Stress Echocardiography

An echocardiogram is a non-invasive test to look at the heart and large blood vessels. Echocardiography uses ultrasound waves to take detailed images of the moving heart.

Some heart conditions surface only during physical activity. A stress echocardiogram is used to assess the heart function in response to stress. Ultrasound images of the heart are taken as the heart beats harder and faster during exercise (or simulated with injected medications).

The images taken during exercise stress are compared to those taken at rest. If any part of the heart contracts abnormally during exercise stress, this may suggest a lack of blood supply to that area.

The coronary arteries are the blood vessels that supply the heart muscles with oxygen-rich blood. When the coronary arteries are narrowed, the heart muscles may only receive enough blood supply in the resting state. However, during stress, the blood flow may be insufficient to meet the increasing oxygen demands of the heart muscles. This lack of blood supply causes symptoms such as chest pain (also known as angina) or shortness of breath, and may be a warning sign of a heart attack.

A stress echocardiogram is an accurate and safe test to detect a lack of blood flow to the heart muscles. A stress echocardiogram is also more accurate than a treadmill electrocardiogram (ECG) test to detect narrowing of the coronary arteries.

Coronary artery disease develops when the arteries that supply blood to your heart become narrowed or blocked by a build-up of fatty cholesterol deposits called plaque. This process is known as atherosclerosis and develops over time.

Your cardiologist may suggest a stress echocardiogram for the following reasons:

• Determine if your symptoms are caused by coronary artery disease
• Evaluate the function of your heart and valves
• Determine how well your heart tolerates activity
• Evaluate the effectiveness of your cardiac treatment plan

There are two different types of stress echocardiography:

Exercise Stress Echocardiography
Exercise stress echocardiography combines an echocardiogram with a treadmill exercise ECG test. Ultrasound images of the heart are taken before and after exercising on the treadmill.

Dobutamine Stress Echocardiography
Dobutamine stress echocardiography uses a medication called dobutamine to increase your heart rate at rest. Ultrasound images of the heart are taken before and during dobutamine infusion. Sometimes atropine is added to dobutamine infusion. This test may be used if you are unable to exercise.

Your cardiologist will decide which type of stress echocardiography is most suitable for you.

Exercise Stress Echocardiography

1. Resting echocardiogram
   • You will be asked to undress from the waist up. You will wear a gown for the procedure.
   • Electrodes, which are small sticky patches, are placed on your chest. These patches are connected to an ECG machine that monitors your heart rhythm throughout the test. Sometimes, shaving of the chest hair may be necessary for the electrodes to stay in place.
   • You will be asked to lie down on your left side on an exam table for the Echocardiogram. A small amount of gel will be applied on your chest. Our sonographer will use an ultrasound probe to acquire images of your heart.
2. Treadmill exercise
   • Under continuous supervision of our staff, you will start walking on the treadmill, which is programmed to get steeper and faster every 3 minutes.  Your blood pressure and heart rate will be measured throughout.
   • Once you have reached a set heart rate target, or if you develop symptoms that do not allow you to continue, the treadmill will stop.
3. Post-exercise echocardiogram
   • Once the treadmill is stopped, you will be asked to quickly lie down on your left side on the exam table. Our sonographer will use an ultrasound probe to acquire images of your heart.

The whole process takes about 60-90 minutes, with the actual exercise time lasting about 6 to 12 minutes.

