Quiz 8 TEE - Dr. Kinkoff Flashcards
What is the element used to create the vibration in frequency and alternating electrical current?
Piezoelectric crystal
Ultrasound transmitted for the transducer into the patient interacts with the tissures in fours ways:
- Reflection
- Refraction
- Scattering
- Attenuation
Selecting the frequency of an ultrasound transducer is a trade off between:
- Image resolution
- depth of penetration
What is the usual frequency used in transesophageal echocardiography?
-3.5 - 7 million cycles per second (MHz)
________ echocardiography uses ultrasound scattered from blood cells to measure the velocity and direction of blood flow.
Doppler
What is the doppler effect?
- increases the frequency of waves scattered from cells moving toward the transducer
- Decreases the frequency of waves from cells moving away
What is the simplified version of Bernoulli equation?
P = 4V^2
P = Pressure gradient V = velocity
M-mode directs pulses of a _____, linear bean of ultrasound into the tissues and displays the distance from the transducer of the returning echoes on the ______ of ta graph with signal strength indicated by brightness. The ______ of the graph shows time and motion of the structures is seen as curved lines.
single
y axis
x axis
What is M-mode good for:
- precisely timing events within the cardiac cycle
- high temporal resolution (Lots of frames per second)
Two-dimensional echocardiography is made by very _______ moving the ultrasound beam through a plane creating ______ scan lines that are displayed simultaneously to construct a 2D tomographic image.
Rapidly
Multiple
How does two dimensional echocardiography accomplish its function?
-probes usually have phased array transducers which consist of 64 - 128 crystals
How many temporal resolution (frame rate) can a two dimensional echocardiography perform:
30 - 60 per second
Pulsed wave doppler measures the _____ and _______ of blood flow in a specific location called ___________, which can be placed by the user in the area of interest of a 2D image.
velocity
direction
sample volume
Velocities going toward the transducer are ____ the baseline of the y axis
above
Velocities going away from the transducer ____the baseline
below
What is the limitation of a pulse wave doppler?
-uses only one transducer to send and receive signals which limits the pulse repetition frequency which in turn limits the maximum doppler shift and blood velocity that can be measure with PWD.
What is the velocity limit of a Pulse Wave Doppler?
1.5 to 2 m/sec
Continuous Wave Doppler (CWD) measures the ______ and _______ of blood flow along the ____ of sight of the ultrasound beam.
velocity
direction
line
T/F: Continous Wave Doppler uses two transducers?
TRUE
T/F: Continous Wave Doppler have limit of the maximum velocity measures of 1.5 to 5 m/Sec.
FALSE (Has no limit)
What is another name for maximum doppler shift:
Nyquist limit
T/F: Continous Wave Doppler cannot determine the depth for the transducer from which a returning signal originated (range ambiguity) only its direction.
True
What conditions does a Continuous Wave Doppler good at measuring velocities?
- Aortic stenosis
- Mitral stenosis
Color Flow Doppler (CFD) is a form of ___ that ___________ the velocity information onto the simultaneously created 2D image of the heart, allowing the ______ and ________ of flow disturbances to be easily seen.
PWD
superimposes
location
timing
On a coloer flow doppler what does the color red mean?
flow toward the transucer
On a color flow doppler what does the color blue mean?
Flow going away from a transducer
Some color flow doppler have a variance map that show green; which signifies?
Turbulence (Mosiac)
What is the frame rate of a color flow doppler?
12 - 24 frames per second
What are the indication for a TEE in the ASA/SCA guidelines?
- All open hearts and thoracic aortic surgical procedures
- Considered in coronary artery bypass graft surgeries
What are the indications for a TEE in the ACC/AHA guidelines?
- vavle repair surgery
- valve replacement surgery with a stentless -xenograft,
- homograft or auto valve
- valve surrgery for infective endocarditis
How should a TEE probe insertion go?
-Gently (No FORCE should ever be used.
Transducer frequency is adjusted to the ______ frequency that provides adequate ______ of penetration to the structure being examined.
highest
depth