Abstract

The Fontan circulation is a result of the last (third stage) surgical procedure to correct a single ventricle congenital cardiac disorder in children. Although the Fontan circulation has been successfully established in surgeries over the years, it is flawed and can lead in certain cases to pre-mature death. The main cause of this failure is due to increased pulmonary vascular resistance due to loss pulse pressure and blood flow. In healthy circulations, the heart pumps directly to the lungs, where as "Single Ventricle" patients must use a single sided heart to supply blood to the rest of the body before the lungs. Improvements to the Fontan circulation have been proposed, but they require extensive care or external devices. We propose a "Self-Powered" Fontan circulation that will inject energy into the pulmonary system by adding an injection jet shunt (IJS) directly from the heart. The IJS will provide the pulse pressure, blood flow, and entrainment that the pulmonary vascular system needs to function at a healthy level. The difference between a healthy and sick Fontan circulation is 3-5[mmHg] in the IVC. The goal of the IJS is to cause this 3-5[mmHg] pressure drop in the IVC. In the analysis of the Fontan, ascertaining energy losses due to flow jet impingements and flow mixing is critical. Moreover, in order to better understand surgical alternatives is it important to have a robust multi-scale 0D-3D CFD analysis tool that permits investigation of surgical alternatives in a virtual physics-based environment. To this end, a lumped parameter model (LPM) is tightly coupled at the time step level with a full 3D computational fluid dynamics (CFD) model. Using this model scheme, the Fontan test section is no longer being modeled by the LPM. Therefore, it is not limited by the 0D nature of the vascular resistance, capacitance, and inertia bed model. The CFD can take over at the area of interest which accounts for flow directionality and momentum transfer that the LPM is unable to capture. To efficiently calculate optimal IJS configurations, a closed loop steady state model was created to solve a simplified Fontan circulation in 3D. Three models were created with several different optimized configurations, a synthetic model (average dimensions of 2-4 year-old Fontan patients), and two patient-specific models (10 and 24-year-old). The model configurations include changes in the IJS nozzle diameter and IJS placement along the pulmonary artery. These configurations are compared to a baseline model with no IJS. All three models suggest that the IJS helps to decrease IVC pressure while increasing pulse pressure and blood flow to the pulmonary system.

Graduation Date

2017

Semester

Spring

Advisor

Kassab, Alain

Degree

Doctor of Philosophy (Ph.D.)

College

College of Engineering and Computer Science

Department

Mechanical and Aerospace Engineering

Degree Program

Mechanical Engineering

Format

application/pdf

Identifier

CFE0006630

URL

http://purl.fcla.edu/fcla/etd/CFE0006630

Language

English

Release Date

May 2017

Length of Campus-only Access

None

Access Status

Doctoral Dissertation (Open Access)

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