What is echocardiography?

Indications and Procedures

Echocardiography is a technique that uses ultrasound waves to detect the structures of the heart. The most common indication for echocardiography is to evaluate chamber size, thickness of the heart muscle, valve abnormalities, and the flow of blood through the heart. The procedure is usually performed to evaluate the functioning of the heart in a patient with heart failure
and can detect any damage to the heart muscles after a heart attack. In addition, valvular abnormalities of any of the four heart valves, such as thickening or leakage, can be detected. Other indications include evaluation of congenital or birth defects of the heart and fluid collection in the sac covering the heart (pericardial effusion). The use of a color Doppler further helps in assessing the velocity of blood flow through the heart.

Transthoracic echocardiography (TTE) is a simple outpatient, noninvasive procedure. While undergoing echocardiography, the patient lies down on his or her back and turns a little toward to the left so that the heart can be better visualized. The area on the left side of chest is wiped dry (no shaving is necessary), and a gel is applied over the skin for better conduction of the ultrasound waves. The operator then applies the transducer or the ultrasound probe over the chest, and two-dimensional images of the heart are seen on the attached monitor. Multiple still and motion pictures of the heart are recorded, which are then read by a cardiologist. The procedure takes about thirty minutes, and the patient is able to go home immediately after the procedure.

Special types of echocardiography include transesophageal echocardiography (TEE) and stress echocardiography. In TEE, the ultrasound probe is mounted on an endoscope and introduced into the esophagus. The structures at the back of the heart and valves are better visualized with this procedure. Stress echocardiography includes performing echocardiography while the patient is undergoing a stress test (while exercising on a treadmill or after medications such as dobutamine have been given). Both these procedures take a longer time and require experienced operators. Patients may be observed for a few hours after the procedure.

Uses and Complications

Echocardiography helps in identifying congenital heart defects such as tetralogy of Fallot, atrial and ventricular septal defects, valvular abnormalities such as stenosis (narrowing) or regurgitation (leaking) of the four heart valves, the functioning of the heart muscle after a heart attack, the collection of fluid in the sac covering the heart, the rupture of heart muscle, and the progression of heart failure.

Different modes of echocardiography are used in clinical practice. The most common is two-dimensional echocardiography (2-D echo), as described above, which detects cardiac structure and function and displays results in two dimensions. A newer, more expensive three-dimensional echocardiography is gaining popularity, as it displays the findings in a three-dimensional form and localizes specific lesions more accurately. Stress echocardiography is used to detect areas in the heart that have a reduced blood flow, especially during exercise or stress. This enables cardiologists to locate the diseased artery and correct it by stenting or by surgery. TEE specifically looks for blood clots in one of the heart chambers called the left atrium and also looks closely at infections of the valves (endocarditis).

TTE is a safe procedure without any known complications. Patients undergoing TEE or stress echocardiography are carefully screened before undergoing the procedure. Rare complications of stress echocardiography are chest pain and heart attack in patients with very poor circulation to the heart, and this procedure should not be performed in persons with ongoing heart attack symptoms. TEE rarely can cause rupture of the esophagus because of the invasive nature of the procedure. Occasionally, aspiration of food contents into the lungs can occur, and hence patients are required to have an empty stomach before the procedure. If complications do occur, then patients are hospitalized and treated appropriately.

Perspectives and Prospects

The term echo was first coined by the Roman architect Vesuvius during the rule of the Roman Empire. Karl Dussik first used ultrasound in medicine to outline the ventricles of the brain. The first use of ultrasound to examine the heart was by W. D. Keidel in the 1940s. Clinical echocardiography was initiated by Helmut Hertz and Inge Edler of Sweden using a commercial ultrasonoscope to examine the heart. Though echocardiography was introduced in the United States by John J. Wild, H. D. Crawford, and John Reid in the 1960s, most of the credit for its further development and popularity goes to Harvey Feigenbaum at Indiana University.

Echocardiography is a great tool for assessing cardiac function. Recent echocardiography machines are portable and allow physicians to do bedside evaluation of the heart. Newer models are handheld, further enhancing ease of use. A role for echocardiography has been proposed in other systemic diseases such as diabetes, hypertension, pregnancy, kidney disease, and thyroid disease and also in the screening of athletes. Echocardiography is a cost-effective, versatile procedure that has a significant role in clinical medicine.

Bibliography

Fauci, Anthony S., et al., eds. Harrison’s Principles of Internal Medicine. 18th ed. New York: McGraw-Hill, 2012.

Feigenbaum, Harvey, William F. Armstrong, and Thomas Ryan. Feigenbaum’s Echocardiography. 7th ed. Philadelphia: Lippincott Williams & Wilkins, 2010.

Health Library. "Echocardiogram." Health Library, March 5, 2013.

NIH National Heart, Lung, and Blood Institute. "What Is Echocardiography?" NIH National Heart, Lung, and Blood Institute, October 31, 2011.

Papadakis, Maxine, et. al., eds. Current Medical Diagnosis and Treatment 2013. [N. p.]: McGraw-Hill, 2012.