Definition

• A Dobutamine stress echo test is used to detect underlying blockages of the arteries of the heart and it is suitable for patients unable to run on a treadmill.
• Dobutamine, a cardiac medication, is injected into a vein to stimulate the heart to beat faster and harder. Ultrasound images of your heart are taken before and during the infusion of the medication to evaluate the pumping function of the heart and detect areas with abnormal muscle contraction (indicating inadequate blood supply).

What are the benefits of a dobutamine stress echo test?

A Dobutamine stress echo test combines the benefits of both the echocardiogram and a stress test using dobutamine.

Benefits of an echocardiogram

• Assess the overall pumping function of the heart eg
  – Presence and aetiology of heart failure
  – How well the heart pumps after a heart attack
• Determine the presence of any structural heart disease eg.
  – Congenital heart diseases (“Holes in the heart”)
  – Valvular heart diseases (Disorders of the heart valves)
  – Myocardial diseases (Disorders of the heart muscle)
  – Pericardial diseases (Disorders of the outer lining of the heart)
• Diagnose underlying Coronary Artery Disease (CAD)
• Diagnose infections affecting the heart eg.
  – Infective endocarditis (Infections of the heart valves)
  – Myocarditis (Infection of the heart muscles)
  – Pericarditis (Infection of the outer lining of the heart)
• Diagnose clots in the heart that can lead to major strokes
• Diagnose cardiac tumors eg atrial myxomas
• Evaluate the progression of valve disease over time
• Evaluate the effectiveness of medical or surgical treatments for hypertension, valvular heart disease or cardiomyopathy (weak heart muscles).

Benefits of a Dobutamine stress test + echocardiogram

• Increases the accuracy of diagnosing underlying blockages of the heart.
• Assesses the ability of the heart function to improve with dobutamine.
• Prognosticates the risk of a cardiac event (eg heart attack).
• Guides treatment of heart disorders eg timing for cardiac surgery such as valve replacement, heart transplantation in patients with heart failure and cardiac bypass surgery in patients with multiple heart artery blockages.

Example of a stress echocardiogram of a 45 year old patient complaining of chest pain wanting to find out whether he has heart artery blockages in view of his strong family history of heart attacks.

a. Parasternal Long Axis view

b. Parasternal short axis view

Findings – Normal augmentation of heart function at peak heart rate.

Conclusion – Normal stress echocardiogram with no evidence of heart artery obstruction.

Who will benefit from this test?

Patients with symptoms of:

• Chest pain
• Shortness of breath
• Irregular heart beats or palpitations
• Recurrent giddiness or fainting spells

Part 1: Baseline resting 2D echocardiogram

• Our female cardiac technician will explain the procedure to you and what the examination will entail.
• You will be asked to remove your clothing from the waist up and we will provide a gown for you to wear during the exam.
• Our cardiac technician will attach 10 ECG electrodes (small flat sticky patches) on your chest and a blood pressure cuff around your right arm. The electrodes are attached to ECG monitor that charts your heart’s electrical activity continuously during the test.

• You will be asked to lie down on your left side on an exam table while our cardiac technician will place a probe (called a sound-wave transducer) on several areas of your chest. The probe will have a small amount of gel on the end to help produce clearer pictures. This gel will not harm your skin.
• To obtain clearer pictures of your heart, you may be asked to change positions and hold your breath several times during the exam.
• It is common to hear your heart sounds (Doppler signals) during the test.
• A slight pressure of the probe on your chest and a coolness on your skin from the gel will be felt during the exam but there will be no major discomfort.

Part 2: Dobutamine stress test

• An Intravenous line (IV) will be inserted into a vein in your arm. This line will be used to deliver dobutamine medication directly into your bloodstream.
• Baseline measurements (Heart rate, Blood pressure and resting ECG) will be recorded before the test is started.

• IV Dobutamine will be administered at gradually increasing doses while the our technician continues to obtain the echo images.
• You may feel your heart react like you were exercising and develop a warm flushed feeling. In some cases, you may feel a mild headache or nausea.
• At regular intervals, our techinican will ask you how you are feeling. Please inform them if you feel any:

1. Chest, jaw or arm pain
2. Shortness of breath
3. Dizziness or light-headedness

• Our technician will also be monitoring your heart rate, blood pressure and ECG response to the medications to decide if the test should be stopped.
• This test will take about 1 hour to complete. The actual infusion time is usually about 15mins long.

• IV Dobutamine infusion will be stopped and your heart rate will return to normal after 5-10mins.
• The IV line will be removed and you will be monitored for at least 30mins after completing the procedure.
• When your dobutamine stress echo is complete, you may return to your normal activities for the remainder of the day.
• Our doctor will review the findings of treadmill test and discuss the results of your test during your next follow-up appointment. Further tests may be recommended if abnormalities are detected.

How does the doctor use this test to treat me?

• If the information gathered during the test reveal that your heart condition is normal, no further tests will be needed. However, if your test results are normal and your symptoms continue or becomes worse, our doctor may recommend further tests (eg a CT coronary angiogram or Coronary Angiogram) to gather more information about your heart condition.
• If the purpose of your stress test was to guide treatment for a heart condition, our doctor will use data from the test to establish or modify your treatment plan, as needed.

• If the results of your dobutamine stress echo suggest underlying blockages of the arteries of your heart or a heart rhythm irregularity, the information gathered during the test will be used to help our doctor develop a treatment plan. You may need additional tests and evaluations, such as a coronary angiogram, depending on the findings.

More information