Stress echocardiography is a test to look for signs of coronary artery disease by studying the effects of stress on the heart using ultrasound imaging.
It is a non-invasive test that is particularly useful if your symptoms are not entirely classical of angina or the doctor wants to be more certain you have angina before committing you to more invasive tests, such as an angiogram. If a stress echo result is normal, it makes it very unlikely that you have any significant coronary disease.
It can also tell if you have had a heart attack in the past. If you do have angina, it can help show which coronary artery is likely to be diseased, which can help plan further angiography, angioplasty or surgery.
Sometimes a stress echo is done to stress the function of a heart valve rather than the arteries — the procedure is similar to a normal stress test, but we concentrate our images on the valves rather than the muscle of the heart.
What does it involve?
Stress echo involves a similar procedure to a standard echo. You will have images taken of your heart at rest. Your heart will then be made to work harder (stressed). There are three ways to stress your heart:
- Dobutamine: This is a medicine that is infused into a cannula in your arm. It causes you heart to speed up and pump stronger – effectively work as though you were out running. The dobutamine infusion is increase until your heart rate achieves a “target” level that has sufficiently stressed your heart. It is then stopped and the effect wears off in a few minutes. Occasionally atropine is given to help speed up the heart as well as the dobutamine. This is the commonest stress test done as it does not require you to exercise. Images are taken as your heart speeds up and at “peak dose”. Sometimes images are taken when your heart has rested too.
- Treadmill: You will be asked to walk and possibly jog on the treadmill until your heart is sufficiently fast or you have “had enough”. You will then have to lie back on the couch and have further images taken of your heart while it is still going fast. It is important that you get back in the right position on the couch as quickly as possible after stopping so that images can be taken before your heart is relaxed. This test is similar to doing an echo before and after a standard exercise test. It has the advantage that no medicines are required but you do need to be able to walk very fast.
- Cycle: You will lie on a special couch that has a cycle machine attached. Your feet will be strapped in and you will be asked to peddle at a steady rate. The peddles will get gradually harder to turn in order that your heart is asked to do more work. During this test, images can be taken throughout. When you have reached your peak heart rate, or had enough, you will stop cycling and a final set of images will be taken.
- The advantages and disadvantages of each form of stress test will be explained to you in advance. You will have ECG and blood pressure monitoring throughout the test and while you recover.
What preparation is needed?
It is helpful if you can wear clothes that are easy to remove. Please let the receptionist know if you will need help with undressing or if you would like a chaparone. If you are doing a treadmill or stress test, please wear clothes and shoes that are comfortable to walk or cycle in (eg loose trousers and trainers). You may want to bring a change of shirt in case you get sweaty. It is best if you do not eat much for 2 hour prior to the test.
Please tell the doctor or nurse if you have glaucoma or prostate trouble — we will avoid using atropine in that case.
You should take all your usual medication on the day of the test, especially any blood pressure tablets. However, unless your doctor says otherwise, the following medication SHOULD NOT be taken on the day of the test:
Adizem, Angitil, Atenolol, Betaloc, Beta-adalat, Beta-cardone, Bisoprolol, Cardicor, Carvedilol, Celiprolol, Co-tenidone, Diltiazem, Emcor, Eucardic, Inderal, Ivabradine,Labetalol, Lopresor, Metoprolol, Nebilet, Nebivolol, Propranolol, Procoralan, Securon, Slozem, Sotacor, Sotalol, Tildiem, Trandate, Verapamil, Zemtard
You can take these medications immediately after the test. If you are unsure, please ask. Please bring your list of medications on the day.
How long does it take?
You should allow about 90 minutes for the test and recovery. The actual test takes about 20-30 minutes to do
What happens after
You will be given tissues for you to wipe off all the ultrasound jelly. You can then put your clothes back on behind a screen. If you had a dobutamine stress test, the cannula will be removed and a plaster applied. You will be asked to wait for about 20 minutes before leaving to ensure you are feeling back to normal. Dobutamine wears off in a few minutes. The effects of atropine can take a few hours to wear off — it can causes blurred vision, a dry mouth and make bright lights dazzling. We recommend that you do not drive for a few hours afterward, so please have someone to take you home.
The study takes a while to report and it is not usually possible to give you the findings immediately after the scan.
Where can it be done?
Stress Echo studies can be performed at Colchester Hospital or the Essex Cardiothoracic Centre.
Each centre uses different machines and occasionally one centre may be recommended over another for technical reasons. The cycle machine is only available at the Essex Cardiothoracic Centre.
What are the risks?
There are no known risks with cardiac ultrasound. If the probe has to be pressed very hard against your chest, you may get a mild tender area but it would be unusual for you to bruise, unless you are on warfarin.
Dobutamine causes your heart to beat fast and strongly. Very rarely it can cause abnormal heart rhythms that need medication to reverse. Since the test is done on patients who are likely to have angina, it can provoke angina and in rare circumstance can cause a heart attack. You will be closely monitored throughout the test and afterward.
Treadmill and cycle stress tests can also very rarely cause angina or extremely rarely provoke a heart attack.
You will be having this stress test in order to see if you have angina. These stress tests are called “non-invasive” tests because they do not involve inserting long catheters into your body (ie angiography) and therefore the risks are much smaller than an angiogram. Your doctor will have only advised this test if they feel the small risk is outweighed by the benefit of the test. The reason for doing the test will be explained to you in clinic in advance.
What are the benefits?
Stress echo is a test that can help your cardiologist decide if you have angina or not. It can also help decide which arteries need treated and which are best left alone. It is a relatively straight forward, low risk study that involves no radiation (unlike other alternatives).
The National Institute for Clinical Evidence (NICE) have recently reviewed diagnostic tests for angina and recommend stress echocardiography for many patients who would previously have had a treadmill stress test.
Occasionally stress echo is done to assess heart valves. In these cases, it can help decide if the valve is severely narrowed or leaky enough to require surgery. Since the symptoms of valve disease, breathlessness, come on during exercise, it is a very good way of seeing whether the valve is causing a problem during a stress, such as exercise.