Dynamic modelling of a stented aortic valve

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dc.contributor.advisorScheffer, C.en_ZA
dc.contributor.advisorGroenwold, A. A.en_ZA
dc.contributor.authorVan Aswegen, Karlen_ZA
dc.contributor.otherStellenbosch University. Faculty of Engineering. Dept. of Mechanical and Mechatronic Engineering.
dc.date.accessioned2008-11-17T13:20:41Zen_ZA
dc.date.accessioned2010-06-01T08:36:43Z
dc.date.available2008-11-17T13:20:41Zen_ZA
dc.date.available2010-06-01T08:36:43Z
dc.date.issued2008-12en_ZA
dc.descriptionThesis (MScEng (Mechanical and Mechatronic Engineering))--Stellenbosch University, 2008.
dc.description.abstractAortic valve replacements are frequently performed during heart surgery. However, since this is quite a stressful procedure, many patients are turned down for medical reasons. Stented valves, designed and manufactured for percutaneous insertion, eliminate many of the risks involved in open-heart surgery, thus providing a solution to patients not deemed strong enough for open-chest aortic valve replacements. The aortic valve is a complex structure, and therefore numerical simulation is necessary to obtain flow and stress data to support the design of a prosthetic heart valve in the absence of viable physical measuring methods. To aid in the design of a prosthetic heart valve, various finite element valve models were created, and the fluid structure interaction (FSI) between the valves and the blood was simulated using commercial finite element software. The effect of the geometry of the leaflets on the haemodynamic behaviour over the cardiac cycle was investigated. It was found that leaflet dimensions should be chosen judiciously, because of their considerable effect on the stress distribution and performance of the valve. A simple leaflet geometry optimisation was done for a 20 mm and 26 mm valve, respectively, by means of existing geometry relationships found in the literature. Simulations were done to obtain the maximum leaflet attachment forces that can be used by a stent designer for fatigue loading, or to investigate the structural strength of the stent. These simulations were numerically validated. The effect of leaflet thickness and stiffness on resistance to opening, stress distribution and strain were investigated. Results showed that leaflet thickness has a greater effect on the performance of the valve than leaflet stiffness, and thereby validated the results of similar tests contained in the literature. After simulating over-, as well as under-dilation of a stented valve, it was found that problems associated with over-dilation can be minimised to a certain extent by increasing the coaptation1 region of the leaflets. A simple pulse duplicator was designed based on a four-element Windkessel model. The pulse duplicator was used to study the performance of the prototype valves by means of high-speed photography, the results of which were fed into one of the numerical finite element models and compared to real valve performance. Some of the prototype valves showed efficiencies of 88%.en_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/1923
dc.language.isoenen_ZA
dc.publisherStellenbosch : Stellenbosch University
dc.rights.holderStellenbosch University
dc.subjectFluid structure interactionen_ZA
dc.subjectProsthetic heart valve -- Designen_ZA
dc.subjectAortic valveen_ZA
dc.subjectDissertations -- Mechanical engineeringen
dc.subjectTheses -- Mechanical engineeringen
dc.subjectAortic valve -- Stenosisen
dc.subjectHeart valve prosthesisen
dc.subject.otherMechanical and Mechatronic Engineeringen_ZA
dc.titleDynamic modelling of a stented aortic valveen_ZA
dc.typeThesisen_ZA
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