Nuclear Stress Test - Cardiovascular Associates of Maryland
What is a nuclear stress test?
A nuclear stress test is an imaging study which takes pictures of the
heart muscle when it is at rest and after it has been stressed from
exercise. A radioactive isotope (called Myoview or Cardiolite) is
injected into the blood stream and travels through the heart arteries,
which allows the nuclear camera (or gamma camera) to capture images of
the heart muscle.
The heart is exercised by the patient walking on a treadmill. If the
patient is unable to exercise on the treadmill, a medicine called
Regadenoson (Lexiscan) or Dobutamine will be used to make the heart
muscle beat faster as if the patient were exercising.
Why is it useful?
The nuclear stress test is useful to determine:
- Extent of a coronary artery blockage
- Prognosis of patients who’ve suffered a heart attack
- Effectiveness of cardiac procedures done to improve circulation in coronary arteries
- Cause (s) of chest pain
- Level of exercise that a patient can safely perform
What happens during the test?
An I.V. will be placed in the arm vein and a technologist will inject
the radioactive isotope into the I.V. approximately 30 minutes after the
injection, the patient’s chest is scanned under the gamma camera which
takes pictures of the heart. During the scanning, the patient will lay
on a scanner table with arms placed above the head. The pictures take
about 15 minutes.
After the pictures have been taken, the patient will either walk on the
treadmill or receive Regadenoson (Lexiscan) or Dobutamine to exercise
the heart muscle. During the stress portion of the test, the patient is
injected with a second dose of isotope through the I.V. The patient then
has the second set of pictures taken under the gamma camera which
captures the images of the heart after exercising.
What does the test show?
- If the test is normal during both exercise and rest, then blood
flow through the coronary arteries is normal. The coronary arteries
supply blood to the heart muscle.
- If the test shows that perfusion (blood flow) is normal during
rest but not during exercise (a perfusion defect), then the heart isn’t
getting enough blood when it must work harder than normal. This may be
due to a blockage in one or more coronary arteries.
- If the test is abnormal during both exercise and rest, there is limited blood flow to that part of the heart at all times.
- If no isotope is seen in a certain part of the heart muscle, the
cells in this part of the heart may be dead from prior heart attack.
(They have become scar tissue.)
It is very important that you arrive on time for your test. The isotopes
ordered for each patient are different depending on the required dose
for that patient. The isotope loses its properties quickly, so if you
are late for your study you may be asked to reschedule if the isotope
can no longer be used.