| Effects of afterload on regional left ventricular torsion. | |
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MedLine Citation:
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PMID: 8759247 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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OBJECTIVE: To determine if left ventricular torsion, as measured by magnetic resonance tissue tagging, is afterload dependent in a canine isolated heart model in which neurohumoral responses are absent, and preload is constant. METHODS: In ten isolated, blood perfused, ejecting, canine hearts, three afterloads were studied, while keeping preload constant: low afterload, high afterload (stroke volume reduced by approx. 50% of low afterload), and isovolumic loading (infinite afterload). RESULTS: There were significant effects of afterload on both torsion (P < 0.05) and circumferential shortening (P < 0.0005). Between low and high afterloads, at the anterior region of the endocardium only, where torsion was maximal, there was a significant reduction in torsion (15.1 +/- 2.2 degrees to 7.8 +/- 1.8 degrees, P < 0.05). Between high afterload and isovolumic loading there was no significant change in torsion (7.8 +/- 1.8 degrees to 6.2 +/- 1.5 degrees, P = NS). Circumferential shortening at the anterior endocardium was significantly reduced both between low and high afterload (-0.19 +/- 0.02 to -0.11 +/- 0.02, P < 0.0005), and also between high afterload and isovolumic loading (-0.11 +/- 0.02 to 0.00 +/- 0.02, P < 0.05). Plots of strains with respect to end-systolic volume demonstrated a reduction in both torsion and shortening with afterload-induced increases in end-systolic volume. Torsion, but not circumferential shortening, persisted at isovolumic loading. CONCLUSIONS: Maximal regional torsion of the left ventricle is afterload dependent. The afterload response of torsion appears related to the effects of afterload on end-systolic volume. |
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Authors:
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G A MacGowan; D Burkhoff; W J Rogers; D Salvador; H Azhari; P S Hees; J L Zweier; H R Halperin; C O Siu; J A Lima; J L Weiss; E P Shapiro |
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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: Cardiovascular research Volume: 31 ISSN: 0008-6363 ISO Abbreviation: Cardiovasc. Res. Publication Date: 1996 Jun |
Date Detail:
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Created Date: 1996-10-11 Completed Date: 1996-10-11 Revised Date: 2007-11-15 |
Medline Journal Info:
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Nlm Unique ID: 0077427 Medline TA: Cardiovasc Res Country: NETHERLANDS |
Other Details:
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Languages: eng Pagination: 917-25 Citation Subset: IM |
Affiliation:
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Division of Cardiology, Johns Hopkins University School of Medicine, Baltimore, MD 21224, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Computers Dogs Heart / anatomy & histology, physiology* Heart Ventricles Magnetic Resonance Imaging Models, Cardiovascular Perfusion Stroke Volume / physiology* Torsion Abnormality |
| Grant Support | |
ID/Acronym/Agency:
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R01-HL-38324/HL/NHLBI NIH HHS; R01-HL-43722/HL/NHLBI NIH HHS; R01-HL-46223/HL/NHLBI NIH HHS |
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