Stress analysis of aortic valve leaflets with smoothed geometrical data.

Abstract A method of smoothing the geometrical data obtained from photogrammetric processing of silicone rubber molds of human aortic heart valves under pressure is proposed. An estimation of the magnitude and orientation of the maximum stresses which would be encountered in an aortic prosthesis is an important component of the design criteria, especially when the prosthesis is to be a leaflet type, central flow device physically resembling the actual valve. The stress patterns are important for both strength and fatigue design requirements. To this end, it is felt that the best description of the stress distribution can be garnered by studying the actual valve in situ . This is accomplished by performing stress analyses on molds made from freshly excised leaflets. The cited references show increasing refinement and reflect the progressive improvement in the analysis methods of structural mechanics. In this paper, further improvements in the analysis procedure which enhance the reliability and repeatability of the results are described. Based on the smoothed data which is felt to be consistent with thin shell theory, a finite element analysis is conducted. Stress patterns consistent with anatomical observations are obtained and stress levels in excess of those previously reported are found. Also, the stress distribution in individual leaflets of the same valves are investigated and the non-coronary leaflet is found to carry the highest maximum stress.