A nuclear stress test is a nuclear cardiology test that allows doctors to view images of your heart with a special camera. The purpose of a stress test is to identify problems with the blood supply to the heart muscle or the coronary arteries that supply it with blood.
It uses a radioactive dye and a machine to create images that show blood flow to the heart. The test analyzes measures blood flow while doing sports and at rest. It can identify problem areas with poor blood flow or damaged parts of the heart.
A radioactive tracer is injected into the patient intravenously to capture two sets of heart images: one during stress and one while at rest.
Sometimes the nuclear stress test is done in combination with other types of tests. A nuclear stress test can help better determine your risk for a heart attack or other cardiac event compared to a classic stress test.
Why Would a Doctor Order a Nuclear Stress Test?
If a patient exhibits shortness of breath or chest pain while performing a regular stress test, he may need a nuclear stress test.
These types of tests can also be done to treat certain heart conditions. The methods by which a doctor may recommend a nuclear stress test are:
Diagnose coronary artery disease. The coronary arteries are the main blood vessels that supply blood to the heart. Coronary artery disease is the most common type of heart disease.
Guide the treatment of cardiac disorders. A nuclear stress test is used to monitor treatment for heart disease.
Nuclear Stress Test Side Effects
Complications in a nuclear stress test are infrequent. However, there are risks such as:
Allergic reaction. Although it is not common, there are cases of allergy to the radioactive dye injected during the test.
Abnormal heart rhythms (arrhythmias). Arrhythmias may appear during the stress test, which generally disappear when activity ceases. The risk of death from arrhythmia is sporadic.
Heart attack. A stress test can cause a heart attack, but it is scarce.
During exertion, dizziness or chest pain may appear.
Low blood pressure. Blood pressure can drop during or immediately after exercise.
Nuclear Stress Test Prep
The hospital center will give you specific instructions on how to prepare for the test. The most common indications are:
Do not eat or drink anything for a few hours before the test.
Do not smoke a few hours before the stress test.
Do not drink caffeine for 48 hours before the test.
If you take any medication, ask your doctor if it is safe to continue taking it, as in some cases, they can interfere with some stress tests.
Indicate if you use an inhaler due to a respiratory problem.
Wear comfortable clothes and sports shoes.
On the stress test day, do not use lotions, creams, or oils on the skin.
What Is a Nuclear Stress Test Like?
Generally, a nuclear stress test is performed in conjunction with a regular stress test, in which the patient pedals on an exercise bike or walks on a treadmill. If the patient is unable to exercise, the medical staff administers an intravenous medication that causes increased blood flow to the heart.
What Is the Duration of a Nuclear Stress Test?
The duration of a nuclear stress test is about two hours or more. The total time of the test depends on the imaging tests used and the radioactive material.
Test Preparation
First, the doctor talks with the patient to inquire about some aspects of his medical history. He will also listen to the heart and lungs to make sure there are no problems with the test.
Typically, the doctor asks the patient if they usually exercise, how hard, and how often to determine the appropriate amount of exercise during the test.
Steps of a Nuclear Stress Test
During the nuclear stress test, the following steps are performed:
A cuff is worn to monitor the patient's blood pressure during the stress test.
A technician places an IV line in the patient's arm to inject a small amount of radioactive dye. When the radiotracer is introduced, the patient might feel a cold sensation. It generally takes 20 to 40 minutes for heart cells to absorb the radiolabel.
The patient lies on a table, and the machinery will capture the first series of images of the heart at rest.
A technician places electrodes on the patient's arms, legs, and chest. The electrodes are used to record the electrical signals that activate the heartbeat. Sometimes the patient is asked to breathe through a tube to control breathing during physical activity.
The patient begins physical activity by pedaling an exercise bike or running on a treadmill. The action starts with a low intensity that is gradually increased.
Exercise stress test ends when the heart rate has reached a set target, or the patient begins to have symptoms that prevent them from continuing.
At maximum heart rate, the technologist re-injects another dose of the radiotracer intravenously.
After 20 to 45 minutes, the patient lies back on a table to capture the second set of resting images of blood flow in the heart.
Possible Nuclear Stress Test Results
The different options that a nuclear stress test can yield are:
Normal blood flow at rest and at maximum intensity. It means that you probably won't need any more tests.
Normal blood flow at rest but altered with high pulsations. In this case, the patient may have a blocked artery, known as coronary artery disease.
Low blood flow during exercise and at rest. A previous heart attack or severe coronary artery disease could explain this case.
If it is observed that there is a lack of radioactive dye in parts of the heart, it may be that these areas of the heart have tissue damage caused by a heart attack.
