The proposed study will be a prospective, multi-center, randomized, blinded trial comparing 2 treatments for pulmonary artery stenosis. Specifically, vessels that fail to respond to balloon inflation at 8 ATM will be individually randomized to 1 of 2 treatment pathways. In the first treatment pathway, the vessel is dilated using a CB, followed by additional low pressure balloon dilation (< 8ATM). In the second pathway,the vessel is dilated with high pressure balloon angioplasty, with balloon inflation pressures exceeding 15 ATM. Cross-over therapy will be permitted for failed high pressure treatment starting with enrollment of patient #15. The primary outcome assessment for efficacy will be a comparison of percent change in minimum lumen diameter before and after randomized therapy, as determined by a core laboratory blinded to pathway assignment. The primary outcome assessment for safety will be a comparison of the proportion of vessel dilations resulting in any serious adverse events, as determined by the Data and Safety Monitoring Board. Patient-level safety endpoints will also be tabulated. Patients can have multiple vessels enrolled; analytical techniques will adjust for potential intra-patient correlation.