Devices and systems to size a luminal organ. At least some embodiments include a catheter comprising an outer elongate tube, an inner elongate tube disposed within the outer elongate tube, a proximal balloon attached to the outer elongate tube, a distal balloon having a first end attached to the outer elongate tube and a second end attached to the inner elongate tube, electrodes positioned on the outer elongate tube, and a pressure transducer positioned on the outer elongate tube.
