Document Detail

Near valve flows and potential blood damage during closure of a bileaflet mechanical heart valve.
MedLine Citation:
PMID:  22010753     Owner:  NLM     Status:  In-Data-Review    
Blood damage and thrombosis are major complications that are commonly seen in patients with implanted mechanical heart valves. For this in vitro study, we isolated the closing phase of a bileaflet mechanical heart valve to study near valve fluid velocities and stresses. By manipulating the valve housing, we gained optical access to a previously inaccessible region of the flow. Laser Doppler velocimetry and particle image velocimetry were used to characterize the flow regime and help to identify the key design characteristics responsible for high shear and rotational flow. Impact of the closing mechanical leaflet with its rigid housing produced the highest fluid stresses observed during the cardiac cycle. Mean velocities as high as 2.4 m/s were observed at the initial valve impact. The velocities measured at the leaflet tip resulted in sustained shear rates in the range of 1500-3500 s(-1), with peak values on the order of 11,000-23,000 s(-1). Using velocity maps, we identified regurgitation zones near the valve tip and through the central orifice of the valve. Entrained flow from the transvalvular jets and flow shed off the leaflet tip during closure combined to generate a dominant vortex posterior to both leaflets after each valve closing cycle. The strength of the peripheral vortex peaked within 2 ms of the initial impact of the leaflet with the housing and rapidly dissipated thereafter, whereas the vortex near the central orifice continued to grow during the rebound phase of the valve. Rebound of the leaflets played a secondary role in sustaining closure-induced vortices.
L H Herbertson; S Deutsch; K B Manning
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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 Sep 
Date Detail:
Created Date:  2011-10-20     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7909584     Medline TA:  J Biomech Eng     Country:  United States    
Other Details:
Languages:  eng     Pagination:  094507     Citation Subset:  IM    
Bioengineering Department, The Pennsylvania State University, University Park, PA 16802.
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