A self-powered, self-contained, intravenous pacing catheter assembly for use in temporary intravenous cardiac pacing therapy, wherein all components of the assembly may be operated and maintained in a sterile environment proximate a patient entry site. In a preferred embodiment, a miniature pacemaker is powered by an attachable dc battery and outputs a selectable electrical pacing signal over an integrally attached intravenous pacing catheter to an electrode pair located at a distal end of the catheter. The combined pacemaker and catheter assembly are housed inside a sterile see-through pouch having at least one openable panel and an adhesive layer forming a continuous ring around the openable panel upon an exterior surface of the pouch. The pacemaker is preferably manipulable, e.g., by an attending physician, through walls of the sealed pouch, so that a sterile patient seal is not disturbed when changing the output signal settings. For example, in preferred embodiments, the pacemaker unit is cylindrical in shape, with one or more rotatable selector switches disposed about its circumference for ease in manipulating through the walls of the pouch, wherein a "two-hand" locking system is preferably employed to prevent inadvertent movement of settings switches.