What Exactly Happens In A Nuclear Stress Test? What Are Some Nuclear Stress Test Side Effects?

Every year, more than 500,000 Americans die of heart disease in the US. To ensure your heart is in good health, your cardiologist might suggest getting a nuclear stress test. Follow this article to learn everything about a nuclear stress test, including some nuclear stress test side effects

Something about mixing the terms “nuclear” and “stress” just doesn’t feel right — at least not at first glance. However, a “nuclear stress test” is an excellent thing. It can help diagnose and manage a wide range of cardiovascular diseases, including coronary artery disease, the leading cause of death in the United States.

Our body functioning is greatly dependent on how well our heart is performing.  In order to maintain the entire body’s health and keep ourselves in optimal shape, keeping a regular check on our heart health is reasonably necessary. Your doctor might advise getting tested to evaluate how well your blood is flowing into your heart if you’ve previously experienced cardiac issues.

One sort of stress test is the nuclear stress test. If you have coronary artery disease, the radiotracer used during a nuclear stress test can assist your doctor in calculating your risk of a heart attack or other cardiac event. A nuclear stress test may be performed after a standard exercise stress test to obtain more information about your heart.

Follow this article if you want to learn all about the basics of nuclear stress tests, why you might need a nuclear stress test, what is involved in a nuclear stress test, and some nuclear stress test side effects. So read on to understand the phenomenon of nuclear stress testing.

What are stress tests?

To evaluate the heart’s functional range, doctors utilize an exercise stress test, also known as a cardiac stress test, exercise ECG, or stress test. We all engage in varying degrees of exercise on a daily basis. The heart is not working very hard when we are sitting down.

Our hearts have to work harder when we take a quick walk, swim, or run. An exercise test is intended to evaluate unbiasedly how effectively the heart performs with increased activity. It is a very effective method of determining the state of the heart.

Stress tests show your heart’s tolerance to physical strain. Exercise increases the speed and energy with which your heart pumps. Some cardiac disorders are simpler to identify while your heart is working hard.

Your heart and activity will be examined as you exercise on a treadmill or stationary cycle during a stress test. You will be prescribed a drug that makes your heart beat more forcefully and swiftly than it would otherwise if you are not in good enough health to exercise.

It’s possible that your heart isn’t getting enough blood if you can’t finish the stress test in the specified time. Blood flow may be lowered by a number of different heart conditions, some of which are highly harmful.

What exactly is a nuclear cardiology stress test?

With this noninvasive test, you can determine if coronary artery disease is the root of your symptoms by analyzing blood flow patterns to the heart muscle. When a patient already has coronary artery disease, the test also assesses how far along the disease has progressed.

Heart muscle blood supply arteries affected by coronary artery disease develop stenosis, narrowing, and sometimes blockages. Your doctor will learn more about the disease’s effects on cardiac blood flow through the nuclear stress test that you undergo to see how it affects blood flow to the heart under stress or during exercise.

Heart disease can be identified using this test. A tracer, also known as a radiopharmaceutical, is a small quantity of radioactive material administered by a medical professional. The tracer is absorbed by your blood arteries and heart muscle, which increases their visibility in photographs. Then the medical professional takes photos of the blood flow within and around the heart using a specialized camera. The test may also be called

  • Cardiac PET (positron emission tomography).
  • Cardiac SPECT (single-photon emission computed tomography).
  • Myocardial perfusion imaging (MPI).
  • Nuclear stress test.

What happens during a stress test?

Usually, the exam involves using an exercise bike or a treadmill to walk on. The treadmill’s inclination and speed will progressively increase. Your heart rate and blood pressure are closely watched as you undergo the test to determine how they are responding. Through an ECG, we can also capture the heart’s electrical activity. Usually, an activity treadmill test lasts no longer than 12 minutes. A person will typically walk for nine minutes on average.

In other cases, such as when a patient is unable to move adequately, medication administered through drip is utilized to improve heart activity instead. To actually assess how well the heart is pumping, this kind of stress test may also be paired with cardiac imaging.

