1. From the Rush Center for Congenital and Structural Heart Disease, Rush University Medical Center, Chicago, Ill (Z.M.H.); UCLA Cardiac Arrhythmia Center, David Geffen School of Medicine at UCLA, Los Angeles, Calif (K.S.); and Department of Pediatrics (Cardiology) and Biomedical Engineering, Oregon Health & Science University, Portland, Ore (D.J.S.).