In cases of transposition of the great arteries, these vessels arise from the wrong ventricle. In this malformation, origination of the aorta is in the right ventricle and origination of the pulmonary artery is in the left ventricle. Systemic venous blood returns through the right atrium to the right ventricle and than to the aorta, and pulmonary venous blood returns trought left atrium to the left ventricule and than to the pulmonary artery. In this circumstances after birth, the life is sustained with existing communication between right and left circulation, e.g. ventricular septal defect, atrial septal defect or patent ductus arteriosus. Surgical management options are: 1. atrial switch procedure that was developed in 1950s (either Mustard or Senning operation) or 2. arterial switch procedure that was developed in 1980s. In our case report, young female, 24 years old patient, which was underwent Senning operation in the childhood, now is presenting with signs of dyspnoea on exercise. In our examinations (echocardiography, cardiac MRI) we have shown the cause of the same: subvalvular stenosis of the pulmonary valve, with high gradient trough the left ventricule outflow tract and the fistula between the venous conduit and right atrium. Now, we consider the further treatment options in this patient. (