1. Department of Pediatrics, School of Medicine, Sapporo Medical University
2. Department of Pediatrics and Child Health, Kurume University School of Medicine
3. Division of Pediatric Cardiology, Saitama Heart Institute, Saitama Medical School
4. Department of Pediatrics, Okayama University Medical School
5. Department of Pediatrics, National Cardiovascular Center
6. Department of Pediatric Cardiology. The Heart Institute of Japan, Tokyo Women's Medical College
7. Division of Cardiology, National Children's Hospital
8. A list of the other contributing investigators appears in the Appendix