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Significance of subendocardial S-T segment elevation caused by coronary stenosis in the dog. Epicardial S-T segment depression, local ischemia and subsequent necrosis.

Authors
  • Guyton, R A
  • McClenathan, J H
  • Newman, G E
  • Michaelis, L L
Type
Published Article
Journal
The American Journal of Cardiology
Publisher
Elsevier
Publication Date
Sep 01, 1977
Volume
40
Issue
3
Pages
373–380
Identifiers
PMID: 900035
Source
Medline
License
Unknown

Abstract

A model of partial thickness ischemia has been developed using subendocardial S-T elevation without epicardial S-T elevation to detect partial thickness ischemia which is sufficient to cause subsequent necrosis. Subendocardial blood flow in this model (measured with radioactive microsphere techniques) may be reduced to 25 percent of normal (P less than 0.001) by coronary stenosis and tachycardia while subepicardial flow remains normal. Epicardial S-T depression seems to indicate reciprocally subendocardial S-T elevation as long as a layer of nonischemic epicardial muscle is present, but when ischemia becomes transmural, epicardial S-T elevation occurs. Regional pressure-flow relations were determined as distal coronary pressure was reduced at a constant aortic pressure, heart rate and cardiac output. These relations revealed remarkably effective autoregulation of epicardial blood flow concomitant with progressive subendocardial ischemia.

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