An exercise stress test provides valuable information about your heart. In some cases, however, exercising on a treadmill is not possible or not advised (contraindicated). An alternative form of a stress test can be a pharmacologic stress with adenisone, dipyridamole or dobutamine.
When Is Dobutamine Used?
Pharmacologic stress is an alternative to exercise stress. If exercise is not possible -- for example, if you have back pain preventing you from walking on a treadmill -- a medication to simulate the heart's response to exercise can be used. Most doctors will use either adenosine or dipyridamole in this setting. These are two types of pharmacologic stress agents that work by dilating the coronary arteries. They are combined with nuclear imaging to create a picture of the heart and its blood flow. However, if you have asthma you may not be able to have this type of pharmacologic stress. An alternative for asthmatics who also cannot exercise is the dobutamine stress test.
Dobutamine acts by increasing the heart rate and strength of the heart’s squeezing (contraction). The effect is similar to exercise and many of the same restrictions apply to its use.
How to Prepare for the Dobutamine Stress Test?
Discuss with your doctor the risks, benefits, and alternatives of the dobutamine stress test prior to proceeding.
Your doctor may instruct you to prepare for the test by avoiding certain foods and medications. You will also be asked to not eat for at least 6 hours before the test.
What Happens During the Dobutamine Stress Test?
The consent, ECGs, and blood pressure readings for the pharmacologic stress test are similar to those for an exercise stress test.
An IV catheter is required for this test.
The dobutamine stress test is done with you lying down. The dose of dobutamine flowing through your IV will be gradually increased. A medication called atropine is sometimes given to speed up the heart. The medical staff in the room will measure your blood pressure as well as your heart rate throughout the test.
Once your heart rate reaches a predetermined target level (based on your age) the radioactive isotope will be injected or the echo images will be done. Alternatively, if you develop concerning symptoms, ECG changes, or blood pressure or heart rate abnormalities the test may be stopped prematurely and imaging done.
Imaging During the Dobutamine Stress Test
Both echocardiography and nuclear imaging can be used with dobutamine. Both rest and stress imaging are required for this test. The order of which comes first depends on the medical center.If you are having a dobutamine echo (ultrasound imaging), a new set of pictures may accompany each increased dose of dobutamine.
Nuclear imaging on the other hand, usually requires only two sets of pictures - a rest and stress.What Happens After the Dobutamine Stress Test?
After both rest and stress pictures are done the test is usually over. A doctor will review the test results and communicate the results to you.
Sources:
ACC/AHA/ASNC 2003 Guidelines for the Clinical Use of Cardiac Radionuclide Imaging.
American College of Cardiology Appropriateness Criteria for a Nuclear Stress test.
ACC/AHA 2002 Guideline Update for Stress Testing.