Date of Award

Fall 2009

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biomedical Engineering

First Advisor

LaDisa, John F.

Second Advisor

Olson, Lars

Third Advisor

Cava, Joseph

Abstract

Coarctation of the aorta (CoA) is a major congenital heart disease, characterized by a severe stenosis of the proximal descending thoracic aorta. Traditionally, surgery has been the treatment of choice for CoA. Dacron patch aortoplasty gained increased popularity after its introduction in the mid-twentieth century due to its advantages over other surgical treatment methods available at the time. A major complication with Dacron patch aortoplasty has been the formation of late aneurysm with as much as 51% incidence reported in follow up studies. The change in aortic morphology and formation of aneurysms after Dacron patch surgery could lead to local adverse changes in hemodynamic conditions which have been correlated to long term morbidity. No study to date has investigated the local hemodynamics in the human thoracic aorta and the alterations occurring in thoracic aorta of Dacron patients in detail. Computational fluid dynamics (CFD) can be used to elucidate local hemodynamics in the thoracic aorta of Normal subjects and surgically treated CoA patients. We tested the hypothesis that Dacron patch aortoplasty causes alterations in vessel wall geometry and hemodynamic indices in the thoracic aorta of CoA patients.

Patient specific CFD models were constructed for six Normal, and six age and gender matched Dacron patients. CFD simulations were performed with physiologic boundary conditions to quantify hemodynamic indices. Localized quantification of simulation results for time-averaged wall shear stress (TAWSS) and oscillatory shear index (OSI) was conducted to obtain axial and circumferential plots at various spatial locations in the thoracic aorta.

Velocity streamlines and vectors quantified from simulation results for Normal subjects were similar to the flow patterns demonstrated previously using medical imaging techniques. Spatial representations of instantaneous and time-averaged WSS as well as OSI were reflective of these velocity results. Alterations in patterns of velocity streamlines, vectors, TAWSS and OSI were observed for Dacron patients with respect to Normal subjects. Altered axial and circumferential patterns of TAWSS and OSI were also demonstrated for Dacron patients by localized quantification. These results may ultimately facilitate greater understanding if sites of long-term morbidity in Dacron patients correspond with these hemodynamic alterations during follow-up.