Myocardial perfusion imaging

Myocardial perfusion is an imaging test. It’s also called a nuclear stress test. It is done to show how well blood flows through the heart muscle. It also shows how well the heart muscle is pumping. For example, after a heart attack, it may be done to find areas of damaged heart muscle. 

A myocardial perfusion scan uses a tiny amount of a radioactive substance called a radioactive tracer. The tracer travels through the bloodstream and is absorbed by the healthy heart muscle. On the scan, the areas where tracer has been absorbed look different from the areas that do not absorb it. Areas that are damaged or don’t have good blood flow do not absorb tracer. 

A stress myocardial perfusion scan assesses blood flow to the heart muscle when it is stressed. The heart can be stressed with exercise or if unable to exercise a medication can be used. 

After the radioactive tracer is injected, a special type of camera is used that can detect the radioactive energy being released. You will be imaged at rest and then again after your heart has been stressed. The two sets of images are then compared.

Why might I need a stress myocardial perfusion scan?
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Your doctor may order a stress myocardial perfusion scan for:

  • Chest pain, either new onset or occurring over a period of days or longer. 
  • To diagnose coronary artery disease (CAD), narrowing of the coronary arteries. 
  • After a heart attack to assess heart muscle damage. 
  • To assess blood flow to areas of the heart muscle after coronary artery bypass surgery, angioplasty, or stent placement. 
  • There may be other reasons for your physician to recommend a stress myocardial perfusion scan.
What are the risks of a stress myocardial perfusion scan?
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  • The exercise part of the test may lead to rare instances of abnormal heart rhythms, chest pain, or heart attack due to the stress on the heart caused by exercise. 
  • The needle used to put in the IV for the injection of the radioactive tracer may cause slight discomfort. Allergic reactions to the tracer are rare. 
  • At Spectrum Health we strive to keep the radiation exposure as low as possible.
How do I prepare for a stress myocardial perfusion scan?
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  • Certain factors may interfere or affect the results of the test. They include, but are not limited to medications containing theophylline, caffeine, nitrate medications, or medications that slow the heart rate. 
  • If you are pregnant or think you may be pregnant or breastfeeding, please check with your doctor before scheduling the exam. 
  • No food or drink for four hours prior to the test. You may have water. 
  • If you are scheduled for a myocardial perfusion scan with medication (pharmacological), you will need to avoid taking any medications containing theophylline or caffeine. Coffee, even decaffeinated, is not allowed, as it contains some caffeine. Nothing with caffeine for 12 hours. Medications for asthma may contain theophylline. If you have asthma, inform your doctor. Theophylline should be stopped for 48 hours. 
  • Please dress comfortably with comfortable shoes. Leave jewelry and valuables at home. 
  • Based on your medical condition, your doctor may request other specific preparation.
What should I bring to my appointment?
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  • Insurance cards 
  • A current list of medications (prescription and over the counter) you are taking. 
    • Please include how much you take (dose in milligrams) and how often you take them.
What happens during a stress myocardial perfusion scan?
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Generally, a stress myocardial perfusion scan follows this process: 

  • An intravenous (IV) line will be started in your hand or arm. You will be injected with the radioactive tracer, wait approximately 30 minutes and then be placed under the camera for resting images. 
  • You will be asked to remove any jewelry or other objects that may interfere with the procedure. 
  • If you have any symptoms during the exam such as dizziness, chest pain, extreme shortness of breath or severe fatigue notify the healthcare provider or technologist.
Exercise scan
  • After resting images. You will exercise on the treadmill. The intensity of exercise is gradually increased. 
  • Your heart rate and blood pressure will be monitored. Once you have reached your maximal exercise point the radioactive tracer will be injected into your IV line. 
  • After the tracer has been injected, you will continue to exercise for several minutes. 
  • After a short wait you will be placed under the camera for stress images.
Pharmacological scan
  • After resting images. If you are unable to exercise on the treadmill you will be given a medicine into your IV that will dilate your blood vessels similar to exercise. 
  • Your heart rate and blood pressure will be monitored. 
  • The tracer will be injected into your IV line. 
  • After a 30 minute wait you will be placed under the camera for stress images.
Imaging, both methods
  • You will lie flat on a table while the images of your heart are taken. 
  • Your arms will be on a pillow above your head. You will need to lie very still while the images are being taken, as movement can affect the quality of the images. 
  • After both sets of images the IV line will be removed.
How long does the test take?
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Three to four hours

What happens after a stress myocardial perfusion scan?
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Drink plenty of fluids and empty your bladder often for 24 to 48 hours after the test. This helps flush the remaining radioactive tracer from your body. When the test is complete, a cardiologist will review your results and enter them into your electronic medical record. Your primary physician will then be notified of the results. The testing staff will be unable to provide you with your results.

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