The normal heartbeat originates in the heart's natural pacemaker called the "sinus node." The sinus node is usually located in the right atrium, though this location can be different in the setting of some congenital heart defects.
When the sinus node fires, a wave of electricity sweeps across the upper chambers of the heart (the atria) causing the upper chambers to squeeze or contract.
The electrical impulse then travels from the atria to the lower chambers of the heart (the ventricles) by way of the "AV node," located in the center of the heart, resulting in ventricular contraction.
Contraction of the atria followed by the ventricles allows for blood to be pumped to the body. Circulating blood supplies the body with oxygen and nutrients. In addition, circulating blood helps to eliminate the waste products of the body's metabolism.
When the sinus and / or AV nodes do not function normally, an artificial pacemaker may be needed. Some people are born with sinus and / or AV node dysfunction (heart block), especially in the setting of some congenital heart defects.
Sinus and / or AV node dysfunction can also be the consequence of certain surgical procedures.
Many other patients may benefit from pacemaker implantation including patients with abnormally fast heart rates, patients who pass out, patients on medications that slow the natural heart rate, patients with heart valves that leak (regurgitation), patients with an abnormally thick heart (hypertrophic cardiomyopathy), and patients with poor heart function.
Artificial pacing helps to restore the heart rhythm towards normal improving the heart's ability to circulate blood through the body.