12 and various essential components to be described below separate bipolar pacing lead assemblies represented by blocks 14 and 16 respectively are adapted for placement in the atrium and the ventricle of the patient 39 s heart in a conventional configuration bipolar lead assembly 14 consists of a pair of conductors typically coils in a flexible sheath inert to body fluids the lead having male terminals at the proximal end for insertion into the female terminals of a lead connector integral with but electrically insulated from the case housing the stimulus generator details of such lead assemblies are well known and not critical to the invention and hence not shown in the drawings in typical fashion for bipolar endocardial leads an atrial lead for example terminates at the distal end in a cathode tip 19 and an anode ring 20 customarily configured as parts of a common electrode assembly the electrode tip is adapted to be positioned in stimulating relationship with excitable myocardial tissue within the right atrial chamber the anode ring is insulatively spaced one half inch or so back from the tip in the electrode assembly of the lead the ventricular bipolar lead assembly 16 is similarly structured with cathode 21 and anode 22 at the distal end adapted to be inserted into the right ventricle often some means of active or passive fixation not shown are provided adjacent the electrode assembly on the lead for retention of the electrodes in the proper position for capture stimulation within the respective chamber.