Stress echocardiography or "stress echo" is an echocardiogram done before and during or immediately after some form of physical stress (such as bicycle or treadmill exercise) to help diagnose coronary heart disease. This is a technique that sends sound waves (like sonar) into the chest to rebound from the heart's walls and valves. The recorded waves show the shape, texture and movement of the valves on an echocardiogram. They also show the size of the heart chambers and how well they're working. This technique does not hurt and poses no risk. A stress echo is performed the same way as ultrasound pictures of a fetus.