Nuclear cardiology stress testing is an important tool to evaluate the presence and severity of coronary artery disease. The test is a noninvasive of looking at blood flow patterns to the muscle of the heart. It is a good way to determine if coronary artery disease is the cause of your symptoms. The test is also useful to evaluate the progression of the disease in patients already diagnosed with coronary artery disease.

Coronary artery disease produces narrowing and potentially blockages, called stenosis, in the coronary arteries that supply blood to the muscle of the heart. This restriction of blood to the heart can cause chest discomfort, shortness of breath, neck pain, chest pain, or a variety of other symptoms. The symptoms may increase as your level of exertion increases. Performing the nuclear stress test will provide your physician with information on the impact the disease has had on blood flow to the heart during exercise (stress) and when relaxing.

A nuclear cardiology stress test is normally composed of both a stress and a resting component. The order that the portions of the test are performed is decided on a case-by-case basis under guidelines of our nuclear cardiologists. Both portions of the test are important to accurately evaluate the severity of the disease and manage your care. The complete test takes up a large portion of the day, but the amount of information that is gained in the process makes taking the time worthwhile. The whole procedure is relatively painless, and you should not feel any different when you leave than when you arrived for your test. The test does require injecting small amounts of a radioactive materials, though the total radiation you are exposed to during the test is about equal to the exposure you would receive during a chest X-ray.

What happens during the stress portion of the test?

The stress portion of the examination will start with obtaining a brief medical history, starting an intravenous line, and placing leads on your chest to monitor your heart. Patients who are cleared to exercise will be taken into the stress lab where the staff will put you on one of our standard exercise programs on the treadmill. The treadmill will increase speed and height according to standard protocols. Wile you exercise, your heart rate and rhythm, blood pressure, and any symptoms you might be having will be monitored closely by the nurse clinician. The cardiologist is available to the nurse at all times for immediate consultation. When you reach an acceptable level of exercise, the radioactive dose will be injected into your intravenous line. The radioactive dose is usually thallium or sestamibi, depending on the protocol used for your test. You will need to exercise for a final minute in order to allow the it to reach your heart. Immediately after exercise, you will be taken to the nuclear camera room.

What happens if I am prevented from exercising?

Patients who are prevented from exercising can have the stress test performed through the use of a drug that acts on the heart the same way that exercise does. When performing a pharmacological stress test, you will be seated in a reclining chair in the stress lab, or on the nuclear camera bed while the procedure is performed. You may experience slight side effects of the drugs used to stress your heart, but they work quickly and the symptoms will disappear rapidly as well. The staff will inject the radioactive dose when they have reached the maximum stress point in the protocol, and then continue for a short period while the dose works through your blood stream. Afterwards, you will be taken into the nuclear camera room to perform the stress imaging portion of the test.

What happens during the stress-imaging portion of the exam?

The stress-imaging portion of the exam will require you to lie on your back, knees flexed and supported, and your arms raised above your head so the camera can be positioned over your heart. There will be a series of short duration images, as well as some longer images. You will be asked to lie quietly and not talk, as movement can distort the heart images. The longer images require the use of EKG leads placed on your chest to allow the imaging equipment to be synchronized with your heartbeat. This is referred to as a "gated" nuclear cardiology determination. Once the leads are in place, the camera will be set up to take a series of images of your heart as the camera moves around your body.

What happens during the resting part of the exam?

After the first imaging session, you may dress, leave the office, and have a light lunch. The nuclear technician will advise you as to your return time, which will be for or more hours after the first session. When you return, you will lie under the imaging camera again, this time for a series resting images. It will not be necessary for you to exercise again, but you will be re-injected with a radioactive dose. The same sequence of images as in the stress-imaging portion of the test are taken of your heart. It is important to remember that the quality of the images will be a direct result of following the nuclear technologist's instructions regarding holding still and not falling asleep during the imaging session.

How does the nuclear cardiologist interpret the exam?

Even distribution of the radioactive isotope indicates adequate blood flow. The presence of defects indicates restriction in the blood flow. Matching defects at stress and rest show areas of the heart that have been affected by a heart attack or myocardial infarction. Areas that have defects at stress that do not show up at rest are consistent with a diagnosis of ischemia. The images from the test can also tell the cardiologist how your heart beats and whether all areas of the heart ventricle contract equally.

What happens after the examination?

The nuclear cardiologist will pull together information from prior studies, the current images, your medical history and your response to the stress test itself in order to interpret your test. The results are then given to your cardiologist who will then contact you to explain the significance of the results. It may be up to 72 hours before you are notified of the results of this test. The results from both the stress and rest portions of the test help to formulate a treatment plan to meet your specific needs.