Stress testing is a way to detect how a person's heart reacts under strenuous activity, such as exercising. It’s purpose is to show the amount of blood flow in a patient during both rest and activity. The scans reveal areas in the heart that have both good and bad blood flow. Often, stress tests reveal diseases such as coronary artery disease. A patient first undergoes an injection of a drug to add stress to their heart, causing it to pump faster. Radio transmitters are injected into the person's bloodstream and attach themselves to the heart muscles. A scan is taken and parts of the heart that are healthy will light up, while the possibly unhealthy parts will remain dark. After 2-4 hours, a second scan is taken to show what the heart looks like while resting. Depending on the results, diagnosis and treatment options may be offered to a patient. For example, a person who has been diagnosed with coronary artery disease may need open-heart surgery or coronary intervention if the blockages are severe. Overall, nuclear stress testing is a way reveal abnormalities in a heart's function during both rest and physical