When You Need to Have a Stress Test: A Patient Guide
A stress test is an objective way of determining your exertional capacity. It can be used for many reasons. By far the most common use is to assess the cause for a patient complaint such as chest pain or shortness of breath on exertion. Additional appropriate uses of stress tests occur after heart attack, angioplasty, or bypass surgery to assess safe exercise capacity, or prior to starting an exercise program for someone at high risk of problems. Such tests permit your doctor to design an appropriate regimen for you, to determine if your medications are at optimal level for your protection, or if you are at an unusually high risk for cardiovascular events.
If you have already been diagnosed with coronary heart disease (CAD), a stress test may enable the doctor to estimate the severity of the blockages. Likewise, if you have just undergone balloon angioplasty or bypass surgery, a stress test helps the doctors monitor the success of the procedure as well as determine an appropriate rehabilitation program for you.
What equipment is used? Will I be in pain?
The stress test involves performing a simple exercise (usually a treadmill, although in Europe a stationary bike is a popular method) while you are monitored using several devices. An ECG (electrocardiogram) records your heart's electrical activity through electrodes that are taped to your shoulders and chest. A blood pressure cuff is used to constantly monitor your blood pressure; it is similar to the one you have used in the doctor's office, and is painless. Monitoring takes place throughout the stress test. In some cases, depending upon the reasons for the stress test, you may be asked to where a mask (to check on your use of oxygen) or an echocardiogram might require a technician to use a transducer (an instrument that looks like a microphone) to record an echocardiogram during the test. If imaging is going to be done with radioisotopes, an intravenous line will be inserted prior to starting exercise. In the case of radioisotopic imaging, you will be asked to lie on a special table so that your heart can be scanned. Radioisotopic echocardiographic scanning are usually done if there is an abnormal baseline electrocardiogram, or a high likelihood of an abnormal test result. Often, in women who have a high likelihood of a false positive test scanning may be added to an ordinary stress test.
Sometimes pharmacologic agents such as adenosine, dobutamine, or persantine are used instead of a treadmill, to simulate the heart's reactions to exercise. These drugs are safe and reasonably well tolerated, and are usually only given when someone is unable to perform the stress test. They are as reliable for evaluative purposes as the exercise test.
How is it done? What if it's too hard for me?
The doctor will increase the speed and incline of the treadmill. These increases will take place every three minutes by protocol while the doctor closely monitors your heart's performance. Do not be concerned about the "difficulty" of the test; your doctor will take your own physical condition into account as the test continues. If you are in poor condition or at high risk for CAD, the increments may be smaller and more gradual.
Throughout the test, your doctor will be observing your function in response to increased "challenge" to the heart. The doctor will be looking for changes in your ECG pattern, heart rate or blood pressure, and/or unusual shortness of breath or chest pain, all of which are possible symptoms of coronary artery obstruction.
How long does it last?
The stress test itself usually lasts between three minutes and fifteen minutes, once you have been connected to the various monitors. The duration of the test will depend upon your conditioning, and the severity of any disease that is present.
Where does it take place?
Although a hospital may have a specific testing facility onsite, you will not necessarily be going to a hospital for your stress test. Many testing facilities are freestanding, like a regular doctor's office.
Do I have to be hospitalized?
When do I get the results? What could they mean?
Your doctor may provide you with feedback very early in the test, by stopping because she or he feels it is unsafe for you. This may be because you are severely out of shape, or because you are clearly showing signs of heart disease. If this is the case, your doctor may recommend further, more invasive testing such as a coronary angiogram, in which dye is injected into your arteries and monitored to determine blockages. (See: Cardiac Catheterization: A Patient Guide)
If you have a successful test (no abnormal ECG or unusual blood pressure or heart rate variations) it is likely that your risk of significant coronary artery disease is low. Stress tests are able to detect individuals with heart disease nearly 90 percent of the time. This means that, if you actually DO have heart disease, the test will accurately detect it nine out of 10 times. Stress tests may not however be specific or accurate. This is true especially for women between the ages of 45 and 70. Women seem to have a higher incidence of "false positive" results. If you do have a "positive" result it may require further testing to clarify the situation. People who have a "positive" test with a very high level of activity tend to have a good prognosis. If you are concerned about the findings of the ECG test, you may wish to discuss them with your doctor at greater length.