A nuclear stress test helps to assess your risk of a severe cardiac event. Depending on your health, a doctor may ask you to take a treadmill test or a chemical test, which uses medications to increase your heart rate.

A stress test is a noninvasive test healthcare professionals use to identify your risk of death or disability from cardiac disease. The test involves increasing demand on your heart and observing how it works under the increased demand. A nuclear stress test includes imaging that shows blood flow to your heart during the test.

Some stress tests have you exercise on a treadmill or bike to elevate your heart rate. But if exercise is challenging or inappropriate because of your physical or medical condition, a doctor or healthcare professional might recommend a pharmacologic stress test.

Also known as a chemical stress test, this version involves giving you medications via an intravenous (IV) line to increase demand on your heart.

If a healthcare professional has recommended a pharmacologic nuclear stress test, keep reading for more information about the test and how to prepare for it.

During a pharmacologic stress test, a technologist will apply electrocardiogram (EKG) leads to your chest and attach wires to measure your heart’s electrical activity. They’ll also monitor your heart rate, blood pressure, and oxygen saturation throughout the process.

You’ll receive a small amount of a radioactive tracer through an IV. The tracer emits radiation that allows a doctor to track blood flow using positron emission technology (PET) or single-photon emission computed tomography (SPECT). The technologist will take a first set of images to view how your heart works when you’re at rest.

You’ll next receive medications designed to simulate how your heart reacts when you exercise. Known as pharmacological stress agents, you receive these via an IV line. Examples of these agents include:

  • adenosine
  • dipyridamole
  • dobutamine
  • regadenoson

The agents widen the blood vessels in your heart, but damaged blood vessels won’t widen as much.

Once your heart and blood vessels respond to the agents, the technologist will give you another dose of the tracer for a second round of imaging. This provides a picture of how your heart works when you’re not at rest.

During this time, you may notice your heart beating faster than usual. But you shouldn’t feel any discomfort during the test.

Healthcare professionals often recommend stress testing for people about to undergo surgery, such as vascular or heart surgery. It’s typically an exercise stress test, which involves walking or lightly jogging on a treadmill to increase your heart rate to a target number based on your age and health.

Pharmacologic stress testing is an alternative to exercise stress testing. Doctors may recommend a pharmacologic stress test for people with the following conditions:

Doctors may also recommend a pharmacologic stress test for people unable to exercise due to limitations in movement. Also, if you fail an exercise test, they may need to follow up with a pharmacologic test.

A pharmacologic nuclear stress test usually takes a few hours. In addition to setup, there are two rounds of imaging and some waiting time in between.

The tracer takes some time to create an effect. Your technologist will usually need to wait 15 to 60 minutes before performing imaging.

The different agents also differ in how long it takes them to have the desired effect. Check with a doctor to learn how the specifics of your nuclear stress test may affect its duration.

Your preparation for a nuclear stress test will depend on which agent the doctor plans to use during the test. For example, if your test uses adenosine, you’ll want to avoid caffeine-containing substances and medications for at least 12 hours before your stress test.

For a dobutamine stress test, you may need to avoid taking beta-blockers at least 24 hours before undergoing the test.

Other preparations for your chemical nuclear stress test include:

  • Refrain from eating or drinking for at least 3 hours before your test. You can usually drink water before your test.
  • Refrain from smoking cigarettes or chewing tobacco for at least 8 hours before your test.
  • Ask a doctor if you should stop taking any other medications before your test.
  • Refrain from applying lotion or creams to your chest before your test starts. This allows the EKG leads to stick to your skin more easily.

Your body should quickly clear out the medications your procedure technologist gives you during a nuclear stress test. You shouldn’t experience any continued effects about 10 to 15 minutes after completing your pharmacologic stress test.

Is a pharmacologic nuclear stress test safe?

Although it’s called a “stress” test, it doesn’t actually cause excessive stress to your heart. But you may experience minimal side effects from the agents. Serious side effects are rare, but may include:

A healthcare professional will monitor you for any adverse symptoms throughout the test.

Will I be radioactive after a nuclear stress test?

As part of a nuclear stress test, you’ll receive a small amount of a radioactive tracer to help doctors spot issues on a nuclear scan. The small amount of tracer won’t make you radioactive. Your exposure to radiation will be about the same as if you had an X-ray or CT scan.

Will they numb your throat for a nontreadmill nuclear stress test?

Because a nontreadmill stress test only involves measuring your body’s responses to stress or heart rate increases, there’s no need to numb your throat before the procedure.

Still, they may give you throat-numbing medications if your stress test involves a transesophageal echocardiogram. In this type of EKG, a doctor inserts a special scope with a camera on its end through your throat to visualize your heart’s functioning.

A pharmacologic nuclear stress test is a method to determine if you’re at risk of a heart attack or harmful cardiac events. A healthcare professional may recommend this test if you aren’t well enough to complete an exercise stress test on a treadmill.

You may receive special instructions from the doctor on how to prepare for the test, such as what medications to hold before your procedure. They should also provide guidance on how long to avoid caffeine, tobacco, and eating before your test.