At visit 5, two weeks after discontinuation of iNO treatment repeat vital signs with oxygen saturation measurement, physical examination, patency of nares, spirometry, 2D-echocardiogram with Doppler (immediately after the 2D - echocardiogram with Doppler NIBP, HR, SpO2 will be measured), ABG, MetHb, 6MWD(with Borg CR10 leg fatigue and dyspnea scale and oxygen saturation measurement), and PRO will be performed. If applicable a last urine pregnancy test will be executed to make sure no pregnancy occurred during the study. If there are no follow-up actions for a patient at this visit, it will be considered as a completion of study participation / end of study for that particular patient.