Exercise stress testing is a very common test used to detect cardiac problems in individuals at risk. Despite many leaps forward in cardiac medicine, coronary artery disease continues to be a major problem in the United States, as it remains one of the leading causes of death. And while exercise stress tests may sound intimidating, they really aren’t. We'll tell you everything you need to know about exercise stress testing so that you can approach it with peace of mind.
What Is It?
The exercise stress test is one of many tests that are used to detect and monitor coronary artery disease. An exercise stress test provides a controlled environment to assess the performance of the heart muscle as well as observing if there are any abnormalities in the way the blood flows through the heart and its arteries. The test can be used to diagnose blood flow problems that indicate coronary artery disease, or it can be used after acute treatments, such as surgeries, to determine the effectiveness of the treatment for that individual person.
Before ordering an exercise stress test, the doctor will review the patient's medical history including:
- Symptoms of coronary artery disease
- Level of physical activity
- Ability to physically perform the test
The doctor uses this information to determine if an exercise stress test is safe for the patient. Though generally considered safe, an exercise stress test might not be recommended for some people.
Individuals with no symptoms of coronary artery disease may also be a candidate for an exercise stress test if they work in a high risk occupation, such as an airline pilot, firefighter or police officer. Women who are over 50 years of age and men who are over 40 years of age who participate or plan to participate in vigorous physical activities, such as marathons or triathlons, may also be candidates for an exercise stress test.
People who have no symptoms but have two or more risk factors for coronary artery disease or chronic diseases, such as diabetes, may also be referred for an exercise stress test in an effort to stop a problem from developing. Also people who have problems with their heart valves may be referred for a stress test to evaluate the function of their heart and to evaluate the effectiveness of the treatment they are receiving.
How Does The Test Work?
The test is relatively simple, non-invasive and painless, in most cases, although some discomfort from the physical activity is common. The test is done in a hospital or in a specialized laboratory and will include an electrocardiogram (ECG) before beginning physical activity and then during the physical activity. This will allow the doctor to see how well the heart works under increased demand. The test will usually last about an hour or until the person can't exercise anymore due to fatigue or other problems. The technician may also end the test if the person reaches a target heart rate.
The test is as simple as walking on a treadmill or riding an exercise bike. While the person is doing this, she will be monitored by an ECG machine as well as have her blood pressure, heart rate and respirations monitored. This is so that the technician can be sure that the patient isn't in any life threatening distress during the test.
The difficulty of the exercise will gradually increase, usually by increasing the speed or incline of the bike or treadmill. It will be similar to riding up a hill or walking quickly. Once the test is completed, the patient will then be monitored until her heart rate returns to normal, which is usually around 15 minutes.
The results of the test will then be interpreted by the technician and the results will be sent to the doctor. The results will be given to the patient at a follow up appointment with her doctor.
Preparing For The Test
The doctor will usually go over instructions on preparing for the test with her patient. While instructions may vary, they typically include the following:
- Don't eat or drink for at least three hours before the test
- Don't smoke for at least three hours before the test
- Don't drink any beverages containing alcohol for at least 24 hours before the test
- Avoid caffeine for at least 24 hours before the test including
- Wear comfortable clothing and athletic shoes
A doctor may advise the patient not to take certain medications before the stress test, such as vasodilators like Viagra, Cialis or Levitra, and in some cases diabetics may be advised not to take their insulin or hypoglycemic agents within a few hours of the test, but this will depend upon how stable their condition is. Certain medications for congestive heart failure, such as Digoxin, may also be withheld before a stress test because they can interfere with the readings of the ECG.
Generally it is not advised to skip medications before a stress test.
The results of the test will include an interpretation of the baseline ECG, noting any differences that occurred when changing positions, since the ECG is performed with the person in a lying, sitting and standing position. Any anomalies in the ECG reading that occur during the exercise will be noted as well.
Any symptoms that the patient experienced during the test will also be noted. The report may say something like "shortness of breath" or "dizziness". Other notes in the report may include things like "exercise stopped at patient's request" if the person couldn't complete the test, or "target rate achieved" if the test was stopped for this reason.
Also contained in the report will be the duration of the exercise as well as the workload. The workload is measure in METS, which is a way to measure metabolic activity. The body uses about 3.5 milliliters of oxygen per minute per kilogram of body weight and this number is used determine the metabolic workload of the body.
An exercise stress test is nothing to be concerned over. The tests are generally safe and the test can give doctors a good picture of the overall cardiovascular health of a patient. If the doctor has any further concerns, additional tests can be ordered such as a stress echocardiogram or a nuclear stress test to pinpoint a specific problem and prescribe treatment, allowing people to get back to their normal lives as quickly as possible.