Abstract: A medical balloon catheter assembly includes a balloon having a permeable region and a non-permeable region. The balloon is constructed at least in part from a fluid permeable tube such that the permeable region is formed from a porous material which allows a volume of pressurized fluid to pass from within a chamber formed by the balloon and into the permeable region sufficiently such that the fluid may be ablatively coupled to tissue engaged by the permeable region. The non-permeable region is adapted to substantially block the pressurized fluid from passing from within the chamber and outwardly from the balloon. The porous material may be a porous fluoropolymer, such as porous polytetrafluoroethylene, and the pores may be created by voids that are inherently formed between an interlocking node-fibril network that makes up the fluoropolymer. Such voids may be created according to one mode by expanding the fluoropolymer.