Stress testing is usually requested by your doctor to evaluate any heart abnormalities, including heart blockages (known as coronary artery disease), but it also may be used to assess generally how your heart works during stress conditions.
A physician may recommend a stress test if you have:
Please ask your doctor for other reasons specific to you for performing a stress test.
Most commonly, three types of stress tests may be performed clinically:
* Note: The nuclear stress test (MPI) is the only test using nuclear medicine technology.
Sample Scan
Get Technical! Read the Journal Article A) Perfusion polar maps of SPECT-MPI at stress and rest show largely reversible anteroapical perfusion defect. (B) 3D volume-rendered CTA images show coronary vessel tree with stenosis of mid LAD and proximal stenosis of first diagonal branch. (C) Fused 3D SPECT/CT images are able to identify stenosis as functionally relevant lesions. (D) Findings were confirmed by coronary angiography. |
A nuclear stress test, also referred to as a myocardial perfusion imaging (MPI) study, is a type of stress test that uses an imaging contrast agent known as a radiotracer to take pictures of your heart during stress and rest conditions. A PET or SPECT camera is used for imaging of your heart. The nuclear medicine expert will look for changes in your images between stress and rest. These may be indicative of heart blockages (coronary artery disease).
Imaging of your heart will occur before and after stress to determine the effects of stress on blood flow through the coronary arteries and the heart muscle.
The three-dimensional images produced by this study are called perfusion images because they show which areas of the heart muscle are perfused, or supplied with blood.
Other names commonly used for this test are a sestamibi or thallium cardiac scan.
A physician may perform a nuclear stress study to:
In order to create "stress" conditions for your heart, the nuclear medicine expert may use one of two techniques:
The choice of the stress technique will depend on your physical condition and your other medical considerations.
You will receive an intravenous injection of a radiotracer—sestamibi/tetrofosmin for SPECT or ammonia/rubidium for PET—which accumulates in the heart muscle. This accumulation is dependent on the amount of blood flow and whether your heart muscle is still functioning. Other less common radiotracers are occasionally used. Next, you will be moved to an imaging suite, where images of the heart will be taken with a SPECT or PET camera. Shortly thereafter, you will be imaged again for the rest study.
There is usually a waiting period between radiotracer injection and scanning.
It is not uncommon for some patients to get only one study—the stress test or the rest test. This is at the discretion of the physician caring for you.
The order in which these tests are performed can be variable from one stress lab to another (stress then rest or vice versa), and they can occasionally be done on different days.
Your physician will ensure the nuclear stress test is appropriate by:
This study is:
IMPORTANT: Please follow your specific lab instructions on how to prepare for the test, including how to modify your diet and medications if specified.
To perform an ECG Stress Test, (also called exercise treadmill testing), electrodes are placed on the patient's chest and attached to an electrocardiography (ECG) machine that measures the electrical activity of the heart.
The patient exercises by walking or running on a treadmill or pedaling on a stationary bicycle, first slowly and then faster and possibly on an incline. Blood pressure readings are taken during the test, which typically involves 10-15 minutes of exercising. The ECG records the heart rate and rhythm, as well as the strength and timing of electrical signals as they pass through each part of the heart during rest and exercise.
Patients who have an abnormal exercise stress test will usually require additional testing, such as an Echo Stress Test, or a nuclear stress test and/or coronary angiography (heart catheterization).
IMPORTANT: Please follow your specific lab instructions on how to prepare for the test, including how to modify your diet and medications if specified.
In an Echo Stress Test, your heart is imaged with echocardiography while you are resting and immediately following exercise. Echocardiography or a heart ultrasound is an imaging technology that uses ultrasound vibrations echoed from the heart structures to create a moving picture of the heart.
A Stress Echo begins with a resting echocardiogram. Next, you’ll walk on a treadmill or ride a stationary bike until the target heart rate is reached. At that point, another echocardiogram is taken. If you are unable to exercise, you may receive an intravenous injection of a medication that makes your heart beat faster and harder. Throughout the procedure, your blood pressure and heart rhythm (ECG) are monitored.
The images reveal how well your heart’s chambers and valves are working when it is under stress. The echocardiogram may identify areas of poor blood flow, dead heart muscle tissue and abnormal muscle contractions.
IMPORTANT: Please follow your specific lab instructions on how to prepare for the test, including how to modify your diet and medications if specified.