How Is a Nuclear Stress Test Done?

If you've been booked for this test, the question most people actually want answered isn't what the scan is called — it's what the morning will feel like, step by step. Will you be on a treadmill? How long will you wait around? When do you get to go home?

The animated video at the top of this page runs through the whole process in 1 minute 46 seconds, so you'll already have the shape of it before you arrive. What follows is that same visit, slowed down into the order you'll experience it.

Before the pictures: rest images first

A nuclear stress test looks at how blood flows to the heart muscle, both at rest and under stress. To do that, the team needs two sets of pictures to compare. A small amount of a radioactive tracer is given, usually through a vein, and a special camera then records how that tracer spreads through the heart while you're resting. The tracer itself is used in a very small amount for imaging — it's what lets the camera create a map of blood flow rather than a simple picture of the heart's shape.

You'll likely be asked about medicines, caffeine, and recent food or drink beforehand, because the clinic's preparation instructions help the images come out clearly. Follow the instructions you're given for your own appointment rather than general advice you read online — preparation can vary between clinics.

The stress part — exercise or medicine

Next comes the stress portion. For many people that means walking on a treadmill that gradually gets faster or steeper while your heart rate, blood pressure, and ECG are monitored, with more tracer given near peak effort. If you can't exercise enough for the test, the team may use a medicine that stresses the heart in a controlled way instead — you won't be asked to push through something unsafe, and staff monitor you throughout either route.

Once that part is done, there's usually a waiting period before the second set of pictures, so the tracer has time to circulate. Then the camera takes the stress images. Put side by side, the rest and stress maps can show whether blood flow holds up when the heart is working harder, or whether it drops in a particular area — information that sits alongside other heart assessments. If you'd like the wider context, our guide to echocardiograms covers another common non-invasive heart test, and this broader overview of diagnostic testing for heart disease puts several tests in one frame.

Afterwards, and how results are read

Most people go home the same day and return to normal routines unless their own team advises otherwise. The images don't come with an instant verdict in the scanning room — a clinician reviews the rest and stress sets together, along with your symptoms, ECG, and history, before explaining what they show and whether any follow-up is needed. A reduced flow pattern on the stress images compared with rest can point the team toward further assessment; a matching pattern may be reassuring. Either way, the result is one piece of a bigger picture, not a stand-alone answer, and what happens next is a decision for your own cardiology team.

MedicalVideos.com has published trusted medical videos since 2007. The site was founded by Dr. Mohamed Ibrahim, MD, PhD — physician-scientist.

Educational only — this article is general information about nuclear stress testing, not medical advice and not a diagnosis. Preparation, testing, and treatment decisions should be discussed with your own medical team.

Frequently Asked Questions

Does a nuclear stress test always involve a treadmill?
No. Many people exercise on a treadmill, but if you can't exercise enough, the team may use a medicine that stresses the heart in a controlled way instead. You'll be monitored either way.

Why are there two sets of pictures?
Because the comparison is the point. Rest images show blood flow when the heart is relaxed, and stress images show it when the heart is working harder. Differences between the two sets are what the clinician reviews.

Is the tracer dangerous?
The tracer is given in a small amount specifically for imaging, so the camera can map blood flow. If you have concerns about radiation, pregnancy, or breastfeeding, raise them with your own team before the appointment so they can advise you directly.

When will I get the results?
Usually not during the scan itself. The rest and stress images are reviewed together with your ECG, symptoms, and history, and your team will explain the findings and any next steps afterwards.