Protocol

The following is a general protocol that describes all of the steps for performing transesophageal echocardiography (TEE).

• 1.
  

  After acquiring patient history and performing a physical examination, assess whether TEE is indicated, and ensure that no contraindications are present ( Table 11.1 ).

  
  
  
  

  Table 11.1

  
  

  Contraindications to TEE

  
  

  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

  Absolute Contraindication	Relative Contraindication
  Esophageal related: esophageal tumor, stricture, fistula, or perforation	Barrett esophagus History of dysphagia (requires appropriate GI evaluation first)
  Active upper GI bleed	Active esophagitis
  Perforated bowel or bowel obstruction	High grade esophageal varices Active peptic ulcer disease
  Unstable cervical spine	Neck immobility (due to arthritis or other causes)
  Uncooperative patient
  	Severe coagulopathy or thrombocytopenia
  	Severe hiatal hernia
  	Prior neck or chest radiation
  	Prior GI surgery
  	Esophageal diverticulum Loose teeth (needs dental evaluation)

   
  

  Adapted from Hahn RT, Abraham T, Adams MS, et al. Guidelines for performing a comprehensive transesophageal echocardiographic examination: recommendations from the American Society of Echocardiography and the Society of Cardiovascular Anesthesiologists, J Am Soc Echocardiogr 26:921–964, 2013.
  
  
  
  
• 2.
  

  Decide on the method of sedation.

  
  
• 3.
  

  Obtain informed consent for the procedure and sedation.

  
  
• 4.
  

  Ensure that NPO status has been maintained for at least 6 hours for solids, and at least 4 hours for liquids (times may be longer for patients with gastroparesis). This includes tube feeding in those with percutaneous endoscopic gastrostomy (PEG)/percutaneous endoscopic jejunostomy (PEJ) or nasogastric (NG) or orogastric (OG) tube.

  
  
• 5.
  

  Prepare the patient for TEE, and make sure appropriate patient monitoring is in place and set up. At a minimum, this includes a blood pressure cuff that recycles every 2 to 3 minutes, respiration and oxygen saturation monitoring, suction catheter, and adequate IV access for medications and fluids. Telemetry should be used in those with American Society of Anesthesiology (ASA) class 3 or higher ( Table 11.2 ). A code cart and advanced airway equipment should be on hand, as should adequate doses of sedation agents and sedation reversal agents.

  
  
  
  

  Table 11.2

  
  

  American Society of Anesthesiology Physical Classification System (ASA Class)

  
  

  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  

  ASA Class	Description	Example
  1	Healthy individual	Someone with no known medical problems; no functional limitations
  2	Mild systemic disease	No functional limitations, one or more controlled medical problems such as well-controlled diabetes or hypertension
  3	Severe systemic disease	Some functional limitations, controlled heart failure, stable angina, poorly controlled hypertension
  4	Severe systemic disease with constant threat to life	Unstable angina, advanced symptomatic heart failure, severe symptomatic chronic obstructive pulmonary disease
  5	Moribund; not expected to survive without an operation or intervention	Multiorgan failure
  6	Brain dead; organs are being removed for donation

   
  

  Adapted from Fitz-Henry J. The ASA classification and peri-operative risk, Ann R Coll Surg Engl 93:185-187, 2011; and Saklad M. Grading of patients for surgical procedures, Anesthesiology 2:281–284, 1941.
  
  
  
  
• 6.
  

  Set up the probe and TEE machine. Make sure all functions work properly and the probe is intact without any cracks.

  
  
• 7.
  

  Perform a procedural time-out per institution protocol.

  
  
• 8.
  

  For patients who are intubated, make sure ventilatory management and/or the critical care teams are aware and have them administer 100% F io ₂ . Nasogastric and oral gastric tubes should ideally be removed. Endotracheal tubes should be positioned to one side of the mouth.

  
  
• 9.
  

  Dentures should be removed, and adequate topical anesthesia should be administered. A bite block should be placed in the mouth or over the probe.

  
  
• 10.
  

  Administer sedation, and after the patient is appropriately sedated, insert the TEE probe as described later in this chapter.

  
  
• 11.
  

  Perform all TEE views that will answer the clinical question first, then complete a comprehensive exam as indicated. Specific tomographic views are discussed in Chapter 12.

  
  
• 12.
  

  Post procedure, the patient should be examined for signs of complications, including visual inspection of the oropharynx.

  
  
• 13.
  

  The patient should be allowed to recover from sedation (requires observation and nursing care). Patients should remain NPO for at least 1 hour after the procedure and should not drive the rest of that day.

  
  
• 14.
  

