Pediatric Heart Surgeries and Interventions
Single Ventricle Physiology
Single-ventricle congenital heart defects are among the most challenging conditions for pediatric heart surgeons to treat. These conditions are uniformly fatal without surgical palliation, and generally require three open heart surgeries starting in the neonatal period. We use multiscale modeling and optimization to design and test novel surgical approaches. This work exemplifies the need for computational tools that can be used to safely test novel high-risk procedures. Our lab has successfully translated a novel Y-graft design for the Fontan surgery into clinical practice at Lucile Packard Children’s Hospital, Stanford University. We have recently proposed a novel surgical concept called the Assisted Bidirectional Glenn (ABG) that could provide an alternative to current methods for the BT shunt surgery, which has the highest mortality of all three stages of single ventricle repair. Performance of the ABG has been tested and optimized using idealized and patient-specific in silico and in vitro models with promising results. We are currently collaborating with reseearchers at Yale and Nationwide Children's Hospital to assess hemodynamics in tissue engineered vascular grants, which are being implanted in Fontan patients. Our goal is to use computational modeling to predict changes in morphology and improve graft performance.
Funding: NIH NHLBI
Pulmonary hypertension (PH), defined as a mean pulmonary artery pressure >25mmHg, leads to structural changes in the pulmonary arteries, increased right ventricular work, and ultimately cardiac dysfunction. In children, PH is most commonly idiopathic (no known cause) or associated with congenital heart disease, and leads to mortality rates as high as 60-70% within five years. No known cure exists, and treatment options include pharmacological therapies, or in the most severe cases, lung or heart-lung transplantation. Disease progression is highly variable and poorly understood. We are using patient specific modeling to evaluate hemodynamics in pulmonary hypertension, and quantify disease progression over time. Computational modeling is used to quantify mechanical stimuli acting on the vessel walls in proximal and distal vessels using multiscale modeling.
FUNDING: STANFORD Vera Moulton Wall center, NSF Graduate Research fellowship
Tetralogy of Fallot
Tetralogy of Fallot (ToF) is the most common cyanotic congenital heart defect, occurring in approximately 1 out of every 2500 babies born in the US each year. ToF is comprised of four defects: a ventricular septal defect, pulmonary valve stenosis (and outflow obstruction), overriding aorta, and right ventricular hypertrophy. After surgical repair, pulmonary valve regurgitation often leaves patients with highly abnormal hemodynamic and biomechanical conditions in the right ventricle and pulmonary outflow tract. It is currently unknown why some patients suffer from early valve failure and others do not. We are using a combination of experiments and simulation to quantify leaflet performance in pulmonary valve replacement. We create 3D printed models of the right ventricular outflow tract in a physiologic in vitro flow loop, and then use 4DMRI to quantify blood flow patterns. We hypothesize that poor hemodynamic conditions caused by differences in right ventricular outflow tract anatomy lead to early valve dysfunction. The goals of this study are to develop surgical guidelines for valve replacement that will increase valve longevity.
Funding: Stanford Child Health Research Institute