The aim of the study is to intensify the follow up of patients with pulmonary arterial hypertension via modern imaging guided methods in due consideration of the possibilities of three-dimensional echocardiography in order to optimize their specific therapy.

The hypothesis is that the increased use of modern imaging guided tools is essential for the follow up.

It is not possible to perform a magnetic resonance imaging in all patients and as a result echocardiography is not only done at screening but also during the follow up. The imaging technologies made a great progress in the last few years and enable a better assessment of the haemodynamic parameters in our days.

Inclusion Criteria:

• age >17
• pulmonary arterial hypertension WHO group I who are going to start a therapy with prostanoid
• written informed consent
• Prostanoid naive
• no change of the pulmonary arterial hypertension therapy within 3 weeks of inclusion into the study

Exclusion Criteria:

• pregnancy and lactation period
• Women of childbearing potential who do not use an effective and secure method for birth control
• severe chronic kidney insufficiency (glomerular filtration rate <30), which will remain for more than 3 months
• liver insufficiency Child C
• life expectancy shorter than the course of the study (for example because of a malignant disease)

pulmonary arterial hypertension WHO group I