricular mRNA of caspases and their endogenous inhibitors from 15 patients with VAD support and successful bridging to transplantation using semiquantitative RT-PCR. Cardiac unloading was shown by the reduction in ventricular Pro-ANP mRNA under VAD. No alteration of mRNA expression under VAD could be observed for initiator caspases, for their selective inhibitors or for apoptotic signal molecules from the mitochondrial intermembrane space. Only two unselective cardiac IAPs (inhibitor of apoptosis protein) were increased under VAD with better recovery in younger patients. In conclusion, our findings indicate that successful hemodynamic unloading by VAD support causes only minor, age-dependent recovery in the expression of IAPs, while presumed alterations in antiapoptotic modulator systems upstream of the caspase cascade still remain to be identified.