1. Division of Cardiology and Center for Pediatric Clinical Effectiveness, The Children's Hospital of Philadelphia, PA
2. Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
3. Leonard Davis Institute at the University of Pennsylvania, Philadelphia, PA
4. Mid America Heart Institute, St Luke's Health System, Kansas City, MO
5. Division of Cardiology, Children's National Health System, Washington, DC
6. Department of Pediatrics, George Washington University School of Health Sciences, Washington, DC