Document Detail


Efficiency of energy transfer from pressure-volume area to external mechanical work increases with contractile state and decreases with afterload in the left ventricle of the anesthetized closed-chest dog.
MedLine Citation:
PMID:  3359589     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We studied the effects of ventricular end-systolic elastance (Ees) and effective arterial elastance (Ea) on the efficiency of energy transfer from pressure-volume area (PVA) to external mechanical work (EW) in the left ventricle of anesthetized closed-chest dogs. PVA represents the total mechanical energy generated by ventricular contraction, which is an intermediate form of energy between oxygen consumption, the total energy input, and EW, the effective energy output. PVA and EW were determined from ventricular pressure and volume, which were continuously measured with a volumetric conductance catheter. Measurements of Ees were obtained by transiently increasing afterload by an inflation of a Fogarty catheter in the thoracic descending aorta. Ea was determined as the ratio of end-systolic pressure to stroke volume. The EW/PVA efficiency of a steady-state contraction increased from 55% to 64%, with a 58% increase in Ees after dobutamine. Ees, which was smaller than Ea before dobutamine, became nearly equal to Ea after dobutamine, maximizing EW for a given end-diastolic volume. EW/PVA efficiency decreased with an abrupt increase in afterload before and after dobutamine. The sensitivity of the decrease in the EW/PVA efficiency to an increase in end-systolic pressure was significantly less after than before dobutamine. We could account for all these changes in EW/PVA efficiency by the relative changes in Ees and Ea in the pressure-volume diagram.
Authors:
T Nozawa; Y Yasumura; S Futaki; N Tanaka; M Uenishi; H Suga
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Circulation     Volume:  77     ISSN:  0009-7322     ISO Abbreviation:  Circulation     Publication Date:  1988 May 
Date Detail:
Created Date:  1988-06-03     Completed Date:  1988-06-03     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  0147763     Medline TA:  Circulation     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1116-24     Citation Subset:  AIM; IM    
Affiliation:
Department of Cardiovascular Dynamics, National Cardiovascular Center Research Institute, Osaka, Japan.
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MeSH Terms
Descriptor/Qualifier:
Animals
Aorta, Thoracic / drug effects,  physiology
Biomechanics
Blood Pressure* / drug effects
Catheterization, Swan-Ganz
Dobutamine / pharmacology
Dogs
Efficiency / drug effects,  physiology*
Electrocardiography
Energy Transfer / drug effects
Heart Ventricles / drug effects
Myocardial Contraction* / drug effects
Oxygen Consumption / drug effects
Stroke Volume* / drug effects
Systole / drug effects
Vascular Resistance / drug effects
Ventricular Function
Chemical
Reg. No./Substance:
34368-04-2/Dobutamine

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


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