An ultrasound (also known as a stress echo), an MRI (sometimes known as a stress MRI), or a nuclear scan may be used for imaging (called a nuclear stress scan). The goal of each test is to put your heart under more strain while closely observing your blood pressure, heart rate, and cardiac function.

How is a nuclear stress test different from a regular stress test?

A nuclear stress test is quite similar to a standard stress test, with the exception that it additionally involves heart imaging based on the principles of Nuclear medicine and the injection of (radioactive dye) into your veins. In order to capture images of the blood flow to your heart during this test, radioactive dye (also known as a radiopharmaceutical or radiotracer) is first injected into your circulation.

During an exercise stress test, your heart is solely monitored by an EKG while you are both resting and working out. However, a nuclear stress test captures pictures of your heart activity both when you are resting and exercising. The images will demonstrate the extent to which different parts of your heart were colored during each of the two stages.

A technician will place an intravenous (IV) line into your arm during a nuclear stress test and administer the radiotracer, which may feel chilly at first. You will be asked to lie down so that the first round of photos may be obtained once your body has had time to absorb the tracer.

After that, the regular stress test procedure is carried out. Contrary to conventional, non-imaging stress tests, imaging stress tests tend to detect congenital cardiac disease and better predict the future risk of a heart attack.

Who conducts the nuclear stress test?

A nuclear medicine specialist physician often performs the stress test with the support of a nurse who has received training in cardiac resuscitation. An NM technician performs the scan. The NM expert doctor interprets the photos.

What is nuclear medicine and the science involved behind it?

Nuclear medicine captures images of your organs and blood vessels using trace amounts of radioactive elements (“radiotracers”). Shortly before your stress test, radiotracers are infused into your circulation. When radiotracers are injected, they release signals that can be traced by the nuclear imaging device, which uses the data to create images that depict how blood flows in and around your heart.

Nuclear stress testing can be used to diagnose heart and blood vessel problems, as well as to screen for evidence of heart damage after a heart attack or another cardiovascular event. Nuclear stress tests are often used to manage treatment, and the imaging results are used to establish how effectively a given treatment works.

What takes place during the stress section of the test?

The test begins with a brief medical history, establishing an intravenous line, and placing leads on your chest to monitor your heart. The nurse clinician will closely monitor the heart rate and rhythm, blood pressure, and any symptoms of patients who exercise.

The radioactive dose will be administered into your intravenous line once you have reached an acceptable level of exercise. You must exercise for one more minute to allow it to reach your heart. You will be transported to the nuclear camera room immediately following the exercise.

Nuclear stress test with exercise

A nuclear stress test identifies the heart muscle regions that experience decreased blood flow during exercise. First, while the patient is at rest, a radionuclide (such as technetium or thallium) is injected into a vein in the arm or hand via an intravenous catheter.

The patient remains motionless on a table while a specialized device known as a gamma camera takes images of the heart after the radionuclide has been injected and has circulated through the bloodstream. This scanning typically takes three to five minutes. This is the heart’s resting scan.

The patient is then put through an exercise stress test while jogging on a treadmill. A second radionuclide dose is administered via the intravenous catheter at the height of exertion. A second scan of the heart is done in the gamma camera after the radionuclide has been injected and has circulated through the bloodstream. This scanning takes roughly 3 to 5 minutes as well.

This is the heart’s stress scan. As a result of their inability to take up the radionuclide, any parts of the heart with blocked or partially clogged arteries would appear as “cold spots” or “defects” on the scans.

Pharmacological (“Chemical”) Stress Test

When a doctor decides that a patient’s medical or physical condition prevents them from exercising on a treadmill, they will do a pharmacologic stress test. In this case, drugs are administered that either increase heart rate or promote dilation of the coronary arteries. This pharmaceutical response is comparable to the response brought on by physical activity.

