The Nuclear Stress Test

A nuclear stress test is similar to a routine exercise stress test, with the exception that images are provided of the heart muscle for analysis.

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A nuclear stress test measures blood flow from the heart muscle. The test is carried out at rest and when stress is put on the heart. It provides images of the heart that show areas where there is low blood flow and areas where there is damaged muscle.

About the Nuclear Stress Test

A nuclear stress test is similar to a routine exercise stress test, with the exception that images are provided of the heart muscle for analysis. The test involves the production of two sets of images of the heart. One set is taken when the patient is exercising, such as walking on a treadmill or riding a stationary bike. Alternatively, medication may be given to the patient in order to simulate stress on the heart when they cannot undertake the level of exercise needed for the test. A second set of images is taken when the patient is at rest where there is no stress on the heart from physical activity or other factors.

When the Test is Needed

A nuclear stress test may be required when a heart problem or coronary artery disease is suspected. The test will help determine if symptoms like shortness of breath or chest pains are the result of issues with coronary arteries. The test will show whether heart muscle is damaged or if they are not receiving the nutrients, blood or oxygen needed to function properly. It may also be carried out as a follow up to a standard exercise stress test in order to narrow in on a diagnosis. A nuclear stress test may also be a common follow up test for patients with heart disease or a heart condition in order to help guide treatment for a variety of heart conditions such as coronary artery disease, arrhythmia.


As with any medical procedure, there are some risks associated with the nuclear stress test. The test is generally safe and complications are rare. The most common complications include allergic reactions to the radioactive dye used for the test, a drop in blood pressure during exercise, abnormal heart rhythms and chest pain. In very rare instances, a heart attack is possible.

What to Expect

When a nuclear stress test is carried out, a patient will be asked about their medical history and their level of physical activity. The information gathered will help determine what is appropriate for the test itself. Before the test, electrodes connected to an electrocardiogram (ECG or EKG) machines will be placed on the patient's chest, legs and arms. A blood pressure cuff will also be placed on the patient's arm. These instruments will be used to monitor the heartbeat and blood pressure during the test.

The exercise will take place on a treadmill or stationary bike, beginning slowly at first and then slowly increasing in intensity. Medication may be injected to simulate exercise if the patient is unable to exercise. The test generally lasts for about eight to twelve minutes, although the duration will depend on each individual. Once a patient has reached their maximum level of exercise, a radioactive dye is injected into the bloodstream via the hand or arm. This radioactive material is used to create images of the heart muscle using a special scanner. Images are also taken when the patient is at rest.

How Results are Used

The test is used in order to gather information about how a patient's heart is functioning and how it responds to stress, such as physical activity. A nuclear stress test can also determine the size and shape of the heart, including whether a heart is enlarged and determine the pumping function of the heart. If test results show that there is not enough blood flowing through the heart, additional tests such as a coronary angiography may be needed. Medical procedures may be also be needed in the case of severe blockages, such as balloon angioplasty, stent placement or a coronary artery bypass to improve blood flow to the heart.