Endpoints. The primary endpoints will be decrease in mean PAP and pulmonary vascular resistance at 3 and 6 months and improvement of functional capacity by the 6MWT. Clinical adverse events (including PA perforation/dissection, acute thrombus formation in the PA, all-cause death, rehospitalization due to PAH, and lung transplantation) will be secondary endpoints and will be assessed by an independent event committee. Statistical analysis. Continuous variables will be expressed as mean + SD. Differences in continuous variables between different time points in the PADN group will be analyzed using paired-sample Student t tests or Wilcoxon signed- rank sum tests, as appropriate nonparametric statistical methods. Each patient in the trial will serve as his/her own control before and after PADN and sham group patients as a control group of overall efficacy of the procedure. The categorical variables will be compared using the Fisher exact test. Statistical significance will be defined as a 2-sided p value < 0.05. All of the analyses will be performed using WinStat statistical software package for Microsoft Excel, version 2009.