The aim of research proposal is to assess and compare the safety and efficacy of radiofrequency denervation of pulmonary arteries on decrease in pulmonary vascular resistance and mean pulmonary artery pressure (MPAP) in 20 patients with IPAH (mean pulmonary artery pressure >25 mmHg) and in 20 patients with secondary pulmonary hypertension due to pulmonary disease or due to left heart disease not responding optimally to medical therapy.