Walter H. Johnson, Jr., MD is Professor of Pediatrics in the Department of Pediatrics, Division of Pediatric Cardiology, Alabama Congenital Heart Disease Center, University of Alabama at Birmingham, Birmingham, AL, USA. Camden L. Hebson, MD is Associate Professor in the Department of Pediatrics, Division of Pediatric Cardiology, Alabama Congenital Heart Disease Center, University of Alabama at Birmingham, Birmingham, AL, USA.