The exercise stress test (also called stress test, exercise electrocardiogram, treadmill test, graded exercise test, or stress ECG) is a test that provides information about how the heart responds to exertion.
It is usually performed on a treadmill or a stationary bike at increasing levels of difficulty, while electrocardiogram, heart rate, and blood pressure of the patient are monitored but also it can be performed with a drug for a people who are unable to exercise.
The test is used to determine the likelihood of having coronary heart disease and the need for further evaluation, to determine if there is adequate blood flow to your heart during increasing levels of activity, to evaluate the effectiveness of your heart medications to control angina and ischemia, to check the effectiveness of procedures done to improve blood flow within the heart vessels in people with coronary heart disease, to identify abnormal heart rhythms and to help patient develop a safe exercise program.
There are three kinds of tests:
- Dobutamine or adenosine stress test – It is used in people who are unable to exercise. A drug is given to make the heart respond as if the person were exercising so the doctor can still determine how the heart responds to stress, but no exercise is required.
- Stress echocardiogram – It can accurately visualize the motion of the heart's walls and pumping action when the heart is stressed and it may reveal a lack of blood flow that isn't always apparent on other heart tests.
- Nuclear stress test – It helps to determine which parts of the heart are healthy and function normally and which are not with a very small and harmless amount of radioactive substance injected into the patient. With a special camera which identifies the rays emitted from the substance within the body, the doctor can see clear pictures of the heart tissue on a monitor at rest and after exercise. A less than normal amount of thallium will be seen in those areas of the heart that have a decreased blood supply.
Before the tests, the patient must not eat or drink anything except water for four hours before the test and do not drink, or eat foods containing caffeine for 12 hours before the test because caffeine can interfere with the results of your test.
The doctor will tell the patient which heart medications must or must not he/she take on the day of the test and if the patient is taking insulin or pills to control blood sugar, the doctor will tell what amount of medication should the patient take the day of the test.
Also, if the patient is using an inhaler for breathing, he/she must bring it to the test and also his/her glucose monitor to check blood sugar levels before and after exercise stress test.
Before the procedure, the technician will perform an EKG to measure patient's heart rate at rest and will take blood pressure. During the procedure, a technician will clean 10 small areas on the chest of a patient and place electrodes (small, flat, sticky patches) on these areas which are attached to an electrocardiograph monitor (ECG or EKG) that charts heart's electrical activity during the test.
The patient will begin to exercise by walking on a treadmill or pedaling a stationary bicycle. The rate of exercise or degree of difficulty will gradually increase and the patient will exercise until he/she feel exhausted.
During the test, the lab personnel will ask the patient how he/she feels and if he/she is having chest, arm or jaw pain or discomfort, shortness of breath, dizzy, lightheaded, or any other unusual symptoms, he/she must tell to the personnel.
The whole procedure lasts about 60 minutes, but the actual exercise time is usually between 7 and 12 minutes.