Transesophageal echocardiography, which physicians call TEE, is a special form of echocardiography. Echocardiography is the second most commonly ordered test in Cardiology. It utilizes high frequency sound waves which are not audible to the human ear. These sound waves are emitted from a special device called a transducer which is held onto the chest wall next to the heart (transthoracic echocardiography ).
Heart tissue reflects these sound waves, and the reflection is recorded onto the screen of an echocardiography machine. With this information, cardiac anatomy, and how this anatomy functions, can be detected, such as the atrial and ventricular chambers and the cardiac valves. Blood flow direction and velocity can also be determined from any of the valves, and this helps in determining whether or not a valve is abnormal.
Sound waves from a transducer held onto the chest wall are absorbed by skin, fat, bone and lung tissue. Because of this, and In spite of the remarkable advances in the transthoracic method of echocardiography since it was initially developed in the 1950’s, 15% of all echoes do not provide sufficient information for the physician. Consequently, TEE was developed in the 1970’s in order to overcome the limitations of transthoracic echocardiography.
TEE utilizes an especially designed ultrasound transducer that can be swallowed. TEE emits sound waves that reflect off the heart that are generated from inside the esophagus, which is next to the heart. None of the images that are obtained by TEE suffer from the sound interruptions that a transducer on the chest wall shows.
Besides providing echo images where transthoracic echo is not satisfactory, TEE has been found very useful in locating and determining the function of various cardiac structures that cannot be imaged at all with a transthoracic echo.
Some examples of the other information available from TEE include:
1. evaluation of artificial heart valves and valve infection
2. evaluation cardiac anatomy in stroke patients
3. evaluation of tears of the aorta
4. evaluation of congenital heart disease
TEE has been found to be very useful in the emergency department and quickly resolves issues such as the cause of cardiovascular shock when patients are too unstable to be sent for tests such as a CT scan or MRI.
Its use in the critical care area is well recognized because it provides cardiac images when there are chest bandages present and when patients are on ventilators. Routine echocardiography in the critical care area is frequently inadequate for the above reasons. It is used routinely in cardiac surgery to provide monitoring of cardiac function.
TEE for an outpatient is performed with the patient supine and rolled onto his side. Individuals which are usually present include the cardiologist, a nurse and an echo technician who controls the echo machine. The head of the patient is elevated slightly with a pillow. An intravenous line is started for administration of mild sedation, and the throat is sprayed with an anesthetic. Patients are not put to sleep during this procedure.
During the procedure the EKG is monitored, and blood oxygen is monitored with a finger optical device. A suction tube is available to remove secretions from the throat which usually accumulate. The TEE transducer is a cable about the diameter of an adult’s small finger and is inserted into the esophagus by having the patient swallow when it is placed in the back of the throat. There is usually some initial gagging, but once the transducer is in the correct place to obtain images, the patients become more comfortable.
Breathing is not disturbed; patients can talk; and occasionally watch their own echoes during the procedure. The procedure requires about 10 minutes to perform. If sedation is used patients are observed for one hour after the procedure. Patients are also told not to drink or eat for 2 hours until the throat anesthetic wears off.
Since its inception, TEE has provided a major leap in diagnostic echocardiography, and has become the gold standard of practical ultrasonic cardiac imaging.
*** The author, Dr. Frazin holds the proud distinction and honor of inventor of the TEE. This incredible accomplishment has literally changed the face of Cardiology and made Dr. Frazin internationally renown