An electrocardiogram (ECG or EKG) is one of the simplest and fastest
procedures used to evaluate the heart. Electrodes (small, plastic
patches) are placed at certain locations on the chest, arms, and legs.
When the electrodes are connected to an ECG machine by lead wires, the
electrical activity of the heart is measured, interpreted, and printed
out for the physician's information and further interpretation.
An exercise ECG is performed to assess the heart's response to stress or
exercise. The ECG is monitored while a person is exercising on a
treadmill or stationary bike. While this procedure is seldom used for
young children, it may be very useful in evaluating adolescents and
An ECG tracing will be taken at certain points during the test in order
to compare the effects of increasing stress on the heart. Periodically,
the incline and treadmill speed will be increased in order to make
exercise more difficult for the person being tested. If the person is
riding a bicycle, he/she will pedal faster against increased resistance.
In either circumstance, the person will exercise until reaching a target
heart rate (determined by the physician based on age and physical
status) or until unable to continue due to fatigue, shortness of breath,
chest pain, or other symptoms.
Other related procedures that may be used to assess the heart include
resting electrocardiogram (ECG), Holter monitor, signal-averaged ECG,
cardiac catheterization, chest x-ray, computed tomography (CT scan) of
the chest, echocardiography, electrophysiological studies, magnetic
resonance imaging (MRI) of the heart, myocardial perfusion scans,
radionuclide angiography, and ultrafast CT scan. Please see these
procedures for additional information.
The heart's electrical conduction system
heart is, in the simplest terms, a pump made up of muscle tissue. Like
all pumps, the heart requires a source of energy in order to function.
The heart's pumping action is regulated by an electrical conduction
system that coordinates the contraction of the various chambers of the
An electrical stimulus is generated by the sinus node (also called the
sinoatrial node, or SA node), which is a small mass of specialized
tissue located in the right atrium (right upper chamber) of the heart.
The sinus node generates an electrical stimulus regularly at 60 to 100
times per minute under normal conditions. This electrical stimulus
travels down through the conduction pathways (similar to the way
electricity flows through power lines from the power plant to your
house) and causes the heart's lower chambers to contract and pump out
blood. The right and left atria (the two upper chambers of the heart)
are stimulated first and contract a short period of time before the
right and left ventricles (the two lower chambers of the heart).
The electrical impulse travels from the sinus node to the
atrioventricular node (also called AV node), where impulses are slowed
down for a very short period, then continue down the conduction pathway
via the bundle of His into the ventricles. The bundle of His divides
into right and left pathways to provide electrical stimulation to the
right and left ventricles.
This electrical activity of the heart is measured by an
electrocardiogram. By placing electrodes at specific locations on the
body (chest, arms, and legs), a graphic representation, or tracing, of
the electrical activity can be obtained. Changes in an EKG from the
normal tracing may indicate one or more of several heart-related
Reasons for the Procedure
Reasons for your physician to request an exercise ECG include, but are
not limited to , the following:
to determine limits for safe exercise in patients who are
entering a cardiac rehabilitation program and/or those who are
recovering from a cardiac event, such as a heart attack
(myocardial infarction, or MI) or heart surgery
to assess leg pain with exercise (also called intermittent
claudication) in patients with suspected occlusion in the legs'
to evaluate blood pressure during exercise
to assess stress or exercise tolerance in patients with known or
suspected coronary artery disease
There may be other reasons for your physician to recommend an exercise
Risks of the Procedure
Because of the stress the heart incurs during the procedure, there is a
small chance for chest pain, heart attack, high blood pressure,
irregular heartbeats, dizziness, nausea, and extreme fatigue. Notify
your physician if you have the following conditions:
aneurysm – a dilation of a part of the heart muscle or the aorta
(the large artery that carries oxygenated blood out of the heart
to the rest of the body) which may cause a weakness of the
tissue at the site of the aneurysm
unstable angina (uncontrolled chest pain)
severe heart valve disease
severe congestive heart failure
recent myocardial infarction (also called MI, or heart attack)
severe hypertension (high blood pressure)
uncontrolled irregular heartbeats
pericarditis (an inflammation or infection of the sac which
surrounds the heart)
severe anemia (low red blood cell count)
If you are pregnant or suspect that you may be pregnant, you should
notify your physician.
