Document Detail

Theoretical maximal flow of the left ventricle is sensitive to change in ventricular afterload.
MedLine Citation:
PMID:  9778446     Owner:  NLM     Status:  MEDLINE    
Systolic mechanical behavior of the ventricular pump can be quantified by both maximal systolic elastance and theoretical maximal flow. How sensitive these two model parameters are to changes in loading conditions has never been examined, however. The aim of the study is to determine the roles of these two parameters in the perturbation of ventricular loads. The loading conditions are altered by the use of methoxamine, a specific alpha1-selective adrenergic agonist. Left ventricular pressure and ascending aortic flow waves in male Fischer 344 rats are measured by a high-fidelity pressure sensor and electromagnetic flow probe, respectively. Isovolumetric pressure of the left ventricle is estimated from the instantaneous pressure of an ejecting contraction by a curve-fitting technique. The two parameters that characterize systolic pumping mechanics of the left ventricle are inferred by making use of an elastance-resistance model. Results in this study show that the theoretical maximum flow, the amount of outflow generated by the ventricle if it were to eject under zero load condition, is sensitive to change in ventricular afterload. On the contrary, the maximal systolic elastance is independent of loading conditions in a given constant contractile state of the ventricle. It is believed that afterload-dependent behavior of the theoretical maximal flow is the major factor responsible for the poor predictive performance of the elastance-resistance model.
K C Chang
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Journal of theoretical biology     Volume:  194     ISSN:  0022-5193     ISO Abbreviation:  J. Theor. Biol.     Publication Date:  1998 Oct 
Date Detail:
Created Date:  1998-11-20     Completed Date:  1998-11-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0376342     Medline TA:  J Theor Biol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  409-17     Citation Subset:  IM; S    
Copyright Information:
Copyright 1998 Academic Press
Department of Physiology, College of Medicine, National Taiwan University, Taipei, Taiwan.
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MeSH Terms
Adrenergic alpha-Agonists / pharmacology
Methoxamine / pharmacology
Models, Cardiovascular*
Rats, Inbred F344
Ventricular Function, Left / drug effects,  physiology*
Ventricular Pressure* / drug effects
Reg. No./Substance:
0/Adrenergic alpha-Agonists; 390-28-3/Methoxamine

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

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