The pacemaker is a device that consists of a generator and a cable or more, according to the needs of each case. The device detects if the heart receives its own stimulus and, if not, is able to create it and thus maintain an adequate heart rate.  
It is usually placed below the clavicle, at the subcutaneous level, by surgery that does not usually require general anesthesia, and the wires are passed through a vein to the heart cavities. The majority of patients who enter to implant a pacemaker can go home 24 hours after the procedure and resume a normal life a few days later.