Myocardial Perfusion Scan

This is a test that uses very small doses of radioactive substance to obtain images of the heart. When the scan is combined with a stress test, areas of the heart that do not get enough blood (due to narrowing of the coronary arteries) will show less activity than areas that have adequate blood supply. Usually 2 sets of pictures are acquired: one at rest and the other one at peak stress (not necessarily in that order). The comparison between the 2 sets of images improves accuracy of the results.

The resting images demonstrate normal perfusion of the left ventricular walls. On the stress pictures there is an obvious defect (arrows in all three views). In this patient the blood supply to the left ventricle is normal at rest, in spite of severe stenosis in one of his coronary arteries. Usually at peak stress the blood supply to the heart increases. Because of the severe coronary blockage, one area does not get enough blood supply and the perfusion defect in noted. This represents “ischemia” (lack of oxygen to the heart muscle) and may manifest itself with symptoms of angina.

Preparation for the Test

Your doctor should tell you whether to take all your regular medications prior to the test (certain types of medications may be held 24-72 hours prior to the stress test)

On the day of the resting scan you will be able to eat, drink and take your medications as usual.

On the day of the stress test you should:

• Not drink caffeinated beverages (coffee, tea, soda) after midnight.

• Not eat or drink anything for at least 4 hours before your test. If you are diabetic, check with your doctor for any other instructions.
  

• Wear comfortable walking shoes and clothing (slacks, shorts, gym suits are OK).
  

• Bring a list of your current medications.
  

What to Expect:

During the stress stage, a technologist will ask you to fill out a questionaire about your demographics, risk factors for heart disease and your heart disease history. Electrodes will be put on your chest and intravenous line be started. According to the type of stress test that was prescribed for you by your doctor, you will either walk on a treadmill (exercise stress, see section “stress test”) or be given a pharmacologic stress with one of 2 types of medication: either Adenosine (this
medication dilates blood vessels which help differentiate normal from abnormal arteries around the heart. Injection time: 3-6 minutes; recovery in 1-10 minutes) or Dobutamine (this drug is given more slowly and gradually in order to reach certain heart rate at a level that stresses the heart. Injection time: 10-25 minutes, recovery in 10-40 minutes). In both cases at peak stress a small amount of radioactive tracer will be injected, and 10-60 minutes following the injection the
post stress images will be obtained using a special instrument (called Gamma Camera).

The resting part is simpler: Through an intravenous line the tracer will be injected and the pictures obtained within 30-60 minutes.

Gamma Camera and Imaging

You will be lying on a narrow bed with one arm strapped above your head. The camera has a rotating head that will turn 180° around your chest and will acquire pictures for 10-30 minutes. This process will take place with the 2 sets of pictures (at rest and following the stress part). The processing of the data by the technician may take 20-30 minutes and include assessment of the heart function (ability of the heart to perform as a pump), and perfusion (how much of the needed blood is delivered to the heart muscle to perform it’s duty).

Safety and Side Effects

Exercise stress test has a very long track record of safety in large number of patients. Very rarely severe side effects may occur. With pharmacologic stress test (either Adenosine or Dobutamine) side effects are more frequent (although usually not severe enough to terminate the test prematurely) and include chest pains, shortness of breath, warm feeling, dizziness, arrhythmias, etc. The injection of radioactive tracer may cause a short “funny taste” for 1-3 seconds after injection. The radioactive material is given in such a small dose, that no
side effects to adults are expected. However, in order to avoid a potential
risk to a fetus (unborn baby), a pregnancy test will be performed on every woman with a capacity to become pregnant.

Your Test Results

Test results will be faxed/mailed to your doctor within 24 hours of termination of the scans. Your doctor is expected to discuss them with you during a future office visit.

Where to Contact

Please contact our office at (414) 649-3366 or (414) 219-3317 for more details about indications, details of your procedure, diagnostic capabilities, or any other questions related to myocardial perfusion scan or other radionuclide (isotopic) studies of the heart.

return to top of page