When your heart rate is unreliable or too slow due to a malfunction
in your SA node, AV node or normal conduction pathway, your physician
may recommend a pacemaker.
With advances in technology, artificial pacemakers today generally
last eight to ten years (depending upon the type of heart condition)
and, in most cases, allow a person to lead a normal life.
In addition, advances in pacemaker circuitry have reduced the
interference risk from certain machinery, such as microwaves, which,
in the past, may have altered or otherwise affected the pacemaker.
Even so, certain precautions must be taken into consideration when a
person has an artificial pacemaker.
A pacemaker is a small electronic device composed of three parts: a
generator, one or more leads, and an electrode on each lead. A
pacemaker signals the heart to beat when the heartbeat is too slow.
A generator is the "brain" of the pacemaker device. It is a
small metal case that contains electronic circuitry and a battery
sealed in a titanium case. The pulse generator is approximately the
size of a silver dollar and usually placed beneath the skin on the
right or left side of the upper chest.
The lead system is an insulated flexible wire, which is connected to
the pulse generator and passed through a vein in the neck or shoulder
into the right side of the heart. Depending on your particular needs,
you may have one or two leads placed into your heart.
The lead carries signals from the heart muscle to the pulse
generator when you have a normal heartbeat. When your heart misses a
beat, the missed heartbeat is "sensed" by the pulse
generator. This then initiates an electrical impulse from the pulse
generator through the lead to your heart muscle. This electrical
impulse will stimulate a heartbeat and keep your heart rate from
becoming too slow.
When the heart is beating at a rate faster than the programmed
limit, the pacemaker will monitor the heart rate, but will not pace.
No electrical impulses will be sent to the heart unless the heart's
natural rate falls below the pacemaker's low limit.
Pacemaker leads may be positioned in the atrium or ventricle or
both, depending on the condition requiring the pacemaker to be
inserted. An atrial dysrhythmia/arrhythmia (an abnormal heart rhythm
caused by a dysfunction of the sinus node or the development of
another atrial pacemaker within the heart tissue that takes over the
function of the sinus node) may be treated with an atrial
A ventricular dysrhythmia/arrhythmia (an abnormal heart rhythm caused
by a dysfunction of the sinus node, an interruption in the conduction
pathways, or the development of another pacemaker within the heart
tissue that takes over the function of the sinus node) may be treated
with a ventricular pacemaker whose lead wire is located in the ventricle.
It is possible to have both atrial and ventricular dysrhythmias, and
there are pacemakers that have lead wires positioned in both the
atrium and the ventricle. There may be one lead wire for each chamber,
or one lead wire may be capable of sensing and pacing both chambers.
There are a number of categories of patients with indications for
Symptoms documented to be related to slow heart rates