A pacemaker insertion is the implantation of a small electronic
device in the chest (just below the collarbone) to help regulate
electrical problems with the heart. When a problem develops,
such as a slow heart rate, a pacemaker may be recommended to
ensure that the heartbeat does not slow to a dangerously low
rate. The heart is basically a pump made up of muscle tissue
that is stimulated by electrical currents, which normally follow
a specific circuit within the heart. This normal electrical
circuit begins in the sinus or sinoatrial (SA) node, which is a
small mass of specialized tissue located in the right atrium
(upper chamber) of the heart. The SA node generates an
electrical stimulus at 60 to 100 times per minute (for adults)
under normal conditions; this electrical impulse from the SA
node starts the heartbeat. The electrical impulse travels from
the SA node to the atrioventricular (AV) node in the bottom of
the right atrium. From there the impulse continues down an
electrical conduction pathway called