STTR Phase I: Hemodynamic Effects Inform Design of an External Stent to Reduce Dialysis Access Failures

The broader impact/commercial potential of this Small Business Technology Transfer (STTR) project is to develop an external stent that can improve the quality and length of life for dialysis patients. Dialysis is the primary lifeline for End-Stage Renal Disease patients. Unfortunately, our current standard of care, which provides no additional support or treatment to the artery-vein connections surgically created in the arm to initiate dialysis (i.e. access sites), results in 40-60% failure rates within the first year. Consequences of these failures are dire: significant pain, suffering, and death for dialysis patients, hospital readmission penalties, and more than $1B in direct costs to Medicare. An external stent that wraps around the vein-artery/-graft junction of dialysis patients at the time of access site creation surgery has been developed to reduce these failures in a preventative fashion. In order to maximize the impact that it can have on the lives of dialysis patients by providing favorable flow conditions (i.e. hemodynamics) through the access site, it is imperative to first optimize device design on the bench with the aid of computational modeling. Findings from this grant will further scientific understanding of external supports and the role that hemodynamics play in access site failures. This STTR Phase I project proposes to create a computational fluid dynamic (CFD) model that successfully predicts flow and deformation conditions at the access site in the presence or absence of an external stent, and to use this model to identify external stent design parameters that promote the most favorable hemodynamic environment for preventing access site failures. First, a 3D printing method of manufacture will be optimized to enable the fabrication of external stents in a highly-repeatable manner conducive to large-scale, FDA-compliant production. A CFD model will be created from empirical results in which surgically-constructed anastomoses (e.g. vein-graft junctions) are exposed to arteriovenous-mimetic pressure and flow conditions in the absence or presence of external stent designs. Empirical ex vivo data to validate the CFD model simulation results will be collected from quantitative measurements of dynamic deformation (e.g. magnitude of expansion) and flow patterns (i.e. velocity fields) in the presence or absence of various external stent designs via 4D flow MRI, which provides spatial and temporal information on 3D flow over the entire anastomosis. This work should result in the identification of a few designs that assert hemodynamic effects conducive to reducing neointimal hyperplasia, the primary culprit of access site failures. 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.