Dobutamine Stress Echocardiography

1. Resting echocardiogram.
   • You will be asked to undress from the waist up. You will wear a gown for the procedure.
   • Electrodes, which are small sticky patches, are placed on your chest. These patches are connected to an ECG machine that monitors your heart rhythm throughout the test. Sometimes, shaving of the chest hair may be necessary for the electrodes to stay in place.
   • A small needle called an IV cannula will be inserted into a vein in your hand.
   • You will be asked to lie down on your left side on an exam table for the Echocardiogram. A small amount of gel will be applied on your chest. Our sonographer will use an ultrasound probe to acquire images of your heart.
2. Dobutamine infusion
   • You will continue to lie on the exam table.
   • Under continuous supervision of our staff, Dobutamine will be given to you through the IV cannula during the test. Your blood pressure and heart rate will be measured continuously.
   • Dobutamine will increase your heart rate, causing your heart to beat faster and harder. You may feel slightly short of breath at this time. These are normal effects of dobutamine and will go away once the infusion stops.
   • Sometimes atropine is added to dobutamine infusion if you are not able to reach the target heart rate with dobutamine alone.
   • Once you have reached a set heart rate target, or if you develop symptoms that do not allow you to continue, the dobutamine infusion will stop.
3. Dobutamine echocardiogram
   • Our sonographer will use an ultrasound probe to acquire images of your heart during and after the Dobutamine infusion.

The whole process takes about 60-90 minutes, but the actual dobutamine infusion is usually 15 minutes. Your heart rate will return to normal after 5-10mins of stopping the dobutamine infusion.

You will need to rest for at least 30 minutes after your exercise stress echocardiogram. After this, you will be able to go about your usual activities.

You may be observed longer or monitored inpatient for a dobutamine stress echocardiogram.  It is advisable to avoid driving after a dobutamine stress echocardiogram, and for someone to drive you home after the test.

There are no side-effects associated with the echocardiogram itself. You may feel minor discomfort from the ultrasound probe being held firmly against your chest. The firmness is necessary to acquire the best quality images of your heart.

Treadmill exercise is very safe and side effects are uncommon. Some of the potential risks are:

• Chest pain
• Breathlessness, dizziness, fainting
• Abnormal heart rhythm (0.1%)
• Heart failure
• Heart attack (0.4%)
• Death (0.01%)
• Muscle/joint injury, fall from a machine

Dobutamine infusion is safe and side effects are uncommon. Some of the potential risks are:

• Palpitations, chest pain, shortness of breath, nausea, vomiting, dizziness and flushing. These are temporary and will disappear within minutes after the test is terminated.
• Leakage of the drug at the infusion site may cause local pain and inflammation.
• Abnormal heart rhythm (0.1%)
• Heart attack (0.4%)
• Death (0.01%)
• Allergy reaction
• Atropine side effects (blur vision, dry mouth, flushing, abdominal discomfort, urine retention

Serious complications from a stress echocardiogram are extremely rare. However, in the unlikely event of serious side effects such as heart attack or irregular heart rhythm, treatment is available. Your doctor will closely monitor you for side effects during and after the test.

No, you will not be exposed to any radiation. This is because echocardiograms use ultrasound waves (high-frequency sound waves) to acquire the images.

Before your stress echocardiogram, you should do the following:

• Do not eat or drink anything for at least 2 hours before the test.
• Avoid all food containing caffeine for 24 hours before the test. This includes coffee (including decaf), tea, and chocolate. Caffeine can affect your heart rate and interfere with the results.
• Do not smoke or consume alcohol on the day of the test.
• Wear comfortable, loose-fitting clothes.
• Wear comfortable shoes if you are going for an exercise stress echocardiogram. You should be able to do the test if you can walk easily or walk briskly.

It is important to tell your cardiologist about any other medical conditions you have (such as mobility issues, glaucoma or prostate problems), or if you are feeling unwell.

If you use an inhaler for asthma or other breathing problems, please bring it along with you.

Medications that slow down your heart rate, such as beta-blockers or calcium channel blockers, need to be stopped 24 hours before your stress echocardiogram. This is because these medications will interfere with the results of the test. You may consume your other regular medications.

Please check with your cardiologist to see if you need to stop any of your medications. Examples of medications that may need to be stopped are:

• Beta-blockers
• Calcium channel blockers

Your cardiologist will review the findings of the stress echocardiogram and discuss the results of your test during your next follow-up appointment. You may be contacted earlier if urgent care is required for your condition. Further tests may be recommended if abnormalities are detected.