  Results should be discussed with the ordering physician and patient/family.

Topical anesthesia

In awake patients, especially those with a strong gag reflex, topical anesthesia improves patient comfort and eases probe insertion, and it should be used unless contraindicated. Multiple techniques can be used to numb the oropharynx, using formulations of benzocaine; a mixture of benzocaine, aminobenzoate, and tetracaine (Cetacaine); or viscous lidocaine. Patients who have a weak gag reflex may find that gargling with 15 mL of viscous lidocaine for 30 seconds is sufficient; otherwise topical anesthetic should be sprayed directly with an atomizer syringe toward the back of the throat, and the patient should then swallow the anesthetic. With adequate topical anesthesia, inserting a tongue depressor and touching the posterior oropharynx should not cause patient discomfort. In those who are particularly sensitive, gauze can be coated with anesthetic and wrapped around a tongue depressor that is slowly inserted farther back into the mouth to more adequately provide topical anesthesia.

A rare but significant complication from the agents used for topical anesthesia (associated mostly with products containing benzocaine) can be methemoglobinemia, which may be suggested by cyanosis, tachycardia, and abnormally low blood oxygen level. Methylene blue should be readily administered if this condition is suspected; it is given as 1.5 to 2 mg/kg IV infusion over 5 to 10 minutes. Methylene blue should not be administered to patients also receiving selective serotonin reuptake inhibitors (SSRIs), given the risk of serotonin syndrome.

Sedation

Moderate sedation is typically used for most awake and stable patients; however, the degree of sedation that is safe depends on the individual. In some circumstances, a TEE can be performed with just adequate topical anesthesia. For ICU patients requiring mechanical ventilation and already receiving sedation, additional assistance may be required from the critical care or anesthesiology teams to select appropriate sedatives. An anesthesiologist should be present for all procedures performed in the OR using general anesthesia agents.

For moderate sedation, a combination of a narcotic and benzodiazepine are the most commonly used agents. Midazolam, given in 1- or 2-mg increments, and fentanyl, given in 25 to 50 μg increments, are preferred agents because they are short acting. Reversal agents, flumazenil for benzodiazepines (0.2-mg starting dose) and naloxone for opiates (0.04- to 0.1-mg starting dose with escalating doses every 2 to 3 minutes until respirations improve), should be immediately available if respiratory depression ^, occurs or if the patient has an untoward reaction to sedatives. For individuals with an ASA class 3 or higher (see Table 11.2 ), those with history of difficulty with sedation, or those with a difficult airway, consultation with an anesthesiologist may be needed to determine the safest method of sedation.

Probe insertion

Before insertion, the probe should be coated with lubricant, just enough to make it easy to slide, but not so much to cause the patient to aspirate significant quantities. Removal of oral and nasogastric tubes is important to prevent interference with imaging and reduce possible injury to the esophagus.

A bite block should be placed in every awake patient to prevent injury to the patient’s teeth, the TEE probe, and the operator’s fingers. For intubated and sedated patients, a lateral bite block can be used, and in the patient under general anesthesia, the bite block is placed over the probe, but not in the mouth until after probe insertion.

The technique used to insert the probe depends on whether the patient is intubated. In nonintubated patients under conscious sedation, the left lateral decubitus position is preferred, with the sonographer on the left side of the patient. A small amount of anteflexion is placed on the probe and it is inserted to the posterior oropharynx. Asking the patient to push the tongue forward sometimes helps. Once the probe is past the tongue, release of the anteflexion may be necessary to allow it to pass into the esophagus. Patients may need to have their head and chin tilted downward to open up the posterior oropharynx; another individual should perform this maneuver. If the individual is awake, asking them to swallow or waiting for them to naturally swallow may be sufficient to help the probe pass into the esophagus if very gentle forward pressure is placed on the probe. A one-handed approach (one hand near the probe head, the other hand on the probe controls) is frequently sufficient; however, if this fails, a two-handed approach should be used. The probe handle is placed on the bed, and one finger is placed in the side of the mouth, which helps guide the probe head when it is inserted by the opposite hand. For most standard TEE probes, the control wheels should be facing downward when the probe is inserted, so that anteflexion is in the correct direction (following the curvature of the tongue) during insertion. For cases where probe insertion is difficult, placement under direct visualization with the help of an anesthesiologist should be performed.

In the intubated, sedated patient, the operator often stands at the head of the supine patient, similar to when an airway intubation is performed; or the operator may stand on either side of the patient as space allows. One hand can insert the probe while the other holds the lower jaw and lifts it out and upward.

