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Diagnostic Tests in Cardiovascular Diseases

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8. Stress Echocardiogram Testing

What is a stress echocardiogram?

A stress echocardiogram test combines an echocardiogram (cardiac ultrasound) of the heart and an electrocardiogram (EKG) with an exercise or pharmacological (medication) stress test. This allows the doctor to understand how the heart functions when it is made to work harder.

What is a stress echocardiogram for?

The most common reason for having a stress echocardiogram is to determine the presence of blockages in the coronary arteries and the extent of heart muscle involvement in the evaluation of chest pain, shortness of breath, or pre-surgical evaluation. Occasionally it is used for evaluation of patient with valvular heart diseases. It is often ordered when there are difficulties in using EKG alone to infer whether there is lack of blood supply to the heart. This occurs in some patients who have conditions that can cause erroneous (false positive) changes in the EKG during exercise, such as pre-menopausal females, patients on certain medication such as Digoxin, or patients who have an abnormal EKG to start with. Alternatively, the patient may have difficulties in walking such as having a stroke or arthritis; then a medication, such as Dobutamine, can be given intravenously to create the stress necessary for the evaluation of the heart.

How is it performed?

A specially trained nurse and a sonographer often assist a cardiologist who has special training in stress echocardiograms perform the test. As discussed, you may be asked to have an exercise stress echocardiogram (ESE) or a Dobutamine stress echocardiogram (DSE).

In either case you will have an echocardiogram before the stress at rest and immediately after the peak stress achieved. The regional and overall contraction of the heart muscles, and sometimes the valvular function will be compared before and after the stress. You will be hooked up with surface EKGs, and a blood pressure monitor during the test. During the test you should report any symptom, such as chest pain, palpitation, or shortness of breath to the supervising doctor, nurse or technician.

In an exercise stress echocardiogram, you will be asked to walk on a treadmill where the speed and slope of the treadmill is increased at predefined intervals (usually every 3 minutes). You should exercise as much as you can tolerate. When you decide you have exercised as much as you can, you should let the doctor and the technicians know and they will end the test. Most patients can exercise between three to 15 minutes depending on the age and physical state. The ability to exercise, heart rate, blood pressure response, the EKG, rhythm during exercise and recovery will be compared. Alternatively, a supine stationary bicycle can be used for this test which is more popular in Europe.

In a Dobutamine stress echocardiogram, an intravenous line will be established and Dobutamine will be infused at incremental rates at pre-defined intervals until the desired age-adjusted target heart rate was achieved or symptoms limiting the continuation of the tests. Occasionally, a medication called Atropine will be given intravenous if there is any difficulty to achieve the target heart rate.

The exercise and Dobutamine stress tests usually takes about 30 to 90 minutes to complete.

How should I prepare for the test?

You should check with you doctor whether or not to withhold some of your cardiac or hypertensive medications. For the purpose of diagnosing ischemia (lack of blood supply to the heart), medications like beta-blockers (e.g. Atenolol, Lopressor), calcium-channel blockers (e.g. Cardiazem) may need to be held 24 to 48 hours prior to the test. Bring all the medications or a list of medications with you to the test so that that the doctors will know what you are taking. If you are undergoing an exercise stress echocardiogram, you should wear light clothing with sneakers or comfortable shoes.

If you have a morning appointment, have a very light breakfast. If you have an afternoon appointment, eat nothing for 3 hours before you test.

What happens after the test?

The doctor will interpret the rest and stress information and generate a report to the referring doctor. There is no special precaution after this test. You may continue your usual activities after the test.