What is myocardial perfusion imaging?

A myocardial perfusion image measures the blood flow and function of the heart. People who have this test are usually given a tracer, or a small amount of a radioactive substance, to be used to track heart problems. The healthy tissues of the heart will absorb the radioactive material and the damaged tissues will be highlighted. Decreased blood flow to damaged areas of the heart may be one reason why the substance is not properly absorbed from these areas. This test can be used to diagnose heart disease and assess the progress of an individual with an existing condition.

An abnormal electrocardiogram (EKG) may indicate the need for myocardial perfusion imaging. The test can show if there is any structural damage inside the heart. People who have cardiac symptoms, such as shortness of breath, excessive fatigue from physical activity, and chest pains, may have this image done as a screen for heart disease that may develop in the future. Also, some doctors may use the test to determine the success of surgery, such as confirming the accurate placement of a surgical device such as a coronary stent.

There are many heart problems that can be shown by myocardial perfusion imaging. Any scar tissue resulting from a heart attack can be seen. The ability of the heart to pump blood adequately can be measured and the arteries can be seen and evaluated. A camera that produces images based on gamma rays emitted by the tracer or radioactive substance is used to take detailed pictures of the heart. Photographs will be taken at various intervals during the test.

In general, the test will have two parts. The first part will assess the heart at rest, while the second part, commonly known as stress myocardial perfusion imaging, will assess the heart in a stressed environment. In general, the stress test is performed by having the patient walk on a treadmill. People who cannot participate in physical exercise may receive adenosine myocardial perfusion imaging. In this procedure, the patient will receive a medication called adenosine to put the heart into a stressed state, similar to that seen in a stress test.

The rest and stress test can be completed on the same day or on different days. The test is usually done on an outpatient basis, but it can also be done on an inpatient basis. Pictures will be taken after each part of the test and then compared. In general, there should not be a significant difference in the images of the two scenarios of a healthy heart. Significant differences may indicate a problem.

Preparation for myocardial perfusion imaging can vary. When preparing for the test, the doctor will need to be aware of conditions that may interfere with the test, such as pregnancy, current medications taken, and allergies to any new medications that may be given during the test. In general, patients will be asked not to eat within a certain period of time before having the image done. After the test, an individual may experience nausea, fatigue, a headache, or some chest discomfort.

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