Maternal hyperoxygenation improves left heart filling in fetuses with atrial septal aneurysm causing impediment to left ventricular inflow

In cases of AAS, short-term maternal hyperoxygenation increases fetal pulmonary venous return, substantially alters LV geometry and promotes antegrade flow in the aortic isthmus. This demonstrates proof-of-concept that maternal hyperoxygenation can improve filling of the left side of the fetal heart in AAS.