An echocardiogram is a test that uses harmless sound waves to create an image of your heart. It shows how well your heart muscle and heart valves are working. It also shows the size of your heart. The image of your heart is created via a transducer device that looks like a microphone. The transducer is coated with a cool gel and is moved firmly over the surface of your chest to record sound waves off your heart. A computer then changes these sound waves into images that are seen on a TV screen.