Ischemic myocardium

Zweier, J.L., Flaherty, J.T. and Weisfeldt, M.L. (1987). Direct measurement of free radical generation following reperfusion of ischemic myocardium. Proc. Natl Acad. Sci. USA 84, 1404-1497. 

Interestingly, counting of the microvessels revealed no difference between MSC-transplanted animals and cell culture medium-injected controls (p>0.05, not shown). However, the amount of vessels in both groups was about twice as high in the area of injection compared to normal non ischemic myocardium (p<0,001) of the same animal pointing towards an influence of the injection procedure in neovascularization events. 

Kocher, A.A., Schuster, M.D., Szabolcs, M.J., Takuma, S., Burkhoff, D., Wang, J., Homma, S., Edwards, N.M. and Itescu, S. (2001). Neovascularization of ischemic myocardium by human bone marrow derived angioblasts prevents cardiomyoc34e apoptosis, reduces remodeling and improves cardiac function. Nat Med 7, 430-446. 

Value of Assessment of Viable and Ischemic Myocardium and Techniques Such as MRI, Radionuclide Imaging... 

In Fig. 2.2, the PET perfusion images show severe stenosis or occlusion of the left circumflex (LCx) and right (RCA) coronary arteries with a moderately severe stenosis of the left anterior descending (LAD) coronary artery proximal to its second diagonal branch. The ejection fraction (EF) and regional LV contraction were normal. Therefore, this example illustrates purely ischemic myocardium without scar and without injured or poorly contracting myocardium. 

For patients with chronic CAD, nuclear imaging is essential for addressing the following major clinical issues (i) detection of ischemic myocardium, (ii) differentiation between viable hibernating or stunned myocardium and scar tissue in mechanically dysfunctional regions, and (ill) risk stratification for future major adverse events. Such information provides the basis for percutaneous coronary intervention (PCI) or coronary artery bypass (CAB) surgery and assessing their outcomes based on detection of residual ischemia and recovery of contractile function. 

Figure 2.10 illustrates a zone at risk by PET perfusion imaging. In this example, there is a moderate resting perfusion defect indicating a small non-transmural scar in the distribution of the LAD. After dipyridamole stress, the perfusion defect becomes larger and more severe, indicating a large border zone of ischemic myocardium around the small scar supplied by a severe stenosis. The... 

Diamond GA, Forrester JS, deLuz PL, Wyatt HL, Swan HJ. Post-extrasystolic potentiation of ischemic myocardium by atrial stimulation. Am Heart J 1978 95 204-209... 

Murry CE, Jennings RB, Reimer KA. Preconditioning with ischemia a delay of lethal cell injury in ischemic myocardium. Circulation 1986 74 1124-1136... 

Wu JC, Chen lY, Wang Y, Tseng JR, Chhabra A, Salek M et al. Molecular imaging of the kinetics of vascular endothelial growth factor gene expression in ischemic myocardium. Circulation 2004 110 685-691... 

Revascularize Ischemic Myocardium in Ways that Cannot Currently Be Done... 

Much work has been done in the area of vascular growth factors to create collateral circulation, but so far clinical efforts have fallen short of predictions. The new field of cell transplantation may provide the necessary milieu and may be more effective at inducing neovascularization in ischemic myocardium. Fibroblast growth factor in... 

Increased collateral flow Improved perfusion to ischemic myocardium... 

The effects of coenzyme Q10 on coronary artery disease and chronic stable angina are modest but appear promising. A theoretical basis for such benefit could be metabolic protection of the ischemic myocardium. Double-blind, placebo-controlled trials have demonstrated that coenzyme Q10 supplementation improved a number of clinical measures in patients with a history of acute myocardial infarction (AMI). Improvements have been observed in lipoprotein a, high-density lipoprotein cholesterol, exercise tolerance, and time to development of ischemic changes on the electrocardiogram during stress tests. In addition, very small reductions in cardiac deaths and rate of reinfarction in patients with previous AMI have been reported (absolute risk reduction 1.5%). 

Corr PB, Gross RW, Sobel BE Amphipathic metabolites and membrane dysfunction in ischemic myocardium. Cite Res 1984 55 136-142. 

G-CSF mobilizes bone marrow-derived cells into the bloodstream. These stem cells can migrate to ischemic myocardium and differentiate into cardiomyocytes, smooth muscle cells and endothelial cells. They may also induce metalloproteinases and vascular endothelial growth factor and thus play a role in tissue healing. Furthermore, G-CSF induces proliferation and enhanced survival of cardiomyocytes. This is accomplished via activation of G-CSF receptors in myocardium. G-CSF in association with TGF- 3 and collagen enhances ventricular expansion in the infarcted area. 

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