1. From the Cardiac Bioelectricity and Arrhythmia Center (S.G., E.K.R., P.K.W., Y.R.), Department of Biomedical Engineering (S.G., Y.R.), and Mallinckrodt Institute of Radiology (P.K.W., Y.R.), Washington University, St Louis, Mo; Division of Pediatric Cardiology, Washington University School of Medicine/St Louis Children’s Hospital, St Louis, Mo (J.N.A., Y.R.); and Eller Congenital Heart Center, Heart Lung Institute, St Joseph’s Hospital and Medical Center, Phoenix, Ariz (E.K.R.).