Document Detail


Physiological and pathophysiological implications of ventricular/vascular coupling.
MedLine Citation:
PMID:  6439084     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The purpose of this paper is to consider "ideal" ventricular/vascular coupling, and how this may be manifest in the time domain and in the frequency domain. The paper will also consider how such "ideal" coupling is achieved, and how it might be disturbed. The arterial system plays a crucial role in ventricular/vascular coupling since it separates the smallest vessels where flow is almost perfectly continuous from the ventricle, whose output is intermittent. Ventricular/vascular coupling can be assessed from measurements of pressure and flow in the ascending aorta (AA) (for left ventricle/systemic circulation), and in the main, pulmonary artery (MPA) (for right ventricle/pulmonary circulation). Ideal coupling is manifest as low pressure fluctuation in AA and MPA. Low pressure fluctuation results in pressure during systole being only slightly greater than pressure throughout the whole cardiac cycle, and pressure during diastole being only slightly less. This is desirable because pressure during systole determines ventricular output (when inotropic state and ventricular filling are constant), and ventricular metabolic requirement, while pressure during diastole in AA is a major determinant of coronary blood flow. In the frequency domain, "ideal" coupling is manifest as a correspondence between minimal values of impedance modulus in AA and MPA with maximal values of flow harmonics in AA and MPA, respectively. Factors responsible for "ideal" coupling have been identified as high distensibility of proximal arteries (with decreasing distensibility in peripheral arteries), wave reflection at arterial terminations, and a "match" between heart rate on the one hand and arterial length and wave velocity on the other. This favourable "match" results in the heart operating for both systemic and pulmonary circulations close to a node of pressure and antinode of flow; this match is improved under conditions which simulate flight and fight. While ventricular/vascular coupling appears to be close to ideal in most large mammals, it appears to be less than ideal in adult humans and some small mammals including guinea pigs, rats, and mice. The cause for mismatch in small mammals is unclear. In humans however, findings are attributable to progressive arterial degeneration which is known to commence in childhood and is apparent in the elderly as dilated tortuous arteries, high pulse pressure, and high likelihood of developing ventricular failure.
Authors:
M F O'Rourke; T Yaginuma; A P Avolio
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Annals of biomedical engineering     Volume:  12     ISSN:  0090-6964     ISO Abbreviation:  Ann Biomed Eng     Publication Date:  1984  
Date Detail:
Created Date:  1985-01-22     Completed Date:  1985-01-22     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:  119-34     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Aorta / physiology
Arteries / physiology
Biomedical Engineering
Blood Circulation* / drug effects
Coronary Circulation
Heart / physiology
Heart Ventricles / drug effects
Humans
Models, Biological
Nitroglycerin / pharmacology
Vascular Resistance
Ventricular Function*
Chemical
Reg. No./Substance:
55-63-0/Nitroglycerin

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


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