Echocardiography

Definition
Purpose
Description
Preparation
Aftercare
Risks
Normal results

Definition

Echocardiography is a noninvasive diagnostic test that uses ultrasound waves to produce an moving image of the heart.

Purpose

Echocardiography is one of the most widely used diagnostic tests for heart disease. Ultrasound waves generated by a device placed on the skin rebound or echo off the heart and are processed by a computer. The resulting image 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 reveal abnormalities such damage to the heart tissue from a heart attack or as a poorly functioning heart valve. Echocardiography is especially useful for assessing disorders of the heart valves. It not only allows doctors to evaluate the condition of the heart valves, but also can show abnormalities in the pattern of blood flow. For example, echocardiography can show the backward flow of blood through heart valves that remain partially open and should be fully closed.

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 chest pain is related to heart disease. Additionally, echocardiography can help detect hypertrophic cardiomyopathy, a condition in which

the walls of the heart thicken in an attempt to compensate for heart muscle weakness.

Echocardiography is also used to evaluate heart murmurs (abnormal heart sounds), determine the causes of congestive heart failure, assess enlarged hearts, hearts with septal defects (holes between pumping chambers), and to monitor the heart in patients with diseases that may affect heart function (e.g., lupus erythematosus, lung diseases). The biggest advantage to echocardiography is that it is noninvasive (it does not involve breaking the skin or entering body cavities), and it has no known risks or side effects. It also gives a more detailed picture of the heart than other imaging techniques. Echocardiography is often used in conjunction with other diagnostic tests for the heart such as electrocardiography.

Echocardiography is usually performed in the cardiology department at a hospital, but may also be performed in a cardiologist’s office or an outpatient imaging center. Because the ultrasound scanners used to perform echocardiography are portable (handheld) or mobile, echocardiography can be performed in a hospital emergency department or at the bedside of patients who cannot be moved.

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 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 to slide smoothly over the skin. The transducer, also called a probe, is a small handheld device at the end of a flexible cable. The transducer is placed against the chest and directs ultrasound waves into the chest. Some of the waves get echoed (or reflected) back to the transducer. Since different tissues and blood reflect ultrasound waves differently, these returning sound waves can be translated into a meaningful image of the heart that is displayed on a monitor and recorded. The patient does not feel the sound waves, and the entire procedure is painless.

Occasionally, variations of the echocardiography test are used. For example, Doppler echocardiography employs a special transducer 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 backflow through the heart valves. By assessing the speed of blood

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flow at different locations around an obstruction, it can also help to precisely locate the obstruction.

An exercise echocardiogram, or stress echo, 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.

A transesophageal is done when it is difficult to get a clear picture of the heart using standard electrocardiogram techniques (e.g., interference from internal scar tissue, obesity). A transducer is attached to an endoscope, a thin tube that is threaded down the throat after it has been numbed. This position allows a clearer picture of the heart.

During the examination, a trained sonographer takes measurements and, using the ultrasound scanner’s computer, make calculations, including measuring blood flow speed. Most ultrasound scanners are equipped with videotape recorders or digital imaging/ archiving devices to record the real-time examination, and with medical image printers to print out hard copies of still images. Information from the echocardiogram is then evaluated by a cardiologist.

Preparation

The patient removes any clothing and jewelry above the waist.

Aftercare

No special measures need to be taken following echocardiography. The procedure is painless.

Risks

There are no known complications associated with the use of echocardiography. There is a slight risk of having a heart attack during an exercise echocardiogram, due to the stress put on the heart during the test, mostly for patients with a history of heart attack or other risk factors.

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 certain types of heart disease.

An echocardiogram may show a number of abnormalities in the structure and function of the heart, including:

• 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
• decreased blood flow through a heart valve due to narrowing of the valve (stenosis)

Resources

ORGANIZATIONS

American College of Cardiology. Heart House. 2400 N Street, NW | Washington, DC 20037. (202) 375-6000. http://www.acc.org (accessed March 19, 2008).

American Heart Association. 7272 Greenville Avenue, Dallas, TX 75231. (800) 242-8721. http://www.americanheart.org (accessed March 19, 2008).

American Registry of Diagnostic Medical Sonographers. 51 Monroe Street, Plaza One East, Rockville, MD 20850. (800) 541-9754. http://www.ardms.org (accessed March 19, 2008).

American Society of Echocardiography. 1500 Sunday Drive, Suite 102, Raleigh, NC 27607. (919) 861-5574. http://www.asecho.org (accessed March 19, 2008).

OTHER

“Echocardiogram.” Medline Plus April 12, 2007 [cited January 4, 2008]. http://www.nlm.nih.gov/medlineplus/ency/article/003869.htm (accessed March 19, 2008).

“Echocardiogram: Sound Imaging of the Heart.” Mayo Clinic July 14, 2006 [cited January 4, 2008]. http://www.mayoclinic.com/health/echocardiogram/HB00012 (accessed March 19, 2008).

Jennifer E. Sisk, MA

Lee Shratter, MD

Tish Davidson, AM

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