1. Department of Congenital Heart Defects and Paediatric Cardiology, FMS in Zabrze, Medical University of Silesia in Katowice, Silesian Centre for Heart Diseases, Zabrze, Poland
2. Department of Cardiology and Internal Diseases, University Hospital No. 1, Collegium Medicum in Bydgoszcz, Nicolaus Copernicus University in Torun, Torun, Poland