A computer picture of the heart created by bouncing high-energy sound waves (ultrasound) off internal tissues or organs of the chest. Echocardiograms show the size, shape, and position of the heart. They also show the parts inside the heart, such as the valves, and the motion of the heart while it is beating. An echocardiogram may be used to help diagnose heart problems, such as abnormal heart valves and heart rhythms, damage to the heart muscle from a heart attack, and heart murmurs. Echocardiograms can also show an infection on or around the heart valves, blood clots or tumors inside the heart, and fluid buildup in the sac around the heart.