TMT (STRESS TEST)
A stress test, also called an exercise stress test, is used to gather information about how well your heart works during physical activity. Because exercise makes your heart pump harder and faster than it does during most daily activities, an exercise stress test can reveal problems within your heart that might not be noticeable otherwise.
An exercise stress test usually involves walking on a treadmill or riding a stationary bike while your heart rhythm, blood pressure and breathing are monitored.
Your doctor may recommend an exercise stress test if he or she suspects you have coronary artery disease or an irregular heart rhythm (arrhythmia). An exercise stress test may also be used to guide your treatment if you've already been diagnosed with a heart condition.
Your doctor may recommend an exercise stress test to:
- Diagnose coronary artery disease.
- Diagnose heart rhythm problems (arrhythmias).
- Guide treatment of heart disorders.
In some cases, stress tests may be used to help determine the timing of cardiac surgery, such as valve replacement. In some people with heart failure, results from a stress test may help the doctor evaluate the need for heart transplantation or other advanced therapies.
Your doctor may recommend a procedure called a nuclear stress test if a routine exercise stress test doesn't pinpoint the cause of your symptoms. A nuclear stress test is a similar procedure that includes the use of radioactive dye and a special scanner to create images of your heart muscle.
You may be asked not to eat, drink or smoke for two hours or more before an exercise stress test. You can take your medications as usual, unless your doctor tells you otherwise.
If you use an inhaler for asthma or other breathing problems, bring it with you to the test. Make sure your doctor and the health care team member monitoring your stress test know that you use an inhaler.
Wear or bring comfortable clothes with you to the exercise stress test.
When you arrive for your exercise stress test, your doctor asks you about your medical history and how often you typically exercise. This helps determine the amount of exercise that's appropriate for you during the stress test.
During an exercise stress test
Before you start the test, a member of your health care team places sticky patches (electrodes) on your chest, legs and arms. The electrodes are connected by wires to an electrocardiogram (ECG or EKG) machine. The electrocardiogram records the electrical signals that trigger your heartbeats. A blood pressure cuff is placed on your arm to check your blood pressure during the exercise stress test.
You then begin slowly walking on the treadmill or pedaling the stationary bike. As the test progresses, the speed and incline of the treadmill increases. A railing is provided on the treadmill that you can use for balance, but don't hang on to it, as that may skew the results of the test. On a stationary bike, the resistance increases as the test progresses, making it harder to pedal. During the test, you may be asked to breathe into a tube to measure the gases in your breath as you exhale.
The length of the test depends on your physical fitness and symptoms. The goal is to have your heart work hard for about eight to 12 minutes in order to thoroughly monitor its function. You continue exercising until your heart rate has reached a set target or until you develop symptoms that don't allow you to continue. These signs and symptoms may include:
- Moderate to severe chest pain
- Severe shortness of breath
- Abnormally high or low blood pressure
- An abnormal heart rhythm
- Dizziness
- Certain changes in your electrocardiogram
A typical exercise stress test lasts 15 minutes or less. You may stop the test at any time if you're too uncomfortable to continue exercising.
Depending on your medical history, your stress test may also include:
Medication to stimulate your heart. If you can't exercise long enough to increase your heart rate, or if you're unable to exercise at all due to a medical condition such as arthritis, your doctor may give you medication to increase your heart rate or increase blood flow to your coronary arteries as a substitute for exercising.
Echocardiogram. An echocardiogram uses sound waves to produce images of your heart, allowing your doctor to see how your heart is beating and pumping blood. In some cases, you may have an echocardiogram before you exercise and after you're done. Your doctor can use the images from the echocardiograms to help identify abnormalities in the heart muscle and valves.
Nuclear stress test. Another stress test known as a nuclear stress test helps measure blood flow to your heart muscle at rest and during exercise. It's similar to a routine exercise stress test but with images in addition to an electrocardiogram. Trace amounts of radioactive material — such as thallium or a compound known as sestamibi (Cardiolite) — are injected into your bloodstream. Special cameras are used to detect areas in your heart that receive less blood flow.
Computerized tomography (CT) and magnetic resonance imaging (MRI). In some cases, your doctor may use these imaging technologies to visualize your heart under stress.