Nuclear Stress Test
Overview
Nuclear stress test uses nuclear medicine imaging to show how well blood flows to the heart muscle, both at rest and during physical activity. During the test, a healthcare professional gives a small dose of a radioactive tracer by IV.
Special cameras capture images of the heart as the material moves through the blood vessels. PET (positron emission technology) and SPECT (single-photon emission computed tomography) scanners provide detailed images to spot areas with limited blood supply or signs of previous damage.
If needed, doctors may order a nuclear stress test after a regular cardiac stress test or use it as the main method to check heart function. Other common names for this kind of test include:
- Cardiac PET study
- Cardiac SPECT study
- Myocardial perfusion imaging (MPI) study
Results from nuclear stress testing guide treatment planning and help identify heart attack risks.
Reasons for Performing This Test
Doctors often request a nuclear stress test when someone has symptoms such as chest pain or trouble breathing, which may point to coronary artery disease (CAD). The test shows whether enough blood and oxygen reach the heart during activity.
Key Purposes
- Diagnose Coronary Artery Disease (CAD): The test can find blockages or narrowing in the coronary arteries. This helps confirm if someone has CAD and shows how serious the problem might be.
- Evaluate Angina: If a patient has chest pain (angina), the test provides details on whether reduced blood flow is the cause.
- Monitor Treatment: For those already being treated for heart problems, the results can show if medicine or other treatments are effective.
- Treatment Planning: The test results guide the healthcare team to make adjustments or changes to the care plan based on how the heart manages stress.
- Assess Exercise Limits: It gives information about how much activity the heart can safely handle.
Possible Issues
A nuclear stress test carries some risks, though serious problems are uncommon. Irregular heart rhythms may occur, but usually go away after the test. Rarely, a heart attack might happen. Minor side effects may include:
- Chest pain
- Shortness of breath
- Fatigue
- Headache
- Nausea
- Flushing
- Anxiety
- Dizziness or feeling faint from low blood pressure
Here is a summary table of potential risks:
| Risk/Side Effect | Likelihood | Notes |
|---|---|---|
| Abnormal heart rhythms | Uncommon | Usually go away on their own |
| Heart attack | Very rare | Serious, but extremely unlikely |
| Chest pain | Sometimes | Mild, goes away after test |
| Shortness of breath | Sometimes | Typically short-lasting |
| Fatigue | Sometimes | Usually mild |
| Radiation exposure | Present | Small amount from the test |
People with a pacemaker should inform their doctor before the test. Most symptoms are short-term and do not cause lasting problems.
Steps for Getting Ready
What to Eat, Drink, and Take
- Most people need to stop eating, drinking, or smoking for a few hours before the test.
- Avoid all foods and drinks with caffeine the day before and the day of the procedure.
- Talk with your healthcare provider about any medicines you take. Some may need to be stopped or changed before the test. Never stop taking them without your provider’s approval.
- Bring your inhaler if you use one for asthma or breathing problems, and let the staff know about it.
Clothes and Things to Bring
- Wear loose, comfortable clothing and non-slip walking shoes.
- Do not put on skin products like lotion, oil, or cream the morning of the test.
- Bring any needed personal items, such as an inhaler or insulin, if it is a part of your routine care.
What You Can Expect
Before starting a nuclear imaging test of the heart, the healthcare team asks about the person’s health history, medications, and exercise habits to set safe goals. They also examine the heart and lungs for any concerns.
People usually receive instructions about what to avoid before the test. This may include not eating or drinking and skipping caffeine or certain medications. These guidelines reduce risk and improve test accuracy.
What Happens During the Procedure
The test usually takes a few hours. First, the technologist places sticky electrodes on the chest—and sometimes on the arms and legs—to monitor heart rhythm through an EKG (electrocardiogram). A blood pressure cuff is used to track blood pressure, and an IV line is placed in the arm.
A radioactive tracer, such as rubidium or technetium, is injected through the IV. The person may feel a brief cool sensation as the tracer moves to the heart muscle. Technologists take two sets of heart images with a gamma camera (or PET or SPECT scanners):
| Step | Action |
|---|---|
| Step 1: Rest | Lay still, first set of heart pictures taken |
| Step 2: Stress (Exercise) | Walk on treadmill or ride a stationary bike |
| Step 3: Second Tracer Dose | More radioactive tracer is given when heart rate is highest |
| Step 4: Stress Images | Second set of pictures taken after stress |
If the person cannot exercise, medicine like dobutamine or a vasodilator is used to increase heart blood flow, simulating physical activity.
During the stress portion, the healthcare team watches for abnormal heartbeats, changes in blood pressure, chest pain, or breathing trouble. The person may stop the test at any time. Sometimes, they are also asked to breathe into a tube to collect more information.
After the Procedure
After the final images, the healthcare team monitors heart rate and breathing for a short time. Most people can resume normal activities soon after. Drinking extra water helps remove the tracer through urine or stool. If needed, additional instructions will be provided. If results are unusual, the doctor will explain what steps to take next.
Test Outcome Details
A healthcare provider reviews the heart images taken at rest and under stress. These show how well blood flows to the heart muscle. By comparing the sets, they can identify reduced blood flow and plan further care.
Possible Findings
- Normal Blood Flow: If blood flow looks typical during both rest and activity, the healthcare provider may not recommend further testing.
- Reduced Blood Flow During Exercise Only: This shows that a part of the heart is not getting enough blood during physical activity. This may point to narrowed or blocked heart arteries.
- Reduced Blood Flow at All Times: When poor blood flow appears both during rest and exercise, this can suggest more severe heart problems or past heart damage.
- No Blood Flow in Part of Heart: If a section of the heart does not take up the radioactive marker, the results may indicate damage from a previous heart attack.
What Happens Next
If poor blood flow is found, the provider may order additional tests, such as coronary angiography.
Treatment Options Table
| Condition Found | Possible Next Steps |
|---|---|
| Mild or no blockage | Observation, lifestyle changes |
| Blockage needing treatment | Angioplasty with stenting |
| Severe blockage or more than one artery | Coronary artery bypass surgery |
