Download How and Artificial Pacemaker Stimulates a Heart

How and Artificial Pacemaker Stimulates a Heart
The pacemaker is essentially the most important part of the heart because its job is to
send electrical impulses through the heart causing it to beat. The body’s natural pacemaker is
called the sinoatrial (SA) node or the sinus node. If the natural pacemaker is somehow
defective, causing irregular heart rhythms, it may be replaced with either a permanent or
temporary artificial pacemaker. Artificial pacemakers are battery operated devices that use
electrical impulses to stimulate the heart back to a regular rhythm. By placing an electrode on
the heart wall, the device can detect all arrhythmia and return it back to normal with artificial
electrical impulses. In many human beings their heart does not always respond in the same
controlled way to create a normal rhythm. Some conditions that may cause a person to need an
artificial pacemaker would be: bradycardia, atrial fibrillation, heart failure, and syncope.
The first pacemaker was invented by Earl Bakken in the 1950’s, at Northwestern
Hospital in Minneapolis, Minnesota. A pacemaker is a device that weights approximately one
ounce and consist of a programmable chip that controls the flow of impulses sent to the heart in
order to control its rhythm. These impulses are delivered by two electrodes attached to the heart
muscles; every time it sends a signal to heart, muscles are contracted and the heart beat is
produced.
Pacemakers can be single, dual and triple chambered.
Single Chamber
These have one insulated lead to carry impulses to the heart and are
either attached to the right atrium or to the right ventricle.
Dual Chamber
Dual chambered pacemakers have two leads, one to the right atrium and
the other to right ventricle; they help the heart to function in a natural way depending on the
human body activity.
Triple Chamber
These kinds of pacemakers have two leads, one to the right atrium and
right ventricle and the other to the left ventricle. These pacemakers are inserted in patients who
have very week heart muscles; hence they help in the contraction of the heart to produce a
normal heart beat.
Each of the above mentioned pacemakers are available in three different varieties.
On Demand Pacemakers
It monitors the hearts natural electrical activity and
discharges impulses whenever the heart beat is slow or it misses a beat.
Fixed Rate Pacemakes
Fixed rate pacemakers discharges impulses at a steady
rate regardless of the hearts own beat.
Rate Responsive
These are designed to meet the body’s need during its physical
activities; it increases and decreases its impulses accordingly.
Reasons for an Artificial Pacemaker
In a normally functioning heart the first signal comes
from a group of electrically charged cells in the very top of the right atrium, this is known as the
body’s natural pacemaker or SA node. The signals then move down through the right and the
left atria and across a bridge known as the atrioventricular node or AV node. The signal moving
through the right and the left atria causes the first contraction of the heart muscle, this
contraction is the smallest of the two because it is not pumping the blood as far as the second
contraction will. You will recognize this contraction as the “lub” in the “lub-dub” heart sounds the
body makes while pumping blood. As the signal leaves the AV node it moves through the right
and left ventricles finally causing the ventricles to contract and force the blood either to the
pulmonary arteries or to the aorta to supply the rest of the body with oxygenated blood. This
seems like a fairly simple procedure, but in many people’s bodies their heart does not always
respond in the same controlled way to create a normal rhythm. Some conditions that may cause
a person to need an artificial pacemaker would be: bradycardia, atrial fibrillation, heart failure,
and syncope. Bradycardia is a condition where the heart beats to slowly to sustain normal
functions; this is very common in elderly people just because their heart has been at work for so
long. Atrial fibrillation is when the left and right atria do not contract in a normal way, commonly
beating rapidly and with no pattern. Heart failure occurs when the heart is not beating
sufficiently or much too slow, this is a big problem because there is a threat of cells being
depleted of oxygen which is irreversible (with this condition the brain cells are usually not
receiving oxygen which can eventually cause brain damage so severe that the person is
essentially brain dead.) Lastly, Syncope is a condition that is usually not as serious and is
simply fainting. When fainting occurs, the heart is usually beating very slowly, so in severe
cases a pacemaker is used to prevent the person from fainting and return their heart rhythm to
normal. An artificial pacemaker is a common treatment for all of these conditions and is very
effective in keeping the heart in a normal healthy pattern.
Follow up Needed for Artificial Pacemakers
After implantation, routine evaluations are
needed to determine if the settings need to be adjusted or modified due to changes in the heart
beat. The doctor or technician does not have to directly come in to contact with the pacemaker
to do the evaluations. They are not at all invasive and are generally preformed over the
telephone with a small machine that the patients are given at the time of implantation. Artificial
pacemakers are however, simply technology which means they need some sort of power
source. The power used to generate the electrical impulses in artificial pacemakers is from a
battery which has a life of approximately 7 years. The procedure to change the battery is
minimally invasive and very routine. Any other problems with the pacemaker would be simply to
wear and tear; common upkeep on pacemakers is things like replacement leads or a complete
replacement of the pacemaker.