1 Department of Medicine; Solna, Karolinska Institutet and ME Cardiology, Karolinska University Hospital, Norrbacka S1:02, Eugeniavagen 27, 171 77 Stockholm, Sweden.
2 Division of Clinical Physiology, Department of Laboratory Medicine, Karolinska Institutet, and Unit of Clinical Physiology, Karolinska University Hospital, Stockholm, Sweden.
3 Endorsed Course in Pediatric Community Medicine, Nihon institute of Medical Science, Saitama, Japan.