Myocardial Perfusion Scan, Stress

Overview

What is a Myocardial Perfusion Scan, Stress?

A myocardial perfusion scan is a type of nuclear scan that uses very small amounts of radioactive materials (radiopharmaceuticals) to assess the heart's function and blood flow.

• myocardial perfusion scan, with exercise
  A myocardial perfusion scan, with exercise, is used to determine what areas of the heart muscle (myocardium) have decreased blood flow during exercise. This is done by injecting a radiopharmaceutical (thallium or technetium) into a vein in your arm or hand while you are exercising on a treadmill. After the radiopharmaceutical is injected into your vein and has circulated through your blood stream, a special machine called a gamma camera will take pictures of your heart while you lie still on a table. This scanning usually lasts about 30 minutes. Any areas of the myocardium that have blocked or partially blocked arteries during exercise will be seen on the scan as "decreased activity spots," or "defects," because these areas will be unable to take the radiopharmaceutical into the myocardium. A second set of scans is taken some hours later, at rest. The resting phase is done in order to compare the results with the exercise phase to see if areas that do not get adequate blood flow while exercising are able to absorb it during rest.
  
  
• myocardial perfusion scan, with pharmacologic intervention
  Your physician may determine that your condition is such that you cannot or should not exercise on a treadmill for this test, but he/she still wants to assess your heart muscle under stress. In this situation, when exercise is not an option, a myocardial perfusion scan with pharmacologic intervention may be done. In this type of scan, you are given a medication that causes the coronary arteries to dilate. This dilation of the coronary arteries increases blood flow and is very similar to the response of the arteries during exercise. A resting scan will be performed afterwards, just as with the actual exercise scan.

Reasons for the Procedure

Possible indications for an exercise or pharmacologic myocardial perfusion scan may include, but are not limited to, the following:

• chest pain, either new onset or occurring over a period of days or longer
  
  
• following a heart attack (Also called myocardial infarction, or MI.)
  
  
• to assess blood flow to areas of the myocardium that have been reperfused (coronary artery blood flow restored) by bypass surgery, angioplasty (the opening of a coronary artery using a balloon or other method), or stent (a tiny expandable metal coil placed inside the artery to keep the artery open)

Risks of the Procedure

The exercise portion of the test may have rare instances of abnormal heart rhythms, chest pain, or heart attack due to the stress on the heart caused by the exercise. The radioactive tracer is used in very small amounts and is considered safe.

NOTE: If you are pregnant or suspect you may be pregnant, or if you are a nursing mother, you should inform your physician.

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