An echocardiogram, also called "echo", is a test that uses ultrasound waves to examine the heart and diagnose a heart problem. The echo can tell the doctor the size of the heart chambers, the thickness of the muscle, and whether or not the heart is pumping at full strength. It can also help the doctor to evaluate the motion and shape of the heart valves, help determine if there is a presence of fluid around the heart, and help locate blood clots or masses inside the heart muscle. During the test, a transducer, or a small microphone-like device, is put against the chest to allow a computer to construct an image using the ultrasound waves. The echocardiogram normally combines three different techniques. The first one, called the M-mode echo, produces a tracing image of the heart. This technique is helpful in measuring the size of the heart chambers. The second more advanced procedure shows the actual shape and motion of the heart's structures. This is called a two-dimensional echo. The Doppler echocardiogram is the final technique. It allows doctors to see the flow of blood through the heart. The echo normally takes about 20 to 45 minutes. If the doctor is present during the test you might even be able to find out the results before you leave.