This study investigates the effects of Treprostinil, a medication for Pulmonary Hypertension (PH), using both traditional clinical indices and computational modelling. Background: PH is a progressive disease affecting the right heart, characterized by high pressure in the pulmonary artery (mPAP). To maintain energetic transfer in the system throughout disease progression and medication, both the right ventricle (RV) and the pulmonary vasculature must adapt. Treprostinil works by dilating downstream blood vessels, reducing pressure and peripheral vascular resistance (PVR) and thus the workload on the ventricle. Understanding the interplay between the RV, and the proximal and peripheral arteries is crucial for treatment effectiveness. Methods: The study compares clinical data and modelling simulations from two PH patients treated with Treprostinil for two years: a responder with moderate PH (mPAP=55mmHg) and a non-responder with moderate to severe PH (mPAP=83mmHg). In both cases, changes in haemodynamic and anatomical parameters are modelled to analyze treatment effects on RV function, proximal pulmonary artery (PA) shape and flow, ventriculo-arterial coupling (VAC), and peripheral resistance. Findings: Compared to the responder, the non-responder had worsened RV function (15% increase vs 20% decrease in end-systolic volume), impaired VAC (0.36 vs 0.60), increased mPAP despite decreased peripheral resistance (mPAP: 89 vs 46mmHg; PVR: 38 vs 13 WU), dilation of proximal PA (15-45% vs 1-6%) with minimal angulation changes, and increased arterial stiffness (pulse wave velocity: 8 vs 4.2 m/s ). Conclusions: Treprostinil appears more effective in earlier stages of PH. In the non-responder case, the dilation of the proximal PA might be a compensatory mechanism for insufficient downstream vasodilation. This explorative study highlights the potential of computational modelling to provide markers to assess treatment responses and disease progression in PH. Limitations: The study only analyzes two cases, limiting generalizability. Further research with larger patient groups are needed to validate these findings.