1 Department of Pediatric Cardiology and Congenital Heart Diseases, Faculty of Medical Sciences in Zabrze, Medical University of Silesia in Katowice, Zabrze, Poland. rfiszer@sum.edu.pl
2 Department of Pediatric Cardiology and Congenital Heart Diseases, Faculty of Medical Sciences in Zabrze, Medical University of Silesia in Katowice, Zabrze, Poland