Force should never be used when inserting the probe because this can injure the oropharynx. This is especially true in the intubated and heavily sedated patient who will not be able to provide feedback to noxious stimuli. The probe should also never be in a locked position during insertion.

If there is significant coughing after the probe is inserted and no clear image is displayed, it is likely that the trachea has been intubated. The cartilage from the trachea may cause an ultrasound artifact on the screen, and this is another clue that the probe should be removed.

Probe manipulation

The probe should be unlocked and freely movable. There are several ways to maneuver the TEE probe, as shown in Figure 11.1 and described in the following:

• •
  

  Anteflexion and retroflexion are usually accomplished by turning the largest wheel on the probe. The wheel direction differs based on probe type. A neutral position is always denoted on the wheel notch. Take note of this position on each probe (see Fig. 11.1 , A ).

  
  
• •
  

  Insertion and withdrawal are performed with the hand near the mouth. This is sometimes important to increase contact or remove an air bubble. The probes are designed with depth markers to help determine where the probe should be (for example, 50 cm is usually in the stomach) (see Fig. 11.1 , B ). During insertion and withdrawal, the probe should be in a neutral position to prevent esophageal injury.

  
  
• •
  

  Omniplane angulation changes the angle of the ultrasound beam, from 0 to 180 degrees. Many TEE probes have biplane and triplane imaging so that orthogonal views can be obtained simultaneously (see Fig. 11.1 , C ).

  
  
• •
  

  Rotation occurs by turning the probe to the patient’s right (clockwise) or to the left (counterclockwise) (see Fig. 11.1 , D ).

  
  
• •
  

  Lateral steering of the probe is accomplished by turning a smaller wheel; however, this is a rarely used maneuver and for most studies is not necessary.

Manipulation of the TEE probe.

The four main motions of TEE manipulation are anteflexion and retroflexion ( A ); insertion and withdrawal ( B ); rotation ( C ); and omniplane angulation ( D ).

Risks and complications

Major risks can be divided into those associated with sedation (respiratory depression, hypotension, aspiration) and those related to probe insertion and manipulation. ^, Risks related to probe insertion and manipulation are shown in Table 11.3 along with their overall incidence, and these should be reviewed with patients as part of the informed consent.

Midesophageal five-chamber view

After initially passing the probe into the esophagus, it is slowly advanced until the aortic valve (AV) and left ventricular (LV) outflow tract comes into view at a probe depth of approximately 30 cm. Slight transducer angle manipulation (10-degree rotation) will allow image optimization of the AV and LV outflow tract. In this plane, the LA, right atrium (RA), left ventricle (LV), right ventricle (RV), mitral valve (MV), and tricuspid valve (TV) will also be imaged, hence the name ME five-chamber view. This view allows visualization of the A ₂ A ₁ and P ₁ P ₂ scallops (from left to right on the imaging plane) of the MV and two of the three AV cusps. Color flow Doppler can be applied to identify aortic, mitral, and tricuspid regurgitation. Because this view may not image the true apex of the ventricles, assessment of global and regional ventricular systolic function may be limited.

Midesophageal four-chamber view

From the ME five-chamber view, the probe is advanced slowly to a depth of approximately 30 to 35 cm until the mitral valve is clearly seen. The image depth is then adjusted to ensure viewing of the left ventricular apex. Note that this view is typically deeper than the ME five-chamber view, and the AV and LV outflow tract will not be visualized. Furthermore, the transducer angle may need to be rotated to approximately 10 to 20 degrees to eliminate the AV or LV outflow tract from the image display and to maximize the tricuspid annular dimension. To better align the MV and left ventricular apex, slight probe retroflexion may be necessary. With an appropriately aligned four-chamber view, a single-plane measurement of the mitral annulus can be made for the assessment of diastolic transmitral stroke volume; a pulsed Doppler sample volume should be placed at the annulus to acquire a spectral Doppler profile for velocity-time integral measurement. Diastolic function assessment by TEE has been validated using the lateral mitral annular e′ velocity (abnormal is less than 10 cm/sec) and transmitral E/e′ ratio (normal is 8 or less) as indicative of diastolic dysfunction. Structures seen include the LA, RA, interatrial septum, LV, RV, interventricular septum, MV (A ₃ A ₂ and P ₂ P ₁ scallops), and TV. The TV septal leaflet adjacent to the interventricular septum is to the right of the sector display, and the TV posterior leaflet is adjacent to the RV free wall, to the left of the display.

