Acute Maternal Hyperoxygenation for Fetal Transposition of the Great Arteries (TGA)

Transposition of the Great Arteries: Prenatal Anatomical and Hemodynamic Findings Associated With Perinatal Outcomes

This prospective study will examine whether transient maternal hyperoxygenation is useful as a diagnostic test to more accurately detect TGA patients with poor vs. good neonatal intra-cardiac mixing of blood, based on the in-utero response to oxygen exposure.

This is a prospective pilot study to examine whether transient maternal hyperoxygenation is useful as a diagnostic test to more accurately detect TGA patients with poor vs. good neonatal intracardiac mixing of blood, based on the in-utero response to oxygen exposure. Acute maternal oxygen administration will transiently increase the fetal oxygen levels to those reached at birth with spontaneous breathing, thus simulating conditions that will naturally occur at the time of birth. Echocardiogram and MRI will be used to examine the effects on the fetal circulation. The prenatal findings will then be compared to the neonatal presentation. The investigators postulate that conditions that predispose newborns to acute neonatal compromise will be detectable and distinguishable prior to birth by echocardiography, MRI, or by combining the findings of both exams.

10-15 L/min of oxygen by face mask for up to 45 minutes for the MRI and up to 30 minutes for the echocardiogram.

Characterize effects of maternal hyperoxygenation on fetal intracardiac shunting measured using MRI fluximetry (ml/min/m2) of AAo, DA, SVC, IVC, UV, and DA. Ductal shunting measured using echo measurements of atrial septal morphology (2D; 4D) and foramen flow (color; 4D flow) of FO diameter and septal excursion. Ductus arteriosus flow (color and Doppler): minimal diameter, reversed end-diastolic flow, systolic peak flow, forward-reverse flow ratio, flow restriction.

Characterize effects of maternal hyperoxygenation on fetal pulmonary blood flow using MRI fluximetry (ml/min/m2) measures of Main PA, RPA and LPA

As measure of patient morbidity, a composite score of 10 variables will be used, assigning a value of 1 for each event that occurred 1) respiratory distress syndrome requiring surfactant; 2) cardiopulmonary resuscitation requiring chest compressions; 3) cerebral vascular injury (intra-ventricular or -parenchymal hemorrhage, ischemic stroke); 4) necrotizing enterocolitis; 5) need of ECMO; 6) infections associated with health care (bloodstream, surgical site, and urinary tract infection); 7) unplanned re-intubation; 8) re-operation for residual cardiac lesions; 9) interventional catheterization for residual cardiac lesions; and 10) unplanned intensive care readmission.

Effects of maternal hyperoxygenation on fetal cerebral perfusion measured by change in cDO2 (mL/min/m2) and cVO2 (mL/min/m2)

Inclusion Criteria: Fetus with simple TGA +/- small VSD Intention of active postnatal management after birth Exclusion Criteria: Fetus with complex form of TGA Significant fetal arrhythmia Major non-cardiac lesions Maternal contraindications for fetal MRI

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