A stress echocardiogram is a diagnostic test which uses sound waves like an ultrasound scan to build up a moving picture of the heart, to check for the furring up of the coronary arteries and assess heart valves and heart function.
If there is partial blockage of an artery, the motion of the heart may be normal when at rest but show irregularities when the heart is pumping faster.
If you’ve previously had a heart attack, abnormal heart wall motion may be seen when you are at rest. A stress echocardiogram is a non-invasive test that does not require intrusive cardiac catheters.
You are advised to wear comfortable clothing and shoes that won’t slip off your feet when you come in for a stress echocardiogram. You may want to bring a cold drink with you to have after the test. You will be advised when you book your appointment whether you need to stop taking any heart medications one or two days before the test.
The test can be performed using a drug that speeds up the heart rate, or the patient can pedal a dedicated stress echo bike to raise their heart rate.
An exercise stress echocardiogram will not be appropriate for all patients: your doctor will order the test which is suitable for you.
You will be asked to eat a light meal a couple of hours before the procedure.
If you’re having a dobutamine stress echocardiogram, you will need to confirm whether you have a significant allergy or a history of glaucoma, because of the effect a further drug used in the test called atropine (an extract of belladonna) has on people with glaucoma.
Patients having a dobutamine stress echocardiogram are advised to get someone to drive them back home and to avoid driving for the rest of the day.
At the start of the test, you will be asked to lie down on a bed. The skin on your chest will be rubbed smooth (if necessary shaved) and small sticky patches called electrodes attached and connected to the echocardiography ultrasound machine.
You will then be asked to lie on your left side and the doctor will obtain images by placing a transducer on your chest. This is a baseline echocardiogram, showing the state of your heart as you rest.
You are asked to lie on your left side and a ventflon, a small plastic tube, is inserted into the arm through which dobutamine and sonobue is administered.
As the heart rate speeds up, pictures of the heart are taken from different angles from the front of the chest. Once the heart rate has peaked at the target rate, the flow of drugs is stopped. The heart rate very quickly returns to base level and further pictures are taken.
Your blood pressure is taken before and after the procedure and if you don’t display any significant symptoms, you are asked to wait in the waiting room for 30 minutes for observations, after which the ventflon is removed and you are discharged home.
The test results may not be immediately available, as the specialist may need more time to analyse the images.
In nine out of ten patients, the image quality degrades when the heart rate starts to speed up, hence a contrast agent called sonobue is used so that the heart's borders are clearly seen.
In an exercise stress echocardiogram, further electrodes are attached to your chest to monitor the electrical activity of your heart. You will be placed on the specialist stress echo bike and asked to start pedalling slowly.
Gradually, the speed or resistance will be increased. Your heart rate and blood pressure level will gradually rise – both will be monitored. You will be encouraged to keep exercising for as long as you can, since this will increase the accuracy of the test.
If you experience any symptoms – discomfort in the chest, arms or legs, excessive shortness of breath, weakness or dizziness – warn the exercise physiologist monitoring you. After you have reached your peak level of exertion, you will be moved to the examination table. A further echocardiogram will be performed while your heart rate is raised.
The test takes approximately one hour.
The doctor who administered the test will analyse the results and prepare a report for your GP.
This is a very safe test. In a dobutamine stress echocardiogram, one in 100 patients may experience nausea, tingling in the back of the head, trembling or an urge to pass water. But these effects fade very quickly when the flow of drug stops.
There are very small risks of an allergic reaction to the contrast agent in a dobutamine stress echocardiogram, or of abnormal heart rhythms in either version of the test.
The limitations of the dobutamine stress echocardiogram are that in some patients it may still produce poor quality images despite using a contrast agent, in which case the procedure is abandoned and alternative tests such as cardiac MRI or a myocardial perfusion scan are considered.
Other limitations include patients being intolerant of the drugs used, shown by their developing severe nausea or light-headedness.
One clear limitation of exercise stress echocardiography is that it isn’t appropriate for patients with arthritis of the hip or knee, as it requires rigorous pedalling of the stress echo bike.
A privately funded (self-pay or insured) stress echocardiogram can be done at Circle within approximately one to two weeks of referral.