What is it?
A nuclear stress test measures the blood flow to your heart both at rest and during stress on the heart during exercise.
This test provides images of the amount of blood flow in all sections of the heart, which can show areas of low blood flow and damaged tissue.
Why do I need it?
How do I prepare for a test?
Avoid all caffeinated products for 12 hours before the test. This includes decaffeinated coffee, coffee, tea, soda. Avoid fatty foods as well as dairy products including butter, milk, and cheese. Fatty foods can alter the imaging results.
Continue your medications up to the day of the procedure. On the day of the test,
Stop these drugs:
Beta blockers (Atenolol, Toprol, Metoprolol, Lopressor, Coreg, Zebeta, Betapace, or Corgard)
Ask your doctor how much insulin you should take the day of the test. Your doctor may recommend you to only take half of the usual morning dose and to eat a light meal 4 hours before the test.
Do NOT take your diabetes medication and skip a meal before the test.
- If you have asthma and use an inhaler, bring it with you to your test
- Do Not smoke on the day of the test… or ever!!!
- Do not apply body lotion on the day of the test
- If you need to cancel your appointment please do so at least 24 hours prior to your test or you may be charged.
What should I expect during the test?
First, a nuclear medicine technologist will place an I.V. into your arm or hand.
You may be injected with an isotope called Cardiolite that allows us to pick up your blood flow on camera.
After this is injected, you will wait about 30 minutes before the first set of “Resting” images are taken.
You will be asked to lie under a gamma camera with both arms above your head for 15-20 minutes. This camera will capture the images of the blood flow through your heart at rest.
Next, the technician will place electrodes on your chest, arms, and legs. These electrodes connect to wires on an electrocardiogram (EKG) machine. The EKG records the electrical activity of the heart.
If a pharmacological stress test has been ordered for you, you will then be injected with a pharmacological medication known as Lexiscan. This medication increases the blood flow to the heart to simulate exercise. This does NOT increase your heart rate, only dilates the vessels as if you were exercising.
Your blood pressure and EKG will be monitored throughout the test.
During the test you may develop symptoms or signs of:
- High or low blood pressure
Finally, after a 30-60 minute breakfast or lunch break you will be asked to again lie under the camera with both arms above your head for 15-20 minutes. The camera will capture the “exercise” images of the blood flow through your heart.
This set of images will be compared to the resting images.
The entire test will take about 3-4 hours.
Once your nuclear stress test is complete, you may return to your normal activities, eating habits, and medications.
What are the risks?
Nuclear stress tests are generally safe and complications are very rare. Although with any medical procedure, it does carry a small risk of complication.
These complications include:
- Infection at the site of intravenous puncture.
- Allergic reaction although uncommon, may be due to the radioisotope injected.
- Hypotension: blood pressure may fall during or after exercise that can cause dizziness.
- Abnormal heart rhythms may occur during exercise. This returns to normal once exercise is ceased.
- Chest pain or flushing feeling may occur from the medication or if you have coronary artery disease.
- As with all radiologic procedures, it is important to inform your physician and technologist if you are pregnant. Radiation exposure during pregnancy should be kept to a minimum.
Dr. Jamnadas or Dr. Kelly will review the results of your nuclear stress test before your next office visit, not the same day as the test.
The results of the test will compare the images of the heart at rest and during exercise.
Interpretations of the results:
- Normal blood flow both at rest and exercise- it is unlikely you have coronary artery disease. No further work up is needed.
- Normal blood flow at rest and an abnormal blood flow during exercise- means part of your heart muscle is Not receiving adequate blood when you are exercising or during strenuous activity. You may have coronary artery disease; a blocked artery. Alteration of medication may be needed.
- Low blood flow at rest and exercise – means a significant amount of your heart is not getting enough blood flow. You may have had a previous heart attack or severe coronary artery disease. Further cardiac evaluation may be needed using a cardiac catheterization and coronary angiography.
In patients with mild to moderate blockage blood flow is not restricted. Usually only coronary blockages of >70% restrict blood flow and will usually show up on a nuclear stress test.
A nuclear stress test showing mild to moderate blockages usually do not show up on a nuclear stress test and do Not need stenting or bypass. This can be cured by lifestyle and preventative changes.