The ME four-chamber view is one of the most comprehensive views available for evaluating cardiac anatomy and function. Turning the probe to the left (counterclockwise) allows imaging of primarily left-sided heart structures. Turning the probe to the right (clockwise) allows imaging of primarily right-sided heart structures. Diagnostic information obtained from this view include mitral and tricuspid valve function, assessment of global left and right ventricular systolic function, and assessment of regional left (inferoseptal and anterolateral walls) and right (lateral wall) function. Color flow Doppler can be used to reveal aortic, mitral, and tricuspid regurgitation. Following slight probe advancement, the coronary sinus is imaged in long axis, immediately above the attachment of the TV septal leaflet to the interventricular septum.

Simultaneous multiplane imaging is unique to the matrix array transducer and allows the use of a dual screen to simultaneously display two real-time 2D images. The primary image is the reference view, and the second view can be generated with typically two modifiable manipulations. First, the angle of the secondary view relative to the primary view can be modified (typical default angle of 90 degrees). Second, the secondary view is lateral to the primary view, but it can be manipulated (typical default position is the midline of the sector). The 90-degree orthogonal image is oriented as if it is forward rotated from the primary view. Thus, once the primary imaging plane reaches 90 degrees, the orthogonal multiplane image may appear reversed compared with standard single plane imaging. The orthogonal view obtained during simultaneous biplane imaging of the ME four-chamber view is the ME two-chamber view (see eFig. 12.1 ). 3D full volume acquisition of the ventricle can be performed to assess ejection fraction.

Midesophageal mitral commissural view

From the ME four-chamber view, rotating the transducer angle to between 50 and 70 degrees will generate the ME mitral commissural view. The MV scallops on the image display (from left to right) are P ₃ , A ₂ , and P _1, although A ₃ and A ₁ segments are frequently adjacent and can also be imaged (P ₃ -A ₃ A ₂ A ₁ -P ₁ ). From this neutral probe orientation, turning the probe leftward (counterclockwise) may allow imaging of the length of the posterior leaflet (P ₃ P ₂ P ₁ ). Turning the probe rightward (clockwise from the neutral position) may allow imaging of the length of the anterior leaflet (A ₃ A ₂ A ₁ ). Turning the probe to the extreme right or left enables visualization of parts of the MV annulus (or sewing ring of prosthetic valves). In addition, the anterolateral and posteromedial papillary muscles with their corresponding chordae tendineae are prominent structures in the ME commissural view. Diagnostic information obtained from this view includes global and regional LV function (anterior/anterolateral and inferior/inferolateral walls) and MV function. The orthogonal view obtained during simultaneous biplane imaging is the ME long-axis (LAX) view (see eFig. 12.1 ). Rotating to the left (counterclockwise) at this transducer angle will result in imaging of the region behind the mitral annulus (i.e., the coronary sinus or circumflex artery). Color flow Doppler can aid in identifying commissural mitral regurgitation jets. Three-dimensional narrow sector acquisition (with or without color) to assess the mitral valve orifice can be performed from this view; the entire mitral coaptation length is imaged in the lateral plane with the coaptation of the two leaflets in the elevational plane.

Midesophageal two-chamber view

From the ME mitral commissural view, rotating the transducer angle to between 80 and 100 degrees will generate the ME two-chamber view. The LA, LA appendage, LV, and MV (P ₃ – A ₃ A ₂ A ₁ ) are visible in this perspective. Diagnostic information obtained from this view includes global and regional LV function (anterior and inferior walls) and MV function. Color flow Doppler applied over the MV aids identification of valvular pathology (regurgitation or stenosis, or both). The coronary sinus is seen in short axis, immediately above the basal inferior LV segment. The orthogonal view obtained during simultaneous biplane imaging is the ME four-chamber view (see eFig. 12.1 ); however, the left side of the heart is now to the left of the display (mirror image of 0-degree view). Rotating the probe to the right (clockwise) at this transducer angle will yield the ME bicaval view (see view #13 in eFig. 12.1 ). The ME left atrial appendage view (see view #15 in eFig. 12.1 ) is obtained by rotating the probe to the left (counterclockwise) at this transducer angle.

Midesophageal long-axis view

From the ME two-chamber view, the transducer angle is rotated to approximately 120 to 140 degrees to image the ME long axis (LAX) view, which is the same as a transthoracic three-chamber view. Visible structures include the LA, LV, LV outflow tract, AV, proximal ascending aorta, coronary sinus, and MV (P ₂ -A ₂ ). Diagnostic information obtained from this view includes global and regional LV function (inferolateral and anterior septal walls), and MV and AV function. The membranous interventricular septum and the RV wall that subtends the right ventricular outflow tract (RVOT) can also be imaged. The orthogonal view obtained during simultaneous biplane imaging is the ME mitral commissural view (see eFig. 12.1 ); however, the anterior/anterolateral LV wall is now to the left of the display (mirror image of 60-degree view). Color flow Doppler can be applied to identify aortic regurgitation.

