Stress Testing
Stress testing is usually done to help diagnose coronary artery disease. Your doctor may order a stress test to evaluate symptoms such as chest pain, shortness of breath or abnormal fatigue. A stress test may also be done because of an abnormal ECG finding or to determine exercise tolerance. There are different types of stress tests including:
Standard Graded Exercise Test (GXT)
During the GXT, you exercise (walk or run) on a treadmill while connected to an ECG machine that records your heart rate and rhythm. Your blood pressure is also monitored throughout the test. Each test has stages that last three minutes and proceeds to a new stage on the treadmill in which the pace becomes faster and incline becomes steeper. An adequate test will attain a pre-determined target heart rate and/or reproduce the patient's symptoms.
Stress Echocardiography
Stress echocardiography is a transthoracic echocardiogram combined with either an exercise or chemical stress test. For an exercise stress test, you walk or run on a treadmill to make your heart beat fast and pump hard. For a chemical stress test, you are given medicine to make your heart beat fast and pump hard. Echocardiography images are obtained prior to and after the exercise portion of the test to identify areas of poor blood flow to the heart muscle.
Nuclear Stress Test
A nuclear stress test is similar to a stress echocardiogram because you walk or run on a treadmill to make you heart beat fast and pump hard. The patient is injected with a radioisotope or imaging tracer to create pictures of the blood flow to your heart. Resting and stress images are obtained under a nuclear scanner or camera to identify areas of poor blood flow to the heart muscle.
If you are unable to exercise, a pharmacologic stress test can be performed. During this test, a small amount of medicine is administered to make the coronary arteries dilate similar to when you perform exercise. A small amount of imaging tracer is injected into a vein at rest and following the medication. The medication does not increase your heart rate. The medication dilates blood vessels leading into the heart, increasing blood flow, therefore simulating exercise for patients unable to exercise on a treadmill. Nuclear or echocardiography imaging is obtained to identify areas of poor blood flow to the heart muscle.
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