In order to perform this test, a radionuclide (technetium) is first injected into a vein in the arm or hand using an intravenous catheter while the patient is at rest. The patient remains motionless on a table while a specialized device known as a gamma camera takes images of the heart after the radionuclide has been injected and has circulated through the bloodstream. This scanning typically takes three to five minutes. This is the heart’s resting scan.

After that, the patient is given the drug while the pharmacologic stress test is conducted. A second radionuclide dose is administered through the intravenous catheter at the time of maximum stress. A second scan of the heart is done in the gamma camera after the radionuclide has been injected and has circulated through the bloodstream.

This scanning takes roughly 3 to 5 minutes as well. This is the heart’s stress scan. As a result of their inability to take up the radionuclide, any parts of the heart with blocked or partially clogged arteries would appear as “cold spots” or “defects” on the scans.

Do I need to adhere to any other guidelines before a nuclear stress test?

Your doctor will review each of your drugs when you have your test scheduled (be sure to bring your complete medication list). Prior to the test, your doctor might advise against taking a particular drug.

You should tell your doctor if you have a serious lung condition, such as asthma or chronic obstructive pulmonary disease (COPD), or if you use any pulmonary medications. Before the test, you should discuss with your doctor if and how long you should stop taking some of your cardiac or hypertensive drugs. Medication such as beta-blockers can be used to diagnose ischemia (lack of blood supply to the heart) ( e.g., Atenolol, Lopressor),

Cardizem and other calcium-channel blockers may need to be avoided 24 to 48 hours before the test. To ensure that the doctors are aware of all your prescriptions, bring a list of all the medications you are taking with you to the test. You should dress comfortably for an exercise stress echocardiogram by wearing light-colored clothing, sneakers, or other casual footwear.

It’s crucial that you abstain from coffee for the whole 24 hours before your consultation. This includes caffeinated and decaffeinated coffee, tea, soda, chocolate, and a few caffeine-containing migraine drugs.

Caffeine can prevent the medicine from working as intended during the test’s stress component. Your test might need to be rescheduled if you’ve had coffee within the previous 24 hours. You will receive the following instructions when you arrange your nuclear stress test.

  • After midnight on the day before your visit, avoid eating or drinking anything other than water or clear drinks.
  • Avoid smoking, coffee, and other caffeinated beverages and foods at least 12 hours before your stress test.
  • Do not take your morning insulin dose if you have diabetes and take it or any other diabetes medications, but do bring your insulin or diabetes pills with you.
  • Any prescription medications you take for your heart or high blood pressure should be disclosed to your doctor. If they think there should be any modifications, they’ll let you know.
  • Bring a list of every drug you are currently taking.
  • Dress comfortably and put on your running or walking shoes.
  • For your stress test, bring a picture ID, your health insurance card, and the recommendation letter from your doctor.
  • Please inform the nuclear medicine team if you are a woman who might be pregnant or who is nursing.

Some other things to keep in mind before getting nuclear stress tests done are

  • Make sure to obtain a decent night’s sleep.
  • Bring your favorite CDs or cassette tapes with you so you may listen to music while you get a scan.
  • Bring a piece of snack with you so you can have it after your test, as you’ll be fasting from the previous night.
  • Do inform your doctor if you are going to be canceling your appointment
  • If you have any sort of anxiety, then bring in someone close to you so that they can be a sort of comfort for you while you get your nuclear stress done.

Why is a nuclear stress test done?

You could require a nuclear stress test if you experience heart disease symptoms or indicators, such as chest pain or shortness of breath. If you have been told that you have a heart issue, a nuclear stress test may also be used to direct your therapy. Your physician might suggest a nuclear stress test to

