Key Points about a Nuclear Cardiac Stress Test

  • There are two types of nuclear cardiac stress tests – with exercise and non-exercise.
  • A nuclear cardiac stress test determines whether there is enough blood flow to the heart
  • This test involves having your heart rate and blood flow monitored while exercising on a treadmill at different intensities, or using a medication that mimics the stress induced by exercise.

Overview

A nuclear cardiac stress test is an assessment that creates images to help a doctor measure blood flow to the heart. There are two types of nuclear cardiac stress tests – with exercise and non-exercise. While both assess your blood flow to the heart at peak stress and at rest, a stress test with exercise uses a treadmill workout to initiate cardiac stress, while non-exercise uses a medication.

For this assessment, your doctor will inject Cardiolite, a radioactive tracer, into a vein in your arm or hand through an IV line. This tracer allows the doctor to take images of blood flow in the body. This material should not affect you in any way.

After injection, you will be asked to wait 45 to 60 minutes to allow the tracer to circulate to your heart. Your doctor will use a Nuclear SPECT (single-photon emission computerized tomography) camera to take images of your heart at rest. Whether you are doing an exercise or non-exercise test, your second set of images will be taken between 45 minutes and three hours following exercise or receiving the medication.

After your physician receives both sets of images, they will review them to determine blood flow to your heart at rest and maximum stress.

Nuclear cardiac stress test with exercise

A nuclear cardiac stress test can measure blood flow to the heart at various levels of exercise and heart rate to ensure that adequate blood is being pumped to the heart.

After you receive Cardiolite and the first set of images are taken of your heart, you will move to a stress  room where electrodes will be put on your chest to monitor your blood pressure, heart rate and EKG during the exercise. You will perform a “graded” exercise test on a treadmill that begins at a slow speed and slight incline, both of which will be increased every three minutes.

About 90 seconds before your exercise ends, a small amount of Cardiolite is injected through your IV line to circulate during the last minute of the workout. A nurse will monitor your heart rate, blood pressure and EKG throughout the study. The second set of images will be taken of your heart between 45 minutes and three hours after your exercise ends.

Nuclear cardiac stress test without exercise

You may be unable to complete a nuclear cardiac stress test with exercise. If you perform a cardiac stress test without exercise, a medication called Lexiscan is administered in place of a physical workout.

The first portion of the test is the same: you will be injected with Cardiolite through an IV line and wait 45 to 60 minutes for it to circulate to your heart before taking the first set of images of your heart using the Nuclear SPECT camera.

Once you move to the stress room and electrodes are placed on your chest to monitor your blood pressure, heart rate and EKG, the Lexiscan will be administered over about 30 seconds. Immediately following the Lexiscan, you’ll receive a small amount of Cardiolite and will continue to be monitored.

Similar to the stress test with exercise, you will take your second set of images 45 minutes to three hours following the Lexiscan. 

Candidates for a nuclear cardiac stress test

You may be a candidate for a nuclear cardiac stress test if you:

  • Have coronary artery disease
  • Are experiencing cardiac symptoms such as shortness of breath or chest pain

Preparing for and performing a nuclear cardiac stress test

With a stress test, you will need to:

  • Avoid eating or drinking after midnight before your test
  • Avoid caffeine for 24 hours. This includes chocolate, brownies, foods, beverages and medications containing caffeine. 
  • Walk for a minimum of five minutes on the treadmill or receive a medication that mimics stress from exercise
  • Have a radioactive tracer administered through an IV
  • Have an EKG attached to your chest
  • Have images taken of your heart as you lie on a table before and after exercise
  • Wear loose, comfortable clothing and comfortable walking shoes
  • The entire testing experience will take three to five hours. You should continue to take all medications up to midnight before your test unless directed otherwise by your cardiologist.

Benefits of a nuclear cardiac stress test

Doctors may use a nuclear cardiac stress test to:

  • Identify coronary artery disease
  • Gather information about to how to treat a specific heart condition
  • Highlight your potential risk of experiencing a heart attack

Risks of a nuclear cardiac stress test

There are no serious risks accompanying a nuclear stress test. Possible but rare symptoms and risks may include:

  • Arrhythmias
  • Heart attack
  • Dizziness
  • Chest pain
  • Low blood pressure

Recovery from a nuclear cardiac stress test

Following a nuclear stress test, you can return to activities as normal. You will be advised to drink lots of water to flush the radioactive tracer out of your body naturally.