An In Vitro Investigation of the Flow Fields Through Bileaflet and Polymeric Prosthetic Heart Valves

Leo, Hwa Liang

Title:

An In Vitro Investigation of the Flow Fields Through Bileaflet and Polymeric Prosthetic Heart Valves

dc.contributor.advisor	Yoganathan, Ajit P.
dc.contributor.author	Leo, Hwa Liang	en_US
dc.contributor.committeeMember	Giddens, Don P.
dc.contributor.committeeMember	Hanson, Stephen R.
dc.contributor.committeeMember	Low, Hong Tong
dc.contributor.committeeMember	Oshinski, John
dc.contributor.department	Biomedical Engineering	en_US
dc.date.accessioned	2006-09-01T19:47:32Z
dc.date.available	2006-09-01T19:47:32Z
dc.date.issued	2005-05-05	en_US
dc.description.abstract	Current designs of bileaflet mechanical heart valves (BMHVs) and trileaflet polymeric heart valves(TPHVs) are plagued by unacceptable levels of hemolysis and thrombus formation in critical areas thereby producing mediocre clinical performance. The objective of this study is: (1) to investigate the influence of BMHV designs on hinge flow characteristics, (2) to quantify the influence of hinge gap width tolerance in a BMHV design, and (3) to investigate the influence of TPHV design on flow characteristics. St. Jude Medical (SJM) provided four transparent mitral BMHVs: one 23 mm CarboMedics (CM), one 27 mm SJM Standard and two 27 mm prototype BHMVs with altered hinge gap widths. Aortech Inc. provided three 23 mm aortic prototype TPHVs. Laser Doppler velocimetry and Particle Image velocimetry were used to measure flow velocity inside these valve prostheses. The flows through the valves were maintained within physiological limits. All valves revealed Reynolds shear stress (RSS) levels greater than 200 Pa far exceeding the threshold for platelet activation and hemolysis. MHV hinge flows in the mitral position were characterized by a strong recirculation during ventricular diastole while leakage jets over and adjacent to leaflets were prominent during ventricular systole. CM hinge flow had higher RSS than in the SJM hinge. The large gap width hinge had the largest leakage jet size and highest RSS (>400 Pa) during ventricular diastole. The Standard gap width hinge showed better washout during systole and provided optimum hemodynamic performance than the prototype designs. In aortic prototype PHVs, elevated RSS conducive to hemolysis was observed along the central jet during systole and the leakage jet at the high central region inside the valve during diastole. This study showed that hinge geometry designs and hinge gap width tolerance governed the success of the bileaflet MHV design. Also the performance of the three aortic PHVs is dependent on commissural designs and leaflet thicknesses. Owing to the critical nature flow fields on clinical outcomes studies such as the current study should be conducted in the pre-clinical evaluation phase for all new MHV or PHVs.	en_US
dc.description.degree	Ph.D.	en_US
dc.format.extent	23446906 bytes
dc.format.mimetype	application/pdf
dc.identifier.uri	http://hdl.handle.net/1853/11644
dc.language.iso	en_US
dc.publisher	Georgia Institute of Technology	en_US
dc.subject	High central region	en_US
dc.subject	Hinge
dc.subject	Commissural region
dc.subject	Hemodynamics
dc.subject	Reynolds shear stress
dc.title	An In Vitro Investigation of the Flow Fields Through Bileaflet and Polymeric Prosthetic Heart Valves	en_US
dc.type	Text
dc.type.genre	Dissertation
dspace.entity.type	Publication
local.contributor.advisor	Yoganathan, Ajit P.
local.contributor.corporatename	Wallace H. Coulter Department of Biomedical Engineering
local.contributor.corporatename	College of Engineering
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