What are pacemakers?

Speed up heart: If your heart is beating too slow, a pacemaker sends a small electric shock to the heart making it beat faster. There is a batery and some electronic circuits which tell the pacemaker when your heart beats too slow.

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....

HeartRhythm or block: Pacemakers are most commonly necessary for patients with bradycardia- slow heart rate, tachycardia - fast heart rate, and heart block - when the heart stops beating for several seconds.

Several indications: There are specific consensus guidelines for pacemaker implantation. In general they are used for patients with abnormally low heart rates, particularly if there are associated symptoms. They are also used when there is a problem with the normal eclectrical system of the heart where the electrical impulse does not conduct from the upper to the lower chamber of the heart, also known as heart block.