Nuclear Stress Test

A nuclear stress test may be ordered by your doctor if they are suspecting you are at risk for heart attack and/or coronary disease. This type of stress test is more detailed than an exercise stress test as it uses a radioactive dye and a machine to take photos of the blood supply throughout major vessels of the heart. Two sets of images are taken during this test: one set while you are at rest, and one set after your heart has been stressed.

At Rest: The first portion of the exam will take about 15-30 minutes to complete and takes images of blood flow to your heart muscles while at rest. You will be given an injection of Cardiolite, a radioactive tracer. The tracer will circulate for 45-60 minutes and then pictures will be taken of your heart.

After Stress: During the exercise portion, electrodes are placed to your chest to monitor your heart rhythm by EKG as you walk on a treadmill. You may be challenged with an incline to increase the heart rate and blood pressure until the target is reached. If you ave a medical condition that inhibits you from walking on the treadmill, your doctor will order a special medication called Lexiscan to help stress your heart without physical exercise. The second round of cardiolite will be injected after the infusion of Lexiscan.

About 45 minutes after the second round of Cardiolite is injected, images of your heart are again taken which takes roughly 20 minutes. These images highlight disruption of blood flow to heart muscles during peak stress and assesses how well the heart pumps out blood to the body.


There are generally no risks associated with having a nuclear stress test beyond slight radiation exposure. You may have a reaction to the radioactive dye if you are allergic.

How to Prepare

  • Consult your doctor about your medications and if they are all safe to take prior to the test. Your doctor may ask you to stop beta blockers or calcium channel blockers a day or two before the exam.
  • Wear comfortable clothes and shoes with nonskid soles.
  • Do not eat or drink anything after midnight, except for a few sips of water if you need to take medications. Avoid caffeine for 24 hours before the test, including: tea and coffee, all sodas (even those labeled caffeine-free), chocolates, and certain caffeine-containing pain relievers.
  • You may resume all activities as normal following the completion of the exam; however, you should avoid small children 24-48 hours after the exam.
  • Results will be delivered to your doctor who will then review them with you at your next visit.

Nuclear Stress Test. Mayo Clinic.