What Is a Pacemaker?
A pacemaker is a small device thats placed
under the skin of your chest or abdomen to help control abnormal heart rhythms.
This device uses electrical pulses to prompt the heart to beat at a normal
rate.
Pacemakers are used to treat heart rhythms that are
too slow, fast, or irregular. These abnormal heart rhythms are called
arrhythmias
(ah-RITH-me-ahs). Pacemakers can relieve some symptoms related to arrhythmias,
such as fatigue (tiredness) and fainting. A pacemaker can help a person who has
an abnormal heart rhythm resume a more active lifestyle.
The Hearts Electrical System
Your heart has its own internal electrical system
that controls the speed and rhythm of your heartbeat. With each heartbeat, an
electrical signal spreads from the top of the heart to the bottom. As it
travels, the electrical signal causes the heart to contract in an organized
manner and pump blood.
Electrical signals normally begin in a group of
cells called the sinus node. As these signals spread from the top to the bottom
of the heart, they coordinate the timing of heart cell activity. First, the two
upper chambers of the heart, called atria (AY-tree-uh), contract. This
contraction squeezes blood into the lower chambers of the heart, which are
called ventricles (VEN-trih-kuls). The ventricles then contract and send blood
to the rest of the body. The combined contraction of the atria and ventricles
is a heartbeat.
For more information about the hearts
electrical system and how a healthy heart works, see the Diseases and
Conditions Index article on
How
the Heart Works.
Overview
Faulty electrical signaling in the heart causes
arrhythmias. A pacemaker uses low-energy electrical pulses to correct faulty
electrical signaling. Pacemakers can:
- Speed up a slow heartbeat
- Help end an abnormal and fast rhythm (only in
implantable cardioverter defibrillator/pacemaker combination devices)
- Make sure the ventricles contract normally if the
atria are quivering instead of beating in a normal rhythm (a condition called
atrial fibrillation)
- Coordinate the electrical signaling between the
upper and lower chambers of the heart
- Coordinate the electrical signaling between the
ventricles (cardiac resynchronization therapy used in
heart
failure)
Pacemakers also can monitor and record your
hearts electrical activity and the rhythm of your heartbeat. Newer
pacemakers can monitor your blood temperature, breathing rate, and other
factors and adjust your heart rate to changes in your activity.
Pacemakers can be temporary or permanent. Temporary
pacemakers are used to treat temporary heartbeat problems, such as a slow
heartbeat due to
heart
attack, heart surgery, or an overdose of medicine. Temporary pacemakers are
used in emergencies until a permanent pacemaker can be implanted or until the
temporary condition goes away. A person with a temporary pacemaker will stay in
the hospital as long as the pacemaker is in place.
In this article, pacemakers refers to
permanent devices, unless stated otherwise.
Doctors also treat arrhythmias with another device
called an implantable cardioverter defibrillator (ICD). An ICD is like a
pacemaker in some ways, but it can use higher energy electrical pulses to treat
certain dangerous types of arrhythmia. For more information on ICDs, see the
Diseases and Conditions Index article on
Implantable
Cardioverter Defibrillator.
Who Needs a Pacemaker?
Doctors recommend pacemakers to patients for a
number of reasons. The most common reason is when a patient's heart is beating
too slow or there are long pauses between heartbeats.
A pacemaker may be helpful if:
- Aging or heart disease damages your sinus node's
ability to set the correct pace for your heartbeat. Such damage can make your
heart beat too slow, or it can cause long pauses between heartbeats. The damage
also can cause your heart rhythm to alternate between slow and fast.
- You need to take certain heart medicines (such as
beta blockers), but these medicines slow down your heartbeat too much.
- The electrical signals between your heart's upper
and lower chambers are partially or completely blocked or slowed down (this is
called heart block). Aging, damage to the heart from a
heart
attack, or other heart conditions can prevent electrical signals from
reaching all the heart's chambers.
- You often faint due to a slow heartbeat. For
example, this may happen if the main artery in your neck that supplies your
brain with blood is sensitive to pressure. In you have this condition, just
quickly turning your neck can cause your heart to beat slower than normal. When
that happens, not enough blood may flow to your brain, causing you to faint.
- You have had a medical procedure to treat an
arrhythmia
called atrial fibrillation. A pacemaker can help regulate your heartbeat after
the procedure.
