A nuclear stress test is a type of imaging test. It uses a camera and a radioactive tracer — a small amount of a radioactive substance injected into a vein — to reveal how a person’s blood flows during rest and activity.
Doctors use nuclear stress tests to check if a person’s heart muscles are getting enough blood flow. People also refer to these tests as thallium stress tests, myocardial perfusion scans, or radionuclide tests.
A person can take the test while resting or while exercising. During the test, a doctor injects a radioactive substance called a radionuclide, or tracer. This substance allows a person’s blood flow to become visible via a camera that picks up radioactive material.
A nuclear stress test generally takes
Read on to learn more about nuclear imaging tests, such as their benefits, how they work, and their risks.
The nuclear stress test can help doctors diagnose certain heart conditions. They do this by providing important information about a person’s heart,
- if there is any narrowing or blockages
- if there is damage from any previous heart attacks
- if they need a coronary angiogram, an imaging scan that checks for blockages in the heart’s blood vessels
- determining the best course of treatment for a person’s chest discomfort
- checking if any previous heart procedures have improved blood flow
- how well their heart manages physical activity
Additional benefits of a nuclear stress test include:
- it is the most accurate test for diagnosing early coronary artery disease (CAD) in people who are at risk of heart attack
- it can help doctors assess a person’s risk of developing CAD
- it is sensitive to minor changes in blood flow to the heart
- it has better accuracy than exercise treadmill testing, or ECG stress tests
During a nuclear stress test with exercise, a doctor injects a tracer into a vein in a person’s arm. Once the tracer is
The person then moves onto a treadmill or stationary bicycle. When a person’s heart is working at its hardest, doctors inject them with another dose of tracer. Once absorbed, the person can resume exercising. During this time, the gamma camera takes photos of the person’s heart.
People with mobility issues, or conditions such as arthritis, may be unable to do physical exercise. These people may do a chemical or pharmacologic stress test.
In a chemical stress test, medical professionals inject a person with medication
- dipyridamole (Persantine)
This medication increases a person’s heart rate, mimicking the effects of exercise.
On the day of the test, a person should wear comfortable, loose-fitting clothes. They should also wear shoes that are comfortable to exercise in.
The American Heart Association (AHA) notes that a person should not eat anything for
A doctor may ask a person not to eat or drink anything containing caffeine 24 hours before the test. A person should not smoke or use tobacco products for
A person should inform their doctor about any medication or supplements they take. Certain medications may interfere with the test.
Medications that may affect a nuclear stress test include:
- PDE-t inhibitors
Before a nuclear stress test, a person should inform their doctor if they are pregnant or may be pregnant. Radiation from the tests may be harmful to a developing fetus.
Nuclear stress tests take place in the hospital or specialized clinic. A nuclear stress test contains the following steps:
- Healthcare professionals ask the person to lie down on an examination table.
- A healthcare professional will insert an IV line into a vein in the person’s arm. The tracer flows through the IV line and into the bloodstream.
- After 15–40 minutes, the person’s heart will have absorbed the tracer. A gamma camera can now pick up a person’s blood flow while they are resting.
- Healthcare professionals then apply flat metal disks called electrodes to a person’s arms, chest, and legs. These electrodes connect to an electrocardiogram (ECG). The ECG monitors a person’s heart rate and lets the gamma camera know when to take a picture.
- Medical professionals will then instruct the person to use either a treadmill or stationary bicycle. If a person is unable to exercise, healthcare professionals will inject medication into their IV line to simulate exercise.
- When a person’s heart is working at its peak activity level, they can stop exercising. A healthcare professional will inject more tracer into the person’s IV line.
- A person then waits another 15–40 minutes for the tracer to absorb. They can then restart exercising. During this exercise, the gamma camera takes more pictures of the person’s blood flow.
Some clinics may monitor a person during exercise first and then rest. Certain clinics may do one test one day and the other the next day.
Following a nuclear stress test, a healthcare professional will monitor a person for 10–15 minutes or until their heart rate returns to pre-exercise levels.
The tracer will pass through a person’s body and into their urine. A person can drink plenty of water to help remove it faster.
A person should avoid babies or young children for the rest of the day following a nuclear stress test. A person may have residual radiation due to the test.
A person can make arrangements to discuss the results of the test with their doctor.
Information from 2022 suggests that the
- chest pain
In rare cases, a person may be allergic to the tracer used during the test.
Two drugs used for nuclear stress tests — Lexiscan and Adenoscan — carry a
The drugs work by increasing blood flow to help identify blockages. This could cause blood to flow more effectively to unobstructed areas, leaving problem areas without blood. In rare cases, this could lead to a heart attack.
Healthcare professionals should not use these drugs in people with unstable angina or other cardiac instability.
Research from 2018 suggests radiation exposure from a nuclear stress test is
A person should not have a nuclear stress test if they have low heart attack risk and no symptoms of heart issues.
Once a doctor receives the results of the nuclear stress test, they can discuss them with a person.
If a person has typical blood flow during both rest and exercise portions of the test, it suggests that their heart is functioning as expected.
However, results can show reduced blood flow to a person’s heart. This can be a result of conditions such as:
- scarring from a previous heart attack
- failure in current heart treatment
- poor physical health
A doctor may therefore recommend further testing.
A nuclear stress test uses a small amount of a radioactive substance to examine a person’s blood flow during rest and activity.
It involves a radioactive substance called a radionuclide, or tracer. This makes a person’s blood flow visible via a camera, which can detect certain heart conditions. While the test is generally considered safe, it is not suitable for pregnant people or individuals with low heart attack risk.
People can discuss the test results with a doctor, who will arrange further tests or treatments if necessary.