Echography/Echocardiography Flashcards
What occurs to amplitude of a sound wave as distance from the sound source increases?
Amplitude (diagonal line) diminishes with distance from the sound source.
What is amplitude in ultrasound a measure of?
tissue compression
Sound waves generated from the pizoelectric crystals in the transducer are transmitted into the surrounding medium at what rate?
proportional to the speed of sound in that medium
What can be determined from the time required of the sound wave to travel from the transducer to the object and back?
distance of object from transducer
Label
What occurs to ultrasound waves as they strike an interface between two different tissue types? (5)
- Specular reflection
- Refraction
- Absorption
- Scatter
- Acoustic impedance
_________ type transducers aid in placement of peripheral lines.
Linear array
In a linear array transducer, what are the near and far fields?
Near field is the columnar portion of the beam.
Far field is the diverging segment.
What MHz is needed to see a baby for instance?
What MHz is needed to see a vessel?
Less MHz, ~3.5
Higher MHz, ~8
Note: See picture to help visualize.
As an object approaches, the apparent frequency increases as object moves toward you. This is known as the _________.
Doppler effect
What are 3 characteristics of the waveforms as an object approaches a person, for example?
increased frequency
increased pitch
compressed wavelength
What are 3 characteristics of the waveforms as an object moves away from a person, for example?
decreased frequency
decreased pitch
elongated wavelength
The movement of red blood cells, frequency transmitted by a tranducer, velocity of RBCs, and speed of ultrasound in blood is known as:
Doppler shift
The doppler shift is directly proportional to the ________.
velocity of the moving target
If the target is stationary, what will frequency reflected (fr) and frequency transmitted (ft) be?
fr = ft
If the target is moving toward the transducer, what will ft and fr be?
fr > ft
Note: r is reflected, t is transmitted.
If the target is moving away from the transducer, what will fr and ft be?
fr < ft
How do you calculate doppler shift?
fr - ft
frequency (reflected - transmitted)
Accurate measurement of blood flow velocity utilizing the Doppler effect requires careful alignment of the interrogating beam __________ to the direct of blood flow.
parallel
What are the two types of Doppler?
_continuous _
pulsed wave
Why were pulsed wave transducers developed?
Continuous wave failed to provide information on distance of target to the transducer.
How does a pulsed wave transducer operate?
The transmitter beam (ft) is emitted in short bursts and the returning echoes (fr) are received by the same transducer.
Because the speed of sound in tissues is nearly constant, the area of interest for pulsed wave Doppler can be selected by what?
time gating the returning signals–only accepting echo information that required the “correct” amount of time to return from the target
What is the main drawback to pulsed wave Doppler?
higher blood flow velocities cannot be accurately measured
When must continuous wave doppler be used?
To accurately measure high peak blood flow velocities through a valvular lesion like aortic stenosis, for example.
How is cross sectional area of a vessel calculated?
gated doppler
Ultrasonic waves pass poorly through _____ and are nearly entirely reflected by ________.
air
dense tissues–such as bone, calcium deposits, and metal
What does near total reflection of transmitted echo signals result in?
Objects beyond the reflecting boundary such as bone, calcium, and metal will not be imaged resulting in “echo shadowing”
How can the resolution of objects be improved by ultrasound imaging?
higher frequency sound waves
What occurs as a result of increasing the frequency of sound waves to improve resolution?
The depth of tissue penetration is a trade-off.
Label the echo image of the heart:
Sound travels faster in water than in blood or bone. True or false?
False
Depth of penetration is directly proportional to _________.
wavelength
What does 1 depict?
Plane 1 depicts the parasternal long-axis view
What view is depicted?
In what state is the heart in?
Identify the chambers.
parasternal long axis view
LV in diastole, atrial systole
What is depicted?
fetus
What is depicted?
LV systole, or, atrial diastole
What are the types of ultrasound resolutions? (4)
Axial
Lateral
Temporal
Contrast
Which resolution distinguishes blood/bone?
Velocity?
contrast
temporal
What is TGC?
time gain compensation
Since the signal weakens with distance in tissue, time-gain can be used to improve the image by making it brighter.
What are the different echography image formats? (4)
A-mode
M-mode
B-mode
Doppler
What is echography format A-mode?
It is the simplest form of interpretation where wave is sent along a single scan line.
Used in opthalmology to assess axial length of the eye.
What is ultrasound format M-mode?
motion mode
Assesses function of moving parts of the heart.
What is ultrasound format B-mode?
brightness mode
Gives 2-D representations of slices of tissue by summation of the returns from multiple scan lines. Good for guiding invasive procedures.
What is Doppler mode?
Assesses velocities of blood flow
Helps with line placement, for example.
What mode is depicted?
What does an increase in amplitude indicate?
A Mode
Strong specular reflection
What mode is depicted?
B Mode
2-Dimensional image is composed of pixels
Identify the arrows:
LV in systole is the shorter arrow
LV in diastole is the longer arrow
What mode is being utilized?
