An exercise or stress electrocardiogram evaluates the heart's response to the stress of physical exercise. The electrical activity of the heart, blood pressure, and heart rate are monitored while you walk on a motor-driven treadmill. During exercise, the heart's need for oxygen increases. If the coronary arteries, which carry oxygenated blood to the heart muscle, are blocked or narrowed, the heart may not get enough oxygen during exercise. The oxygen-deprived heart may produce abnormalities in the ECG.

Why Performed

An exercise stress test is most often performed to determine the cause of unexplained chest pain when coronary heart disease is suspected. In patients with known heart disease an exercise test may be useful in determining the severity of the disease and the present exercise capacity in order to help plan treatment and rehabilitation. Stress tests are often performed following a heart attack or heart surgery to determine the capacity of the heart for exercise or work.

An exercise test may also be used to look for abnormal heart rhythms when symptoms such as dizziness, fainting, or palpitations occur during exercise or activity.

Some experts recommend that anyone over the age of 35 who has been generally inactive should have a stress test.

If you are over the age of 40, have been sedentary for many years, and have other risk factors for heart disease (high blood pressure, cigarette smoking, elevated cholesterol levels, and a family history of heart attacks at young ages), then a stress ECG might be helpful before undertaking a strenuous exercise program.

Preparation

• Tell your doctor if you are taking any medications.
• Before the test you are required to sign a consent form.
• You should not eat, smoke, drink alcohol or caffeinated beverages for 2-3 hours before the test. Continue taking all regularly prescribed medications, except beta blockers, unless your doctor directs otherwise. Your doctor may ask you to taper off certain heart medications a few days before the test. Wear exercise clothing and shoes (such as shorts, t-shirt, jogging pants, rubber sole shoes).

Procedure

An exercise test is usually performed in an office, clinic, or special hospital lab by a technician or physician. A physician is available before testing starts.

To prepare your skin for the placement of the ECG electrodes, several areas on your chest will be shaved (if necessary), cleaned with alcohol, and gently rubbed to remove dead skin and excess oils. Several small metal discs will be attached to your chest with adhesive. The electrodes are then connected with long wires to an ECG machine, which will record the electrical activity of your heart as a series of wavy lines on moving graph paper. A blood pressure cuff will be wrapped snugly around your upper arm so that your blood pressure can be checked every two minutes during the test.

You will be shown how to step on and off the slowly moving treadmill.

At first the treadmill will move slowly with a slightly inclined position. Every three minutes the treadmill will increase in speed and elevation.

In the treadmill tests your ECG, heart rate, and blood pressure will be recorded during the exercise. The work load is gradually increased until you reach your maximum or "target" heart rate or until you experience fatigue, extreme shortness of breath, or chest pain. The test may be stopped if you develop abnormalities on the ECG or blood pressure measurements.

When the exercise phase is completed you will be asked to sit down and rest. Your ECG and blood pressure will be checked every 2 minutes, during this recovery period. The electrodes are then removed from your chest, and you may resume your normal activities. The entire test usually takes 15-30 minutes.

How Does It Feel?

During the exercise you may experience leg cramps or soreness, fatigue, breathlessness, lightheadedness, dry mouth, perspiration, and perhaps some chest discomfort. Mention these sensations as you notice them to the technician or doctor.

Risks

There is no possibility of electric shock during the test, since the electrodes only detect the electrical impulses produced by your heart. Exercise testing is generally safe. In a large study involving 73 medical centers and 170,000 exercise tests, death occurred in less than 1 in 10,000 patients. Sometimes transient episodes of irregular heart rhythms may develop but they can usually be quickly corrected. Though the risks are minimal, emergency equipment and a physician trained in resuscitation are available in the testing area.

Results

Your doctor may be able to discuss with you the preliminary results immediately after the test. A complete interpretation may take several days. Chest pain during exercise, abnormalities in the heart rhythm or ECG tracing, or a fall in blood pressure (blood pressure normally rises during exercise) may indicate heart disease.

Further tests such as Myoview scanning or coronary arteriography are often necessary to confirm the presence and extent of heart disease.