The goal of this clinical trial is to test the efficacy of tadalafil in patients with group II pulmonary hypertension with elevated pulmonary vascular resistance (PVR). The main question it aims to answer is: • Can tadalafil improve patients with group II pulmonary hypertension with elevated PVR? Participants will undergo right heart catheterization (RHC) to make sure they are fulfilling the inclusion criteria, then will be asked to take tadalafil 20 mg for two weeks then 40 mg if tolerated for 12 weeks, then participants will be followed up. Investigators will compare the drug group with another age- and sex- matched control placebo group.