ERI: Fluid dynamics of non-Newtonian blood substitutes in heart valve

Michigan Technological University, Houghton MI

Investigators

Abstract

The implantation of an artificial heart valve alters the blood flow in the heart, which makes flow assessment post-implant of utmost importance. To understand outcomes after aortic valve replacement procedures, especially related to clot formation, experimental protocols to emulate cardiovascular performance and operation have been established. Because of the challenges associated with performing laboratory experiments with whole human blood, blood substitutes are generally used. The majority of blood substitutes are Newtonian mixtures, whereas blood is non-Newtonian. A non-Newtonian fluid is a fluid that is characterized by a viscosity that varies with shear rate. This effect becomes important in areas that are subjected to flow stagnation and therefore thrombosis, which current experiments do not fully consider. Therefore, the aim of this project is to understand the impact of non-Newtonian behavior on the surrounding flow dynamic environment. The project will also encompass significant educational activities, including undergraduate involvement and an outreach program for students in local communities. The goal of this project is to find an adequate blood substitute with non-Newtonian properties to accurately model blood’s interactions with the surrounding aortic root anatomy, mainly the sinus and neo-sinus, under various physiological conditions in benchtop flow testing chambers. Then, experiments to characterize the resulting flow properties in the aortic root will be performed using high-fidelity imaging tools consisting of particle image velocimetry. The influence of non-Newtonian rheology on flow stagnation assessment under pulsatile physiological conditions, such as cardiovascular applications, is an underexplored territory. We aim to address that using two specific aims: (i) preparing and developing a non-Newtonian blood analog solution and testing its rheological properties and (ii) assessing the effects of non-Newtonian properties on flow stasis under pulsatile conditions after valve implantation. The research described in this proposal is novel in that, the sinus and neo-sinus flows after valve replacement will be experimentally evaluated using non-Newtonian blood analogs and a comparison between resulting flow stasis properties such as velocity, shear stress, and washout that are associated with thrombosis in Newtonian versus non-Newtonian fluids will be established. The project would contribute to further the understanding of hemostasis-related thrombosis, a scientific area that is constantly growing. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.