This test is often requested for patients who are unable to exercise. The medication regadenoson (Lexiscan) acts to dilate blood vessels and mimics the normal response of blood vessels to physical exercise. More information about what to expect during the test is provided below.
Women who are or may be pregnant should inform their physicians and the stress test personnel prior to the test.
Please follow these important instructions to prepare for your test.
48 hours prior to your test do not take any of the following medications:
• Any Ephedrine-containing medications
• Any Theophylline-containing medications
24 hours before your test do not take any of the following medications:
• Darvon Compount
12 hours before your test do not eat or drink anything containing caffeine (even decaf). Examples of caffeine-containing products include:
• Coffee (regular and decaffeinated)
• Soft drinks
What to expect
For the test, a small intravenous tube (IV) is inserted into a vein. The patient then receives an injection of a tracer which travels in the blood and is taken up by the heart muscle. Images of the heart muscle are taken 45 minutes later to obtain pictures which represent blood flow to the heart muscle at rest. In order to obtain the images, the patient lies under a gamma camera for 20 minutes.
A dose of regadenoson is subsequently injected over 30 seconds, and immediately thereafter a second injection of the tracer is given through the IV. A second set of images is obtained 45 minutes later. In order to obtain the images, the patient lies under a gamma camera a second time for another 20 minutes.
All aspects of the test may be performed typically over a 2-3 hour period in one day, or if more convenient for the patient, the test can be performed over a two-day period in two 1-2 hour sessions. The test involves exposure to radiation from the tracer (Technicium-99), and the amount of radiation is comparable to that from an abdominal CT scan. This amount of radiation exposure is considered both reasonably safe and within acceptable limits.
Many people experience no unpleasant effects, but there are some common feelings patients may have with regadenoson. These include a burning sensation at the IV site, flushing, headache, nausea, effort-breathing, and chest or abdominal discomfort. The unpleasant effects are usually tolerable and will go away within 2-4 minutes after the test is completed. In addition, a patient who has unpleasant effects may be given a medication (aminophylline) to alleviate the effects. It should be noted that caffeine, cocoa products, and some medications interfere with and block the intended effects of regadenoson, and should be avoided for at least 12 hours prior to the test.