| Mechanisms of improving regional and global ventricular function by preload alterations during acute ischemia in the canine left ventricle. | |
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MedLine Citation:
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PMID: 4042300 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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We examined the influence of left ventricular end-diastolic pressure (LVEDP) on the mechanical interaction between ischemic and nonischemic areas during acute myocardial ischemia. Circumferentially oriented ultrasonic segment gauges were implanted in the midwall of the anterior apex and posterior apex of the left ventricle in seven anesthetized dogs. Stroke volume was measured with a flow probe around the ascending aorta in five of these animals. We varied LVEDP with vena caval occlusion and dextran infusions to three matched levels (7, 12, and 19 mm Hg) before and 30 min after complete occlusion of the mid left anterior descending coronary artery. With acute ischemia, the anterior apex or ischemic zone demonstrated marked segmental lengthening during isovolumetric systole (end-diastole to aortic valve opening) and akinesis during the ejection phase (aortic valve opening to closure). In the posterior apex or nonischemic area, isovolumetric shortening increased and ejection phase shortening decreased during acute ischemia when compared with those under control conditions at the same LVEDP. Thus, a portion of the shortening generated by the nonischemic area was expended in stretching the ischemic zone during isovolumetric systole, thereby reducing the amount of ejection phase shortening. As LVEDP was increased, there was a parallel decrease in both the amount of isovolumetric lengthening in the ischemic zone and the isovolumetric shortening in the nonischemic area. As a result, acute ischemia produced less of a reduction in ejection phase shortening in the nonischemic area and in stroke volume at high as compared with low LVEDP. We conclude that the ischemic zone imposes a mechanical disadvantage on the nonischemic area, the magnitude of which is directly proportional to the amount of isovolumetric lengthening or bulge in the ischemic zone. An increase in LVEDP during acute ischemia improves regional and global ventricular function by both the Frank-Starling mechanism in the nonischemic (but not the ischemic) area and by reducing the mechanical disadvantage that the ischemic zone imposes on the nonischemic area. |
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Authors:
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W Y Lew; E Ban-Hayashi |
Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Circulation Volume: 72 ISSN: 0009-7322 ISO Abbreviation: Circulation Publication Date: 1985 Nov |
Date Detail:
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Created Date: 1985-11-21 Completed Date: 1985-11-21 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0147763 Medline TA: Circulation Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 1125-34 Citation Subset: AIM; IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Coronary Disease / physiopathology* Diastole Dogs Female Heart Ventricles / physiopathology* Male Pressure |
| Grant Support | |
ID/Acronym/Agency:
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HL-28644/HL/NHLBI NIH HHS |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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