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Figure 1. Cornoary artery plaque and plaque rupture. (A) Plaque is made up of a lipid-core containing free lipid and foam cells covered by a fibrous cap denuded of normal endothelium. (B) Unstable plaque may rupture exposing circulating blood to underlying thrombogenic material with the consequent formation of a thrombus.

Figure 1. Cornoary artery plaque and plaque rupture. (A) Plaque is made up of a lipid-core containing free lipid and foam cells covered by a fibrous cap denuded of normal endothelium. (B) Unstable plaque may rupture exposing circulating blood to underlying thrombogenic material with the consequent formation of a thrombus.

logic testing in patients able to exercise adequately because it provides an assessment of well validated prognostic markers such as workload, ST segment depression, anginal symptoms and heart rate/blood pressure response.

Maximal exercise results in a 3-4-fold increase in coronary blood flow secondary to (1) an increase in myocardial oxygen consumption due to an increase in heart rate and contractility and (2) flow-mediated vasodilatation from release of endothelial derived relaxing factor (EDRF = nitric oxide) from normal endothelial cells in response to shear stress from increased flow. In the presence of a hemodynamically significant coronary stenosis, there is a submaximal increase in coronary flow resulting in flow heterogeneity. The radiopharmaceutical is injected at peak exercise and the patient

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