Currently, few applications of computational hemodynamics predict outcomes after palliative surgery for congenital heart defects such as hypolastic left heart syndrome in infants. Here, we report on three-dimensional imaging methods for modeling recoarctation that commonly occurs in the distal aortic arch following the Norwood procedure. We used computer-aided design to simulate seven stages of increasing stenosis, analyze the resulting hemodynamics, and visualize the impairment of blood flow. A disproportionate drop in pressure occurred when stenosis reached 20% of the cross-sectional area of the descending aorta. The corresponding decrease in blood flow in the descending aorta was relatively small, however. Accordingly our findings suggest a reasonable approach to this phenomenon is watchful waiting rather than immediate surgical intervention. Such patient-specific predictions appear to be valuable for minimizing the risks of corrective surgery. These methods also may be applied to procedures for alleviating other congenital heart defects.