B-mode (2-D mode)
What did contrast echo formally utilize to produce images?
Air, but now use oil
What is depicted?
In what motions can the probe move?
Transesophageal echo
Flexion, rotation
What part of the TEE is the arrow pointing to?
transducer that contains a round phased array of pizoelectric crystals
What does piezo-electric mean?
pressure-electric
What type of array is depicted and in what type of equipment is it used in?
Phased array
TEE which alows it to undergo shape changes.
What is this picture telling us about phased array TEE?
sweeping motion even though moved in a linear array
A phased array TEE scanning from left to right and back enable what to be imaged?
a volume of tissue
A ____________ is produced by phased excitation of the transducers in a phased array TEE.
focused beam
The phased array TEE projects a _________.
3-dimensional beam
What flexing motions can the TEE undergo?
Anteflex
Retroflex
Flex to left
Flex to right
What is the flex angulation the TEE can achieve?
What is the rotation angulation the TEE can achieve?
90º
180º
Label the TEE probes and identify the arrows
T = transverse plane
L=longitudinal
What part of the heart will be captured in the apex of the image sector?
Will the image be in the transverse or longitudinal plane?
The apex of the sector will project the inferior portion of the heart.
transverse
What are the following positions called?
I
II
III
I. Basal short-axis
II. Four-chamber (long-axis)
III. Transgastric short-axis
What position is the TEE with this view of the heart?
I. basil short-axis
What position is the TEE with this view of the heart?
II. Four-chamber long axis
What position is the TEE with this view of the heart?
III. Transgastric short-axis
What position is the TEE with this view?
I. with longitudinal axis
What position is the TEE with this view?
II. in longitudinal view
What position is the TEE with this view?
III with longitudinal view
What view is achieved by advancing the probe 1-2cm further from the four-chamber view and retroflexing 10-30º?
Will the probe be higher or lower in the esophagus?
A four-chamber view that can better identify arrhythmias, atrial dilation, and thrombi.
Higher
Short or long axis?
Long
Short or long axis?
Long
Short or long axis?
Short
Short or long axis?
Short
Short or long axis?
Short
What can be evaluated with respect to cardiac function with a TEE? (7)
Cardiac Output and Stroke Volume
Ejection Fraction
Contractility
Wall Thickness
Wall Motion
Preload
Pulmonary Blood Flow
What equation can be used to get the pressure gradient across any restrictive orifice?
Bernoulli
What type of tracing is depicted from an echocardiogram?
Pulsed wave
How does echo determine stroke volume?
Volumetric flow can be determined from a combination of area and volume measurements.
Blood flowing away from the transducer is coded _____.
Blood flowing toward the transducer is coded ______.
blue
red
Note: BART is on boards.
What are the advantages and disadvantages of pulsed wave flow echo?
Measures velocities at selected areas
Cannot measure fast blood flow > 1m/sec
Note: Measures well in low flow areas of the heart such as pulmonary veins and mitral valve.
What are the advantages and disadvantages of continuous wave echo?
Detects BF velocities up to 7m/sec
Cannot identify location of the peak velocity
Note: Used to measure flow in the aorta, aortic valve, stenotic lesions, and regurgitant flow.
What are the disadvantages of color flow?
Like pulsed wave, cannot measure fast flow well.
Note: Used to better recognize valvular abnormalities, intracardiac shunts, and aortic dissections.
TEE is more sensitive than PA catheter or ECG for detecting ischemia. True or false?
True.
The extent of wall motion abnormaility relates to the severity of coronary insufficiency to the affected area. True or false?
True.
What is normal radial shortening of the heart walls and wall thickening?
>30%
+++
Mild hypokinesis is characterized by:
_____ radial shortening
_____wall thickening
10-30%
++
Severe hypokinesis is characterized by:
______ radial shortening
________ wall thickening
0-10%
+
Dykinesis is characterized by:
_______ radial shortening
_________ thickening
no shortening, LENGTHENING
0
How is systolic wall thickening determined?
Computerized division of the LV wall during systole and diastole and thickness of 8-32 segments are analyzed.
What are category I indications for TEE?
Note: Category I means that it is supported by strongest evidence.
- Acute persistent hemodynamic changes
- All types of valve surgery
- Congenital heart surgery
- Repair of hypertrophic obstructive cardiomyopathy
- Endocarditis
- Thoracic aneurysm, dissection
- Pericardial window
What are category II indications for TEE?
Note: Category II is supported by weaker evidence and better outcome is less certain.
- Increased risk of MI
- Repair of cardiac aneurysms
- Removal of foreign bodies
- Detection of air emboli
- Evaluation of anastamoses after heart transplant
- Monitoring placement of cardiac assist devices
What are category III indications for TEE?
Note: III has little scientific support.
- Evaluation of cardiac perfusion
- Monitoring for emboli during ortho cases
- Evaluation of pleuropulmonary diseases
- Placement of intra-aortic balloon or PA cath
- Monitoring cardioplegia administration
