| Alterations in transmural strains adjacent to ischemic myocardium during acute midcircumflex occlusion. | |
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MedLine Citation:
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PMID: 15821645 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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OBJECTIVE: Helically oriented left ventricular fibers assemble into transmural sheets, which are important for wall-thickening mechanics: 15% fiber shortening results in 40% cross-fiber left ventricular wall thickening and a 60% ejection fraction through sheet extension, thickening, and shear. Normal cardiac microstructure and strains are optimized; deviations could result in apoptosis and deleterious matrix remodeling, which degenerates into global cardiomyopathy. We studied alterations in transmural strains adjacent to ischemic myocardium during acute midcircumflex occlusion. METHODS: Nine sheep had radiopaque markers implanted to measure left ventricular systolic fractional area shortening; 3 transmural bead columns were inserted into the midlateral wall for strain analysis. Three-dimensional marker coordinates were obtained with biplane videofluoroscopy before and during 70 seconds of ischemia. Systolic strains were quantified along circumferential, longitudinal, and radial axes (n = 9) and were transformed into fiber-sheet coordinates by using quantitative microstructural measurements (n = 5). RESULTS: A functional border was defined in the midlateral left ventricle; ischemia decreased posterolateral fractional area shortening, and anterolateral fractional area shortening increased. In this demarcation junction, subepicardial end-systolic radial wall thickening decreased (0.16 +/- 0.08 vs 0.11 +/- 0.06) and sheet-normal shear was abolished (0.08 +/- 0.04 vs -0.01 +/- 0.03). Longitudinal shortening decreased in the subepicardium and midwall (-0.05 +/- 0.04 vs +/- -0.01 +/- 0.06), but circumferential-radial shear increased at these depths (0.04 +/- 0.04 vs 0.11 +/- 0.05). Subendocardial fiber stretch occurred during early systole (-0.01 +/- 0.03 vs 0.02 +/- 0.03), and end-systolic fiber-sheet shear increased (0.07 +/- 0.01 vs 0.11 +/- 0.04, all P < .05). CONCLUSIONS: Increased circumferential-radial shear and altered fiber-sheet strains reflect mechanical interactions between ischemic and nonischemic myocardium, which might be important in triggering remodeling processes that evolve into global ischemic cardiomyopathy. |
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Authors:
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Filiberto Rodriguez; Frank Langer; Katherine B Harrington; Allen Cheng; George T Daughters; John C Criscione; Neil B Ingels; D Craig Miller |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The Journal of thoracic and cardiovascular surgery Volume: 129 ISSN: 0022-5223 ISO Abbreviation: J. Thorac. Cardiovasc. Surg. Publication Date: 2005 Apr |
Date Detail:
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Created Date: 2005-04-11 Completed Date: 2005-05-19 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 0376343 Medline TA: J Thorac Cardiovasc Surg Country: United States |
Other Details:
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Languages: eng Pagination: 791-803 Citation Subset: AIM; IM |
Affiliation:
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Department of Cardiothoracic Surgery, Stanford University School of Medcine, Stanford, CA 94305-5247, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Biomechanics Cineradiography Endocardium / physiopathology Heart Ventricles / physiopathology* Imaging, Three-Dimensional Models, Cardiovascular Myocardial Contraction / physiology Myocardial Ischemia / physiopathology* Myocardium / cytology Myofibrils / physiology Pericardium / physiopathology Sheep Stress, Mechanical Systole / physiology Ventricular Function, Left / physiology Ventricular Pressure / physiology |
| Grant Support | |
ID/Acronym/Agency:
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HL-29589/HL/NHLBI NIH HHS; HL-67025/HL/NHLBI NIH HHS; HL67025-01S1/HL/NHLBI NIH HHS |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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