10 Questions
How many segments are evaluated for TEE evaluation?
17
What is the preferred starting point for TEE evaluation?
TG mid papillary SAX
What is the advantage of fractional shortening over other LV function measurements?
It is less time-consuming
What is the normal range for fractional shortening?
25-45%
What is the formula for calculating fractional shortening?
(LVED - LVES) / LVED * 100
What is the limitation of fractional shortening and fractional area change?
They may not reflect ventricular function
How is cardiac output determined using Doppler?
Measuring LVOT diameter and stroke distance
What is the main advantage of using Doppler to measure cardiac output?
It is less time-consuming
What is the purpose of evaluating the aortic valve using TEE?
All of the above
What is the limitation of using TEE to evaluate ventricular function?
It may not reflect ventricular function accurately
Study Notes
TEE Transducer Lens
- The TEE transducer lens is known as a multiplane or omni plane lens.
- It allows imaging in different axes by rotation of the lens, changing the view and providing a SAX or LAX depending on the structure of interest.
Lens Adjustment
- The planes on the lens can be thought of as a beam on the face of a clock.
- The image acquired by the transducer is not oriented in the same way that it is obtained, it is flipped top to bottom and then rotated left to right.
Challenges to Imaging
- Body planes are at right angles to each other, and the heart lies in multiple planes, requiring adjustments to the transducer to acquire images and evaluate structures.
- The heart is a 3D structure being imaged on a 2D screen, requiring changing the transducer orientation and position within the esophagus and stomach to evaluate anterior, posterior, left, and right structures.
Anatomical Features
- The aorta and pulmonary arteries are at right angles to each other.
- Pulmonary veins are parallel to the base of the heart.
- Superior and inferior vena cava are at right angles to the base of the heart.
- The left main stem bronchus is anterior to the aortic arch, making it impossible to assess the ascending portion of the aorta.
Image Acquisition
- The probe is advanced into the esophagus in a systematic fashion, and different structures are seen at different depths.
- All structures should be evaluated in different planes.
TEE Cardiac Evaluation
- Standard TEE is comprised of over 20 different views, useful for a complete exam to evaluate the entire cardiac muscle.
- A left ventricle evaluation and a hemodynamic evaluation are more practical in dynamic evaluation or cases of shock.
LV Evaluation
- ME views and TG views are necessary for LV function evaluation, which consists of systolic function, diastolic function, and combined evaluation.
- The LV is not in a convenient anatomical plane, and axis of the heart varies from person to person, requiring evaluation in different positions.
LV Function Measurement
- LV function evaluation consists of evaluating anterior and posterior surfaces and left and right margins.
- LV is divided into thirds from base to apex.
- Fractional shortening is used to evaluate LV function, which is the percentage of change in left ventricular dimension with contraction.
Terminology
- UE: upper esophageal view (20-25 cm)
- ME: mid-esophageal view (30-40 cm)
- TG: trans-gastric view (40-45 cm)
- Deep TG: deep trans-gastric (45-50 cm)
- SAX: short axis view, a cross-section view of the structure
- LAX: long axis view, a view of the structure along its long axis
Understand the importance of minimizing trauma to the esophagus during probe flexion and learn about the TEE transducer lens, its features, and adjustments.
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