What is a pacemaker?

Heart device.: A cardiac pacemaker is a device that is implanted in the chest to permanently regulate heartbeat rhythms. The pacemaker monitors the heartbeat to make sure it is not beating too slowly, and when necessary transmits electric pulses to the heart to increase the heartbeat pace. Pacemakers are periodically replaced every several years when the battery runs out.

Pacemaker: A pacemaker is an electronic device which uses a lead as an antenna to sense the heart's electrical activity. It uses the same lead(s) to deliver a small electrical impulse to the heart to make it contract if the heart isn't going as fast as the device was programmed to maintain. Pacemakers both sense heart activity and pace it to produce activity. They maintain heart rate. Other things too....

Pacemaker : It is a device helping heart beating at certain rates in very simple terms