- You have heart muscle problems that cause
electrical signals to travel through your heart muscle too slow. (Your
pacemaker will provide cardiac resynchronization therapy for this problem.)
To decide whether a pacemaker will benefit you, your
doctor will consider any symptoms you have of an irregular heartbeat, such as
dizziness, unexplained fainting, or shortness of breath. He or she also will
consider whether you have a history of heart disease, what medicines you're
currently taking, and the results of heart tests.
A pacemaker won't be recommended unless your heart
tests show that you have irregular heartbeats.
Tests That Help Determine Whether You Need a
Pacemaker
A number of tests are used to detect an arrhythmia.
Your doctor may recommend some or all of these tests.
EKG (Electrocardiogram)
This simple and painless test detects and records
the electrical activity of the heart. An
EKG
shows how fast the heart is beating and the heart's rhythm (steady or
irregular). It also records the strength and timing of electrical signals as
they pass through each part of the heart.
Holter Monitor
A
Holter monitor, also called an ambulatory EKG, records the
electrical signals of your heart for a full 24- or 48-hour period. You wear
small patches called electrodes on your chest that are connected by wires to a
small, portable recorder. The recorder can be clipped to a belt, kept in a
pocket, or hung around your neck.
During the 24 or 48 hours, you do your usual daily
activities and keep a notebook, noting any symptoms you have and the time they
occur. You then return both the recorder and the notebook to your doctor to
read the results. Your doctor can see how your heart was beating at the time
you had symptoms.
The purpose of a Holter monitor is to record heart
signals during typical daily activities and while sleeping, and to find heart
problems that may occur for only a few minutes out of the day.
Echocardiogram
This test uses sound waves to create a moving
picture of your heart. An
echocardiogram
shows the size and shape of your heart and how well your heart is pumping
blood. The test can identify areas of heart muscle that aren't contracting
normally or getting enough blood flow.
Electrophysiology Study
For an
electrophysiology study, your doctor threads a small, flexible
wire from a blood vessel in your arm or leg to your heart. The wire
electrically stimulates your heart to see how your heart's electrical system
responds. The electrical stimulation helps to find where the heart 's
electrical system is damaged.
Stress Test
Some heart problems are easier to diagnose when your
heart is working harder and beating faster than when it's at rest. During
stress
testing, you exercise to make your heart work harder and beat faster while
heart tests, such as an EKG or echocardiogram, are performed.
How Does a Pacemaker Work?
A pacemaker consists of a battery, a computerized
generator, and wires with electrodes on one end. The battery powers the
generator, and a thin metal box surrounds both it and the generator. The wires
connect the generator to the heart.
The pacemaker's generator sends the electrical
pulses that correct or set your heart rhythm. A computer chip figures out what
types of electrical pulses to send to the heart and when those pulses are
needed. To do this, the computer chip uses the information it receives from the
wires connected to the heart. It also may use information from sensors in the
wires that detect your movement, blood temperature, breathing, or other factors
that indicate your level of physical activity. That way, it can make your heart
beat faster when you exercise.
The computer chip also records your heart's
electrical activity and heart rhythms. Your doctor will use these recordings to
set your pacemaker so it works better at making sure you have a normal heart
rhythm. Your doctor can program the computer in the pacemaker without having to
use needles or directly contacting the pacemaker.
The wires in your pacemaker send electrical pulses
to and from your heart and the generator. Pacemakers have one to three wires
that are each placed in different chambers of the heart.
- The wires in a single-chamber pacemaker usually
carry pulses between the right ventricle (the lower right chamber of your
heart) and the generator.
- The wires in a dual-chamber pacemaker carry
pulses between the right atrium and the right ventricle and the generator. The
pulses help coordinate the timing of these two chambers' contractions.
- The wires in a triple-chamber pacemaker are used
for heart muscle weakness and carry pulses between an atrium and both
ventricles and the generator. The pulses help coordinate the timing of the two
ventricles with each other.
Cross-Section of the Chest With a
Pacemaker
The illustration shows a
cross-section of the chest with a pacemaker. Figure A shows the location and
general size of a double chamber, or double lead, pacemaker in the upper chest.
