Evaluate Real-World Use of Next Generation Infusion Pumps to Administer Remodulin

This is a virtual, patient-centric, observational study that will follow approximately 60 participants through 8 weeks following initiation of Remodulin therapy via their UTC-developed next generation infusion pump and consists of remote and electronic assessments administered to patient via the uMotif® data capture platform at Study Enrollment, Week 2, Week 4, and Week 8 or Early Withdrawal (if applicable). The study population will consist of 2 cohorts of PAH patients: 1. De Novo Cohort: patients new to parenteral prostacyclin-class therapy. 2. Transition Cohort: patients who had been receiving SC treprostinil therapy via a previous generation infusion pump prior to transitioning to a next generation infusion pump. The De Novo Cohort will initiate subcutaneous (SC) Remodulin via a next generation infusion pump as prescribed by their healthcare professional. Participants will be followed from day of Study Enrollment, which will be Day 1, through 8 weeks while using next generation infusion pump, or until discontinuation of Remodulin (early withdrawal), whichever comes first. The Transition Cohort will have previously been receiving SC treprostinil utilizing a previous generation infusion pump prior to transitioning to delivery of Remodulin via next generation infusion pump, as prescribed by their healthcare provider. Participants will be followed from day of Study Enrollment, which will be Day 1, through 8 weeks while using next generation infusion pump, or until discontinuation of Remodulin (early withdrawal), whichever comes first. Following the completion of study assessments at Week 8 or Early Withdrawal (if applicable), participants will continue Remodulin therapy via their infusion pump at their prescriber's discretion.