Stress echocardiogram, also called a stress echo, combines an echocardiogram with a stress test to show how the heart works during “stress” or exercise. The echocardiogram uses sound waves to produce an image of the heart on a monitor before and during exercise. Stress echocardiography helps cardiologists diagnose coronary heart disease. Thallium/myocardial perfusion scan is a type of nuclear medicine procedure. It is used to assess the blood flow to the heart muscle (myocardium) and to determine what areas of the myocardium have decreased blood flow. It is given while the patient is at rest or after exercise that may reveal areas of the heart muscle that are not getting enough blood.