The wires with electrodes are inserted into the right atrium and ventricle of
the heart through a vein in the upper chest. Figure B shows the electrode
electrically stimulating the heart muscle. Figure C shows the location and
general size of a single chamber, or single lead, pacemaker in the upper chest.
The wire with the electrode is inserted into the right ventricle of the heart
through a vein in the upper chest.
Types of Pacemaker Programming
There are two main types of programming for
pacemakersdemand pacing and rate-responsive pacing.
A demand pacemaker monitors your heart rhythm. It
only electrically stimulates your heart if its beating too slow or if it
misses a beat.
A rate-responsive pacemaker will speed up or slow
down your heart rate depending on how active you are. To do this, the
rate-responsive pacemaker monitors your sinus node rate, breathing, blood
temperature, or other factors to determine your activity level. Most people who
need a pacemaker to continually set the pace of their heartbeat have
rate-responsive pacemakers.
What To Expect During Pacemaker Surgery
Placement of a pacemaker requires minor surgery,
which is usually done in a hospital or special heart treatment laboratory. You
will be given medicine right before the surgery that will help you relax and
may make you fall nearly asleep. Your doctor will give you a local anesthetic
so you won't feel anything in the area where he or she puts the pacemaker.
First, your doctor will place a needle in a large
vein, usually near the shoulder opposite your dominant hand. The doctor will
then use the needle to thread the pacemaker wires into a vein and to the
correct location in your heart.
An x-ray "movie" of the wires as they pass through
your vein and into your heart will help your doctor place the wires. Once the
wires are in place, your doctor will make a small cut into the skin of your
chest or abdomen. He or she will then slip the pacemaker generator/battery box
through the cut, place it just under your skin, and connect it to the wires
that lead to your heart.
Once the pacemaker is in place, your doctor will sew
up the cut. The entire surgery takes a few hours.
What To Expect After Pacemaker Surgery
Expect to stay in the hospital overnight so your
heartbeat can be monitored and your doctor can make sure your pacemaker is
working properly. You probably will have to arrange for a ride to and from the
hospital because your doctor may not want you to drive yourself.
For a few days to weeks after surgery, you may have
pain, swelling, or tenderness in the area where your pacemaker was placed. The
pain is usually mild and often relieved by over-the-counter medicines. Consult
with your doctor before taking any pain medicines.
Your doctor also may ask you to avoid any vigorous
activities and heavy lifting for about a month. Most people return to normal
activities within a few days of having pacemaker surgery.
What Are the Risks of Pacemaker Surgery?
Your chance of having any problems from pacemaker
surgery is less than 5 percent. These problems may include:
- Swelling, bleeding, bruising, or infection in the
area where the pacemaker was placed
- Blood vessel or nerve damage
- A collapsed lung
- A bad reaction to the medicine used to make you
sleep during the procedure
- Infections that can become difficult to
treat
How Will a Pacemaker Affect my Lifestyle?
Once you have a pacemaker, you have to avoid close
or prolonged contact with electrical devices or devices that have strong
magnetic fields. Devices for which close and prolonged exposure can interfere
with a pacemaker include:
- Cell phones
- iPods
- Appliances, such as microwave ovens
- High-tension wires
- Metal detectors
- Industrial welders
- Electrical generators
These devices can disrupt the electrical signaling
of your pacemaker and stop it from working properly. You may not be able to
tell whether your pacemaker has been affected. How likely a device is to
disrupt your pacemaker depends on how long you're exposed to it and how close
it is to your pacemaker.
To be on the safe side, some experts recommend not
putting your cell phone or iPod in a shirt pocket over your pacemaker (if they
are turned on). You may want to hold the cell phone up to the ear thats
opposite the site where your pacemaker was implanted. If you strap your iPod to
your arm while listening to it, put it on the arm farthest from your
pacemaker.
You can still use household appliances, but avoid
close and prolonged exposure, as it may interfere with your pacemaker.
You can walk through security system metal detectors
at your normal pace. You also can be checked with a metal detector wand as long
as it isn't held for too long over your pacemaker site. You should avoid
sitting or standing close to a security system metal detector.
Stay at least 2 feet away from industrial welders or
electrical generators.
