Congenital heart defects (CHDs) represent one of the most prevalent categories of neonatal defects, and maternal dietary patterns have been linked to the risk of these conditions. Branched-chain amino acids (BCAAs), particularly leucine, are essential for various metabolic and physiological processes involved in heart development. In this study, we examined the molecular mechanisms through which elevated levels of leucine induce defects in cardiac microvascular endothelial cells.