An apparatus for automatically retroperfusing a coronary vein includes an intraluminal cannula having a main body portion extending between a proximal end portion and a distal end portion. In one aspect, an apparatus may include a ground plane, one or more openings defined in the ground plane, such as, for example, conjoined via openings andor slots, and one or more conductive bridges coupled with the ground plane that traverse the one or more openings. The irradiated light of the light source reflected by the document is incident on the imaging element.