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Abstracts: ASAIO Bioengineering/tissue Engineering Abstracts


Dumont, Kris1; Vierendeels, Jan2; Segers, Patrick1; Van Nooten, Guido3; Verdonck, Pascal1

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In vitro studies on the ATS heart valve have observed that valve opening is less in an expanding conduit compared to opening in a straight conduit. We have studied bileaflet valve behavior using a new computational fluid-structure interaction model. A 3D model of the ATS valve was studied in two geometries, simulating the valve in a geometry with a sudden expansion downstream of the valve and in a straight conduit. Mitral and aortic flow patterns are simulated. The computer model was used to study clinical performance parameters. The ATS valve in the expanding geometry showed opening to a maximum angle of 77.5°. This finding was confirmed by earlier clinical and in vitro studies. The mean and maximum transvalvular pressure gradients are 2.1 mmHg and 4.6 mmHg. The effective orifice area is 2.5 cm2. The maximum shear stress calculated on the leaflet is 25 Pascal. Maximum opening of the valve is achieved in the straight conduit. The mean and maximum pressure gradients are 1.1 mmHg and 4.3 mmHg. The effective orifice area is 2.3 cm2. The maximum shear stress calculated on the leaflet is 35 Pascal. Our numerical study confirms that valve haemodynamics and leaflet motion are dependent on the geometrical conditions of the valve: the presence of a diverging flow influences the maximum opening angle of the valve leaflets. The model can be used to predict pressure gradients, effective orifice area, and shear stress loading of mechanical heart valves. This model will be a major research tool to unravel the haemodynamics of existing and new mechanical heart valves.

Copyright © 2005 by the American Society for Artificial Internal Organs