Midesophageal AV LAX view

From the ME LAX view, slight withdrawal of the probe while maintaining a transducer angle of 120 to 140 degrees yields the ME AV LAX view. Fine tuning by turning the probe to the right (clockwise) may be needed. Reducing the depth of field allows concentrated imaging of the LV outflow tract, AV, and proximal aorta, including the sinus of Valsalva and sinotubular junction. This view is useful in evaluating the AV function and obtaining the dimensions of the annulus and sinotubular junction. The anterior (far field) AV cusp is the right coronary cusp; not infrequently the right coronary ostium is imaged from this view. The posterior (near field) cusp can be the noncoronary cusp or the left coronary cusp, depending on the window; when perfectly centered on the aorta, however, the plane of imaging may be at the commissure between these two cusps. The orthogonal view obtained during simultaneous biplane imaging is the ME AV short-axis (SAX) view (see later); however, the left side of the heart is now to the left of the display (mirror image of 0-degree view). Color flow Doppler can be applied to reveal aortic regurgitation as well as flow within the right coronary ostium.

The ME AV LAX view is one of the main views used for transcatheter aortic valve procedures. ^, The sagittal plane measurement of the annulus and left ventricular outflow tract is performed from this view. The use of simultaneous biplane imaging may assist acquisition of the largest annular diameter. A user-defined (zoomed) 3D volume of the aortic valve can be obtained from this view (or the AV SAX view, described later) to measure annular area and perimeter ^, as well as the location of the coronary ostia. Color Doppler 3D acquisition can be useful for assessing the severity of aortic regurgitation.

Midesophageal ascending aorta LAX view

From the ME AV LAX view, withdrawal of the probe, typically with backward rotation to approximately 90 degrees, leads to the ME ascending aorta LAX view. This view allows evaluation of the proximal ascending aorta. The right pulmonary artery (PA) lies posterior to the ascending aorta in this view. Although aortic flow is typically perpendicular to the insonation beam from this view, color flow Doppler may still be useful in identifying some pathologies. When the image plane is centered on the SAX image of the right PA (in the near field), turning the probe to the left (counterclockwise) with possible retroflexion will result in LAX imaging of the main PA and the PV. This view aligns the insonation beam with PA flow and optimizes the imaging plane for pulsed wave, continuous wave, and color Doppler of the RVOT, PV, or main PA. The orthogonal view obtained during simultaneous biplane imaging is the ME ascending aorta SAX view (see later); however, the left side of the heart is now to the left of the display (mirror image of 0-degree view).

Midesophageal ascending aorta short-axis view

From the ME AV and ascending aorta view, backward rotation of the transducer to approximately 0 to 40 degrees provides a transition to the ME ascending aorta short-axis (SAX) view. In addition to the ascending aorta in SAX and superior vena cava, the main PA and right lobar PA can be seen. From this neutral probe orientation, turning the probe to the left (counterclockwise) allows imaging of the PA bifurcation. Turning the probe to the right from the neutral position allows imaging of a greater extent of the right lobar PA. The left lobar PA is difficult to image because of the left main bronchus. The pulmonary valve (PV) can also be imaged from this plane in some patients. The orthogonal view obtained during simultaneous biplane imaging is the 90-degree view of the right pulmonary veins. Pulsed wave, continuous wave, and color Doppler of the PA may be useful. Careful insertion of the probe should allow imaging of the proximal left coronary artery and the bifurcation to the left anterior descending and circumflex coronary arteries.

Midesophageal right pulmonary vein view

From the ME ascending aorta SAX view (and typically at 0 degrees), advancing the probe and turning to the right (clockwise) yields the ME right pulmonary vein view. The inflow of the inferior pulmonary vein is typically perpendicular to the insonation beam; however, superior pulmonary vein inflow is typically parallel to the beam and Doppler imaging from this view can be performed. In addition to the right pulmonary veins, the superior vena cava (SAX) and ascending aorta (SAX) are also imaged. The orthogonal view obtained during simultaneous biplane imaging is the ME ascending aorta LAX view. The right pulmonary veins can also be imaged from the 90- to 110-degree view by first obtaining a ME bicaval view (view 13, later) and rotating the probe to the right (clockwise). Note that the left pulmonary veins may be imaged by turning the probe to the left (counterclockwise).