  • Identify coronary artery disease. Coronary arteries are the main blood vessels that bring oxygen, nutrients, and blood to your heart. When these arteries become damaged or ill, usually as a result of the accumulation of deposits containing cholesterol and other materials, coronary artery disease results (plaques). A nuclear stress test can help identify whether you have coronary artery disease and how serious it is if you experience symptoms like chest pain or shortness of breath.
  • Make a treatment strategy. A nuclear stress test can show your doctor how well your treatment is working if you have coronary artery disease. By measuring how much activity your heart can withstand, the test also assists your doctor in selecting the best course of treatment for you.
  • A patient’s heartbeat could be erratic, or their heart rate might increase or decrease during a stress test. A cardiologist can evaluate the heart rhythm and identify any underlying problems or concerns that may be connected to the heart rhythm.
  • A stress test can assist in making a diagnosis if a patient exhibits any heart-related symptoms, such as chest pain or breathing difficulties. By successfully treating the patient at the first sign of symptoms, a stress test can also help prevent future cardiac problems.
  • A stress test can be a helpful activity to detect whether a patient’s condition is improving even after the patient has been diagnosed with heart disease. A stress test can also identify whether the patient needs additional operations or forms of treatment to get better.
  • A stress test can be used by patients recovering from a heart ailment or who wish to get healthier to learn more about how to safely engage in regular activity.

Nuclear stress test side effects

In general, a nuclear stress test is secure. But as we know, rare complications can occur with any sort of test. Similarly, a nuclear stress test holds no exceptions. There is a possibility of problems with any medical procedure, which may include:

  • Irregular heartbeats (arrhythmias). Arrhythmias that develop throughout a stress test typically disappear as soon as you stop working out or the drug wears off. Arrhythmias can be fatal but are uncommon.
  • Lexiscan and Adenoscan, two medications used for nuclear stress testing, have a sporadic risk of heart attack and abrupt death. Medical experts use these medications to simulate exercise in patients who are unable to do so.
  • Low blood pressure. While exercising or right after, blood pressure may drop, which could make you feel lightheaded or faint. Following your cessation of exercise, the issue ought to disappear.
  • Dizziness or chest pain. When doing a nuclear stress test, these symptoms may appear. During the stress test, some patients also experience nausea, trembling, headaches, flushing, shortness of breath, and anxiety. Even though these signs and symptoms are typically minor and transient, let your doctor know if they persist.
  • Allergies. There is a slight chance that someone will be allergic to the tracer used in the test.
  • Extra efficient blood flow. The medications work by enhancing blood flow to reveal obstructions. Blood may flow more efficiently to unobstructed areas, as a result, depriving troubled areas of blood. Rarely, this could result in a heart attack.
  • Radiation exposure. According to 2018 research, there is little radiation exposure during a nuclear stress test. The AHA does acknowledge that there is a chance. That radiation can be dangerous at any dose. Therefore, if a person has a low risk of heart attack and no signs of a cardiac condition, they shouldn’t undergo a nuclear stress test.
  • Nursing. Due to the possibility of the tracer contaminating breast milk, you should let your doctor know if you are breastfeeding.

What advantages do nuclear stress tests have?

The nuclear medicine cardiac stress test is a straightforward, low-risk, non-invasive procedure that enables your doctor to determine whether you have substantial coronary artery disease and how well your heart muscle is functioning. It is excellent at determining the likelihood that you may have a serious cardiac event (heart attack) and the significance of other clinical symptoms.

What can you expect from a nuclear stress test?

A nuclear stress test might sound complicated, but you’ll be properly guided by your healthcare professional in what kind of steps you are to take in terms of performing your nuclear stress test. They would guide you while closely monitoring how you react to the procedure throughout.

If you are facing some sort of difficulty, they would halt the process there and then give you the required medical assistance so that you don’t suffer any medical difficulty. Here is what happens before, during, and after a nuclear stress test.

  • What is done before a nuclear stress test?
  • What to expect during the test?
  • When will you be asked to stop exercising?
  • What happens after a nuclear stress test?

What is done before a nuclear stress test?

Your doctor will inquire about your medical history, frequency of exercise, and level of activity. This aids in figuring out how much exercise is optimal for you throughout the exam. In order to rule out any issues that might affect the outcome of your test, your doctor will also listen to your heart and lungs.

