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Thesis
Computational Modeling of a Geometrically Tunable Blood Shunt for Norwood Recipients
Master of Science (M.S.), Drexel University
Sep 2018
DOI:
https://doi.org/10.17918/6kjh-rf26
Abstract
The low availability of suitable heart transplants requires the use of palliative treatments for infants with severe congenital heart defects. Out of every 10,000 live births, 2-4 infants have a severe form of congenital heart defect characterized by a single functional ventricle. In order to survive, these infants require the first of a series of palliative surgeries--the Norwood procedure--within hours or days after birth. The modified Blalock-Taussig shunt (MBTS) is one type of shunt used in the Norwood procedure to redirect blood flow. With this shunt, the single functional ventricle performs the work of two ventricles. The proper growth and development of the infant depends on a delicate balance of blood flow between the body and the lungs, the ratio of which is determined by the size, orientation, and conditions of the shunt. A model of the MBTS in a neonatal aortic arch is developed and evaluated using computational fluid dynamics. Parameters are modified individually to study their effect in steady-state, including multiple shunt geometries and a range of physiological conditions. Additionally, time-variant simulations are conducted to simulate the dynamics over the duration of a heartbeat. In comparison to a model of the healthy anatomy, the MBTS model creates more complex fluid patterns that have higher amounts of shear stress. These factors indicate less overall cardiac efficiency. Variations to the shunt diameter are used to validate the model against well-established concepts. Geometry variations with additional curvature and flaring had more pulmonary flow, which suggested more favorable uniform flow behaviors. Results of the physiological variations connect the significance of low cardiac output with blood oxygenation and poor clinical outcomes. The impact of moderate shunt dysfunction is found to be relatively minor. The inlet behavior of the time-variant simulations corresponds to a neonatal heartbeat, but the results do not mimic realistic fluid behavior over the entire duration because of limitations in the boundary conditions.
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Details
- Title
- Computational Modeling of a Geometrically Tunable Blood Shunt for Norwood Recipients
- Creators
- Ellen Elizabeth Garven - DU
- Contributors
- Amy Throckmorton (Advisor) - Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Master of Science (M.S.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- xix, 120 pages
- Resource Type
- Thesis
- Language
- English
- Academic Unit
- School of Biomedical Engineering, Science, and Health Systems (1997-2026); Drexel University
- Other Identifier
- 9322; 991014632161204721