Midesophageal AV SAX view

From the ME right pulmonary vein view, repositioning the probe (turning to the left, counterclockwise) to center the aorta in the display (as in the ME ascending aorta SAX view), then advancing and rotating the transducer angle to between 25 and 40 degrees leads to the ME AV SAX view. Slight anteflexion may be required. For a trileaflet valve, the left coronary cusp will be posterior and to the right on the display, the noncoronary cusp will be adjacent to the interatrial septum, and the right coronary cusp will be anterior and adjacent to the RVOT. AV morphology and function can be evaluated from this view. In addition, with a subtle degree of withdrawal, the left coronary artery (arising from the left coronary cusp) and the right coronary artery (arising from the right coronary cusp) can be imaged. In addition to the AV, a portion of the superior LA, interatrial septum, and RA can be imaged. This superior portion of the interatrial septum is important because shunting associated with a patent foramen ovale may often be imaged. In addition, the RVOT and PV may be seen in the far field. Color flow Doppler (and when appropriate, pulsed wave and continuous wave Doppler) should be used to assess all imaged structures. The orthogonal view obtained during simultaneous biplane imaging is the ME AV LAX view. Three-dimensional imaging of the AV from this view should be considered, particularly to assess coronary ostia position.

Midesophageal right ventricle inflow-outflow view

From the ME AV SAX view, the ME RV inflow-outflow view is reached by slightly advancing the probe and rotating the transducer angle to 50 to 70 degrees until the RVOT and PV appear in the display. Structures in this view include the LA, RA, interatrial septum, TV, RV (on left of display), RVOT (on right of display), PV, and proximal (main) PA. From this view, RV size and function (including RVOT diameter), TV morphology and function, and PV morphology and function can be assessed. Visualization of two of the PV leaflets (typically the left or right and anterior) is frequently limited by acoustic noise from the AV or periaortic fibrous tissue. Advancing the probe and orienting the RVOT perpendicular to the insonation beam enhances imaging for measurement of RVOT diameter. Color flow Doppler and spectral Doppler of both valves should be performed. This view and the subsequent view can be particularly useful for imaging tricuspid regurgitant jets directed toward the interatrial septum. Simultaneous multiplane imaging (140 to 160 degrees) of the tricuspid valve may allow better imaging of these small, medially-directed jets. Three-dimensional imaging of the PV and TV can be performed from this view.

Midesophageal modified bicaval TV view

To transition from the ME RV inflow-outflow view to the ME modified bicaval TV view, the transducer angle is maintained at 50 to 70 degrees, and the probe is turned to the right (clockwise) until the center of the view contains primarily the tricuspid valve. The LA, RA, interatrial septum, inferior vena cava, and TV can be clearly imaged from this perspective. Occasionally the right atrial appendage as well as the superior vena cava will be visible. Because of the radially short septal TV leaflet, many tricuspid regurgitant jets are eccentric and directed toward the interatrial septum. From this view the septal TV leaflet is imaged en face, and jets directed toward the interatrial septum are parallel to the insonation beam. Color flow Doppler and spectral Doppler (particularly continuous wave Doppler) should be performed in this view.

Midesophageal bicaval view

From the ME modified bicaval TV view, the transducer angle is rotated forward to 90 to 110 degrees, and the probe is turned to the right (clockwise) to obtain the ME bicaval view. Imaged in this view are the LA, RA, inferior vena cava, superior vena cava RA appendage, and interatrial septum. Motion of the interatrial septum should be observed because atrial septal aneurysms are associated with interatrial shunts. From this view, interatrial septum morphology and function should be assessed. In addition, inferior vena cava and superior vena cava inflow can be clearly imaged. The orthogonal view obtained during simultaneous biplane imaging is an ME four-chamber view focused on the interatrial septum. Further rotation to the right (clockwise) with slight withdrawal of the probe allows imaging of the right pulmonary veins (orthogonal to view 9, described previously).

Midesophageal right and left pulmonary veins view

At a transducer angle of 90 to 110 degrees imaging of either the right or left pulmonary veins can be performed. From the ME bicaval view, turning the probe further to the right (clockwise) will permit imaging of the right pulmonary veins, with the superior vein to the right of the display. Turning the probe to the left (counterclockwise) facilitates imaging progressively through the entire heart (past the LA) to the ME left pulmonary veins view. The left superior vein is to the right of the display, and inflow is typically parallel to the insonation beam, allowing accurate spectral Doppler assessment.

