We propose to examine circumferential flow-function, relationships using two-dimensional echocardiography (2D echo) and radioactive microsphere techniques in ischemic and infarcted conscious dog models. Although previous studies using unidimensional techniques have examined flow-function relationships in the normal and ischemic myocardium, the mapping of these relationships into a two-dimensional """"""""slice"""""""" model of the heart has not yet been performed. Since most clinical diagnostic imaging modalities now display the heart in two-dimensions, precise mapping of 2D flow-function relationships has important clinical significance in interpreting the results of commonly used cardiac imaging modalities. In the regionally ischemic heart, zones adjacent to the central ischemic area have been noted to be normally perfused, but functionally abnormal; however, the size and hemodynamic properties of this """"""""functional"""""""" border zone are not well understood. In the infarcted heart, regional recovery occurs with variability but flow-function relations during this recovery process are poorly understood. In the reperfused heart, a """"""""no-reflow"""""""" phenomenon may occur with evidence of a """"""""stunned"""""""" myocardium; the interrelationships of perfusion and function in this setting have not been completely evaluated. In the hypertrophied heart, regional ischemia may produce a larger hypoperfused area and extent of dysfunction compared to the nonhypertrophied state; these perfusion and functional abnormalities may bear significantly on the increased mortality in hypertrophic disease. In this proposal, we will examine these issues and specifically: 1) measure the spatial extent of the functional border zone, and study the effect of loading and linotropic interventions, 2) study circumferential flow-function relations during functional recovery following completed infarction, 3) examine the circumferential flow-function profiles early and late following coronary reflow, and 4) evaluate the effect of regional ischemia in the hypertrophied heart. We will accomplish this by producing and analysing circumferential flow-function maps derived from cross-sectional """"""""slice"""""""" data from wall thickening by 2D echo and myocardial blood flow of corresponding regions using radioactive microspheres. Thus, this proposal should have direct clinical relevance to: 1) the sizing of myocardial ischemia and infarction by two-dimensional functional parameters, 2) understanding mechanisms of functional recovery following coronary occlusion and myocardial infarction, 3) interrelationships of flow and function in the reperfused heart, and 4) the effect of myocardial ischemia in the hypertrophied heart.
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