Dobutamine Thallium Test

Your doctor has recommended that you have a dobutamine thallium test to allow more accurate evaluation of the condition of your heart. The dobutamine thallium test will help your doctor determine whether your coronary arteries have become narrowed or blocked as a result or coronary artery disease. The test will also provide information about how much blood your heart pumps. Results from the test will assist your doctor in selecting the best course of treatment.

The information below is intended to answer some of the questions you may have about the dobutamine thallium test. Please contact your physician to discuss anything that you do not understand or would like more information about.

Your Heart and Coronary Artery Disease
To better understand why your doctor has recommended the dobutamine thallium test, it is important to understand something about your heart and the arteries that supply it with oxygen.

Your heart is an amazing pumping machine that is responsible for supplying all the organs in your body with blood that contains oxygen and other life-giving nutrients they need to stay healthy. To do its job, your heart must receive a sufficient supply of blood and oxygen through a special network of blood vessels called the coronary arteries.

The inner walls of the coronary arteries are normally smooth, allowing blood to flow through them easily. Over time, however, a condition called coronary artery disease can develop in which fats and other materials carried in the bloodstream begin to adhere to the artery walls. When these materials build up, they become a substance known as plaque, which narrows or blocks the arteries and restricts blood flow. As a result, the heart may not receive the oxygen it needs to perform the work it is being called upon to do.

Preparation for the Test

• Do not use nicotine products or consume caffeine for 4 hours before the test.
• Do not eat for 4 hours prior to the test. Diabetics may, however, have clear liquids. (If you are diabetic, please consult your physician regarding your diet for the test.)
• Continue taking your medications with sips of water.
• Wear a comfortable two-piece outfit.
• Bring your doctor's order with you.
• Bring a list of your medications with you.
• Arrange for someone to drive you home after the test as a medication called atropine may be used during the test. This medication can make eyes sensitive to bright sunlight.

The Day of the Exam
The dobutamine thallium exam consists of two separate testing periods which are performed on the same day. The testing periods each take approximately 1½ hours to complete, with a 3-hour delay in between.

The first and most important thing to remember while undergoing a dobutamine thallium exam is that the cardiologist who is conducting the test is also there to answer any questions you may have. A registered nurse, nuclear medicine technologist and a technologist will also be present.

During the test, the physician and technologists will monitor your heart with a machine called an electrocardiograph. To do this, ten electrodes, connected by wires to the electrocardiograph machine, will be placed on your chest. Your blood pressure will also be monitored.

An intravenous line (IV) will be placed in your arm. Dobutamine and thallium will be given directly through the IV line. The dobutamine will be administered at increasing dosages until a desired heart rate is achieved (similar to how exercise increases your heart rate). Most patients just feel their hearts beating faster. However, if you have any unusual sensations during the test, it is important to report them to the doctor.

Following dobutamine, the nuclear medicine technologist will administer the thallium. A special camera that is able to detect thallium will be placed close to your chest. This camera will take images of the thallium as it is carried to your heart through the coronary arteries.

Once the images have been taken, you may leave the Nuclear Medicine Department and have a light meal. Before leaving the department, you will be informed of a time at which to return for the second part of your test.

Upon your return, you will be given another injection of thallium, and asked to sit in the Waiting Room for about an hour. You will then be escorted to the camera area where a second set of pictures will be made of your heart at rest.

Side by side comparison of both sets of pictures will enable the physician to better evaluate your condition. A written report will be provided to your referring physician within 5 to 7 days after the test.

Reducing your Risk for Heart Disease

• Don't smoke
• Have your blood pressure checked regularly
• Reduce your intake of fats and cholesterol
• Maintain your ideal weight
• Exercise regularly according to your physician's guidelines

Inquiries
Our goal is to provide you with excellent care. If you have any questions or comments, please contact:

Jan Duval, RN
Coordinator, Heart Station
847-723-5480