Document Detail


Experimental technique of measuring dynamic fluid shear stress on the aortic surface of the aortic valve leaflet.
MedLine Citation:
PMID:  21744927     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
Aortic valve (AV) calcification is a highly prevalent disease with serious impact on mortality and morbidity. The exact cause and mechanism of the progression of AV calcification is unknown, although mechanical forces have been known to play a role. It is thus important to characterize the mechanical environment of the AV. In the current study, we establish a methodology of measuring shear stresses experienced by the aortic surface of the AV leaflets using an in vitro valve model and adapting the laser Doppler velocimetry (LDV) technique. The valve model was constructed from a fresh porcine aortic valve, which was trimmed and sutured onto a plastic stented ring, and inserted into an idealized three-lobed sinus acrylic chamber. Valve leaflet location was measured by obtaining the location of highest back-scattered LDV laser light intensity. The technique of performing LDV measurements near to biological surfaces as well as the leaflet locating technique was first validated in two phantom flow systems: (1) steady flow within a straight tube with AV leaflet adhered to the wall, and (2) steady flow within the actual valve model. Dynamic shear stresses were then obtained by applying the techniques on the valve model in a physiologic pulsatile flow loop. Results show that aortic surface shear stresses are low during early systole (<5dyn/cm(2)) but elevated to its peak during mid to late systole at about 18-20 dyn/cm(2). Low magnitude shear stress (<5dyn/cm(2)) was observed during early diastole and dissipated to zero over the diastolic duration. Systolic shear stress was observed to elevate only with the formation of sinus vortex flow. The presented technique can also be used on other in vitro valve models such as congenitally geometrically malformed valves, or to investigate effects of hemodynamics on valve shear stress. Shear stress data can be used for further experiments investigating effects of fluid shear stress on valve biology, for conditioning tissue engineered AV, and to validate numerical simulations.
Authors:
Choon Hwai Yap; Neelakantan Saikrishnan; Gowthami Tamilselvan; Ajit P Yoganathan
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of biomechanical engineering     Volume:  133     ISSN:  1528-8951     ISO Abbreviation:  J Biomech Eng     Publication Date:  2011 Jun 
Date Detail:
Created Date:  2011-07-12     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7909584     Medline TA:  J Biomech Eng     Country:  United States    
Other Details:
Languages:  eng     Pagination:  061007     Citation Subset:  IM    
Affiliation:
Wallace H. Coulter School of Biomedical Engineering, Georgia Institute of Technology and Emory University, 315 Ferst Drive, Atlanta, GA 30332.
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