A novel flow performance metric for the assessment of prosthetic heart valves

Despite new prosthetic heart valves entering the market, prosthetic heart valves still do not come close to mimicking our natural heart valves. As important as it is to design new prosthetic heart valves, just as important is the need for appropriate performance metrics to evaluate prosthetic heart valves. This paper is focused on addressing this concern by proposing a novel metric of prosthetic heart valve performance and showing evidence that supports this claim. More specifically, existing flow performance metrics for prosthetic heart valves currently used by the Food and Drug Administration are based on basic flow characteristics which do not take into account the flow novelties exhibited by varying prosthetic heart valve designs. A more sophisticated flow performance metric, based on characterizing vortex ring formation in the heart and past prosthetic heart valves, is investigated herein to gain insight into the usefulness of the Vortex Ring Formation Number. Vortex Ring Formation Number is derived from understanding vortex ring formation, which is an important mechanism for fluid transport during ventricular filling. To the best of our knowledge, this is the first study to investigate Vortex Ring Formation Number across a variety of cardiac operating conditions. Our in-vitro results show that vortex ring formation can differentiate the performance of prosthetic heart valve designs. The implications are: improving prosthetic heart valve performance metrics, enabling surgeons to guide patients in selecting the most appropriate prosthetic heart valve to implant, and aiding engineers/scientists who continuously seek to improve prosthetic heart valve designs.