Implantable frames for use in body passages are provided herein. The implantable frames comprise one or more of certain preferred structural features that are generally applicable to frames comprising a plurality of curved and straight member portions that together define an interior lumen extending along a longitudinal axis between a proximal end and a distal end. The implantable frames have an exterior surface comprising a plurality of openings between the interior lumen and the exterior surface, and preferably include one or more undulating hoop members attached to one or more longitudinal connecting members. The implantable frames can be formed from any suitable material, but preferably comprise material permitting the frame to radially self-expand from a radially compressed configuration to a radially expanded configuration. The implantable frames are useful for endolumenal implantation within a body vessel, for example as a stent or as a support frame of an implantable valve.