A chemical stress test for the heart works by injecting a chemical into a vein, causing the heart to react as if it were stressed by exercise, CVS.com states. The procedure evaluates the heart's performance when a physical stress test is not an option.
During a chemical stress test, the patient lies on a table with electrodes attached to the chest, CVS.com explains. After baseline blood pressure and electrocardiography (ECG) measurements are taken, the chemical is given intravenously. Medical personnel monitor heart rate and blood pressure and sometimes take additional ECG readings. In certain cases, symptoms such as chest pain, difficulty breathing and dizziness force the testing to stop.
Patients who have chronic back pain or arthritis or who have had strokes are often not good candidates for exercise stress tests, according to CVS.com. These individuals have difficulty using treadmills or stationary bikes intensely, so chemical stress tests are used to challenge the heart. Information from chemical tests help doctors diagnose heart conditions, artery blockages and irregular heart rhythms. During medical treatment, the tests monitor the heart's condition. In addition, health care providers use results to plan rehabilitation as patients recover from heart attacks.
The procedure takes three to four hours, CVS.com says. Sometimes it is spread over two days. Full results are often not available for two to three days.