An echocardiogram is a test that uses ultrasound waves to examine the heart. A transesopageal echocardiogram, or TEE, is an echocardiogram that is done from inside the esophagus (the tube leading from the mouth to the stomach).

Because the esophagus lies just behind the heart, the TEE provides much clearer images of the heart than a standard echocardiogram, which is performed from outside the heart.

During the TEE, a long probe (flexible tube) about the width of a little finger is inserted into the mouth and down the esophagus. A small transducer at the tip of the probe sends ultrasound waves that reflect (echo) off the various parts of the heart. The images produced show the shape and movement of different heart structures, and the flow of blood through the heart chambers and valves.

Reasons a TEE should be done may include:

• to detect blood clots or masses inside the heart.
• to assess the severity of some valve defects.
• to examine prosthetic (artificial) heart valves.
• to evaluate holes between heart chambers.
• to detect infection of heart valves.
• to diagnose a dissection (tear) in the lining of the aorta (the body's main artery).
• when the standard echocardiogram is of poor quality or inadequate (such as in people who are obese or have chronic lung disease).