A stress test, sometimes called a treadmill test or exercise test, helps a doctor find out how well your heart handles work. As your body works harder during the test, it requires more oxygen, so the heart must pump more blood. The test can show if the blood supply is reduced in the arteries that supply the heart. It also helps doctors know the kind and level of exercise appropriate for a patient.
Stress Testing is a general screening tool to test the effect of exercise on your heart. The test gives a general sense of your hearts health. It is non-invasive, safe, and the preliminary results are available quickly.
During the test, the electrical activity of the heart is measured while you walk on a treadmill or pedal a stationary bicycle. This measures the heart’s reaction to your body’s increased demand for oxygen.
What is stress echocardiography?
Stress echocardiography or “stress echoes” are echocardiograms done before and during or immediately after some form of physical stress and are used by doctors to help diagnose coronary heart disease.
How does a stress test help reveal problems?
In many cases, patients with coronary artery blockages may have minimal symptoms and an unremarkable or unchanged echocardiogram under normal (resting) conditions, but the signs and symptoms of heart disease are revealed under the stress of exercise. During exercise, healthy coronary arteries open up to supply more blood to the heart muscle. Narrowed or blocked arteries end up supplying reduced flow to the heart starving the muscle. This will cause symptoms like chest discomfort or inappropriate shortness of breath, and an echocardiogram taken during this time will produce characteristic abnormalities the doctor can use to diagnose problems.
When will the doctor want a Stress Test?
A regular stress test is considered in the following circumstances:
- Patients with symptoms or signs that are suggestive of coronary artery diseases.
- Patients with significant risk factors for coronary artery diseases.
- To evaluate exercise tolerance when patients have unexplained fatigue and shortness of breath.
- To evaluate blood pressure response to exercise in patients with borderline hypertension.
- To look for exercise-induced serious irregular heart beats.
What can I expect during a regular Stress Test?
Most commonly, a motorized treadmill is used for exercise, but in some cases a stationary bicycle is used.
The patient is brought to the exercise laboratory where the heart rate and blood pressure are recorded at rest. Sticky electrodes are attached to the chest, shoulders and hips and connected to an Electrocardiogram machine. Each wire represents a different portion of the heart.
After readings are taken at rest, the treadmill is started at a relatively slow “warm-up” speed. The treadmill speed and its slope or inclination will be increased periodically to gauge different levels of exertion. Your blood pressure will likely be taken at least one time, and perhaps several times throughout the procedure.
You may be asked to breathe into a tube for a couple of minutes.
You can stop the test at any time if needed.
Throughout the test, your echocardiogram will be constantly displayed on a monitor, but it will also be recorded on paper strips so the doctor can refer back to it. The treadmill will be stopped when your heart rate reaches a predetermined number of beats–this is usually 85% of the maximal heart rate predicted for the patient’s age-but if the patient is doing well at peak exercise the test may be continued further.
The doctor or technician will stop the test if the patient develops significant chest discomfort, shortness of breath, dizziness, unsteady gait, etc., or if the echocardiogram shows alarming changes or serious irregular heart beats. The physician may also stop the test if the patient’s blood pressure rises or falls beyond acceptable limits.
What is meant by stress test with nuclear?
Regular stress tests are adequate for stable patients or those with a low suspicion of coronary artery disease who are being assessed for exercise tolerance (for example, prior to undergoing a structured exercise or rehab program), but such tests are heavily dependent upon interpretation of EKG changes produced by exercise.
A normal stress test is not reliable if there are significant echocardiogram changes at rest for patients with long standing high blood pressure, artificial cardiac pacemakers, patients who use medications like digitalis, or other heart abnormalities.
For these patients, the doctor will usually order a Stress Test with Nuclear, particularly if he or she suspect coronary artery disease.
A stress test with nuclear is similar to normal stress test as is is usually done along with an exercise stress test on a treadmill or bicycle.
During the exercise a small amount of a radioactive substance called thallium is injected into the bloodstream. Afterward, the patient lies down on a special table under a camera that can see the thallium and take pictures. The thallium mixes with the blood in the bloodstream and heart’s arteries and enters heart muscle cells. If a part of the heart muscle doesn’t receive a normal blood supply, this will be revealed.
The first pictures are made shortly after the exercise test and show blood flow to the heart during exercise. The patient then lies quietly for four hours and another series of pictures is made. These show blood flow to the heart muscle during rest.
If the heart is normal during both exercise and rest, then blood flow through the coronary arteries will be identical. If the test shows the blood flow is normal during rest but not during exercise, then the heart isn’t getting enough blood when it must work harder than normal. This may be due to a blockage in one or more coronary arteries. If the test is abnormal during both exercise and rest, there’s limited blood flow to that part of the heart at all times. If no thallium is seen in some part of the heart muscle, the cells in this part of the heart are dead from a prior heart attack.
What if I can’t perform an exercise test?
Sometimes you can’t do an exercise test because you’re too sick or have physical problems. In this case, a drug such as dipyridamole (di-pi-RID’ah-mol) or adenosine is given. This drug increases blood flow to the heart and thus “mimics” an exercise test. Then the thallium test is given.
What do I need to do before a stress test?
The following recommendations are “generic” for all types of cardiac stress tests:
- 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. No caffeine or smoking 24 hours prior to the test.
- Specific heart medicines may need to be stopped 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.
- An explanation of the test is provided and the patient is asked to sign a consent form.
How long does the entire test take?
A patient should allow approximately four hours for the entire test, including the preparation.
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.). As noted earlier, experienced medical staff is in attendance to manage the rare complications like sustained irregular heart beats, unrelieved chest pain or even a heart attack.
The physician conducting the test will be able to give you the preliminary results before you leave the exercise laboratory. However, the official result may take a few days to complete. The results of the test may help confirm or rule out a diagnosis of heart disease. In patients with known coronary artery disease (prior heart attack, known coronary blockages, previous treatment with angioplasty, stents or bypass surgery, etc.), the study will help confirm that the patient is in a stable state, or that a new blockage is developing.
The results may influence your physician’s decision to change your treatment or recommend additional testing such as cardiac catheterization, Echo Stress test, or a nuclear stress test.