1 Ward Family Heart Center, Children's Mercy Kansas City, Kansas City, MO, USA.
2 Prenatal Cardiology Program, Children's National Hospital, George Washington University School of Medicine, Washington, DC, USA.
3 The Fetal Heart Program at the Cardiac Center at the Children's Hospital of Philadelphia, Philadelphia, PA, USA.
4 Division of Pediatric Cardiology, Department of Pediatrics, University of California San Francisco, San Francisco, CA, USA.
5 Division of Pediatric Cardiology, Ann and Robert H Lurie Children's Hospital of Chicago, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.