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Transesophageal Echocardiographic Views and Their Corresponding Anatomical Structures (I)

Transesophageal Echocardiographic Views and Their Corresponding Anatomical Structures (I)

Preface

Chatting with an old friend about transesophageal echocardiography (TEE), he thought that TEE is much more difficult than transthoracic echocardiography (TTE). However, this is not the case. TEE is usually targeted, and its acoustic windows are generally much clearer than those of TTE.


The previous series discussed the anatomical structures corresponding to each view of transthoracic echocardiography (TTE). Referring to domestic and foreign guidelines and combining with work experience, we will next talk about the corresponding cardiac anatomical structures of transesophageal echocardiography (TEE).

For beginners, colleagues in cardiac centers or those engaged in cardiac surgical anesthesia, familiarity with the 28 commonly used views of transesophageal echocardiography (TEE) is sufficient to meet the needs of daily work.

The transducer produces different images at different depths and angles in the esophagus.

Approach to Transesophageal Echocardiography Examination

When seeing a patient scheduled for a TEE examination in the outpatient clinic, first and foremost, it is crucial to clarify the purpose of the TEE for the patient—that is, to determine which contents and indicators need to be monitored. For instance, in patients with atrial fibrillation, it is necessary to check for the presence of thrombi in the atria and the left and right atrial appendages; for those undergoing left atrial appendage occlusion, not only should the presence of thrombi in the left atrial appendage be assessed, but also the specific diameters of the left atrial appendage need to be measured. Since outpatient TEE is generally performed on patients under local anesthesia, it is essential to be targeted in the examination, minimize the duration that the transducer remains in the patient’s body, and perform the procedure gently to alleviate the patient’s discomfort such as vomiting reactions.

 Intraoperative TEE also requires clear identification of the monitoring contents. For example, in cases of mitral regurgitation, intraoperative TEE for surgical procedures needs to further clarify the anatomical structure of the mitral valve apparatus, including whether the valve leaflets are thickened or calcified, the size of the annulus, the presence of leaflet prolapse or chordae tendineae rupture, as well as the assessment of the risk of systolic anterior motion (SAM), etc. It provides direct evidence for the formulation of the surgical plan. After myocardial reperfusion following mitral valve plasty, it is necessary to evaluate the effect of the plasty (whether mitral regurgitation is significantly reduced) and the presence of SAM, among other factors.

Certainly, TEE also has its special significance. For example, in recent years, the level of interventional surgery in cardiac centers has advanced by leaps and bounds. For patients with severe mitral regurgitation who cannot tolerate surgical treatment, TEE-guided mitral valve clipping and other procedures can be performed.

Obtain the basic views of transesophageal echocardiography (TEE)

Unlike transthoracic echocardiography (TTE), transesophageal echocardiography (TEE) presents distinct challenges. During a TTE examination, it is relatively easy to adjust the approach: if the desired image cannot be obtained, the transducer can be moved conveniently. However, once the TEE transducer is inserted into the patient’s esophagus, the space for movement is extremely limited. In fact, there are certain knacks for manipulating the handle and adjusting the angle. Just like driving a car, one must first establish a reference point, and then advance, retract the transducer, or adjust the angle based on this reference.
The reference mentioned here is the four-chamber view visualized on the image when the transducer is inserted into the esophagus at 0 degrees, which locates the mid-esophagus.

