Transesophageal echocardiography (TEE) involves performing an echocardiogram of the heart through the esophagus. The exam is also known colloquially as a swallow echo. Transesophageal echocardiography is used when certain structures in the heart cannot be adequately visualized by means of echocardiography of the heart performed externally.
What is transesophageal echocardiography?
Transesophageal echocardiography (TEE) is an echocardiogram of the heart performed through the esophagus. The exam is also known colloquially as a swallow echo. Prior to the examination, local anesthesia of the pharynx may be administered, depending on the patient’s preference, as insertion of the tube into the esophagus may be considered uncomfortable. For TEE, the patient must swallow a transducer. This is attached to a flexible tube, allowing 180°C rotation of the transducer. The device is placed near the heart via the esophagus. There, the transducer emits ultrasound waves. These are reflected to different degrees by the various tissue structures of the heart. These reflected ultrasound waves are registered again by the transducer and assembled into images of the heart structures by complex computing processes in the computer of the ultrasound device. There are various imaging possibilities. The most common is the B-scan method, in which the heart and its structures are displayed in two dimensions. The so-called Doppler method can even be used to assess the blood flow in the heart and thus diagnose any valve defects or vasoconstrictions that may be present.
Function, effect, and goals
Transesophageal echocardiography is used whenever cardiac imaging by transthoracic echocardiography, i.e., echocardiography through the chest wall, is not sufficient to make a diagnosis. In particular, the atria of the heart as well as the main artery, the aorta, cannot be adequately visualized by transthoracic echocardiography. Since the esophagus lies directly behind the heart, very accurate ultrasound images of the heart can be obtained from here without interfering intermediate structures such as the chest, lung tissue or ribs. Transesophageal echocardiography is also used in the event of artifacts, i.e. possible technically induced display errors, in transthoracic echocardiography. TEE is the diagnostic procedure of choice in cases of suspected valvular heart disease. It can be used to determine whether one or more of the four heart valves are not closing properly (valvular insufficiency) or are no longer opening properly due to a narrowing. This is referred to as valvular stenosis. Transesophageal echocardiography can also be used to assess when these valve defects can no longer be treated with medication and when surgical valve replacement is necessary. TEE is also used to monitor the progression and function after the insertion of an artificial heart valve. Atrial fibrillation is one of the most common cardiac arrhythmias and often remains undetected. In contrast to ventricular fibrillation, atrial fibrillation is not directly life-threatening. The congestion of blood in the atria, which no longer contract due to fibrillation, can cause blood clots to form that break loose, travel through the arteries to the brain and cause a stroke. To detect these blood clots in the atrium early, transesophageal echocardiography is also performed if atrial fibrillation is suspected. TEE is also the diagnostic procedure of choice for endocarditis, an inflammation of the inner lining of the heart. The same applies to the diagnosis and monitoring of untreated aortic aneurysms. An aortic aneurysm is a bulge in the aorta. Aortic aneurysms are often accidental findings; they rarely cause pain. The major danger of these vascular outpouchings is rupture with uncontrollable and usually fatal internal bleeding. Like aortic aneurysms, plaques of the aorta are observed by EET. Plaques are calcium deposits in and on the vessel walls of the arteries. If these become detached, they can migrate to the brain or other organs, depending on their location, and cause acute vascular occlusion with drastic consequences such as stroke or renal infarction. Tumors of the heart or the mediastinum (middle pleura) are also diagnosed with transesophageal echocardiography.Another field of application of the diagnostic procedure is the early detection of deficient perfusion of the heart tissue. These deficient perfusions can occur, for example, after a heart attack and carry the risk of tissue death resulting in heart failure.
Risks, side effects, and hazards
To prevent vomiting, the patient must be fasting during the exam, meaning he or she should not eat or drink for about five to six hours before transesophageal echocardiography. If anesthesia of the pharynx is performed, the patient should not consume any food or liquid even three hours after the examination because of the risk of choking. If the patient has also received an injection to sedate them, they are not allowed to drive for the next 24 hours. Transesophageal echocardiography is a low-risk and well-tolerated diagnostic procedure. In rare cases, however, complications can occur. For example, vessels, nerves and tissues of the esophagus, larynx or trachea can be injured when the transducer is inserted. If the patient has loose teeth, damage to the dentition and tooth loss can occur. The ultrasound waves can cause cardiac arrhythmias or disorders of the cardiovascular system. If sedatives are also administered, breathing disorders are also observed in rare cases. In addition, hypersensitivity reactions to the anesthetic may occur, resulting in severe cases of anaphylactic shock with the risk of organ failure and suffocation. EET must not be performed in patients with esophageal varices. Esophageal varices are varicose veins of the esophagus that can occur, especially in severe liver disease. If these varices are injured, life-threatening bleeding is the result. Other contraindications to the ultrasound procedure include tumors of the esophagus (esophageal cancer) or bleeding in the upper gastrointestinal tract.
