In one embodiment, a device is provided including an expandable support member having a first portion and a second portion is provided. The first portion is adapted to have a smaller expansion index than the second portion. A therapeutic or diagnostic instrument is supported, at least in part, by the expandable support member first portion. In another embodiment, the support member is adapted for non-uniform expansion of the first and second portions. There are also described methods of forming therapeutic devices. There are also described methods of providing therapy to tissue in a body by positioning a device in proximity to tissue in a body selected to receive therapy. Next, the expandable support member second portion is expanded until the instrument is at a therapeutic position relative to the tissue in a body selected to receive therapy. Thereafter, therapy or diagnosis is provided to the selected tissue using the device.