Systems and methods deploy a therapeutic or diagnostic element into
contact with a body tissue region. The systems and methods can sense
position of the therapeutic or diagnostic element relative to a targeted
tissue region without direct or indirect visualization, by sensing fluid
pressure in a fluid path having an outlet located at or near the
therapeutic or diagnostic element. The systems and methods can also
inflate the therapeutic or diagnostic element during use, while taking
steps to avoid over-inflation and/or while dynamically monitoring the
pressure conditions within the expanded element.