Document Detail


An experimental technique for estimating regional myocardial segment work in vivo.
MedLine Citation:
PMID:  8060027     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We determined the capabilities and limitations of an experimental approach to measure segment work (force x distance) of myocardial regions in the in vivo beating heart. In 18 open-chest anesthetized dogs, segment length was measured using ultrasonic dimension transducers, and developed force was measured with miniature force transducers. Work was defined as the integrated multiples of instantaneous force and shortening during a single (averaged) beat, corresponding to the area under the length-force loop. Changes in work over a range of 9.78 x 10(-4) to 2.93 x 10(-2) J/g/min were produced by vena caval constriction, aortic constriction, atrial pacing, and isoproterenol (0.5 and 1.0 micrograms/kg/min). Work was measured in both major and minor axes. In 60% of the animals, work in the minor axis was 9.2-fold greater than in the major axis. In the others, all interventions changed regional work to the same extent in both axes (r = 0.802; p < 0.05). Work changes were also compared between the base, anterior, and posterior walls. The response was directionally similar in all regions, ranging from -79 +/- 1% during caval occlusion to 278 +/- 98% during isoproterenol. The effective size of the measured muscle mass was limited to the transducer area because the amplitude and pattern of both force development and segment shortening were not changed until deep myocardial cuts were as close as 2 mm from the measuring area. We conclude that work measurement in the minor axis is quantitatively representative of fiber work in that region.
Authors:
J Kedem; W W Lee; H R Weiss
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Annals of biomedical engineering     Volume:  22     ISSN:  0090-6964     ISO Abbreviation:  Ann Biomed Eng     Publication Date:    1994 Jan-Feb
Date Detail:
Created Date:  1994-09-13     Completed Date:  1994-09-13     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0361512     Medline TA:  Ann Biomed Eng     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  58-65     Citation Subset:  IM    
Affiliation:
Department of Physiology and Biophysics, UMDNJ-Robert Wood Johnson Medical School, Piscataway 08854-5635.
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MeSH Terms
Descriptor/Qualifier:
Animals
Artifacts
Blood Pressure / drug effects,  physiology
Dogs
Energy Metabolism*
Female
Heart Rate / drug effects,  physiology
Heart Ventricles / anatomy & histology,  drug effects,  ultrasonography
Isoproterenol / pharmacology
Male
Myocardial Contraction / physiology*
Reproducibility of Results
Transducers
Ventricular Function
Ventricular Function, Left / drug effects,  physiology*
Chemical
Reg. No./Substance:
7683-59-2/Isoproterenol

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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