Transesophageal echocardiogram
Encyclopedia
A transesophageal echocardiogram, or TEE (TOE in the United Kingdom, reflecting the spelling transoesophageal), is an alternative way to perform an echocardiogram. A specialized probe containing an ultrasound transducer at its tip is passed into the patient's esophagus
. This allows image and Doppler evaluation which can be recorded.
It has several advantages and some disadvantages compared to a transthoracic echocardiogram
(TTE).
In adults, several structures can be evaluated and imaged better with the TEE, including the aorta
, pulmonary artery, valves of the heart, both atria, atrial septum, left atrial appendage, and coronary arteries. TEE has a very high sensitivity for locating a blood clot inside the left atrium.
is induced in the patient to ease the discomfort and to decrease the gag reflex
, thus making the ultrasound probe easier to pass into the esophagus. Mild or moderate sedation
can be induced with medications such as midazolam
(a benzodiazepine
with sedating, amnesiac qualities), fentanyl (an opiod), or propofol
(a sedative/general anesthetic, depending on dosage) . Usually a local anesthetic spray is used for the back of the throat, such a xylocaine and/or a jelly/lubricant anesthetic for the esophagus. Children are anesthetized
. Unlike the TTE, the TEE is considered an invasive procedure and is thus performed by physicians in the U.S., not sonographers.
Esophagus
The esophagus is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. During swallowing, food passes from the mouth through the pharynx into the esophagus and travels via peristalsis to the stomach...
. This allows image and Doppler evaluation which can be recorded.
It has several advantages and some disadvantages compared to a transthoracic echocardiogram
Transthoracic echocardiogram
A standard echocardiogram is also known as a transthoracic echocardiogram , or cardiac ultrasound. In this case, the echocardiography transducer is placed on the chest wall of the subject, and images are taken through the chest wall. This is a non-invasive, highly accurate and quick assessment...
(TTE).
Advantages
The advantage of TEE over TTE is usually clearer images, especially of structures that are difficult to view transthoracicly (through the chest wall). The explanation for this is that the heart rests directly upon the esophagus leaving only millimeters that the ultrasound beam has to travel. This reduces the attenuation (weakening) of the ultrasound signal, generating a stronger return signal, ultimately enhancing image and Doppler quality. Comparatively, transthoracic ultrasound must first traverse skin, fat, ribs and lungs before reflecting off the heart and back to the probe before an image can be created. All these structures, along with the increased distance the beam must travel, weaken the ultrasound signal thus degrading the image and Doppler quality.In adults, several structures can be evaluated and imaged better with the TEE, including the aorta
Aorta
The aorta is the largest artery in the body, originating from the left ventricle of the heart and extending down to the abdomen, where it branches off into two smaller arteries...
, pulmonary artery, valves of the heart, both atria, atrial septum, left atrial appendage, and coronary arteries. TEE has a very high sensitivity for locating a blood clot inside the left atrium.
Disadvantages
- TEE requires a fasting patient, (the patient must follow the ASA NPO guidelines(i.e. usually not eat or drink anything for eight hours prior to the procedure)
- Requires a team of medical personnel
- takes longer to perform
- May be uncomfortable for the patient
- May require sedationSedationSedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure...
or general anesthesia - has some risks associated with the procedure (esophageal perforation -- 1 in 10,000, and adverse reactions to the medication).
Process
Before inserting the probe, mild to moderate sedationSedation
Sedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure...
is induced in the patient to ease the discomfort and to decrease the gag reflex
Gag reflex
The pharyngeal reflex or gag reflex is a reflex contraction of the back of the throat, evoked by touching the soft palate or sometimes the back of the tongue. It prevents something from entering the throat except as part of normal swallowing and helps prevent choking...
, thus making the ultrasound probe easier to pass into the esophagus. Mild or moderate sedation
Sedation
Sedation is the reduction of irritability or agitation by administration of sedative drugs, generally to facilitate a medical procedure or diagnostic procedure...
can be induced with medications such as midazolam
Midazolam
Midazolam is a short-acting drug in the benzodiazepine class developed by Hoffmann-La Roche in the 1970s. The drug is used for treatment of acute seizures, moderate to severe insomnia, and for inducing sedation and amnesia before medical procedures. It possesses profoundly potent anxiolytic,...
(a benzodiazepine
Benzodiazepine
A benzodiazepine is a psychoactive drug whose core chemical structure is the fusion of a benzene ring and a diazepine ring...
with sedating, amnesiac qualities), fentanyl (an opiod), or propofol
Propofol
Propofol is a short-acting, intravenously administered hypnotic agent. Its uses include the induction and maintenance of general anesthesia, sedation for mechanically ventilated adults, and procedural sedation. Propofol is also commonly used in veterinary medicine...
(a sedative/general anesthetic, depending on dosage) . Usually a local anesthetic spray is used for the back of the throat, such a xylocaine and/or a jelly/lubricant anesthetic for the esophagus. Children are anesthetized
Anesthesia
Anesthesia, or anaesthesia , traditionally meant the condition of having sensation blocked or temporarily taken away...
. Unlike the TTE, the TEE is considered an invasive procedure and is thus performed by physicians in the U.S., not sonographers.