Document Detail


Tube collapse and valve closure in ambulatory venous pressure regulation: studies with a mechanical model.
MedLine Citation:
PMID:  9497206     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
PURPOSE: To determine the role of valve closure and column segmentation in ambulatory venous pressure regulation. METHODS: Using a mechanical model consisting of a graduated adjustable valve and a collapsible tube, we studied the differential effects of valve closure and tube collapse on venous pressure regulation. By utilizing materials with differing wall properties for the infravalvular tube, the influence of wall property changes on tube function and pressure regulation was explored. RESULTS: Valve closure, per se, does not cause venous pressure reduction. Collapse of the tube below the valve is the primary pressure regulatory mechanism. The nonlinear volume-pressure relationship that exists in infravalvular tubes confers significant buffering properties to the collapsible tube, which tends to retain a near-constant pressure for a wide range of ejection fractions, residual tube volumes, and valve leaks. Changes in tube wall property affect this buffering action, at both the low and high ends of the physiological venous pressure range. CONCLUSIONS: The valve and the infravalvular venous segment should be considered together in venous pressure regulation. Tube collapse of the segment below the valve is the primary pressure regulatory mechanism. An understanding of the hydrodynamic principles involved in pressure regulation derived from this model will provide the basis for construction of more complex models to explore clinical physiology and dysfunction.
Authors:
S Raju; A B Green; R K Fredericks; P N Neglen; C A Hudson; K Koenig
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of endovascular surgery : the official journal of the International Society for Endovascular Surgery     Volume:  5     ISSN:  1074-6218     ISO Abbreviation:  J Endovasc Surg     Publication Date:  1998 Feb 
Date Detail:
Created Date:  1998-04-23     Completed Date:  1998-04-23     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  9500580     Medline TA:  J Endovasc Surg     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  42-51     Citation Subset:  IM    
Affiliation:
Department of Surgery, the University of Mississippi Medical Center, Jackson, USA.
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MeSH Terms
Descriptor/Qualifier:
Biomechanics
Blood Pressure / physiology*
Blood Vessels / physiology*
Humans
Models, Biological*
Polytetrafluoroethylene
Chemical
Reg. No./Substance:
9002-84-0/Polytetrafluoroethylene

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


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