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Graded Exercise Test (GXT)
The Graded Exercise Test is a general screening tool used to evaluate the heart’s response to exercise.
The heart normally contracts regularly due to an orderly spread of electrical activity from an area of specialized heart cells called “pacemaker cells” to the rest of the heart. An electrocardiogram (ECG) represents a surface mapping of the electrical activity of the heart.
There is a normal pattern of changes in the electrical activity of the heart with exercise. With different types of heart disease, there will be various other patterns of changes in the electrical activity of the heart during the exercise process. For example, the response in the rate and regularity of a heart’s contractions are affected by some forms of heart disease while, in others, the spread of electrical activity within the heart is affected. The resulting change in the shape of the surface mapping of the electrical activity is recorded on the ECG.
You can have a light breakfast with juice the morning of the test but no caffeine (no tea, coffee, decaffeinated products, chocolate, soda pop or medications containing caffeine).
You should bring comfortable exercise clothing and shoes (preferably running shoes) appropriate for exercising on a treadmill.
Bring a list of all present medications.
Your physician may decide to temporarily discontinue certain heart medications prior to the test. These are discontinued because they may offset the effectiveness of the test. Your physician MUST inform you whether to discontinue these heart medications 48 hours prior to the test. DO NOT STOP any medication on your own without checking with your physician. You may resume taking your medications following the exercise test.
Prior to the test, you will be asked to sign a consent form. Please read it carefully and if you have any questions, ask the technologist or the physician supervising the test. He or she can explain the entire procedure before it begins.
Several electrode pads will be placed on your chest to obtain an ECG. Men may need to have small areas of their chest shaved. These electrode pads will be connected to an electrocardiograph (ECG) monitor so that your heart rhythm can be watched closely throughout the test. A cuff will be applied to your arm to monitor blood pressure.
You will exercise by walking on a treadmill. The treadmill will start slowly and then the speed and grade will increase in stages. As exercise increases, your heart rate and blood pressure will rise. This is a normal response and they will be monitored along with your ECG.
You will be encouraged to exercise for as long as you can because this increases the effectiveness of the test. If you experience any symptoms at any time, such as chest pain, shortness of breath or lightheadedness, immediately tell the individual monitoring the test so adjustments can be made.
After the exercise portion of the test, you will be seated in a chair for a few minutes. Your blood pressure and ECG will continue to be monitored while you recover.
A written report will be sent to your physician upon completion of analysis of the test. Your physician will then explain the test results to you.
The test lasts anywhere from 30 – 45 minutes depending on exercise and recovery time. However, you should allow about one hour for the entire test.
The exercise portion of the test constitutes a risk factor equivalent to 1,500 kilometers of highway driving.
You can take your heart medications after completion of the test.