Clinical Utility of Acute Maternal Hyperoxygenation Testing for Fetal D-Transposition of the Great Arteries.

Acute maternal hyperoxygenation (MH) testing may be useful to predict need for balloon atrial septostomy (BAS) in fetal d-transposition of the great arteries/intact ventricular septum (d-TGA/IVS). We present our d-TGA/IVS MH experience. MH was performed in late third trimester with O2 at 8 L/min via a non-rebreather mask for 10 min followed by evaluation of septum primum position, patent foramen ovale (PFO) dimension, and pulmonary vasoreactivity (PVr). Mean gestational age of 18 d-TGA/IVS fetuses at MH and birth were 35.9 and 39 weeks respectively. Nine newborns underwent BAS. During MH, in BAS group, septum primum phasically centralized but stayed leftwards of the septum secundum in 8/9 fetuses. Atrial septum was assessed in 8/9 fetuses in the no BAS group. In all 8, septum primum was bidirectional phasically crossing rightwards of the septum secundum. Mean MH sagittal PFO dimension between BAS and no BAS groups were 2.5 ± 0.6 and 4.7 ± 0.9 mm respectively (p < 0.001). PVr was noted in 15/16 fetuses with available data. Interobserver reliability for septum primum position showed 100% agreement. d-TGA/IVS fetuses commonly demonstrate PVr with MH. Smaller PFO dimension and septum primum not crossing rightwards of the septum secundum despite PVr predicted need for BAS. Larger prospective studies are needed to validate these findings.