Release of Cardiac Biomarkers and Inflammatory Response during Cardiopulmonary Bypass: Comparison of Different Biocompatible Materials Used in Cardiopulmonary Bypass
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Coronary Artery Bypass Grafting (CABG) is an effective and invasive cardiac surgery to salvage blocked coronary artery. Cardiopulmonary bypass (CPB) is usually applied to support circulation during temporary cardiac arrest. Studies have demonstrated that cardiac injury, inflammation, and oxidative stress could be induced during CABG with CPB. We conducted two studies to investigate the release of cardiac biochemical markers and inflammatory response as well as to compare the effect of different coating biomaterial of CPB on the induction of inflammation and oxidative stress during CPB. We investigated the release patterns and the serum levels of cardiac markers as well as inflammatory markers in patients undergoing elective CABG at different time points after initiation of CPB. In this study, we demonstrated that cardiac markers such as creatine kinase isoenzyme MB (CK-MB), and cardiac troponin I (cTnI) and inflammatory markers such as tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and high sensitivity C-reactive protein (hsCRP) were highly elevated after CPB. Moreover, we confirmed that cTnI is still a better biochemical marker for cardiac injury than others following CABG with CPB. Other nonspecific but highly sensitive markers such as lactate dehydrogenase (LDH), lactate, TNF-alpha, IL-6, and hsCRP could be potential surrogate markers for evaluation of cardiac injury following CPB. Based on these findings, we conducted a further investigation to demonstrate our hypothesis that different biocompatible materials used in CPB may affect the inflammation and oxidative stress differently. Biocompatible materials are thinly coated on CPB tubes to provide similar environment like endothelial cells during cardiac surgery. There are several biocompatible materials available in the market. Each of them has unique characteristics. Inflammatory response is one of the body’s fundamental defense mechanisms against foreign invaders. However, inappropriate or excessive response can lead to harmful, potentially life-threatening consequences due to severe inflammatory tissue destruction. CPB-induced inflammatory response can be one of the factors, which can affect surgical outcomes. Depending on the presence of different biocompatible materials in CPB circuits, the degree of immunoreactions can be varied. In this study, we analyzed hsCRP, an acute phase protein, and tau protein, a marker of neurocognitive deficiency. Furthermore we analyzed inflammatory cytokines including TNF-alpha, IL-6, IL-10, and interferon-gamma (IFN-gamma) to evaluate the levels of inflammation. Serum levels of oxidized nitric oxide as a marker of oxidative stress were also assessed. We demonstrated that different biocompatible material has different impacts on inflammation and oxidative stress. In the aspect of anti-inflammation, heparin-coated biocompatible material is better than others whereas surface-modifying additives biocompatible material is worse than others. Overall, different coating biomaterial of CPB results in various inflammatory response. In terms of oxidative stress, we did not observe significant difference between different biomaterial-coated CPB.
DegreeMaster of Science (M.Sc.)
CommitteeLee, Paul; Xiang, Jim; Qureshi, Mabood; Krahn, John; Wu, Lingyun