Chemical Stress Test Overview

A stress test is used to make sure the heart muscles are able to get enough blood when the heart rate and workload are increased. To do this, your heart needs to be looked at during a period of rest and then again during a period of increased activity. A chemical stress test uses chemical agents injected into the body through the vein. These chemicals make the heart function as if it were under stress.

There are many different ways to examine the heart during a stress test. The heart can be examined with:

• Stress echocardiogram
• MRI
• Nuclear imaging ( nuclear stress test )

Prior to Test

Your doctor may do the following:

• Physical exam
• Resting electrocardiogram (ECG, EKG)—a test that records the heart's activity by measuring electrical currents through the heart muscle
• Echocardiogram—a test that uses sound waves (ultrasound) to examine the size, shape, and motion of the heart and the function of its valves
• Review of your medicines—some may prevent the heart rate from increasing appropriately

Talk with your doctor before the day of the test to discuss how long you should fast (not eat or drink). Your doctor may recommend that you:

• Do not eat or drink anything with caffeine 12-24 hours before the test.
• Do not eat or drink anything, except water, four hours before the test.
• Do not smoke for several hours before the test.
• Wear comfortable clothing.
• Bring a list of your current medicines to the test.
• If you have diabetes, bring your glucose monitor to the test.
• Tell your doctor if you have asthma or chronic obstructive pulmonary disease (COPD).

Description of Test

You will lie down on a table. A technician will place electrodes on your chest. Your resting blood pressure and ECG readings will be taken. An IV (hollow needle and thin tube) will be placed in your arm. You will be hooked up to a heart monitor that will record your heart’s activity. Your blood pressure and heart rate will be checked often. A small amount of chemical will be injected through the IV and into your body. Depending on which chemical is used, your heart will beat faster and/or the blood vessels near your heart will open wider. An ECG may also be done at this time.

If you have chest pain, trouble breathing, dizziness, or any other symptoms, tell your doctor or technician right away. The test may need to be stopped. Changes in the ECG may also be a reason to stop the test.

If you are getting nuclear imaging, the technician will inject a mildly radioactive chemical through your IV. Thirty to sixty minutes after the chemical injection, a special camera or an MRI will be used to track the flow of the chemical through and around your heart. Images will be taken to find areas of the heart that may not be getting enough blood or are blocked. If you are getting a stress echocardiogram, an ultrasound will be taken at specific time points. The doctor will compare the pictures of your heart under stress with pictures of your heart at rest.

After Test

Your blood pressure, heart rate, and ECG will be monitored until levels return to normal. You will be able to leave after the test is done.

Typically takes 3-4 hours to complete (may be done over 1-2 days)

No, you should not feel pain during the test. You may feel a pinch when the IV is inserted. You may also feel a flushing sensation when the medicine is injected.

Your doctor may discuss some of the results on the same day as the test. It may take 2-3 days for the full results to be ready.

One or more of the following are considered a positive stress test:

• ECG changes that show low oxygen supply to the heart
• Significant blood pressure drops or rhythm changes
• You have chest pain or trouble breathing, especially if linked with ECG changes
• Stress test pictures that show areas of your heart having low blood flow or abnormal movements

A positive test may mean that you have CAD. Not everyone tests positive for it. Based on your results, your doctor may recommend more tests or care.

RESOURCES:

American Heart Association
http://www.americanheart.org/

American Society of Nuclear Cardiology
http://www.asnc.org/

CANADIAN RESOURCES:

Canadian Heart & Stroke Association
http://ww2.heartandstroke.ca/

Canadian Society of Nuclear Medicine
http://www.csnm-scmn.ca/

References:

American Heart Association website. Available at: http://www.americanheart.org . Accessed November 14, 2009.

American Society of Nuclear Cardiology website. Available at: http://www.asnc.org/ . Published September 23, 2009. Accessed November 14, 2009.

Libby P, Bonow RO, Mann DL, Zipes DP. Exercise stress testing. In: Braunwald E, ed. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia, PA: WB Saunders; 2007.

Pearson TA, Blair SN, Daniels SR, et al. AHA guidelines for primary prevention of cardiovascular disease and stroke: 2002 update. Circulation. 2002;106:388-391.

Recovery road booklet. Canadian Heart & Stroke website. Available at: http://ww2.heartandstroke.ca/splash/ . Published June 11, 2009. Accessed November 14, 2009.