TEE Flashcards
What produces medical ultra sound?
-Piezoelectric Crystals
What causes the Piezoelectrical crystals to vibrate?
-High frequency alternating electric current
Ultrasound can interact with tissue in what 4 ways?
- Reflection
- Refraction
- Scattering
- Attenuation
What is the trade off when selecting a frequency?
-Resolution or depth of penetration
Higher frequencies have what advantage/disadvantage?
- Better resolution
- Less depth of penetration
How does Doppler echocardiography work?
-Ultrasound scattered from blood cells measures velocity and direction of blood flow.
Doppler accuracy requires the angle between blood flow and ultrasound to be less than what?
20 degrees
Describe M mode
- Pulses of a single, linear beam
- Plotted on a graph
What is M mode useful for?
- Timing of the cardiac cycle
- Detection of high frequency oscillating motion
High frequency detection of oscillating motion of M mode can detect what?
-Vibrating vegitation
Describe 2D Mode
- Rapidly moving beam through a plane
- Multiple scan lines displayed simultaneously
What is frame rate?
-Number of 2D images displayed per second
What is the frame rate for 2D mode
30-60
What does 2D detect?
Motion in the heart
What does Pulsed Wave Doppler mode measure?
-Velocity and direction of blood in a specific location
Velocity and direction of blood in a specific location is called what?
Sample volume
Describe the pulsed wave doppler mode
- One transducer to send and receive signals
- Limited velocity measurement (1.5-2m/sec)
- Further from the probe, less velocity it can measure
With a pulsed wave doppler, if the velocity is is above the baseline which way is it moving?
toward the transducer
What does continuous wave doppler measure?
-velocity and direction along the line of site of the beam
How many transducer does continuous doppler use and what do they do??
-2, one for continuously sending and one for continuously receving
What does the pulse wave do that the continuous wave cannot?
-Measure depth (range ambiguity)
What problem of PWD does CWD overcome?
-No limits on maximum velocity
Why use CWD over PWD?
- To measure velocity too high for PWD
- Aortic / Mitral Stenosis
Explain Color flow doppler
- Form of PWD
- Superimposes velocity info on 2D image
What Mode allows for the location and timing of flow disturbances to easily be seen?
Color flow doppler
Name the colors in the colors flow mode and what they represent.
- Red = towards transducer
- Blue = Away from transducer
- Green = Turbulent flow
What is a mosaic pattern seen in color flow doppler?
- Flow with a velocity too high that color flow cannot accurately depict
- Appears as mixture of red and blue
What is a variance map?
-When turbulent flow is added to color flow doppler and represented by the color green
In color flow doppler when does the image become jerky?
Less than 15 frames per second
What does tissue doppler do?
Measure velocity of tissue motion
What 2 modes are forms of PWD and have the same speed limitations?
- Color Flow
- Tissue doppler
Most common application for tissue doppler?
-Mitral annular motion which assess LV systolic function
What are two less common applications for tissue doppler?
- Strain (Tissue deformation)
- Strain rate (rate of deformation)
Patient history that contraindicates TEE.
- Dysphagia
- Odynphagia
- Mediastinal radiation
- Upp GI surgery/Bleeding
- Thoracic Aortic aneurysm
Esophageal pathology that contraindicates TEE
- Stricture
- Tumor
- Diverticulim
- Varices
- Esophagitis
- Chest trauma
Complications of TEE
- Dental injury
- Laryngeal dysfunction
- Aspiration
- ETT displacement
- Bronchial / Aortic compression in infants
- GI bleed
- Phaynx / esophagus perf
Transducer frequency is adjusted to provide _______ frequency and _________ depth of penetration.
Highest
Adequate
Where should the image depth be centered?
To the center of the structure being examined
Image gain and dynamic range should be adjusted to what?
- Black blood
- Gray tissues
What should be adjusted to provide uniform brightness in near and far fields?
-Time gain compensation
What eliminates background noise?
CFD gain
Where would the probe be place for a mid-esophageal view?
-Posterior to the Left Atrium
What can be viewed with ME view?
-All cardiac chambers and valves
How are transgastric views obtained?
-Probe into stomach with view superiorly to heart.
What structures are viewed with TG view?
- Both ventricles
- Mitral and tricuspid valves
In TG, if you line up view parallel to to flow you can see what 2 things?
- Left ventricular out flow tract
- Aortic valve
In the upper esophageal view, where is the probe placed?
-Level of the aortic arch
What can be examined with UE view?
- Pulmonary artery
- Pulmonic valve
What is the normal LV size? and where is it best measured?
- Women < 5.4 cm
- Men < 6.0 cm
- ME or TG 2 chamber
What is normal thickness for LV wall and where is it best measured?
- < 1.2 cm
- TG mid SAX
What is the 2D equivalent of ejection fraction? And what is normal?
- Functional area change
- >0.5
Left global function and Functional area change (EF) is best viewed with what?
-TG mid SAX
Qualitative assessment if LV function is performed how?
-Considering all views of LV and estimating ejection fraction
What is normal estimated ejection fraction (EEF)
- > 55%