The Localization Reference for TEE Examination – Mid-Esophageal View at 0 Degrees (LA: Left Atrium; LV: Left Ventricle; RV: Right Ventricle)

The key points for obtaining this view are as follows: Orient the crystal towards the patient’s mandible, insert the transducer into the patient’s esophagus at a 0-degree angle, and advance the transducer to visualize the cardiac chamber structures. However, due to variations in cardiac anatomy among individual patients—such as cardiomegaly, cardiac displacement, or rotation—the obtained image is often non-standard and not as perfect as the one shown above. For example, the image may be tilted or unclear. In such cases, do not panic. Rotate the transducer slowly to adjust it to the reference view. Once the mid-esophageal four-chamber view is standardized and clearly visualized, further increase the angle, or advance and retract the transducer to obtain the desired views and images.The Localization Reference for TEE Examination – Mid-Esophageal View at 0 Degrees (LA: Left Atrium; LV: Left Ventricle; RV: Right Ventricle)

In addition, the TEE transducer is positioned posterior to the heart, meaning it examines the cardiac chambers from the posterior to the anterior direction of the heart; the TTE transducer is positioned anterior to the heart, meaning it examines the cardiac chambers from the chest wall to the posterior direction. Therefore, the imaging of TEE is reversed anteroposteriorly compared with that of TTE, while the left-right orientation remains unchanged. — The above skills are based on personal experience. If there are any inappropriate points, experts are welcome to criticize and correct them.

1. Mid-Esophageal Four-Chamber View (ME-4C) — Reference: The mid-esophageal four-chamber view (0°) is obtained by placing the transducer in the mid-esophagus, posterior to the left atrium; thus, the structure adjacent to the transducer is the left atrium. The visualized structures include the left atrium (LA), left ventricle (LV), right atrium (RA), right ventricle (RV), interatrial septum (IAS), interventricular septum (IVS), mitral valve (MV), and tricuspid valve (TV).
Schematic Diagram of the ME-4C View
ME-4C: The red arrow indicates the mitral valve, and the displayed area is A3-A2-P2-P1.
2. Mid-Esophageal Mitral Commissural View (ME-MC) It is imaged at an angle of 50° to 70° in the mid-esophagus. The visualized structures include the left atrium (LA), left ventricle (LV), and mitral valve (MV).
Schematic Diagram of the ME-MC View
ME-MC: The red arrow indicates the mitral valve, and the displayed region is P3-A3-A2-A1-P1.
3. Mid-Esophageal Two-Chamber View (ME-2C): By increasing the transducer angle to approximately 80–100° at the mid-esophagus, the observable structures include the left atrium (LA), left ventricle (LV), and mitral valve (MV).

Schematic Diagram of the ME-2C View

ME-2C: The red arrow indicates the mitral valve, and the displayed region is P3-A3-A2-A1.
4. Mid-Esophageal Long-Axis View (ME LAX): On the basis of the mid-esophageal two-chamber view, further increase the transducer angle to 120–130°. The observable structures include the left atrium (LA), left ventricle (LV), ascending aorta (AAO), aortic root (aortic sinuses, sinotubular junction), aortic valve (AV), and mitral valve (MV).
Schematic Diagram of the ME-LAX View
ME-LAX: The red arrow indicates the mitral valve, and the visualized region is P2-A2.
5. Mid-Esophageal Aortic Valve Long-Axis View (ME-AV LAX): Slightly retract the transducer on the basis of the previous view to obtain the aortic valve long-axis view. The observable structures include the aortic root, aortic valve (AV), left ventricular outflow tract (LVOT), mitral valve (MV), left atrium (LA), and left ventricle (LV).
Schematic Diagram of the ME-AV LAX View
ME-AV LAX: The red arrow indicates the aortic valve (AV). The right coronary cusp and non-coronary cusp are visualized in the standard view.
6. Mid-Esophageal Five-Chamber View (ME 5C): Retract the transducer from the ME 4C view (0°) until the aortic valve and aortic root appear in the field of view, and the mid-esophageal five-chamber (5C) view is obtained. The observable structures include the left ventricular outflow tract (LVOT), as well as the aortic valve (AV), left atrium (LA), left ventricle (LV), right atrium (RA), right ventricle (RV), interatrial septum (IAS), interventricular septum (IVS), mitral valve (MV), and tricuspid valve (TV).
Schematic Diagram of the ME-5C View
ME-5C: The red arrow indicates the mitral valve, and the visualized region is A2A1-P1.

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