What to expect during the test?

In addition to an exercise stress test when you walk on a treadmill, a nuclear stress test may also be conducted. You will be given medicine through an IV if you are unable to exercise since it increases blood flow to your heart and acts as a substitute for exercise. A nuclear stress test may last two hours or longer, depending on the radioactive material and imaging techniques utilized.

  • Your doctor will inquire about your medical history, frequency of exercise, and level of intensity. This aids in figuring out how much exercise you should get before the test. In order to rule out any anomalies that might affect the outcome of your test, your doctor will also listen to your heart and lungs.
  • A technician places an intravenous (IV) line in your arm and administers a radioactive dye before you begin the exam. (radiopharmaceutical or radiotracer).
  • When the radiotracer is first injected into your arm, it could feel cold. Your heart cells absorb the radiotracer in 20 to 40 minutes on average. Your heart will then be at rest as you lie still on a table and have your first round of photographs taken.
  • A nurse or technician will apply electrodes to your arms, legs, and chest. For them to stick, some regions might need to be shaved. An electrocardiogram machine, which records the electrical signals that cause your heartbeats, is wired up to the electrodes and can read the data from the EKG. Your blood pressure is measured using a cuff on your arm during the test. As part of the exam, you could be asked to breathe into a tube to demonstrate how well you can breathe while exercising.
  • If you are unable to exercise, your doctor will administer medication through an IV line that acts as a substitute by boosting the blood flow to your heart to simulate exercise. Exercise-related adverse effects such as flushing or shortness of breath could also be potential side effects. A headache could happen.
  • You will be required to use a stationary bike or a treadmill for an exercise stress test. The activity will start easy for you and get more challenging as the exam continues. The railing on the treadmill can be used for balance. Holding on too tightly could skew the results, so you’ll be advised to let go.

When will you be asked to stop exercising?

You will keep working out until your heart rate reaches a predetermined goal, or you start experiencing symptoms that make it impossible for you to continue, or you experience one of the following symptoms:

  • Chest pain that ranges from mild to severe
  • Severe breathing difficulties
  • Blood pressure that is unusually high or low
  • A heartbeat that is not typical
  • Dizziness
  • Variations in your electrocardiogram
  • Your doctor and you will talk about how much exercise is safe for you. If the test makes you feel uncomfortable, you can stop it at any time.
  • You will receive another radiotracer injection when your heart rate reaches its maximum. The second set of photos of your heart will be created 20 to 40 minutes later. Any locations with poor blood flow are visible, thanks to the dye.
  • A comparison of the blood flow through your heart under normal and stressful conditions will be made by your doctor using the photographs.

What happens after a nuclear stress test?

After your workout is over, you might be asked to sit still for a short while with the monitors attached before lying down for a time. Your heart rate and respiration will return to normal as your doctor keeps an eye out for any anomalies.

Unless your doctor advises you otherwise, you can resume your regular activities when the test is over. Your urine or stool will naturally expel the radioactive particles from your body. To aid in flushing the color from your system, drink a lot of water.

What do the test results show?

After you are done with your test procedures and the doctor has everything under control, including your breathing and your blood flow then, your doctor will discuss your nuclear stress test results with you. Your results could show:

  • Normal blood flows both when exercising and when resting. You might not require any more tests.
  • Normal blood flow while at rest but not when working out. When you strain yourself, a portion of your heart doesn’t get enough blood. This could indicate that one or more of your arteries are obstructed (coronary artery disease).
  • Reduced blood flows both at rest and during exercise. Your severe coronary artery disease or a recent heart attack may be to blame for a portion of your heart not receiving adequate blood at all times.
  • Sections of your heart don’t contain radioactive dye. A heart attack has damaged your heart’s tissue in the areas of your heart that don’t show the radioactive dye.
  • You might need to get coronary angiography if your heart isn’t pumping enough blood. This examination focuses specifically on the blood vessels feeding your heart. If you have serious blockages, you might require open heart surgery or a coronary intervention (angioplasty and stent implantation) (coronary artery bypass).

