Doppler Waveform Analysis Flashcards
what are the capabilities of physiologic testing
diagnosis aprox location & severity of arterial occlusive disease
gives functional information
does not discriminate between stenosis or complete occlusion
limitations of physiologic testing
5
cast/bandages ambient temp affects waveform quality CHF results in dampened WF cannot be specific for stenosis or occlusion tech dependent and often difficult test
Patient position during test is important during what part
sentimental pressures due to hydrostatic pressures
other positions besides supine for physiologic testing
rt / lft lateral decubitus
prone
what is the Doppler effect
blood is moving target , transducer is stationary
wave is reflected from moving target, frequency of wave is received as different (that difference is doppler shift) from the transmitted frequency
The doppler effect occurs with ______ motion between the ____ and the _____ of sound
relative motion
between the source and the receiver of sound
with continuous wave Doppler one crystal is ______sending ultrasound while the other is _________receiving reflected waves
continuously
the reflected frequency can be higher or lower depending on the transmitted frequency depending on the direction of flow (T/F)
True
two types of velocimetry are _______ and _____
zero crossing frequency meter - analog system
FFT fast fourier transform - duplex system (digital)
what is the paper speed set on zero crossing frequency meter
25mm/sec
high freq waves have ____oscillations
many
low freq waves have _____oscilations
few
zero crossing freq meter counts how many times the _____ crosses over the ______
oscillations cross over the baseline
direction of blood flow _____with cardiac cycle
varies
machine estimates _______ present in _____ _____ and displays them
frequencies
reflected signals
what are drawbacks of zero crossing frequency meter
2
noise less sensitivity (estimation)
when system is activated __________ is done
self calibraration
important to remember about zero crossing frequency meter system ??????
It averages out the reflected frequencies
what does the y and x axis represent in the interpreting the zero crossing frequency meter and the FFT spectral analysis system
y is distance (meters) of frequency shifts
x is time
Doppler effect: when wave is reflected from a moving target, the reflected freq is diff from transmit freq. The ____ of that change is ______proportional to the speed and direction of _________
magnitude
directly proportional
the moving target
it is proportional to the speed and direction of flow
magnitude refers to
speed at which an object is moving or its size
Doppler shift formula and relationships
change in frequency =
2 x transmit freq MHz x RBC freq cm/sec x Cos angle of ultrasound beam and flow direction
/
the speed of sound 1540 m/sec
what MHz Doppler probe is used for waveform Doppler analysis of extremities
8-10 MHz
what sites are doppler waveforms recorded on upper etremity studies
5
subclav a ax a Brachial a @anticubital fossa Radial a @wrist Ulnar a @wrist
doppler velocity waveforms are recorded from the following arteries bilaterally
6
CFA SFA Pop A PTA (medial malleolus) DPA (top of the foot) Peroneal (if necessary ) (lateral malleolus)
with CW analysis what three things are combined for interpretation
waveforms audible and visual qualities + segmental pressures
CW potential sources for error
5
insufficient period of rest before test excessive pressure on probe tip incorrect angle of incidence incorrect probe positron inadequate amount of gel
qualitative interpretation CW
triphasic WF characteristics of UE and LE arteries
5
rapid upstroke sharp peak rapid downstroke flow reversal resumption of forward flow
biphasic WF characteristics of UE and LE arteries
5
rapid upstroke sharp peak fairly rapid down stroke flow reversal * no resumption of forward flow
monophasic WF characteristics of UE and LE arteries
4
slow upstroke
rounded peak
slow downstroke
no reversal
deterioration in signal quality from _____ ______ to the _____ as well as deterioration from _______ _____ should be checked out when preforming CW doppler exam
from one level to the next
from previous tests
monophasic/pulsatile signal is often obtained _____ to an obstruction
proximal
vasodialation of the _____ vessels often occur with ____obstruction which reduces the _______ of the WF and causes the signals to have lower resistant _____ flow quality
distal vessel vasodilation occurs with
proximal obstruction reducing the
pulsitility & causes lower resistant
steady flow quality
well collateralilzed occlusions can appear similar to flow distal to ___________
a stenosis
Subclavian artery signal should look
high resistant multiphasic
flow patterns in hand are ________
variable
may have lower resistant signals that can be
Doppler waveforms post excercize:
Normal should appear
pre excercize wave form qualitites are maintained
may be augmented and contain no reverse component because of dialation of distal vascualar bed
Doppler waveform characteristics post excersize
Abnormal
rounded peak, no reverse component
Absent doppler signals may suggest __________ or _____ ______ vessel
occlusion or pre-occlusive vessel
pre occlusive vessle waveform nick name
string sign
the string sign on CW analog format will appear as
absent signal
Analog Doppler is not capeable of portraying velocities of less than
6cm/sec
Trouble shooting-
what should you do to get rid of noise
increase filter
turn down gain
turn machine off and on
Trouble shooting -
what do you do if the stylus is stuck
re-set
or
re -center
Trouble shooting
what do you do if the stylus is not recording
make sure that proper test selection and probe type is selected
what is inflow disease and what is a common type
inflow represents blood flowing into the lower extremities
Aorto-iliac disease
what is outflow disease and what would be an example
`blood going out into the extremities
femoral popliteal disease
what is pulsatililty index (PI)
peak -to-peak frequency difference systole to systolic flow reversal
(P1 - P2)/ Average cardiac frequency
higher number is gen. indicative of disease
sometimes used the the CFA
(AT) Acceleration time measures what
onset of systole to max peak
what causes a slowing in the time interval between the onset of systole & max peak ?
prox arterial obstruction
what parameter @ CFA AT suggests presence of prox iliac disease
> 133 msec
a greater AT or Lesser value AT is normal ?
Short AT time = normal
Long AT time = abnormal
