Echocardiogram

Definition

An echocardiogram is a non-invasive diagnostic test that uses ultrasound waves to produce a moving image of the heart. This test is also called a cardiac echo, cardiac Doppler, or heart ultrasound.

Purpose

An echocardiogram is used to evaluate heart health. This test makes it possible to see whether the heart is abnormally enlarged, track heart contractions, evaluate damage to the heart muscle from heart attack , examine the functioning of the valves between the heart chambers, evaluate the pumping strength of the heart, and track the flow of blood through the heart and surrounding arteries. An echocardiogram may be ordered when the patient has chest pain , abnormal heart sounds (heart murmurs), abnormal heartbeat, or any suspicion that blood flow through the heart is abnormal. The test is also used to assess damage after a heart attack, to assess certain effects of coronary artery disease, to evaluate the heart's response to drugs or treatment, or when systemic disease (e.g., systemic lupus erythematosus, lung diseases) is thought to have affected heart function. Sometimes an echocardiogram is done both before and after exercise to assess the effects of stress on heart function.

Precautions

An echocardiogram is extremely safe; it uses the same ultrasound scanning technology that allows a fetus to be seen in the mother's womb during pregnancy. No radiation is involved. There is a slight risk of having a heart attack during an exercise echocardiogram. This is not caused by ultrasound waves of

Description

An echocardiogram is a common, painless, non-invasive test. Echocardiograms can be done in a hospital, doctor's office, or freestanding imaging clinic. The echocardiogram equipment is portable, so it can be used in emergency rooms and at the bedside of patients who are too ill to be moved. The procedure usually takes about 45 minutes to perform.

There are four different types of echocardiograms. The most common is the transthoracic echocardiogram (TTE). For a TTE, the patient removes clothing and jewelry from the upper body and lies either on the back or left side. A technician spreads a conducting gel on the chest. A device called a transducer is then moved across the chest. The transducer generates ultrasound waves that cannot be heard by the human ear. These sound waves rebound or echo off the tissues and blood in the chest at different rates. A computer processes these echoing sound waves and creates a picture of the heart as it moves. The picture is visible on a monitor and is stored either digitally or on videotape for later analysis. The technician may move the transducer to several different locations to get pictures of the heart from different angles. At times the patient may be asked to change positions or to remain very still.

A Doppler echocardiogram is done to visualize blood flow through the heart and its major arteries. The procedure for a Doppler echocardiogram is similar to that of a TTE, only a different type of transducer is used. When ultrasound waves hit moving blood cells, the waves make certain sounds. The Doppler transducer picks up these sounds and uses this information to show the direction and speed of the blood flowing through the heart. Doppler echocardiograms can be used to pinpoint blockages in blood vessels. A TTE and a Doppler echocardiogram are often done in the same diagnostic session.

A stress or exercise echocardiogram is done in the same way as a TTE, but is done after the patient has exercised on a treadmill or stationary bike. This helps the cardiologist diagnose certain defects, such as insufficient pumping, that only become apparent when the heart is stressed. If the patient is too ill to exercise, drugs can be given to stimulate the heart to pump faster. Sometimes an echocardiogram is done both before and after exercise for comparison.

If a TTE does not produce a good view of the part of the heart that is of interest to the cardiologist, a transesophageal echocardiogram (TEE) may be done. For a TEE, the patient is given a sedative and the back of the mouth is numbed with a topical anesthetic. The patient then swallows an endoscope, which is a thin, flexible tube that has a transducer attached to one end. This places the transducer in the esophagus, much closer to the heart. A TEE is especially useful when the aorta is being evaluated. During a TEE the patient's oxygen level is monitored and supplemental oxygen may be given. This procedure takes longer than other types of echocardiograms.

QUESTIONS TO ASK YOUR DOCTOR

• Why have you ordered this test?
• What type of echocardiogram will I have: transthoracic, transesophageal, stress, or Doppler?
• What will you be able to tell from the results of this test?

Preparation

No special preparation is required for a TTE or Doppler echocardiogram. If a transesophageal echocardiogram or a stress echocardiogram is to be done, the patient may be told to avoid eating for several hours before the test.

Aftercare

No special aftercare is needed unless the patient has had a transesophageal echocardiogram. There is no pain, and the patient should be able to leave the test location immediately. A patient who has had a TEE will have a brief recovery period and should arrange for someone else to drive home following the procedure because of the effects of the sedative drug.

Complications

No complications are expected from this test. People who have a transesophageal echocardiogram may have a slight sore throat.

Results

The information from an echocardiogram helps tell the cardiologist whether the heart is performing normally. If heart function is not normal, the echocardiogram often can indicate the source of the dysfunction. Common heart problems that are diagnosed

KEY TERMS

Aorta —The main artery that carries blood from the heart to the rest of the body. The aorta is the largest artery in the body.

Coronary artery disease —Also called atherosclerosis; it is a build-up of fatty matter and debris in the coronary artery wall that causes narrowing of the artery.

Systemic lupus erythematosus (SLE) —A chronic, inflammatory, autoimmune disorder in which the individual's immune system attacks, injures, and destroys the body's own organs and tissues. SLE may affect many organ systems including the skin, joints, lungs, heart, and kidneys.

Caregiver concerns

Most echocardiograms are performed by a cardiac sonographer, who is a technician with special training in performing diagnostic cardiac ultrasounds. A physician performs TEEs. The echocardiogram is interpreted by a physician, usually a cardiologist who has been certified by the National Board of Echocardiography as having special competence in performing and interpreting echocardiograms.

Resources

“Echocardiogram.” Medline Plus. April 12, 2007 [cited February 26, 2008]. http://www.nlm.nih.gov/medlineplus/ency/article/003869.htm.

Mayo Clinic Staff. “Echocardiogram: Sound Imaging of the Heart.” Mayo Clinic. July 14, 2006 [cited February 26, 2008]. http://www.mayoclinic.com/health//HB00012.

American College of Cardiology, Heart House, 2400 N Street, NW, Washington, DC, 20037, (202) 375-6000, (800) 253-4636 x8603, (202) 375-7000, resource@acc.org, http://www.acc.org.

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

American Registry of Diagnostic Medical Sonographers, 51 Monroe Street, Plaza One East, Rockville, MD, 20850, (301) 738-8401, (800) 541-9754, (301) 738-0312, http://www.ardms.org.

American Society of Echocardiography, 1500 Sunday Drive, Suite 102, Raleigh, NC, 27607, (919) 861-5574, (919) 787-4916, http://www.asecho.org.

Tish Davidson AM