Project: Research project

Project Details


At the time of an acute coronary artery occlusion, the behavior of
myocardium "remote" from the distribution of the acutely occluded vessel is
critical. This myocardial region must compensate for ischemic dysfunction
in the zone of the occluded vessel. Some experimental animal data have
shown anatomic and biochemical alteration in "remote" myocardium even when
supplied by normal coronary arteries. Clinical studies have shown that
when "remote" myocardium is supplied by stenosed vessels, it may
demonstrate marked asynergy at the time of acute occlusion of another
artery. The aims of the research plan are (1) to assess myocardial
perfusion and wall thickening in "remote" myocardium supplied by a
critically stenosed circumflex artery when the left anterior descending
artery is suddenly occluded; (2) to determine the cause of any alterations
observed in perfusion in or function of "remote" myocardium; (3) to assess
infarct/risk ratio when the left anterior descending is occluded in the
presence of a circumflex stenosis. Regional blood flow will be assessed by
using radiolabeled microspheres, and wall thickening will be determined by
using sonomicrometer crystals. Regional wall thickening and myocardial
perfusion will be assessed during hypotension, during sympathetic
stimulation, and in he setting of enhanced collateral development. These
studies will be performed in anesthetized open-chested dogs. Infarct/risk
ratios will be determined in awake dogs with enhanced collateral
development. The hypothesis to be tested is that "remote" wall thickening
and perfusion do not increase appropriately, or even decrease, in the
setting of an acute left anterior descending occlusion and a critical
circumflex stenosis. We hypothetize that these alterations are related to
hemodynamic factors, the magnitude of collateral development, and to
inappropriately high sympathetic discharge. We also hypothetize that the
size of the infarct/risk ratio will be greater when the left anterior
descending is occluded in the setting of a critical circumflex stenosis.
Many patients who experience acute myocardial infarction have underlying
multivesse disease. The experimental protocols described in this proposal
are intended to give us a better understanding of the pathophysiological
alterations that occur in this setting.
Effective start/end date1/1/8512/31/85


  • National Heart, Lung, and Blood Institute

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