Evaluating the performance of prosthetic heart valves: transvalvular pressure drop vs. vortex ring formation number

Abstract

Heart valve replacement surgery is the second most common heart operation worldwide. This surgery is often the result of congenital disorders, valve malfunctioning, and heart failure. Although prosthetic heart valves have evolved since the first heart valve replacement surgery, prosthetic heart valves still do not come close to the performance of natural and healthy heart valves. A prominent performance metric used by the FDA to evaluate prosthetic heart valves is transvalvular pressure drop. Through in-vitro experimentation, this paper showcases the value of also using vortex ring formation number as a metric of prosthetic heart valve performance because it offers deeper insight into the performance of not only the prosthetic heart valve but the performance of the heart itself. The Vortex Ring Formation Number is an index used to quantify how optimal the vortex ring is in the heart. Vortex rings naturally form when the fluid shear layers shed past the tips of the heart valve leaflets. If the vortex ring formation number is outside of the optimal range, it results in negative effects to the heart. Herein, we evaluate three prosthetic heart valves and compare vortex ring formation numbers across a variety of simulated heart conditions, healthy and diseased. Vortex ring formation number shows great promise in differentiating prosthetic heart valve performance and provides deeper insight into how well the heart is performing. We propose for vortex ring formation number to become a standard performance metric for the Food and Drug Administration approved prosthetic heart valves.