Browsing by Subject "pulmonary valve"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Computational construction and simulation of novel heart valve and vein valve designs(2023-04) Li, JirongAs a heart valve substitute with growth potential and improved durability, tissue-engineered heart valves can prevent reinterventions that are currently often needed in children with congenital heart defects. Our group successfully made a pediatric tri-tube/tri-leaflet valved conduit which has shown growth capability in growing lambs. However, the optimal design for valve performance is unknown. To obtain optimal values of valve geometry parameters which can provide efficient guidance for animal tests to save costs and time, we utilized computer-aided simulations to evaluate multiple valve designs. We performed both the valve construction process and this optimization in silico. This is a complex optimization problem due to multiple components of the objective function for valve performance. We thus applied a multi-objective genetic algorithm, which is an elitist strategy, a parameter-free, simple, yet efficient, constraint-handling method used in many applications. A robust finite element method (FEM)-based algorithm for in silico construction of the valve was developed to facilitate optimization for the case of valve closure, identifying the optimal leaflet height and tube diameter that minimizes peak diastolic stress and maximizes coaptation. A strain energy constitutive equation for our novel material, an aligned tissue grown in the lab, was developed based on biaxial testing and implemented in the FEM model. Fluid-structure interaction (FSI) simulation of the optimal design under steady flow was also conducted as a prelude to a next-stage optimization that includes valve dynamic performance metrics. The same methods for the heart valve were also applied to the computational construction and simulation of a stented bileaflet venous valve that includes a sinus design. Steady FSI simulations were used to investigate the effects of the sinus geometry and non-Newtonian blood rheology on the hemodynamics of the novel transcatheter venous valve.Item Development of a Tubular Biological Tissue-Engineered Heart Valve with Growth Potential(2016-05) Reimer, JayThis thesis investigates tissue-engineered cardiovascular devices for pediatric patients and their function and growth potential in preclinical testing. Specifically, engineered tissue tubes were fabricated by entrapping dermal fibroblasts in a fibrin gel and allowing them to replace it with circumferentially-aligned extracellular matrix. Following in vitro culture, the engineered tubes possessed physiological strength and were decellularized to increase their shelf-life and reduce their immunogenicity. An allogeneic tubular heart valve was fabricated by inserting one engineered tube inside of another and attaching them together using degradable sutures. Extensive hemodynamic testing was performed in order to optimize and verify valve design. The growth potential and in vivo function of a single engineered tube (as a pulmonary artery replacement) and pulmonary heart valve were evaluated in a growing lamb model. We observed extensive host cell invasion and growth of the valve root/single tube, but to a lesser degree in the leaflets, which resulted in diminished valve function. A modified animal model is proposed and proof-of-concept studies were performed in order to address this shortcoming.