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Definition Echocardiography is a diagnostic test that uses ultrasound waves to create an image of the heart muscle. Ultrasound waves that rebound or echo off the heart can show the size, shape, and movement of the heart's valves and chambers as well as the flow of blood through the heart. Echocardiography may show such abnormalities as poorly functioning heart valves or damage to the heart tissue from a past heart attack. Purpose Echocardiography is used to diagnose certain cardiovascular diseases. In fact, it is one of the most widely used diagnostic tests for heart disease. It can provide a wealth of helpful information, including the size and shape of the heart, its pumping strength, and the location and extent of any damage to its tissues. It is especially useful for assessing diseases of the heart valves. It not only allows doctors to evaluate the heart valves, but it can detect abnormalities in the pattern of blood flow, such as the backward flow of blood through partly closed heart valves, known as regurgitation. By assessing the motion of the heart wall, echocardiography can help detect the presence and assess the severity of coronary artery disease, as well as help determine whether any chest pain is related to heart disease. Echocardiography can also help detect hypertrophic cardiomyopathy, in which the walls of the heart thicken in an attempt to compensate for heart muscle weakness. The biggest advantage to echocardiography is that it is noninvasive (doesn't involve breaking the skin or entering body cavities) and has no known risks or side effects. Precautions Echocardiography is an extremely safe procedure and no special precautions are required. Description Echocardiography creates an image of the heart using ultra-high-frequency sound waves--sound waves that are too high in frequency to be heard by the human ear. The technique is very similar to ultrasound scanning commonly used to visualize the fetus during pregnancy. An echocardiography examination generally lasts between 15-30 minutes. The patient lies bare-chested on an examination table. A special gel is spread over the chest to help the transducer make good contact and slide smoothly over the skin. The transducer, a small hand-held device at the end of a flexible cable, is placed against the chest. Essentially a modified microphone, the transducer directs ultrasound waves into the chest. Some of the waves get echoed (or reflected) back to the transducer. Since different tissues and blood all reflect ultrasound waves differently, these sound waves can be translated into a meaningful image of the heart, which can be displayed on a monitor or recorded on paper or tape. The patient does not feel the sound waves, and the entire procedure is painless. In fact, there are no known side effects. Occasionally, variations of the echocardiography test are used. For example, Doppler echocardiography employs a special microphone that allows technicians to measure and analyze the direction and speed of blood flow through blood vessels and heart valves. This makes it especially useful for detecting and evaluating regurgitation through the heart valves. By assessing the speed of blood flow at different locations around an obstruction, it can also help to precisely locate the obstruction. An exercise echocardiogram is an echocardiogram performed during exercise, when the heart muscle must work harder to supply blood to the body. This allows doctors to detect heart problems that might not be evident when the body is at rest and needs less blood. For patients who are unable to exercise, certain drugs can be used to mimic the effects of exercise by dilating the blood vessels and making the heart beat faster. Preparation The patient removes any clothing and jewelry above the chest. Aftercare No special measures need to be taken following echocardiography. Risks There are no known risks associated with the use of echocardiography. Normal results A normal echocardiogram shows a normal heart structure and the normal flow of blood through the heart chambers and heart valves. However, a normal echocardiogram does not rule out the possibility of heart disease. Abnormal results An echocardiogram may show a number of abnormalities in the structure and function of the heart, such as: - thickening of the wall of the heart muscle (especially the left ventricle)
- abnormal motion of the heart muscle
- blood leaking backward through the heart valves (regurgitation)
- decreased blood flow through a heart valve (stenosis)
- Noninvasive
- Pertaining to a diagnostic procedure or treatment that does not require the skin to be broken or a body cavity to be entered.
- Regurgitation
- Backward flow of blood through a partly closed heart valve.
- Transducer
- A device that converts electrical signals into ultrasound waves and ultrasound waves back into electrical impulses.
- Ultrasound
- Sound waves at a frequency of over 20,000 kHz, often used for diagnostic imaging.
For Your Information Books - Faculty Members of the Yale University School of Medicine. The Patient's Book of Medical Tests. Boston: Houghton Mifflin Co., 1997.
Periodicals- Rose, Verna L. "American College of Cardiology and American Heart Association Address the Use of Echocardiography. American Family Physician 56 (1 Oct. 1997): 1489-90.
Organizations- American Heart Association. 7320 Greenville Ave. Dallas, TX 75231. (214) 373-6300. http://www.americanheart.org
- National Heart, Lung and Blood Institute. PO Box 30105, Bethesda, MD 20824-0105. (301) 251-1222. http://www.nhlbi.nih.gov
Source: Gale Encyclopedia of Medicine, Published December, 2002 by the Gale Group
The Essay Author is Robert Scott Dinsmoor.
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