Dobutamine Stress Echo

What is a Dobutamine Stress Echocardiogram Test?

A Dobutamine Stress Echocardiogram is a test that combines an ultrasound study of the heart with a stress test. It looks at how the heart functions when it is made to work harder. A stress test usually involves exercising, either on a treadmill or stationary bike. For patients who are unable to exercise adequately, the test may be performed with a drug called Dobutamine. Dobutamine has an effect on the heart similar to exercise.

What is Dobutamine?

Dobutamine is a positive inotropic agent and mild chronotropic agent, meaning it increases the contractility of the heart with minimal changes in heart rate. As Dobutamine is given, it is normal to feel your heart pound for a few minutes. In addition, you may experience side effects such as chest pain/pressure, headache, dizziness, nausea, shortness of breath, shaky, warm and flushed. If you begin to notice these symptoms or other symptoms of concern notify the stress lab personnel immediately. Most patients do not experience any side effects. Dobutamine has a short duration of action so its effects wear off quickly once the Dobutamine infusion is turned off.

What does the test show?

A Dobutamine Stress Echocardiogram test is performed to evaluate the function of your heart, mainly your left ventricle (main pumping chamber) when the heart is under stress. This test can help evaluate the following:

• Your risk for coronary artery disease.
• If the symptoms you are experiencing (ie., chest pain or pressure, shortness of breath, unexplained fatigue, palpitations, lightheadedness, ,etc.) are caused by a blockage to your heart or other heart condition.
• It can help detect heart problems that may not be present at rest.
• It is used for cardiac clearance before surgery or other procedure.
• If you have already been diagnosed with coronary heart disease, a stress test may enable the doctor to estimate the severity of the blockages.
• If you have just undergone balloon angioplasty or bypass surgery, a stress test can help monitor the success of the procedure as well as determine an appropriate rehabilitation program for you.

Normally, all areas of the heart muscle pump more vigorously when your heart rate increases. If an area of the heart muscle does not pump as it should with an increase in heart rate, this often indicates that it is not receiving enough blood because of a blocked or narrowed artery. The Dobutamine Stress Echo shows which areas of the heart muscle that do not receive an adequate blood supply. However, it does not provide images of the actual coronary arteries.

How do I prepare for the test?

• Do not eat or drink for 4 hours prior to the test. This will help prevent the possibility of nausea and vomiting which may accompany the infusion of dobutamine. If you are diabetic or need to eat/drink with your medication, get special instructions from your doctor.
• No smoking 4 hours prior to the test. Smoking may interfere with the test results.
• Wear a two-piece outfit because women will wear a hospital gown and men will be asked to take off their shirt.
• Do not wear oils or lotions before your test. Small sticky patches (electrodes) will need to stick to your chest.
• Do not take the following heart medications on the day of your test unless your physician tells you otherwise or if the medication is needed to treat chest discomfort:
  • Beta Blockers (for example, Tenormin, Lopressor, Propanolol)
  • Isosorbide dinitrate (for example: Isordil, Sorbitrate)
  • Isosorbide mononitrate (for example: Ismo)
  • Nitroglycerin (for example: Deponit, Nitrostat)
• Your physician may also ask you to stop taking other heart medications on the day of your test. If you have any questions about your medications, ask your physician. NOTE: Do not discontinue any medication without first talking with your physician

What happens during the test?

When you enter the stress testing room, the Cardiology Tech/Nurse will have you sign a consent form and he/she will make sure you understand the test. Women will be asked to change into a gown and men will be asked to take off their shirt. Your skin will be abraded with an alcohol wipe and a cloth to clean off any oils or lotions on your skin. You will be shaven if you have a hairy chest. Ten patches are placed on your chest and torso. Wires will be attached to the patches in order to hook you up to the EKG machine. The EKG allows the doctors and Cardiology Tech/Nurse to monitor your heart rate and rhythm throughout the test. The Cardio Tech/Nurse will put a blood pressure cuff around your arm to monitor your blood pressure throughout the test.

An IV will be started in a vein in your arm. The Echo Tech obtains the resting images of your heart while you lie on a stretcher. Gel is applied to the chest and a transducer (small probe) is moved to various areas to obtain the pictures of your heart. The transducer sends ultrasound waves that bounce off the various parts of the heart. These echoes are converted into moving images of the heart. The image is displayed on a screen and recorded on videotape.

The Cardiologist will perform a quick assessment, review your medical history, and look at the echo images before the dobutamine is infused. The dobutamine will be infused (injected very slowly over about 12 minutes) into your vein. The drug causes your heart to pump faster and harder, as if you were exercising. Additional sets of echo images are obtained during the infusion of dobutamine and afterwards. The dobutamine infusion is turned off before the 12 minutes if:

• You exceed a "target" heart rate based on your age
• The Cardiologist or Cardio Tech/Nurse detects abnormal changes on your EKG
• You experience significant symptoms, such as shortness of breath, chest pain, chest tightness, dizziness, etc. that do not permit you to exercise any longer.
• Your blood pressure goes up too high

The dobutamine is infused longer than the 12 minutes if your heart rate has not reached the predicted “target” heart rate. Sometimes the Cardiologist will have the Nurse give you a drug called Atropine through your IV if your heart rate has not sufficiently increased.

A final set of echo images are obtained once your heart rate slows down. Sometimes the Cardiologist will have the Nurse give you a drug called Lopressor through your IV if your heart rate is taking a long time to decrease. The Cardiologist compares the images (before, during and after the dobutamine) to determine how your heart responds to the stress induced by the dobutamine.

When do I get the results and what do they mean?

The Cardiologist conducting the test may be able to give you preliminary test results before you leave the testing room. A test report will be sent to your primary Physician in about 3-5 business days so your Physician can discuss the test results with you during a future office visit.

If your test is positive (abnormal), the Cardiologist conducting the test, along with your Physician, will help develop a treatment plan that is best for you. The Cardiologist may recommend another stress test (see Nuclear Stress Test for more information). Or, the Cardiologist may recommend further, more invasive testing such as a Cardiac Catheterization.

Is the test safe?

The test is generally safe. A small amount of risk exists because it stresses the heart. Possible rare complications include abnormal heart rhythms and low blood pressure. Experienced staff are able to handle any emergency.

Where is the test performed?

On the second floor of Sparrow Hospital in the cardiology department Heart Center or on the third floor of the St. Lawrence Campus.

How long does this test take?

The test takes approximately 1 hour.