Document Detail


The congenital bicuspid aortic valve can experience high-frequency unsteady shear stresses on its leaflet surface.
MedLine Citation:
PMID:  22821994     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The bicuspid aortic valve (BAV) is a common congenital malformation of the aortic valve (AV) affecting 1% to 2% of the population. The BAV is predisposed to early degenerative calcification of valve leaflets, and BAV patients constitute 50% of AV stenosis patients. Although evidence shows that genetic defects can play a role in calcification of the BAV leaflets, we hypothesize that drastic changes in the mechanical environment of the BAV elicit pathological responses from the valve and might be concurrently responsible for early calcification. An in vitro model of the BAV was constructed by surgically manipulating a native trileaflet porcine AV. The BAV valve model and a trileaflet AV (TAV) model were tested in an in vitro pulsatile flow loop mimicking physiological hemodynamics. Laser Doppler velocimetry was used to make measurements of fluid shear stresses on the leaflet of the valve models using previously established methodologies. Furthermore, particle image velocimetry was used to visualize the flow fields downstream of the valves and in the sinuses. In the BAV model, flow near the leaflets and fluid shear stresses on the leaflets were much more unsteady than for the TAV model, most likely due to the moderate stenosis in the BAV and the skewed forward flow jet that collided with the aorta wall. This additional unsteadiness occurred during mid- to late-systole and was composed of cycle-to-cycle magnitude variability as well as high-frequency fluctuations about the mean shear stress. It has been demonstrated that the BAV geometry can lead to unsteady shear stresses under physiological flow and pressure conditions. Such altered shear stresses could play a role in accelerated calcification in BAVs.
Authors:
Choon Hwai Yap; Neelakantan Saikrishnan; Gowthami Tamilselvan; Nikolai Vasilyev; Ajit P Yoganathan
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Publication Detail:
Type:  Comparative Study; In Vitro; Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2012-07-20
Journal Detail:
Title:  American journal of physiology. Heart and circulatory physiology     Volume:  303     ISSN:  1522-1539     ISO Abbreviation:  Am. J. Physiol. Heart Circ. Physiol.     Publication Date:  2012 Sep 
Date Detail:
Created Date:  2012-09-17     Completed Date:  2012-11-23     Revised Date:  2013-09-17    
Medline Journal Info:
Nlm Unique ID:  100901228     Medline TA:  Am J Physiol Heart Circ Physiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  H721-31     Citation Subset:  IM    
Affiliation:
Wallace H. Coulter School of Biomedical Engineering, Georgia Institute of Technology, Atlanta, USA.
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MeSH Terms
Descriptor/Qualifier:
Animals
Aortic Valve / abnormalities*,  physiopathology*
Biomechanics
Blood Pressure
Calcinosis / etiology*,  genetics,  physiopathology
Genetic Predisposition to Disease
Heart Defects, Congenital / genetics,  physiopathology*
Hemodynamics*
Laser-Doppler Flowmetry
Models, Cardiovascular
Pulsatile Flow
Risk Factors
Stress, Mechanical
Swine
Time Factors
Grant Support
ID/Acronym/Agency:
HL-070262/HL/NHLBI NIH HHS
Comments/Corrections

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