Nuclear Stress Test
A nuclear stress test, also known as Myoview, is performed for the purpose of diagnosing coronary artery disease. This test assesses blood flow to various portions of the heart muscle at rest and during exercise. During the test a tracer, called Tetrafosanin, is injected into the patient’s bloodstream The tracer will accumulate in the parts of the heart muscle that have good blood flow, however if a coronary arteries is blocked, or partially blocked, due to a narrowing, not as much of the tracer will collect in the muscle. Using Tetrafosanin increases the accuracy of the stress test in diagnosing coronary artery disease.
During this procedure, the patient lies on the examination table, while a gamma-ray camera moves around the chest area to take pictures of the heart. The stress test begins one hour after the first set of pictures has been taken. The technician places small disks, called electrodes, on the patient's chest; these electrodes are attached to wires (or leads) that are connected to an electrocardiogram (ECG) machine to record heart activity during the test. The patient may then be asked either to exercise on the treadmill, causing the arteries to open up and deliver more blood, or be given (through a vein in the arm) a medication called Persantine that will dilate the coronary arteries to produce an effect similar to exercise. A doctor will supervise the exercise or the Persantine part of the procedure, while the technologist takes more pictures. The tetrafosanin tracer is then administered a few minutes later through the same vein when the maximum level of exercise is attained. The parts of the heart muscle that do not have an adequate blood supply will pick up the tracer very slowly or not at all. The test is completed when the final set of pictures has been taken.
The scans created by the gamma camera can detect the Tetrafosanin, thus enabling a doctor to locate the areas of the heart muscle that are not receiving enough blood supply, or areas of the heart that are permanently damaged from a heart attack.
Patients are advised not to eat any foods or drinks containing caffeine or nicotine before and during the procedure so as not to obscure the pictures.
This test takes approximately 4 to 5 hours to complete.
Special Note: The radiation exposure from the Tetrafosanin tracer used during this test is minimal and the doses are safe