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Nuclear Stress Test
What is it?
A nuclear stress test is a common test
that doctors use to diagnose coronary artery disease or to
determine if there is a lack of blood flow to your heart as it
relates to previously known blockages. This test uses a
radioisotope injected into the blood stream during a normal
resting state and then a second dose during the stress test. Two
images are taken of your heart with a Gamma camera within two
hours of having each injection.
A comparison is made between the two images which
determines whether or not you have significant blockages in the
heart arteries which are affecting the blood flow to the heart.
What should I expect?
You will be mailed or given detailed
instructions with the specifics about not eating or drinking
prior to the test and about bringing your medications and a
snack with you. In
general, do not eat or drink for 6 hours before the test.
DO NOT HAVE items that contain caffeine, which is found
in coffee, tea, sodas, chocolate, and some over-the-counter pain
relievers. Also, be sure to ask your doctor about any
medicines you are taking and whether you should stop taking them
before the test. There
are certain medications that can interfere with testing and
should be held 24 to 48 hours prior to testing. The nuclear
stress test takes between 4 and 5 hours to complete.The day of the test, you will initially
have your medication bottles reviewed, discuss the test, sign an
informed consent, and have your height and weight recorded.
You will have an IV started and a resting injection of
the radioisotope (nuclear medicine) will be administered.
It is not a dye and will not make you feel differently.
After that, you will be allowed to take your medications
if they do not interfere with the test, and eat breakfast.
YOU CAN NOT HAVE CAFFEINE UNTIL TESTING IS COMPLETED.
After about 45 minutes, a resting image
is taken. You will
either sit up or lie down on a Gamma camera and have a 15 minute
scan of your heart.
You must remain very still during this image or it will have to
be repeated.
Then you will have a 30 minute to 1 hour
wait before the stress test is performed.
You will be connected to a 12 lead EKG machine for the
stress test whether you walk on the treadmill or have a
pharmacological (or chemical) stress test.
Alcohol is used to clean the areas of
your skin where the electrodes will be placed. The alcohol
may feel cold. Next, electrodes will be placed on your
chest. The electrodes are attached to an electrocardiograph
machine, which records your heart’s electrical activity. A
healthy person’s electrocardiogram has a certain pattern, and
changes in that pattern can tell doctors if there is a problem
with your heart. You will also wear a blood pressure cuff around
your arm, which will be used to watch your blood pressure during
the test.
Before the stress test, your blood
pressure and pulse will be checked. They will also record your
heart’s electrical activity before you start exercising (called
a resting EKG).
If you have the exercise test, you will
walk on a treadmill to achieve a target heart rate.
Once that heart rate is achieved a second dose (or stress
dose) of the radioisotope (nuclear medicine) will be injected.
You will need to walk at least one minute following the
injection to let it circulate before stopping.
The nurse with you during the stress test
will increase the speed and slope of the treadmill every third
minute. He or she will look for changes in the electrocardiogram
patterns and blood pressure levels, which may tell doctors that
your heart is not getting enough oxygen. Other signs of coronary
artery disease include chest pain or unusual shortness of breath
while you are exercising.
If your doctor would rather you not
exercise, a medication can be administered with you lying on a
stretcher to achieve the stress test.
If you are not able to walk safely on the treadmill, have
certain ekg patterns, a pacemaker, or a defibrillator it may be
best to do the chemical stress test as opposed to exercise.
If you try the treadmill and cannot achieve the target
heart rate, then a chemical stress test will be necessary. The
radioisotope (nuclear medicine) is administered during that
chemical stress test.
At the end of the test, you will have a
cool-down phase and be asked to drink something cold prior to
the last scan of your heart.
That scan will be on the same Gamma camera you were on at
the beginning of the morning.
After the test is completely over, you may eat,
drink, and take all medications including those that may have
been held prior to testing.
You can go back to your normal activities.
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