The Effect of Bileaflet Prosthetic Heart Valve Orifice Area on Differences in Distal Flow Characteristics

Abstract

Abstract One objective in the design of a mechanical prosthetic heart valve is to maximize the orifice area of the valve. Increasing this parameter decreases the resistance to flow imposed by the valve, minimizing the valvular workload on the heart. Changes in valve design which increase the orifice area may also alter the local flow field, which influences the likelihood of thrombosis related events. Stagnation zones near prosthetic heart valves have been correlated with thrombus deposition (Yoganathan et al, 1979). Blood platelets exposed to turbulent shear stresses above 300 dynes/cm2 for over 100 ms become activated, and can initiate thrombus formation (Wurzinger et al, 1985). The purpose of this work was to study the differences in the flow fields just distal to bileaflet valves of different orifice areas, while concentrating on areas of high turbulent shear stress and flow stagnation.