1. Children's Heart Centre, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands;
2. Kardiocentrum and Cardiovascular Research Center, University Hospital Motol, Prague, Czech Republic;
3. Clinical Physics Laboratory, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; and
4. Pediatric Cardiology Unit, Edith Wolfson Medical Center, Holon, Israel