1. Children's Heart Institute; Cincinnati Children's Hospital Medical Center; Cincinnati Ohio USA
2. Department of Cardiology, Academic Medical Center, Amsterdam; Interuniversity Cardiology Institute of the Netherlands, Netherlands Heart Institute; Utrecht The Netherlands
3. Department of Medicine, Groote Schuur Hospital, The Cardiac Clinic, Department of Medicine; Groote Schuur Hospital and University of Cape Town; Cape Town South Africa
4. Department of Pediatrics; Red Cross War Memorial Children's Hospital and University of Cape Town; Cape Town South Africa
5. Division of Biostatistics and Epidemiology; Cincinnati Children's Hospital Medical Center; Cincinnati Ohio USA
6. Adolescent and Adult Congenital Program, Children's Heart Institute; Cincinnati Children's Hospital Medical Center; Cincinnati Ohio USA