Transesophageal Echocardiography (TEE)
Transesophageal echocardiography refers to the ultrasound examination of the heart from the esophagus. This examination is somewhat more invasive and less comfortable for the patient.Usually the patient is anaesthetized with a sleeping pill before the examination so that the examination is not unpleasant. Then a movable tube, which has a small ultrasound probe at its end, is pushed through the mouth and throat into the esophagus.
Since no bones, muscles or fat restrict the view during this examination, the heart is often easier to visualize. Particularly small blood clots (thrombi) can be easily detected in the ears or atria of the heart. Due to the mobility of the ultrasound probe around its own axis, all layers of the heart can be visualized.
The most common indication for this form of invasive echocardiography is poor assessability, due to obesity, pulmonary emphysema or other anatomical conditions, in classical echocardiography. This form of imaging of the heart is performed under stress and is therefore also called “stress echo”. The most common indication for carrying out this examination is the suspicion of a circulatory disorder of the heart as part of coronary heart disease (CHD).
The stress can be caused by two types. Within the scope of mechanical stress, the patient lies on a bicycle ergometer in a left-side position. While the patient pedals in slowly increasing resistance, the doctor performs the ultrasound examination of the heart.
Another possibility is the drug-induced triggering of stress. This is carried out when patients cannot ride a bicycle due to physical limitations. To medically trigger stress in the heart, dobutamine or adenosine or dipyridamole with atropine is administered intravenously.
The drugs lead to an increase in heart rate and an increase in stroke volume and cardiac output. As a result, the heart reaction that sport triggers is medically induced. Regardless of the type of exercise, a “stress echo” is performed in several exercise levels.
First, the left ventricle is always displayed at rest. Afterwards, the load is slowly increased until abort criteria are met. These include reaching the target heart rate, chest pain of the patient or visible wall movement disorders in the ultrasound.
Chest pain or wall movement disorders during the “stress echo” are clear indications of coronary heart disease (CHD). During the examination, the ejection phase (systole) of the heart is usually recorded in the apical 4-chamber view, in the apical 2-chamber view and in the parasternal long and short axis. These images are taken at the different load levels. Afterwards, the load levels of a gaze can be played back synchronously. This makes it easier to find possible wall movement disorders.