You also need to avoid some medical procedures that
can disrupt your pacemaker. These procedures include:
- Magnetic resonance imaging (also called MRI)
- Shock-wave lithotripsy to get rid of kidney
stones
- Electrocauterization to stop bleeding during
surgery
Let all of your doctors, dentists, and medical
technicians know that you have a pacemaker. You also should notify airport
screeners. Your doctor can give you a card that states what kind of pacemaker
you have. Carry this card in your wallet.
Physical Activity
In most cases, having a pacemaker won't limit you
from doing sports and exercise, including strenuous activities. You may need to
avoid full-contact sports, such as football. Such contact could damage your
pacemaker or shake loose the wires in your heart. Ask your doctor how much and
what kinds of physical activity are safe for you.
Followup
Your doctor will want to check your pacemaker
regularly. Over time, a pacemaker can stop working properly because:
- Its wires get dislodged or broken
- Its battery fails
- Your heart disease progresses
- Devices giving off strong electrical, magnetic,
or radio waves have disrupted its electrical signaling
To check your pacemaker, your doctor may ask you to
come in for an office visit several times a year. Some pacemaker functions can
be checked remotely through a telephone call or a computer connection to the
Internet. Your doctor also may ask you to have an
EKG
(electrocardiogram) to monitor changes in the electrical activity of your
heart.
Battery Replacement
Pacemaker batteries last between 5 and 15 years,
depending on how active the pacemaker is. Your doctor will replace the
generator along with the battery before the battery begins to run down.
Replacement of the generator/battery is a less
involved surgery than the original surgery to implant the pacemaker. The wires
of your pacemaker also may need to be replaced eventually. Your doctor can tell
you whether you need to replace your pacemaker or its wires.
Key Points
- A pacemaker is a small device that's placed under
the skin of your chest or abdomen to help control irregular heartbeats. This
device uses electrical pulses to prompt the heart to beat at a normal rate.
- Pacemakers are used to treat heart rhythms that
are too slow, fast, or irregular. These abnormal heart rhythms are called
arrhythmias.
- Pacemakers can relieve some symptoms related to
arrhythmias, such as fatigue (tiredness) and fainting, and can help people who
have arrhythmias resume a more active lifestyle.
- A pacemaker is similar to an
implantable
cardioverter defibrillator (ICD), but an ICD can use higher energy
electrical pulses to treat certain dangerous arrhythmias. (To treat fast heart
rhythms, a pacemaker is combined with an ICD in a single device.)
- Your doctor may recommend a pacemaker if aging,
heart disease, or other factors make your heart beat too slow, too fast, or
irregularly.
- Symptoms such as fainting, shortness of breath,
and fatigue (tiredness) may be due to an irregular heartbeat that a pacemaker
could correct. Your doctor will confirm whether you need a pacemaker based on
your symptoms, any medicines you take, and test results.
- A pacemaker consists of a battery, a computerized
generator, and wires. The generator sends the electrical pulses that correct or
set your heart rhythm, and the wires carry pulses to and from various chambers
of your heart and the generator.
- Pacemaker surgery is usually done in a hospital
or special heart treatment laboratory. You will be given medicine to help you
relax. The surgery takes just a few hours, but you will stay in the hospital
overnight so your doctor can monitor your heart rhythm and make sure your
pacemaker is working properly.
- Problems from pacemaker surgery are rare. Most
people can return to normal activities within a few days.
- Your doctor may ask you to avoid any vigorous
exercise or heavy lifting for a short period after your surgery. After you have
fully recovered from surgery, discuss with your doctor how much and what kinds
of physical activity are safe for you.
- Once you have a pacemaker, you have to avoid
close or prolonged contact with electrical devices or devices that have strong
magnetic fields. You also need to avoid certain medical procedures that can
disrupt your pacemaker.
- Let all of your doctors, dentists, and medical
technicians know that you have a pacemaker
- Have your pacemaker checked regularly. Some
pacemaker functions can be checked remotely through a telephone call or a
computer connection to the Internet. Your doctor may ask you to come to his or
her office to check your pacemaker.
- Pacemaker batteries have to be replaced every 5
to 15 years, depending on how active your pacemaker is. The wires of your
pacemaker also may need to be replaced eventually. Your doctor can tell you
whether you need to replace your pacemaker or its wires.
Links to Other Information About Pacemaker
NHLBI Resources
Non-NHLBI Resources
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