Abstract: A fully implantable cardiac pacemaker system is provided. The pacemaker system includes a pacemaker having an electrode sub-assembly containing an electrode and a base into which the electrode is embedded. It also includes an implantable package that has electronic components for providing electrical pulses to a patient's heart. The pacemaker also has a power supply and a flexible electrically conductive lead that connects the electronic components to the electrode. In addition to the pacemaker, the pacemaker system includes a removable insertion casing that is physically attached to the base portion of the electrode sub-assembly. Upon insertion of the pacemaker into a patient's heart, the pacemaker is detached from the removable insertion casing and deployed fully in the patient's chest. The pacemaker system has particular use in fetal applications.