Every heart has a natural pacemaker called the sinoatrial node or sinus
node. It is a small mass of specialized cells in the top of the heart’s
right atrium that makes the electrical impulses which cause the heart to beat.
If this natural pacemaker is defective, the heart may beat too fast or
too slowly, or the heart’s electrical pathways may be blocked. If
that occurs, it may be necessary for artificial pacemakers to be inserted
to regulate the heart.
An artificial pacemaker is a small, battery-operated device used to regulate
the heart beat. Some are inserted permanently and some are temporary and
used externally. Pacemakers use batteries to send electrical impulses
to the heart. Electrodes are placed next to the heart wall and small electrical
charges travel through the wire to the heart. Most pacemakers are demand
pacemakers. Sensors turn the signal off when the heartbeat is above a
certain level and back on when the heartbeat is too slow.