Exercise Stress Test
This is a test of heart function by making the heart exercise,typically on a motorised treadmill accompanied by monitoring of your heart rate, blood pressure, ECG tracings . Speed and slope gradually increase every three minutes, but the level of exercise is usually no more strenuous
than a brisk walk.
You will be constantly monitored during your test and for 5 minutes after.
What is an Exercise Treadmill Test?
A stress test, sometimes called a treadmill test or exercise treadmill 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.
How does a Stress Test Work?
Patients with coronary artery blockages may have minimal symptoms and an unremarkable or unchanged ECG while at rest. However, symptoms and signs of heart disease may become unmasked by exposing the heart to the stress of exercise. During exercise, healthy coronary arteries dilate (develop a more open channel) than an artery that has a blockage. This unequal dilation causes more blood to be delivered to heart muscle supplied by the normal artery. In contrast, narrowed arteries end up supplying reduced flow to it's area of distribution. This reduced flow causes the involved muscle to "starve" during exercise. The "starvation" may produce symptoms (like chest discomfort or inappropriate shortness of breath), and the ECG may produce characteristic abnormalities.
A stress test is considered in the following circumstances:
Patients with symptoms or signs that are suggestive of coronary artery diseases (CAD).
Patients with significant risk factors for CAD.
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.
Please remember that the regular stress test is heavily dependent upon interpretation of ECG changes produced by exercise. Therefore, the reliability drops drastically if there are significant ECG changes at rest (for example in patients with long standing high blood pressure, an artificial cardiac pacemaker, use of medications like digitalis, or presence of a bundle branch block pattern, etc.). In such cases, the physician can order an Echo Stress Test, particularly if he or she is suspecting coronary artery disease. However, a regular stress may be sufficient in 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).
Preparing for the 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.
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 one hour for the entire test, including the preparation.
How safe is a 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 are in attendance to manage the rare complications like sustained irregular heart beats, unrelieved chest pain or even a heart attack.
What is the reliability of a Regular Stress Test?
If a patient is able to achieve the target heart rate, a regular treadmill stress test is capable of diagnosing important disease in approximately 67% or 2/3 rd of patients with coronary artery disease. The accuracy is lower (about 50%) when patients have narrowing in a single coronary artery or higher (greater than 80%) when all three major arteries are involved. Approximately 10% of patients may have a "false-positive" test (when the result is falsely abnormal in a patient without coronary artery disease).
How quickly will I get the results and what will it mean?
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, coronary CT angiogram or Echo Stress test.