The Stress Test -- also called an exercise stress test, exercise electrocardiogram, treadmill test, graded exercise test, or stress ECG -- is a test used to provide information about how the heart responds to exertion. It usually involves walking on a treadmill or pedaling a stationary bike at increasing levels of difficulty, while your electrocardiogram, heart rate, and blood pressure are monitored.
Patients with coronary artery blockages may have minimal symptoms and unchanged EKG while at rest. However, signs of heart disease may come up by exposing the heart to the stress of exercise.
Why you may need a Stress Test
- To determine if there is adequate blood flow to your heart during increasing levels of activity.
- To determine the likelihood of having coronary heart disease and the need for further evaluation.
- To check the effectiveness of procedures done to improve blood flow within the heart vessels in people with coronary heart disease.
- To identify abnormal heart rhythms.
- To help you develop a safe exercise program.
- To evaluate the effectiveness of your heart medications to control angina and ischemia.
How is a Stress Test performed?
The test usually takes about 1 hour, including the preparation, but the actual exercise time is usually between 7 and 12 minutes. The patient is attached to an ECG machine, and a blood pressure cuff is placed on one arm. Sometimes a clothespin-like sensor is attached to the finger to measure the
amount of oxygen in the blood. After a baseline ECG is obtained, the patient begins to perform a low level of exercise, either by walking on a treadmill, or pedaling a stationary bicycle. Every three minutes, the level of exercise is increased. At each "stage" of exercise, the pulse, blood pressure and ECG are recorded, along with any symptoms the patient may be experiencing.
With a "maximal" stress test, the level of exercise is gradually increased until the patient cannot keep up any longer because of fatigue, or until symptoms (chest pain, shortness of breath, or lightheadedness) prevent further exercise, or until changes on the ECC indicate a cardiac problem. Maximal stress tests should be performed when the goal is to diagnose the presence or absence of coronary artery disease.
With a "sub maximal" stress test, the patient exercises only until a pre-determined level of exercise is attained. These tests are used in patients with known coronary artery disease, to measure whether a specific level of exercise can be performed safely.
After the test, the patient remains monitored until any symptoms disappear, and until the pulse, blood pressure and ECG return to baseline.
Preparing for the Stress Test
- Do not eat or drink for three hours prior to the procedure. This reduces the likelihood of nausea that may accompany strenuous exercise after a heavy meal. Diabetics, particularly those who use insulin, will need special instructions from the physician's office.
- If you take medications, check with your doctor. You may need to stop taking cerian medications one or two days prior to the test. Such instructions are generally provided when the test is scheduled.
- Wear comfortable clothing and shoes that are suitable for exercise. No Flip-flops or slippers!
Preparing for the test if you have diabetes
- If you take insulin to control your blood sugar, ask your doctor what amount of your medication you should take the day of the test. Often, you will take only half of your usual morning dose and eat a light meal four hours before the test.
- If you take pills to control your blood sugar, do not take your medication until after the test is complete.
- Do not take your diabetes medication and skip a meal before the test.
- If you own a glucose monitor, bring it with you to check your blood sugar levels before and after your exercise stress test. If you think that your blood sugar is low, tell the lab personnel immediately.
- Plan to eat and take your blood sugar medication following your stress test.
How safe is a Regular Treadmill Stress Test?
The risk of the stress portion of the test is very small and similar to what you would expect from any strenuous form of exercise (jogging in your neighborhood, running up a flight of stairs, etc.). Experienced medical staff is in attendance to manage the rare complications like sustained irregular heart beats, unrelieved chest pain or even a heart attack.