The pacemaker is a battery operated electronic device which transmits electrical impulses to the heart to keep it beating in a regular manner.
In a healthy heart the regularity of beating is controlled by a special system of muscles called the sinoatrial node, situated in the right atrium (the right hand upper chamber of heart) which sends out regular impulses to the heart muscle. When this mechanism breaks down and the heart beat becomes irregular (arrhythmia) or even stops (heart block) an artificial pacemaker is used. A pacemaker is usually implanted in the body on the front of the chest, about 5 cm below the middle of the collar-bone.
The electrical impulses produced by the electronic circuit are sent to the heart via the electric wires which are passed into the right ventricle (the right hand lower chamber of heart) via a large vein and the right atrium. The batteries used in pacemaker usually need replacement once in 10-15 years.
