During a stress test, you will usually exercise by walking or running on a treadmill, or by peddling a stationary bicycle. While your heart is working hard, one of several types of stress tests will be used to evaluate how much blood flow is getting to the heart and how effectively the heart is pumping. Occasionally, your doctor may use a stress test that only measures the electrical activity in your heart while you exercise. In other instances, your doctor may couple your stress test with an echocardiogram, which uses ultrasound waves to evaluate your heart's shape and movement while beating. A third type of stress test is a nuclear test. In this case, you will receive an injection of a special radioactive tracer, and a nuclear camera will be used to take color-coded pictures of the heart that measure blood flow before, during and after exercise.
If you are not strong enough to exercise, your doctor may choose to give you a special medication to make the heart beat quickly and forcefully. In essence, the medication makes your heart "exercise" when you cannot. This type of stress test is called a pharmacologic stress test, because medicine is used in place of exercise to make the heart beat fast. During a pharmacologic stress test, the test of electrical activity, ultrasound imaging or nuclear imaging can be coupled with the artificial exercise to evaluate the heart, just as with real exercise.