A myocardial perfusion imaging measures the blood flow and function of the heart. Individuals getting this test usually receive a tracer or a small amount of a radioactive substance, that will be used to trace problems in the heart. Healthy heart tissues will absorb the radioactive material and damaged tissues will be highlighted by it. Decreased blood flow to the damaged areas of the heart may be one reason why the substance is not adequately absorbed in these areas. This test may be used to diagnose heart disease and to evaluate the progress of an individual with an existing disease.
An abnormal electrocardiogram (EKG) may indicate the need for a myocardial perfusion imaging study. The test can show if there is any structural damage within the heart. Individuals presenting with cardiac symptoms such as shortness of breath, excessive tiredness upon physical activity, and chest pains may have this imaging done as a screen for heart disease that may develop in the future. Additionally, some doctors may use the test to determine the success of a 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 heart's ability to adequately pump blood can be measured and arteries can be seen and evaluated. A camera which produces images based on gamma rays given off by the tracer or radioactive substance is used to take detailed pictures of the heart. Pictures will be taking at various intervals throughout the test.
Generally, the test will have two parts. The first part will evaluate the heart in a resting state, while the second part, commonly known as a stress myocardial perfusion imaging, will evaluate the heart in a stressed environment. Generally, the stress test is done by having the patient walk on a treadmill. Individuals not able to participate in physical exercise may be given an adenosine myocardial perfusion imaging. In this procedure, the patient will be given a drug called adenosine to put the heart in a stressed state, similar to that seen in a stress test.
The resting and stress test may be completed on the same day or on different days. Typically, the test is done on an outpatient basis, but it may be done inpatient as well. Pictures will be taken after each portion of the test and will later be compared. Generally, there should not be a significant amount of difference in the pictures of the two scenarios of a healthy heart. Significant differences may indicate a problem.
Preparation for a myocardial perfusion imaging may vary. In preparing for the test, the doctor will need to be made aware of conditions that may interfere with the test such as a pregnancy, current medications taken, and allergies to any new medication which may be given during the test. Generally, patients will be asked not to eat within a certain amount of time before having the imaging done. After the test, an individual may experience nausea, fatigue, headache, or some discomfort in the chest.