US Patent 7778705 Electronic and biological pacemaker systems

Heart pacing systems include at least one electronic or biological pacemaker as a primary pacemaker, and at least one electronic or biological pacemaker as a backup pacemaker. When implanted, the primary pacemaker(s) produce primary pacing stimuli that modulate cardiac function. The backup pacemaker(s) provide backup pacing stimuli when the electronic pacemaker is unable to modulate cardiac function at the predetermined pacing rate. The heart pacing systems are implemented by implantation in regions where they can provide pacing stimuli to cardiac tissue.