Midesophageal left atrial appendage view

From the ME left pulmonary veins view (at a transducer angle of 90 to 110 degrees), rotating the probe to the right (clockwise) with possible advancement and/or anteflexion of the probe, will open the left atrial appendage (LAA) for the ME LAA view. Often the left superior pulmonary vein is also imaged. Given the complex and highly variable anatomy of the LAA, a complete assessment of morphology typically requires imaging the LAA in multiple views. Rotate from 90 to 110 degrees backward to 0 degrees while imaging the LAA and/or simultaneously performing multiplane imaging. Color flow Doppler and pulsed wave Doppler may be useful, particularly for evaluating contractile function. Assessing the LAA by 3D echocardiography has been well-documented. Using the simultaneous imaging modality may be helpful in excluding thrombus as well as positioning catheters during percutaneous procedures. Real-time 3D TEE is useful for defining the variable anatomy of the orifice and the relationship to the pulmonary veins, both before and during the procedure.

Transgastric basal SAX view

From the ME views and at a transducer angle of 0 degrees, the probe is straightened and advanced into the stomach. With this movement, the coronary sinus inflow as well as the inferior vena cava and hepatic vein can often be imaged before reaching the transgastric (TG) level. During advancement of the probe, deep esophageal views of the tricuspid valve and the coronary sinus are frequently possible. Once the probe is in the gastric cavity, anteflexion will typically lead to the TG basal SAX view. This view demonstrates the typical SAX view or “fish mouth” appearance of the MV in the TG imaging plane, with the anterior leaflet on the left of the display and the posterior leaflet on the right. The medial commissure is in the near field, and the lateral commissure is in the far field. MV morphology and function and LV size and function can be evaluated from this perspective. The orthogonal view obtained during simultaneous biplane imaging is a two-chamber view of the base of the LV (including the MV), which may be useful for assessing MV morphology and function. Color flow Doppler of the MV in this view may help characterize regurgitant orifice morphology.

Transgastric midpapillary SAX view

To progress from the TG basal SAX view to the TG midpapillary SAX view, the anteflexed probe can be relaxed to a more neutral position while contact is maintained with the gastric wall. Alternatively, the probe may be advanced further into the stomach. Proper positioning may require multiple probe manipulations while varying probe depth and degree of anteflexion. The transducer angle should typically remain at 0 degrees. The TG midpapillary SAX view provides significant diagnostic information and can be extremely helpful in assessing LV size and volume, and global and regional function. This is the primary TG view for intraoperative monitoring because myocardium with vascular supply from the left anterior descending, circumflex, and right coronary arteries can be seen. The orthogonal image during simultaneous multiplane imaging is the TG two-chamber view, which may be useful to ensure on-axis SAX views. This orthogonal view should be perpendicular to the insonation beam. If the mitral valve (seen on the right side of the secondary image) is higher (closer to the apex of the sector) than the apex, the probe should be advanced. If the mitral valve is deeper than the apex, the probe should be withdrawn. Ensuring on-axis imaging of these views permits more accurate assessment of wall motion.

Transgastric apical SAX view

To progress from the TG midpapillary SAX view to the TG apical SAX view, the probe is slightly advanced and/or retroflexed while maintaining contact with the gastric wall. The RV apex is imaged from this view by turning the probe to the right (clockwise). The apical segments of the LV and RV can be evaluated from this view. This image may be difficult to obtain, because retroflexion within the stomach may prevent adequate probe contact with the gastric wall.

Transgastric RV basal view

Returning to the TG basal SAX view (anteflexed, at a transducer angle of approximately 0 degrees) and then turning the probe toward the patient’s right (clockwise) leads to the TG RV basal view. The TV is imaged in SAX view, whereas the RVOT is imaged in LAX view. The orthogonal view obtained during simultaneous biplane imaging of the TV is with the TG RV inflow view (view 23, described later). The orthogonal view obtained during simultaneous biplane imaging of the RVOT is with the TG RV inflow-outflow view (mirror image of view 20, described later). Color flow Doppler of the TV in this view may help characterize regurgitant orifice morphology.

Transgastric RV inflow-outflow view

From the TG RV basal view (transducer angle of 0 degrees), maximal right flexion yields the TG RV inflow-outflow view. The anterior and posterior leaflets of the TV and the left and right cusps of the PV are typically imaged in this view. Advancing the probe may be necessary to align RVOT flow with the insonation beam. The mirror image of this view can be also be obtained with the probe in a neutral position (no flexion) and turned to the right (clockwise) so that the right ventricle is in view, and then forward rotating to 90 to 120 degrees. Transgastric views of the PV can be used to align transpulmonic flow with the Doppler beam.

Deep transgastric five-chamber view

From the TG RV inflow-outflow view (transducer angle of 0 degrees), advancing the probe to the deep transgastric level, with anteflexion and often with left flexion, leads to the deep TG five-chamber view. The Doppler beam lies parallel to the LVOT, AV, and proximal aortic root, so spectral Doppler interrogation of the LVOT and AV is possible. The MV is also imaged, and complete Doppler interrogation of this valve may also be attempted.

