Coronary Artery Bypass Grafting

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Coronary Artery Bypass Grafting (CABG) an essential surgical procedure for treating heart diseases paradoxically induces myocardial injury due to oxidative stress. It has been estimated that the predicted risk of developing myocardial infarction during surgery has increased by 30% over the past decade (Kathiresan,S. et al., 2004). The free radicals generated during oxidative stress can damage every major cellular component including membrane lipids, proteins, carbohydrates and DNA. Among the various strategies to reduce the injury, use of antioxidants as additives has been extensively investigated.(Fadillioglu,E. et al., 2004 ; Kizilitepe,U. et al., 2004; Pichon,H. et al., 1997; Yau,T.M. et al., 1994). One such agent, N acetylcysteine, a thiol containing antioxidant has been investigated in this study. Cardiac Troponin I (cTnI) has been used as a biomarker for myocardial injury due to oxidative stress. Nevertheless we have undertaken this study to monitor both cTn I and other markers of oxidative stress for more comprehensive evaluation. Study by Kormaz.I. et al., (2006) reported a drastic reduction in the level of cTn I in the NAC treated group of patients undergoing cardiac surgery,suggestive of its cardioprotective effect. On the contrary, study conducted at Montreal Heart Research Institute by Ismail, E.H.et al., (2007) has completely rejected the NAC’s cardioprotective effect, by concluding that the use of NAC during CABG with CPB does not lead to improvement in neither the biochemical nor the clinical markers. In our study the levels of cTn I in the NAC administered group has not shown any significant difference when compared with the patients who have not received NAC and hence cTn I does not appear b... ... middle of paper ... ...e enrolled before ascertaining the data. Such type of patients will have increased oxidative stress induced by less tolerance to ischemia and hence more amenable to antioxidant treatment. Unfortunately most clinical studies including ours tend to be conducted only in a small number of low risk patients that makes the detection of significant biochemical outcome differences difficult.Most importantly, the patients safety is of great importance with ethical considerations. To conclude, cTnI alone may not be a dependent biomarker to ascertain the cardioprotective effect of NAC. The glutathione reductase seems to be more reliable bio marker for assessing the oxidative stress with reference to NAC in patients undergoing CABG with CPB. Further, a thorough study on the beneficial role of free radicals in myocardial protection and adaptation is necessary.
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