A chemical stress test shows how well the heart functions using medication that increases the heart rate as if the patient were exercising, according to the California Heart Center. During the test, the medication moves into the bloodstream through an intravenous line, and the technician takes pictures of the heart.
Patients sometimes find the test uncomfortable. They might experience shortness of breath, chest pain, flushing or nausea, according to the California Heart Center. A physician remains with the patient during testing to monitor his condition and make sure he remains safe during the test. Some patients require a two-day test for the most accurate understanding of the way their heart works under stress.