VIRTUAL DESIGN FOR THE FONTAN PROCEDURE: FROM IDEALIZED TO PATIENT SPECIFIC MODELS USING CFD AND DERIVATIVE-FREE OPTIMIZATION

摘要

Single ventricle congenital heart defects are among the most challenging for pediatric cardiologists to treat. Children bom with these defects are cyanotic, and these conditions are nearly uniformly fatal without treatment. A series of surgeries is performed to palliate single ventricle defects. The first stage consists of aortic reconstruction in a Norwood procedure. In the second stage, the Bidirectional Glenn procedure, the superior vena cava (SVC) is disconnected from the heart and redirected into the pulmonary arteries (PA's). In the third and final stage, the Fontan procedure, the inferior vena cava (IVC) is connected to the PA's via a straight Gore-Tex tube, forming a T-shaped junction with or without offset. Patient specific modeling tools provide a means to evaluate new designs with the goal of lowering long-term morbidity and improving patients' quality of life. Previous studies have shown that the traditional Fontan T-junction design may result in unfavorable hemodynamic performance and energy loss. A new Y-graft design, in which the IVC is connected to the left and right PA's by two branches, has been proposed by two groups using idealized [1] and patient specific models [2]. Initial studies using a patient specific model with rest and exercise flow conditions and respiration, showed that the Y-graft design increases energy efficiency and improves flow distribution to the right and left PA's compared to traditional T-junction designs [2].