Cardiovascular MRI and Cardiopulmonary Exercise Capacity After Neonatal ASO) in Young Adults

Inclusion Criteria: * former EMAH (adults with congenital heart defects) patients \> 18 years old * after neonatal ASO for TGA at the Department of pediatric cardiac surgery * also if applicable with a correction of an aorta isthmus stenosis neotal or in infancy Exclusion Criteria: * contraindications of MRI as metallic implants, claustrophobia * contraindications of MRI contrast agents * severe chronic kidney disease (estimated glomerular filtration rate \< 30 ml/min) * contraindications of exercise stress test with dobutamine or cardiopulmonary exercise stress test (e.g. instable angina pectoris, complex arrhythmia) * disabled persons not able to perform cardiopulmonary exercise stress test * pregnancy and breast feeding