An exercise stress test is used to determine how the heart responds to exercise-induced stress. The test, usually done on a treadmill or stationary bike at increasing levels of difficulty, helps doctors evaluate how the heart performs during exercise. Doctors use exercise stress tests to assess blood flow to the heart during activity, the effectiveness of a cardiac treatment plan, and the likelihood of coronary artery disease. Exercise stress tests are also called stress tests, exercise tolerance tests, graded exercise tests, exercise EKGs, stress EKGs, or treadmill tests.
An exercise stress test may be performed in conjunction with echocardiography (a stress echo), or with radioisotope dyes injected into the bloodstream (nuclear stress tests). With these tests, doctors gain additional information about the structure of and blood flow in the heart.
How It Works
The test is usually done on a treadmill or stationary bike at increasing levels of difficulty. An electrocardiogram (EKG) records the electrical activity of the heart before, during, and after exercise. Measurements are taken to measure blood pressure, respirations, and heart rate. If a patient is too sick to exercise, a drug that has the same effect on the body as exercise can be used.
What To Expect
Patients will receive protocols from their doctors regarding eating, drinking, and smoking prior to the test and regarding taking medication before the test, including insulin and inhalers. Patients should wear exercise clothing and shoes. Lotions or creams should not be used on the day of the test.
The EKG, blood pressure cuff, and other monitoring devices are placed. Baseline recordings are taken. During the test, the patient is asked to walk on a treadmill or to ride a stationary bike. Every 2 or 3 minutes, the doctor or the technician increases the speed and slope of the treadmill or stationary bike. At regular intervals, the testing personnel will ask how the patient is feeling. Chest, arm or jaw pain or discomfort; shortness of breath; dizziness; lightheadedness; or any other unusual symptoms should all be reported. It is normal for the patient’s heart rate, blood pressure, breathing rate, and perspiration to increase during the test. The doctor or technician watches for changes in the EKG patterns, blood pressure, and pulse, including any changes that might suggest that the test should be stopped. The patient is asked to exercise vigorously until exhaustion. At the end of the test, a cool-down phase allows the patient to walk or pedal slowly, then lie down or sit quietly while the monitoring is concluded and the heart rate, blood pressure, and respirations return to normal. Although the appointment lasts about 60 minutes, the actual exercise time is usually between 7 and 12 minutes.
Texas Heart Institute www.texasheartinstitute.com/HIC/Topics/Diag/distress.cfm
Hoag Heart Institute www.hoaghospital.org/heartinstitute/Coronary-Diagnose.aspx
The Cleveland Clinic www.clevelandclinic.org/heartcenter/pub/guide/tests/electrocard/gxt.htm