Expression of Angiogenic Factors in Myocardial Tissue in Diabetic and Non-diabetic Patients Undergoing Coronary Bypass Surgery

• tissue levels of HIF-1, VEGF and angiostatin [ Time Frame: initiation of CPB/ day 1 ] [ Designated as safety issue: No ]
  The investigators will evaluate tissue levels of HIF-1, VEGF and angiostatin in diabetic and non-diabetic patients coming for on-pump CABG.
  
  

Coronary artery disease and its complications are the leading cause of death in the western world. Diabetes mellitus (DM) is one of the major risk factors to develop coronary artery disease, myocardial infarction and post-infarction complication1-3. Furthermore, mortality from myocardial infarction is almost doubled in diabetic patients compared to non-diabetics4. Despite significant amount of research, the basis for these differences in outcome still remains unclear. The survival of myocardial tissue subjected to ischemia can be increased by the ability to promote growth of new blood vessels into ischemic areas, thus limiting regions of impairment and ultimately preserving myocardial function. Hypoxia inducible factor (HIF) -1 is a transcription factor that promotes the expression of several genes that confer protection against hypoxia/ischemia through angiogenesis, erythropoiesis, vasodilation, and altered glucose metabolism5,6. Our hypothesis is that angiogenesis may be impaired in diabetes mainly via decreased protein expression and activation of HIF-1 and its main downstream target vascular endothelial growth factor (VEGF), as well as the inhibitor angiogenesis factor, angiostatin7, in the heart. Therefore the purpose of this study is to examine whether the angiogenic process during coronary ischemia is influenced by diabetes. To address these questions, HIF-1, VEGF and angiostatin protein expression will be evaluated in atrial tissue obtained from patients with and without diabetes who will undergo coronary bypass surgery. In addition comparison between emergency and elective procedure will be performed in regard to HIF-1 and VEGF protein levels and correlation with chronic statin therapy will be performed.

During the cannulation process, prior to initiation of cardiopulmonary bypass (CPB) during heart surgery, a small piece of the right atrium is cut in order to insert a venous cannula into that chamber. The investigators intend to use this piece of tissue (that is routinely wasted) in our protein and histological analyses.