Mechanical configurations for a multi-site leadless pacemaker

A human-implantable apparatus comprising:

• an epicardially or endocardially implantable electrostimulation electrode assembly, including:
• an electrostimulation unit, including a housing carrying an electrostimulation generation circuit, the electrostimulation generation circuit configured to generate electrostimulations for stimulating an excitable tissue;
• at least first and second electrodes, coupled to the electrostimulation unit, the at least first and second electrodes configured to be capable of independently delivering respective electrostimulations to respective separate first and second stimulation sites on or in the excitable tissue;
• and
• at least one fixation guide, included in or coupled to the housing of the electrostimulation unit, the at least one fixation guide configured:
• to receive a maneuvering device;
• to permit using the maneuvering device to position the electrostimulation electrode assembly at a target implant location;
• and
• to permit using the maneuvering device to steerably position and secure the first electrode to the first stimulation site, and to steerably position and secure the second electrode to the second stimulation site when the first electrode has been secured to the first stimulation site.