Prolonged application of the adhesive electrode patches may cause tissue
breakdown or skin irritation at the application site.
There may be other risks depending upon your specific medical condition.
Be sure to discuss any concerns with your physician prior to the
Certain factors or conditions may interfere with or affect the results
of the test. These include, but are not limited to, the following:
intake of a heavy meal, caffeine, and/or smoking prior to the
high blood pressure
electrolyte abnormalities, such as too much or too little
potassium, magnesium, and/or calcium in the blood
heart valve disease
enlarged left ventricle
Before the Procedure
Your physician or the technician will explain the procedure to
you and offer you the opportunity to ask any questions that you
might have about the procedure.
You will be asked to sign a consent form that gives your
permission to do the procedure. Read the form carefully and ask
questions if something is not clear.
You will be asked to fast for a few hours before the procedure.
You should not smoke for two hours prior to the procedure.
If you are pregnant or suspect that you may be pregnant, you
should notify your physician.
Notify your physician of all medications (prescription and
over-the-counter) and herbal supplements that you are taking.
Wear flat shoes that are comfortable for walking and
loose-fitting pants or shorts. Women should wear a short-sleeved
top that fastens in the front for ease of attaching the ECG
electrodes to the chest.
The area(s) where the electrodes are to be placed may be shaved.
Based upon your medical condition, your physician may request
other specific preparation.
During the Procedure
exercise ECG may be performed on an outpatient basis or as part of your
stay in a hospital. Procedures may vary depending on your condition and
your physician’s practices.
Generally, an exercise ECG follows this process:
You will be asked to remove any jewelry or other objects that
may interfere with the procedure.
You will be asked to open your blouse or shirt in the front (men
may be asked to remove their shirts). The technician will ensure
your privacy by covering you with a sheet or gown and exposing
only the necessary skin.
If your chest is very hairy, the technician may shave small
patches of hair, as needed, so that the electrodes will stick
closely to the skin.
Electrodes will be attached to your chest and abdomen.
The lead wires will be attached to the skin electrodes.
Once the leads are attached, the technician may key in
identifying information about you into the machine's computer.
A blood pressure cuff will be attached to your arm while you are
sitting down. Initial, or baseline, ECG and blood pressure
readings will be taken while you are sitting down and standing
You will be instructed on how to walk on the treadmill.
Alternately, you may exercise on a bicycle. You will be told to
let the technician, physician, or nurse know if you begin to
have any chest pain, dizziness, lightheadedness, extreme
shortness of breath, nausea, headache, leg pains, or other
symptoms during exercise.
You will begin to exercise at a minimal level. The intensity of
the exercise will be gradually increased on the treadmill by
increasing the incline and speed of the treadmill every few
ECG and blood pressure readings will be taken periodically
during the exercise to measure how well your heart and body are
responding to the exercise.
The exercise will end once you have reached a target heart rate
(determined by the physician based on your age and physical
condition). The test may also be stopped if you develop severe
symptoms such as chest pain, dizziness, nausea, severe shortness
of breath, severe fatigue, or elevated blood pressure.
Once you have reached your target heart rate, the rate of
exercise will be slowed for a "cool down" period to help avoid
any nausea or cramping from sudden stopping of exercise.
You will sit in a chair and your ECG and blood pressure will be
monitored until they return to normal or near-normal. This may
take 10 to 20 minutes.
Once your ECG and blood pressure readings are acceptable to the
physician, the ECG electrodes and blood pressure cuff will be
removed. You may then put on your shirt or blouse.
After the Procedure
You should be able to resume your normal diet and activities,
unless your physician instructs you differently.
Generally, there is no special care following an exercise ECG.
You may feel tired for several hours or longer after the
procedure, particularly if you do not normally exercise.
Otherwise, you should feel normal within a few hours after the
procedure, if not sooner. If your fatigue lasts longer than a
day, you should notify your physician.
Notify your physician if you develop any signs or symptoms you
had prior to the test (e.g., chest pain, shortness of breath,
dizziness, or fainting).
Your physician may give you additional or alternate instructions
after the procedure, depending on your particular situation.
The content provided here is for informational purposes only,
and was not designed to diagnose or treat a health problem or
disease, or replace the professional medical advice you receive
from your physician. Please consult your physician with any
questions or concerns you may have regarding your condition.
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