A nuclear stress test is suggested for patients with suspected coronary or heart diseases, in order to measure the rate of blood flow to the cardiac muscles. Medically referred to as Myocardial Perfusion Imaging, it helps in detecting weakened heart muscles and portions that receive low amount of blood, lesser than what is required for normal functioning of the cardiac muscles. Before we discuss the test results, let's try to understand about the basics of this imaging test procedure.
What is a Nuclear Stress Test?
If you consider the test procedure, it is nearly identical to the regular exercise stress test or echo stress test. The difference lies in the usage of safe traces of radioactive material (thallium) for imaging. This trace material is used for imaging purposes. Also known as thallium stress test, radioactive imaging test is carried out under two conditions, one at rest and another, after exposing the body to stress.
The cardiac stress test procedure is developed with the fact that a slightly blocked arterial vessel may be able to supply adequate blood to the cardiac muscle during rest. However, when the body is subjected to stress, the same narrowed artery is not able to increase blood flow, which is required at the moment. Thus, with reference to the nuclear stress test results, the doctor can tell how efficient the heart is during rest and while performing exercise.
During the test, a prospective candidate will be asked to perform treadmill exercise or a medication is administered in specific dose for inducing controlled stress. Usually, medicine is given to people, who are not in a position to perform optimal physical activities. As medication (not exercise) is involved for the procedure, this particular test is known as chemical stress test. With this, the doctor will be able to compare the images of coronary blood circulation during rest and while performing exercises.
The thallium stress test results are normal, if the blood supply by the coronary arteries to the cardiac muscles during resting period and exercising is optimal. If such is the case, the candidate has a healthy heart and normal blood circulation. He/she is less likely to develop coronary artery disease in the immediate future.
For people who have normal blood flow during rest, and reduced blood flow during exercise, it is concluded that there is a blockage of one or more coronary arteries. The doctor will recommend further diagnostic procedures to identify the blocked parts. Another case of abnormal result is low blood flow, in both the situations; during rest and during exercise. This lack of blood circulation may be because of coronary artery diseases or other heart diseases.
The nuclear tests results are also abnormal, if some of the cardiac muscles lack radioactive dye. The reason for this is, dead cardiac tissues, which may be caused due to previous stroke or heart attack incidences. For people showing abnormal results, a coronary angiography procedure is usually conducted for diagnosing underlying heart problems. As per the results, the doctor may explain the optimal exercise level suited for the patient to maintain fitness.
Precisely, the test results are helpful for detecting the severity of coronary artery disease. In asymptomatic individuals, this test helps in identifying whether they are at the risk of developing a coronary condition in the near future or not. Nevertheless, this diagnostic procedure may be associated with certain cons. In some cases, the adverse effects are severe and irreversible. Thus, knowing the probable side effects of such a test is of utmost importance for every prospective candidate.