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Heart disease stress tests

Stress tests are performed by a doctor and/or trained technician to determine the amount of stress your heart can manage before developing either an abnormal rhythm or evidence of ischaemia (not enough blood flow to the heart muscle). The most commonly performed stress test is the exercise stress test.

What is an exercise stress test?

The exercise stress test - also called an exercise electrocardiogram or treadmill test - provides information about how the heart responds to exertion. It usually involves walking on a treadmill or pedalling a stationary bike at increasing levels of difficulty, while your electrocardiogram, heart rate and blood pressure are monitored.

Why do I need a stress test?

Your doctor uses the stress test to:

  • Determine if there is adequate blood flow to your heart during increasing levels of activity
  • Evaluate the effectiveness of your heart medications to control angina and ischaemia
  • Determine the likelihood of having coronary heart disease and the need for further evaluation
  • Check the effectiveness of procedures done to improve blood flow within the heart vessels in people with coronary heart disease
  • Identify abnormal heart rhythms
  • Help you develop a safe exercise programme

What types of stress tests are there?

Adenosine stress test: This is used in people who are unable to exercise. A drug is given to make the heart respond as if the person were exercising. This way the doctor can still determine how the heart responds to stress, but no exercise is required.

Echocardiogram: An echocardiogram (or "echo") is a graphic outline of the heart's movement. An echo can accurately visualise the motion of the heart's walls and pumping action when the heart is stressed; it may reveal a lack of blood flow that isn't always apparent on other heart tests.

Nuclear stress test: This helps to determine which parts of the heart are healthy and functioning normally and which are not. A small and harmless amount of radioactive substance (thallium) is injected into the patient. Then the doctor uses a special camera to identify the rays emitted from the substance within the body; this produces clear pictures of the heart tissue on a monitor. These pictures are done both at rest and after exercise. Using this technique, a less than normal amount of thallium will be seen in those areas of the heart that have a decreased blood supply.

Preparation for these types of stress tests will vary. Ask your doctor about any specific instructions.

How should I prepare for the exercise stress test?

Your doctor will give you specific advice about how to prepare for the exercise stress test.

Before the stress test usually people are advised:

  • Do not eat or drink anything except water for four hours before the test.
  • Do not drink or eat foods containing caffeine for 12 hours before the test. Caffeine will interfere with the results of your test.
  • Do not take isosorbide or nitroglycerin on the day of your test unless your doctor tells you otherwise, or if the medication is needed to treat chest discomfort the day of the test. If you have any questions about your medications, ask your doctor. Do not discontinue any medication without first talking with your doctor.
  • If you use an inhaler for your breathing, please bring it to the test
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