What is a nuclear scan?
A nuclear scan is a method of examining the heart in order to get
information about the blood supply to the heart muscle. Special cameras
take a series of pictures of the heart during the scan. A radioactive
substance, or tracer is injected into the bloodstream.
The tracer attaches to certain cells and makes them visible to the special
camera. The tracer attaches to the muscle cells of the heart so the
imaging camera can take pictures of the heart muscles. If an area of the
heart does not have a good blood supply, then the cells in that area will
not receive as much tracer. This will show up as a darker area on the
picture taken by the camera.
Patient preparation
To prepare for the nuclear stress test, do not eat or drink after
midnight. Please do not drink or eat anything containing caffeine for 48
hours before the test; this includes decaffeinated coffee, pops, teas, and
chocolate. Please do not smoke on the day of the test. If you are
diabetic, you will need special instructions from your doctor or the
clinic nurse. All patients should bring a list of current medications they
are taking to assist the staff.
During the examination
Once an intravenous (IV) line is started a small amount of the radioactive
tracer is injected into the bloodstream. After allowing
time for the tracer to circulate the first pictures will be done. You
will lie flat on a table with your arm above your head. The technologist
will help you get comfortable. A large imaging camera will be brought
close to your chest for the scans. A technologist will make the necessary
adjustments and the imaging will begin. It is important to lie still
during the scan. A technologist will be nearby if you need anything. This
part of the scan lasts about 25 minutes. This set of pictures will show
blood flow to the heart muscle in the resting state.
Next you will walk on the treadmill, let
the staff know when you are tired and only able to continue about another
minute. The technologist will then inject a second
radioactive tracer. After approximately an hour the second set of pictures
are completed. This second set of pictures will show blood flow to the
heart muscle in an exercise state. Results are achieved when the two sets of pictures are
compared. You can expect the entire test to take approximately 2 to 3
hours.
What does the
nuclear stress test show?
- If the test is normal during both
exercise and rest, then blood flow through the coronary arteries is
normal.
- If the test shows that perfusion is
normal during rest but abnormal during exercise (a perfusion
defect), then the heart isn’t receiving enough blood in when it
has to work harder than normal. This may be due to some blockage in
one or more coronary arteries.
- If the test is abnormal during both
exercise and rest, there’s limited blood flow to that part of the
heart at all times.
- If no tracer is seen in some part
of the heart muscle, it means that this part of the heart has had a
previous heart attack and the cells are dead. (They have become scar
tissue.)
What if I can’t perform an exercise
test?
Occasionally someone can’t do an exercise test because they’re too
sick or have physical problems. In this case, a drug such as adenosine is
given to the patient instead of performing an exercise test. This drug
increases blood flow to the heart and thus “mimics” the exercise
test.
Is the
nuclear stress test dangerous?
It is unlikely that you will feel any
effects from the injection. The amount of radiation you will be exposed to
is no more than you would receive from other x-ray tests and is not
harmful to you. However, if there is any chance you might be pregnant,
please notify your doctor.
Where should I go for my
nuclear stress test?
Please report to the St. Alexius Medical
Center admission’s area located on 10th Street. They will then direct you to the Radiology / Special Imaging department where you will be
checked in.
How will I get my results?
Your doctor will be given the results of
your test within one to two days. You will be contacted by telephone by
your doctor or a return visit may be scheduled to discuss the results. If
you encounter any problems after your test, or if you have any questions,
please contact your doctor’s office or the clinic nurse.
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