There are several different vendors and models of transesophageal echocardiography (TEE) technology. This chapter provides a generalized overview of the basics of TEE, equipment setup, and handling. Equipment and protocols for handling TEE hardware and storing images vary from institution to institution, and it is recommended that the anesthesia technicians be familiar with these policies and practices at their institution.

Energy is all around us in different forms. Heat from a fire and light from the sun are the most familiar examples; however, sound too is a form of energy. This form of energy is used frequently in nature by creatures like whales and dolphins. They emit sound waves underwater to detect objects in their surroundings. Submarines and ships have adopted a similar idea by emitting “pings” and gauging the distance to another object by the amount of time it takes for the “ping” to return. Closer objects will send the “ping” back sooner, whereas farther objects will cause the “ping” to return much later. This is because it takes the sound waves more time to travel to the farther object and then return back to the submarine.

Somewhat similar to the submarine or the ship, the transesophageal probe (TEE) houses a crystal near the tip that generates several thousand “pings” per second and displays an image based on the time it takes for their return. The TEE probe is placed into the esophagus, and the crystal near the tip emits lots of tiny “pings” that travel through the wall of the esophagus and to the heart. When the “pings” bounce off the parts of the heart and return to the probe, the probe converts the “pings” to the image on the screen.

Two-dimensional (2D) TEE has been the imaging modality used most commonly for TEE procedures. More recently, three-dimensional (3D) TEE has made its way into mainstream cardiac operating rooms. 3D TEE is typically used in conjunction with 2D TEE to attempt to answer questions about structures of the heart that are not obvious with 2D images alone. TEE in general is helpful in evaluation of heart valves, heart function, cardiac masses, and even in evaluation of placing cannulae in the heart. If your institution has a limited number of 3D-capable TEE machines and probes, the 3D TEE machines should be reserved for valve surgeries or more complex procedures. However, one should always check with the anesthesia provider to inquire about whether 3D imaging will be necessary for a particular case. In cases that do not involve a valve, such as coronary artery bypass grafting (CABG), a 3D probe may not be necessary. For emergency cases that require TEE, the first TEE probe and machine available should be used, unless instructed otherwise.

To obtain a 3D image, a 3D probe and an ultrasound machine that contains 3D software are required. If a 3D probe is placed in a patient and the ultrasound machine is not capable of 3D imaging, the probe may be disconnected from the machine (but kept in the patient) and reconnected to a machine that has 3D capability. However, if a 2D capable probe is inserted into a patient that requires 3D imaging, the probe will have to be replaced with a 3D probe connected to a 3D-capable machine for 3D imaging.

The ultrasound machine is a computer processing unit. Some of the important components
include a screen or monitor, keyboard, knobboard, pin ports for insertion of probe transducers (whether for TEE or other types of ultrasound probes), and outlets for transfer of information for digital storage. It is housed on wheels with a braking and locking system located at the bottom front of the machine. These machines can cost up to $250,000.

The TEE transducer is a long, flexible probe that collects the picture information to be processed and viewed on the ultrasound machine. At one end of the probe is the housing unit that fits into the insertion port of the ultrasound machine. The locking mechanism on this housing unit should be set to “open” and once it fits snugly into the insertion port, the locking mechanism is turned 90 degrees to lock the connector into place. Different brands of TEE machines may have different mechanisms to engage the TEE probe onto the TEE machine. Further down the probe is the handle of the TEE. The handle consists of two rotating knobs and two rubber buttons. The rotating knobs control the movement of the tip of the probe anteriorly, posteriorly, left, and right. The larger knob moves the tip up (anterior) and down (posterior), whereas the smaller knob moves the tip left and right (Fig. 39.1). These knobs are also sometimes useful for distinguishing between 2D and 3D probes. For example, some vendors assign 2D probes black knobs and 3D probes gray knobs (Fig. 39.2). There is a locking lever located right next to the movement-control knobs that secures the probe tip in its current orientation. The lever should be released or “unlocked” and checked for resistance prior to placement of the probe in a patient. The probe should never be manipulated inside the patient with the tip in the locked position (Fig 39.3). In a fixed or locked position, the probe tip can damage the oropharynx, esophagus, or stomach. If the control knobs become incompetent, the probe loses its ability to be maneuvered and should not be placed in a patient. The two rubber buttons on the side of the probe control the plane of the sound beam emitted from the tip of the probe. The black cord between the handle and the tip contains electrical wires, which may become exposed after teeth repeatedly rub against the cord covering. Damage to the electrical cords may also occur if a patient bites down with enough force. Therefore, in patients with teeth, it is prudent to place a bite guard to protect the cord from the patient. The tip of the probe houses the key elements that send out and receive the ultrasound waves. If the tip is broken, the probe requires repair. TEE probes themselves can cost up to $50,000.

TEE is most commonly used in cardiac surgeries, liver and lung transplants, and major vascular surgeries. Specific guidelines for use can be found at the American Society of Anesthesia/Society of Cardiovascular Anesthesia/American Society of Echocardiography Web sites. Caution should be exercised in placement of the probe in conditions where the patient has had any neck, mouth, esophageal, stomach, or bleeding problems. Major complications include creating trauma or bleeding anywhere in the body where the probe comes into contact with. The question that must be always asked is: does the benefit of this procedure outweigh the risks? Some situations such as life-threatening emergencies may warrant the risk. Other options may be considered if a TEE cannot be placed safely, but information about the heart is needed. In these situations, transthoracic echocardiography (TTE) can be performed before surgery and/or an epiaortic exam (ultrasound of the heart and aorta in the surgical field) can be done once the chest is open. These technologies require different probes but can use the same ultrasound machine to process the signals and display an image.

Absolute contraindications include: patient refusal, esophageal problems (esophageal stricture, tracheoesophageal fistula, postesophageal surgery, esophageal trauma, hole, rings/webs, tumor), unstable cervical spine, and previous esophagectomy or esophagogastrectomy.

Relative contraindications include: recent surgery in the throat, fragile veins in the esophagus (esophageal varices seen in liver disease), problems swallowing or pain on swallowing, neck arthritis, outpouchings in the esophagus or stomach, history of radiation to the chest or neck, or problems with bleeding.

Fortunately, serious complications from TEE are rare. The following are the reported complications from TEE use: esophageal perforation, esophageal bleeding, problems swallowing (dysphagia), pain on swallowing (odynophagia), thermal burn injury to the esophagus or stomach from the probe tip heating up, lip trauma, dental damage, and rarely vocal cord damage from inadvertent endotracheal intubation.

The TEE

Stay updated, free articles. Join our Telegram channel

Join