The Echocardiogram

By Richard N. Fogoros, M.D., About.com

The echocardiogram is an extremely useful test for studying the heart's anatomy. It is non-invasive and entirely safe, and when interpreted by well-trained cardiologists, is very accurate.
How is the echocardiogram performed?
The echocardiogram is a simple test to have done. You will lie on an examination table, and a technician will hold a transducer (a device that resembles a computer mouse) against your chest, slowly sliding it back and forth. (The technician will apply a Vaseline-like gel to your chest to aid in sliding the transducer.) You may be asked to roll on your side during the test, or hold your breath for a few seconds. The test takes 30 to 60 minutes to complete.
How does the echocardiogram work?
The transducer that's placed on your chest sends sound waves toward the heart. Like the sonar on a submarine, the sound waves bounce off the heart,and are collected by by the transducer.

These returning sound waves are processed by a computer, assembled into a two-dimensional image of the beating heart, and displayed on a TV screen (which you will be able to see if you wish). By aiming the transducer, the technician will be able to image most of the important cardiac structures.
What are some of the variations used with the echocardiogram?
Echocardiograms are sometimes used in conjunction with stress tests. An echo test is made at rest, and then is repeated during exercise, to look for changes in the function of the heart muscle when exercise is performed. Deterioration in muscle function during exercise can indicate coronary artery disease.

A special microphone (called a Doppler microphone) can be used during the test to measure the velocity of blood flow in the heart. This information can be useful in assessing heart valve function.

A transesophageal echocardiogram can create images of cardiac structures that are difficult to see from a standard echo test, and also offers a way to produce echo images during heart surgery when access to the chest itself is not available to the echocardiographer.
What is the echocardiogram good for?
The echocardiogram reveals important information about the anatomy of the heart. It is especially useful for detecting problems with the heart valves (such as aortic stenosis or mitral valve prolapse). It is also an extremely useful test for evaluating congenital heart disease. The echocardiogram is also a good way to get a general idea of the overall function of the heart muscle.
What is the echocardiogram not good for?
The echo does not image the coronary arteries, and is not useful for detecting coronary artery disease. It is not as accurate as the MUGA scan for measuring overall cardiac muscle function. Various physical variations (a thick chest wall, for instance, or emphysema) may limit the ability to image cardiac structures. These physical variations, however, can be overcome by performing a transesophageal echo test.