Abstract: The present invention relates to the use of PDE 5 inhibitors generally and in particular of known 2-phenyl-substituted imidazotriazinone derivatives for manufacturing medicaments for the treatment of pathological states which can be treated by raising cGMP levels in certain tissues, such as, for example, of, for example: primary pulmonary hypertension, secondary pulmonary hypertension, pulmonary arterial hypertension, portopulmonary hypertension, hepatopulmonary syndrome, pulmonary hypertension caused by medicaments (amphetamines), interstitial lung disease, pulmonary hypertension occurring with HIV, thromboembolic pulmonary hypertension, pulmonary hypertension in children and neonates, pulmonary hypertension induced by atmospheric hypoxia (altitude sickness), COPD, emphysema, chronic bronchial asthma, mucoviscidosis-related pulmonary hypertension, right heart failure, left heart failure and global failure, and which can be treated by raising cGMP levels in certain tissues, such as, for example, isolated syst