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Exercise Stress Test
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What is the test?
The exercise stress test,
also known as the treadmill test or exercise tolerance test, indicates
whether your heart gets enough blood flow and oxygen when it's working
its hardest, such as during exercise. Often, stress tests are given
to people with chest pain or other symptoms who appear to have coronary
artery disease, based on a medical exam and EKG. In addition, these
tests are sometimes used for other purposes, from assessing the effectiveness
of heart disease treatment to gauging the safety of a proposed exercise
program.
Stress tests are among
the best tools for diagnosing heart disease, and some research
suggests that they may also be useful in estimating disease risk
in people who don't have symptoms but have risk factors such as
high cholesterol. If you are over age 40 and are at risk for coronary
artery disease because you smoke or have high blood pressure or
other risk factors, ask your doctor if you should have this test.
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How do I prepare for
the test?
Wear comfortable, loose-fitting
clothing and athletic shoes. Let the doctor performing the test
know if you think that you won't be able to walk on a treadmill
for any health reason, such as arthritis. Also let the doctor know
if you have diabetes; since exercise can lower blood sugar, he
or she may want to check your blood sugar level before the test
begins, to be sure it is not too low (see
"Diabetes alert," below). It's also important to tell the doctor
or other health professional in the testing room if you've had
any chest pain or pressure on the day of the test. Try to avoid
eating a large meal right before the test, which could make exercising
uncomfortable.
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What happens
when the test is performed?
First you have an EKG
both while lying down and standing up. Your blood pressure is taken.
Several plasticcoated wires, or leads, are taped to your arms and
one leg so that your heart's electrical pattern can be detected
while you exercise.Your blood pressure and heart rate also are
monitored during the test. You are asked to walk on a treadmill
for about 10 minutes. The speed and steepness of the treadmill
will increase several times while you exercise. Let the person
who is monitoring you know immediately if you feel chest pain or
heaviness, shortness of breath, leg pain or weakness, or other
unusual symptoms, or if you think you can't continue exercising.After
the exercise period is completed, your blood pressure will be checked
again.
A variation of this test
uses a radionuclide to visualize parts of the heart that are not
getting enough blood. This test is called either an exercise-thallium
test or exercise-MIBI test (depending on the radionuclides used).
If you have this test, you will probably need to repeat it on a
day when you have not been exercising hard, for the sake of comparison.
An exercise stress test
strongly suggests coronary artery disease if walking on the treadmill
produces symptoms such as chest discomfort, shortness of breath,
or dizziness, and these symptoms are accompanied by EKG changes
that indicate inadequate blood flow to parts of the heart. A test
is considered normal if you can perform a normal amount of exercise
without symptoms or EKG changes. Many people have chest discomfort
but no EKG changes, or vice versa. In these cases, the exercise
test is of less help, and the result will be interpreted as consistent
with coronary artery disease, but not conclusive. Further testing
may then be required.
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What risks are
there from the test?
If you have cardiac disease,
you might develop chest pain during the test. Because this is a
sign that your heart isn't getting enough oxygen and could be in
danger of damage, it's important that you alert the medical staff
immediately so that the test can be stopped. While many people
worry that an exercise stress test could be dangerous to someone
with heart disease, it is extremely safe if doctors examine patients
beforehand to make sure that they are healthy enough for it.
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Must
I do anything special after the test is over?
If your blood pressure becomes
unusually high, or if it suddenly drops during exercise, a nurse will
recheck your blood pressure a few minutes after the test and may continue
to monitor your EKG. If you develop chest pain, you might be given
some nitroglycerin tablets to relieve the pain and lower the demand
on your heart by dilating your blood vessels.
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How
long is it before the result of the test is known?
It usually takes several
days for the doctor to completely evaluate the printout of your
heart's electrical pattern.
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