TEE Probe Orientation, Manipulation, and Complications

 
Transesophageal Acoustic Windows
Nomenclature for indicating the view of the image is standardized by the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists. The acoustic window is combined with the imaging plane to describe the image's orientation.  The transesophageal acoustic windows are:
  • Upper esophageal (UE)
  • Middle esophageal (ME)
  • Transgastric (TG)
  • Deep Transgastric (DTG)
Animation of TEE Acoustic Windows
 
Anatomic Relationships of the Esophagus
 
Transthoracic echocardiographic (TTE) scans can yield poor quality scans because of anatomic structures or pathological/physiolgical conditions that cause signal attenuation.  Ribs, excessive fat, improper positioning, and excessive air in the lungs may cause a poor scan.  A scan from the esophagus, however, does not have any of these issues, except for air in the stomach or a hiatal hernia.  High quality scans are usually possible from the esophagus.  The esophagus starts at it's narrowest point, the posterior pharynx and extends through the mediastinum, posterior to the trachea and the left bronchus, posterior to the left atrium and the left ventricle, through the diaphragm, and enters the stomach.  A probe placed into the stomach (transgastric) can be retroflexed to contact the inferior wall and the apex of the left ventricle, if placed distally (deep transgastric) in the stomach.  Note that the axis of the esophagus and of the heart is not in parallel, therefore, some probe manipulation will be required to obtain correct cardiac axis cuts. 
 
The trachea is situated between the distal ascending aorta and the esophagus.  A probe located in the esophagus cannot image this segment of the aorta.  The aorta then travels from anterior to posterior, descending along with the esophagus posterior to the heart and through the diaphragm.  From the esophagus, images of the heart, ascending aorta, arch aorta, descending aorta, both pleural spaces, liver, superior vena cava, and the inferior vena cava are possible.  The segment of the ascending aorta that is not able to be visualized because of the intervening left bronchus is the one consistent area that cannot be scanned.
 
Transesophageal Probe Preparation Insertion
 
To Prepare the Probe:
  • Attach the probe to the console
  • Establish proper electrical performance by the echo machine
  • Inspect the probe for cracks in the housing
  • Inspect the transducer for cracks
  • Check the Flywheel Mechanism
  • Check the buttons
  • Put a bite block on the probe
  • Lubricate the probe
 

To Insert the Probe:
  • Trap the base of the probe against the bed or place it around your neck so both or your hands are free
  • Insert the probe into the mouth following the curvature of the mouth and pharynx
  • Advance the probe into the esophagus - only the slightest of resistance should be present
  • If significant resistance is present do one or all of the following:
    • Turn the head to the left
    • Deflate the cuff of the endotracheal tube
    • Lift the mandible anteriorly with a jaw thrust
    • Flex the head
    • Use a larngoscope to place the probe under direct vision
The probe should be able to be inserted easily in almost all patients.  A slight, noticeable loss of resistence should occur when the probe passes from the posterior pharynx into the esophagus. 
 
Transesophageal Probe Manipulation
 
The transesophageal echocardiography probe can be advanced or withdrawn, rotated leftward(counter clockwise) or rightward (clockwise), anteflexed(anterior flexion)or retroflexed(posterior flextion), and flexed leftward or flexed rightward. Also, the plane of the sector scan can be rotated from transverse to longitudinal. The transesophageal probe is advanced or withdrawn to the acoustic windows upper esophageal, mid esophageal, transgastric, and deep transgastric. The sector scan can be rotated from transverse to longitudinal at each acoustic window to view the proper cardiac axis or cut. If anatomical variants exist such that the structures are not easily visualized, the probe can be flexed leftward or rightward to bring the image into full view. Anteflexion or retroflexion are used at the acoustic window to view the proper cardiac axis or plane. Rotation of the transesophageal probe allows visualization of cardiac structures that may be peripherally located or in an anatomically difficult area to visualize.
 
Advance/Withdraw Probe Rotate Left or Right Flex Left or Right Anteflex or Retroflex
Advanced/Withdrawn Rotation Left/Right Flex Left/Right Anteflex/Retroflex Transverse/Longitudinal Plane
 
Complications
 
Probe Complications
 
The complications are divided into complications to the patient and complications to the probes. Complications to a probe:
  • Piezoelectric Crystal Damage
  • Housing Damage
  • Electrical Wire Fracturing
  • Tension Wire Damage
Figure 5.1 Cracked Transducer
The crystal in all probes is easily damaged if the crystal is struck with enough force to crack it (Figure 5.1). Proper care of the probe requires that the crystal be protected at all times and avoiding contact with hard surfaces. A protective sleeve is available for transesophageal echocardiography probes and should be utilized when being stored.  
 
When inserting a transesophageal echocardiography probe, a bite block should be used. The function of a bite block is to prevent injury to the patient and to prevent damage to the probe. If a patient were to bite the probe electrical leaks or electrical fiber breakage can occur. The probe should be inspected for cracks and leaks prior to each patient use and have regular maintenance to check for electrical leaks and probe function.
Figure 5.4 IV Pump as a Table
When the probe is not in use it should not be stored, as in Figure 5.5, where the probe's tubing is not at acute angles which can damage the probe housing and the wheel mechanism contained in the probe.  The probe should be stored or placed where the probe is not likely to fall and damage the probe (Figure 5.4).
 
 
Figure 5.2
Protective Sleeve		 Figure 5.3
Bite Blocks
Image 5.5 TEE Probe Stored Wrong
Patient Complications
 
Complications to patients can occur with transesophageal echocardiographyGillinov AM, Pettersson G, Rice TW: Esophageal injury during radiofrequency ablation for atrial fibrillation. J.Thorac.Cardiovasc.Surg. 2001; 122: 1239-40. Complications  include:
 
  • Prolonged skin staining from the cleaning solution
  • Soft tissue damage of the oropharynx
  • Dental damage
  • Airway obstruction
  • Tracheal extubation
  • Vascular compression
  • Right mainstem intubation
  • Esophageal erosion, burns, bleeding and/or perforation
  • Gastric burns, erosion, bleeding and/or perforation
  • Electrical shock
  • Arrhythmias
  • Vocal cord paralysis
  • Dysphagia/Odynophagia
 
While these complications are rare, relative contraindications such as esophageal varicies, esophageal stricture, Zenker's diverticulum, esophageal webs, history of radiation therapy to the esophagus, esophageal resections, etc should be sought during a history and physical examination. While presence of conditions that may increase the risk of complications, the appropriate risk/benefit ratios must be considered prior to utilizing transesophageal echocardiography.  A hiatal hernia is not necessarily a contraindication, but it can increase the likelihood of poor imaging.  Complete evacuation of air via orogastric tube may be helpful in these patients.
 
When removing the transesophageal probe, unlock the probe so it will not remain in a rigid, flexed position during withdrawal.  Withdrawing a locked transesophageal probe increases the risk of esophageal damage.