Computerised Stress Test
What is a computerised stress test?
This is an exercise test used to evaluate the response of the heart to the physical stress. This is accomplished by having patient walk on a treadmill, the speed and inclination of which is gradually increased, while the electrocardiogram (ECG) and blood pressure are continuously monitored.
Exercise stress testing is tremendously informative in screening for coronary artery disease as well as periodically following known heart disease. This test is usually ordered for patients who are experiencing symptoms of chest discomfort, shortness of breath or palpitations (irregular heart beat). Often these symptoms are related to physical activity. As the body works harder during the test, it requires more oxygen to meet the increased metabolic demands of exercise. The ECG is monitored continuously during the test to watch for any changes that suggest ischemia-- an insufficient delivery of oxygen to the working heart muscle. It also provides information regarding the level of physical fitness and can be used to bring out any heart rhythm disturbances.
Pre- Exercise Test, please follow these instructions
- Do not eat or drink two hours prior to the treadmill, however, patient may brush teeth, drink water and have light breakfast maintaining a gap of 2 hours from the test. A full stomach may lead to nausea during exercise.
- Do not have any caffeine for at least 3-4 hours prior to the test. Coffee, tea, soft drinks and chocolate may contain caffeine.
- Do not smoke prior to the test.
- A shower or bath should be taken prior to the test in order to allow good skin contact with the electrodes. Do not use lotion.
- Wear walking shoes and comfortable clothing on the day of the test. Do not wear boots, high-heeled shoes or slippers.
- Physically and mentally relax before the test; no strenuous exercise should be performed.
- Take all the routine medications unless specifically instructed by doctor to stop any medications prior to the test.
- Insulin dependent Diabetic Instructions: For morning treadmill test, do not take the morning insulin dose and have a light breakfast.
- A relative or a friend has to accompany the patient for this test.
How is the test performed?
- Patient must have heard of mishaps that have occurred just after or during a stress test. It is therefore essential that a brief history be taken along with clinical examination (includes 2D Echo scanning) so as to make sure that patient is fit to undergo the test.
- The test is then explained to patient. Once this is completed patient will be asked to read and sign a consent form. The staff will answer any questions relating to the consent form.
- The technician will then prepare the chest skin so that the ECG can be monitored throughout the test without interference from motion and sweat. For men, this involves shaving the skin, scrubbing it vigorously with medicated spirit (alcohol). For women only skin scrubbing with spirit is required. Ten electrodes are then applied to the chest.
- During the stress test there is always an experienced Physician immediately available. All the necessary resuscitation equipment and emergency medications are readily available.
- Before the test the blood pressure and ECG will be recorded in the sitting and standing position.
- Then the actual walk on treadmill is begun. Initially the treadmill will be flat and moving very slowly. During the test, patient’s symptoms will be monitored and the blood pressure will be recorded every 3 minutes. The ECG is monitored continuously and taken every 3 minutes as a permanent record print. The speed and inclination of the treadmill will progressively increase every 3 minutes as the test progresses.
- The test is a heart rate limited and symptom limited test. The target heart rate is 85% of the maximum predicted heart rate (220-Age in years). The test will be terminated if patient develops symptoms or if patient achieves the target heart rate, whichever occurs first. The test will also be stopped if the doctor sees significant changes in the ECG or blood pressure.
During the test, patient should immediately report following symptoms:
- chest, arm, throat or jaw discomfort
- shortness of breath
- dizziness or lightheadedness
- leg cramps or soreness
At the completion of the test the clinical condition, blood pressure and ECG will be monitored until everything returns to baseline.
What are the instructions after the Regular Treadmill Stress Test?
- Patient may resume the normal activity unless otherwise directed by the testing physician.
- Take the regular medications as directed unless otherwise directed by the testing physician.
- Keep any scheduled follow-up appointments.
The final report of the exercise stress test will be given to the patient on the same day within 15-20 minutes.
Is there any risk involved?
The risk of the treadmill is very small and is equivalent to the risk of a similar degree of exercise experienced by the person in his/ her daily life. The careful evaluation prior to the test, monitoring of the ECG, blood pressure and symptoms during the test, all serve to further minimize the small risk of the test.
It has obvious advantages over other tests that renders this test as the first screening test in evaluation of coronary artery disease:
- it is not expensive
- it´s the most physiologic way to test the heart
- it imitates every-day stress realistically
- it can be repeated as often as necessary without imposing health risks on the patient due to x-rays, drugs, or risks associated with invasive procedure