Calculating Wall Shear Stress in Infant Pulmonary Veins

The purpose of this study is to better understand pediatric pulmonary vein stenosis (PVS), which is the narrowing of blood vessels that connect the lungs to the heart. PVS is a life-threatening disease without a clear cause. The investigators think patients who develop PVS have an increased Wall Shear Stress (WSS) level in the pulmonary veins, which is the force placed on the walls of the veins. This study will determine if WSS can be calculated in the pulmonary veins of infants using Ferumoxytol enhanced Cardiac Magnetic Resonance Imaging (FcMRI). If possible, the investigators aim to use FcMRI to better screen patients at risk of PVS and to help guide therapy in patients with PVS.