Ischemia detection

Camacho AN, Guindo J, Bayes de Luna A. Usefulness of silent subendocardial ischemia detected by ST-segment depression in postmyocardial infarction patients as a predictor of ventricular arrhythmias. Am J Cardiol 1992 69 1243. 

In summary, the failure of medical therapy, a history of recent MI (<3 months), demonstration of significant inducible ischemia, detection of unequivocally reduced fractional flow reserve, or the presence of specific angiographic features of coronary stenoses should guide utilization of PCI in patients with stable coronary lesions (8). 

Sorensen, A.G., et al.. Human acute cerebral ischemia detection of changes in water diffusion anisotropy by using MR imaging. Radiology, 1999. 212(3) p. 785-92. 

A. Yiifera, A. Rueda, J.M. Munoz, et al., A Tissue Impedance Measurement Chip for Myocardial Ischemia Detection, IEEE Transactions on Circuits and Systems I Regular Papers, vol. 52, no. 12, pp. 2620-2628, 2005. 

Subdivision of these methods into the classes - flow dependent and ischemia detection - is arbitrary because significant reduction of blood flow leads to ischemia. In the cerebral circulation where reduced blood flow leads to prompt ischemic damage methods measuring the two phenomenon are virtually indistinguishable. In peripheral circulation where reduced blood flow can be tolerated for prolonged periods methods measuring the two phenomena can be quite different. The cardiac circulation lies between cerebral and peripheral in the speed with which flow reduction leads to ischemia. Most of the discussion which follows will deal with the peripheral and cardiac circulatory beds. 

Globus MY, Busto R, Lin B, Schnippering H, Ginsberg MD. Detection of free radical activity during transient global ischemia and recirculation effects of intraischemic brain temperature modulation. J Neurochem 1995 65 1250-1256. 

A. Wennmalm, B. Lanne, and A.S. Petersson, Detection of endothelial-derived relaxing factor in human plasma in die basal state and following ischemia using electron-paramagnetic resonance spectrometry. Anal. Biochem. 187, 359-363 (1990). 

In earlier studies the in vitro transition metal-catalyzed oxidation of proteins and the interaction of proteins with free radicals have been studied. In 1983, Levine [1] showed that the oxidative inactivation of enzymes and the oxidative modification of proteins resulted in the formation of protein carbonyl derivatives. These derivatives easily react with dinitrophenyl-hydrazine (DNPH) to form protein hydrazones, which were used for the detection of protein carbonyl content. Using this method and spin-trapping with PBN, it has been demonstrated [2,3] that protein oxidation and inactivation of glutamine synthetase (a key enzyme in the regulation of amino acid metabolism and the brain L-glutamate and y-aminobutyric acid levels) were sharply enhanced during ischemia- and reperfusion-induced injury in gerbil brain. 

NSTEMI differs from UA in that ischemia is severe enough to produce myocardial necrosis, resulting in release of detectable amounts of biochemical markers, primarily troponin I or T and creatine kinase myocardial band (CK-MB) from the necrotic myocytes into the bloodstream. 

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. 

Alternatives to FDG for detecting viable myocardium are based on myocardial leak of creatine phos-phokinase, inosine, inorganic phosphate [100-103] due to impaired cell membrane function induced by ischemia and/or necrosis. Therefore, the use of a potassium analogue reflecting myocardial cellular membrane function and the myocardial potassium space represents an alternative for a quantitative assessment of... 

Detect and Monitor Established Heart Failure or Ischemia... 

Schlegel TT, Kulecz WB, DePahna JL, et al. Real-time 12-lead high-frequency QRS electrocardiography for enhanced detection of myocardial ischemia and coronary artery disease. Mayo Clin Proc. Mar 2004 79(3) 339-350. 

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