Normal results

After analyzing your results, if the doctor observes that your test results are normal, your heart’s coronary arteries are receiving normal amounts of blood. You would probably not be advised of any further action.

Abnormal results

If your doctor observes things are out of the ordinary and everything is not how it is supposed to be, your test results aren’t normal. Such test results are an indication that you need medical assistance or need to go through a medical procedure. Abnormal results may indicate:

  • Decreased blood flow to a portion of your heart brought on by one or more arteries supplying your heart muscle being narrowed or blocked.
  • Decreased blood flow to a portion of your heart brought on by one or more arteries supplying your heart muscle being narrowed or blocked.
  • Heart disease
  • A heart that is too big could mean further cardiac issues

In order to identify whether you have a cardiac condition, your doctor might need to conduct more tests. Your doctor will use the outcomes of this test to create a treatment strategy tailored just for you.

How long does a nuclear stress test take?

The time a stress test takes can vary. Your session will typically last between two and four hours. A portion of this time is spent getting ready for the test and watching for the heart to absorb the tracer that has been injected into the bloodstream. While the actual exercise will take between 7 and 12 minutes, the stress test and image acquisition will take roughly 60 minutes. The testing may occasionally be divided over two days.

What takes place during the exam’s stress-imaging section?

To allow the camera to be placed directly over your heart, you will be instructed to lay on your back with your arms raised above your head, and your knees flexed and supported. EKG leads will be applied to your chest so that the imaging technology can be synchronized with your heartbeat for longer images. This nuclear cardiology test is referred to as “gated.” The camera will be set up to take a series of pictures of your heart as it goes throughout your body once the leads are in place.

How is the test analyzed?

If the radioactive isotope you were given is dispersed uniformly, there is sufficient blood flow. If it’s not, faults are preventing your blood from flowing as it should. It is possible to identify the parts of the heart that have been impacted by a heart attack or myocardial infarction by comparing these defects under stress and at rest.

Ischemia, or impeded blood flow, is indicated by regions exhibiting abnormalities during stress but not at rest. The cardiologist can also see the results of this test and learn how your heart beats.

What happens following the test?

Your cardiologist will be informed of the test results by a nuclear cardiologist who specializes in nuclear imaging, who will then get in touch with you to go through the findings. Before you are informed, it could take up to 72 hours. A therapy strategy tailored to your individual needs is developed using the results from the test’s stress and resting phases.

What happens after you are done with your nuclear stress test?

Most people are able to resume their regular routine right away following the exam. Meals, medication, and other activities are included in this. Your exposure to radiation during this test is regarded as very minimal. You won’t need to take any additional safety measures afterward.

It all depends on the testing facility and how and when you receive your results. The majority of labs will immediately provide you with a summary of the findings. If the examination reveals issues, you will be provided guidance on what to do next.

You probably won’t learn the official test findings until a cardiologist has examined the photos, even if there are no immediately noticeable issues. In this instance, the person who ordered the test will be the one to provide you with the findings. You will then talk about what, if anything, needs to be done after that.

What should I avoid doing following a nuclear cardiology stress test?

After the test, your healthcare practitioner will give you directions to follow. Usually, people are able to resume their regular activities right away. To help the tracer leave your body, you may wish to drink a lot of water. You can have fatigue, vertigo, or headaches following the examination. Those symptoms ought to disappear with time and with rest.


A nuclear stress test would be suggested by your doctor if you have a history of health diseases or are currently susceptible to having one. It is a general test that allows your doctor to examine your heart health so that they can take precautionary measures to ensure you get to live a long healthy life with a healthy heart.

A stress test might sound overwhelming, but it’s nothing to be afraid of, and it’s better to get one for better heart health in the future. There are not many nuclear stress test side effects; as long as you provide all the necessary details to your healthcare provider for them to examine so they can suggest the best method to put you through the stress test, you are probably going to be safe.