The study is designed as a non-interventional, multicenter, prospective single-arm study to observe the therapy with REMODULIN (Treprostinil) applicated by an implantable pump in patients with pulmonary arterial hypertension (PAH).

Patients that suffer from progressing PAH are medicated with intravenous prostanoids since the 80's of the last century. Nowadays, specific treatment of PAH can be realized by the huge number of substances that are currently available. Still, the time point of starting an intravenous medication is not defined yet. By evaluation of data concerning risk strata of PAH patients, this issue may be enlightened properly.

Previously collected data concerning risk-adapted therapy in PAH-patient have shown that the mortality is little in the "low-risk-status" patients, only. Thus, all efforts must be undertaken to define the patients in this functional class. For most patients this means a combined therapy of available substances according to well defined procedures. Patients whose status remain as "intermediate-risk-status" after receiving a dual therapy over 3-6 months shall undergo a subsequent triple therapy including Selexipag. However, this therapy may not lead to an improvement of the risk-status or even worsened. In these cases, a subcutaneous or intravenous therapy with prostanoids is indicated.

Currently, there are no data available for those patients treated with at least three months with Selexipag as part of a triple therapy that undergo a subsequent intravenous therapy with Treprostinil if there is no change in their risk-status. In the planned study LPS-II, patients are specifically selected on being treated in a dual therapy and having a stagnating intermediate-risk status. These patients receive an implantation of the medical pump LENUS pro, that enables a permanent infusion of Treprostinil.

The aim of this study is to examine, whether patients can reach an improvement in their intermediate-risk-status after six months of treatment.

Inclusion Criteria:

• diagnosis of pulmonary arterial hypertension (WHO group I) accordingly to international guidelines
• intermediate or high risk-profile of PAH after at least three months treatment with vasoactive substances including Selexipag
• indication of intravenous therapy with Treprostinil
• informed consent given for implantation of the medical pump LENUS pro
• informed consent given for participation in the LPS-II study

Exclusion Criteria:

• contraindications according to package information leaflet (LENUS pro) and/or summary of product characteristics (Treprostinil)
• Patient is diagnosed with PAH with an etiology different from that of the inclusion criteria
• chronic kidney insufficiency (estimated GFR < 30)
• hepatic insufficiency: CHILD C (known information from patients medical records)
• intake of substances with potential for infections: intravenous drug abuse, prednisolone, azathioprine, cyclophosphamide
• suffering from diseases with potential for infections: immunodeficiency syndrome, diabetes mellitus, diabetic gangrene
• pregnant or breastfeeding women
• women of childbearing potential who are not on a reliable and safe form of contraception

Patients with PAH (Pulmonary arterial hypertension) who need to undergo treatment with Treprostinil, administered by an intravenous pump system (LENUS pro)