Transgastric two-chamber view

The probe is returned to the TG midpapillary SAX view, and the transducer angle is rotated to approximately 90 to 110 degrees to obtain the TG two-chamber view. The anterior and inferior walls of the LV are imaged in addition to the papillary muscles, chordae tendineae, and MV. Although the LA and LA appendage are often visible, far-field imaging may not allow accurate assessment of LA appendage pathology.

Transgastric right ventricle inflow view

From the TG two-chamber view (transducer angle of 90 to 110 degrees), rotating to the right (clockwise) will lead to the TG RV inflow (or RV two-chamber) view. The anterior and inferior walls of the RV, papillary muscles, chordae tendineae, and TV can be imaged. The proximal RVOT is also frequently seen, and slight advancement of the probe may allow imaging of the PV.

Transgastric long-axis view

From the TG RV inflow view, rotating to the left to return to the TG two-chamber view, then rotating the transducer angle to 120 to 150 degrees leads to the TG LAX view. Portions of the inferolateral and anterior septum, the LV outflow tract, AV, and proximal aorta can be imaged, although turning the probe slightly to the right might be necessary to view the LV outflow tract and AV. Doppler beam alignment is parallel to the LV outflow tract, AV, and proximal aortic root, so spectral Doppler interrogation of the LV outflow tract and AV is possible. This view is most equivalent to a right parasternal view of the aortic valve and can often yield the highest transvalvular velocities.

Descending aorta SAX and LAX views

Imaging of the descending aorta with TEE is easily performed, because the aorta is immediately adjacent to the stomach and esophagus. From the TG LAX view, the transducer angle is returned to 0 degrees and the probe turned to the left (counterclockwise). Although the descending aorta is first visible below the diaphragm (typically beginning at the celiac artery), abdominal gas and variable aortic position may obscure the view; therefore the probe may have to be withdrawn to just above the diaphragm to clearly image the descending thoracic aorta. The short axis of the aorta is obtained at a transducer angle of 0 degrees, whereas the long axis is obtained at a transducer angle of approximately 90 degrees. Image depth should be decreased to enlarge the aorta, and the focus should be set to the near field. Finally, gain should be increased in the near field to optimize imaging. While keeping the aorta in the center of the image, the probe can be advanced or withdrawn to image the entire descending aorta. Because there are no internal anatomic landmarks in the descending aorta, describing the location of pathologic changes is difficult. One approach to this problem is to identify the location in terms of distance from the incisors. The descending thoracic aorta is posterior and to the left of the esophagus, and when imaging this structure, the TEE probe faces the left side of the thoracic cavity. Thus intercostal arteries are typically seen arising from the aorta toward the right side of the screen. When imaging the descending thoracic aorta, the hemiazygos vein (which drains the left posterior thorax) may be seen in the far field of imaging. In the mid to upper thorax, this vein joins the azygos vein (which drains the right posterior thorax). This venous structure is typically parallel to the aorta and aortic arch, eventually draining into the superior vena cava. Because their walls are contiguous, the two structures could be mistaken for a dissection flap within the aorta. Color flow Doppler or pulsed Doppler easily distinguishes venous from arterial flow within each lumen.

Upper esophageal aortic arch long-axis view

While analyzing the descending aorta SAX view (transducer angle 0 degrees) and withdrawing the probe, the aorta will eventually become elongated, the left subclavian artery may be imaged, indicating the beginning of the distal aortic arch. At this location, the aorta is anterior to the esophagus. Thus the upper esophageal (UE) aortic arch LAX view is best imaged by turning the probe to the right (clockwise) so that it faces anterior. This allows imaging of the midaortic arch. In addition to the aorta, the left innominate vein is frequently imaged with venous flow by color flow Doppler. Because the left main bronchus typically crosses between the esophagus and the aorta, a portion of the proximal aortic arch and distal ascending aorta may not be visualized.

Upper esophageal aortic arch short-axis view

From the UE aortic arch LAX view, the transducer angle is advanced toward 70 to 90 degrees to obtain the UE aortic arch SAX view. The main PA and PV can frequently be seen in long axis in the far field but may require adjustment of imaging depth, probe frequency, and focal zone. The Doppler beam lies parallel to the PV and main PA, so spectral Doppler interrogation of the PV may be performed. Because the aorta is curved, the right brachiocephalic and left common carotid arteries may be seen arising from the aorta between the LAX and SAX views. These arteries are typically visible in the near field and to the right of the screen.