1 Clinical Research Support Center, Tokyo Metropolitan Children's Medical Center, 2-8-29 Musashidai, Fuchu, Tokyo, 183-8561, Japan. morikawa@2005.jukuin.keio.ac.jp.
2 Department of General Pediatrics, Tokyo Metropolitan Children's Medical Center, Tokyo, Japan.
3 Clinical Research Support Center, Tokyo Metropolitan Children's Medical Center, 2-8-29 Musashidai, Fuchu, Tokyo, 183-8561, Japan.
4 Department of Cardiology, Tokyo Metropolitan Children's Medical Center, Tokyo, Japan.