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33 terms

Vascular technology Doppler waveform analysis

STUDY
PLAY
Doppler waveform analysis capabilities include
indicating the severity of the occlusive process can be used in combination with segmental pressures
Limitations to doppler waveform analysis include____
*patients with casts or bandages
*waveform affected by temp
*CHF may result in dampened waveform
unable to discriminate STENOSIS from OCCLUSION; technically dependent test.
___ is a type of velocimetry that employs a zero-crossing frequency meter to display the signals graphically on a strip chart recorder
analog
____ estimates frequencies present in the reflected signal and displays them. The circuitry counts ea time the input signal crosses through the baseline within a time span.
zero crossing detector
with zero-crossing detection ___ frequency waves have many oscillations and ___ frequency waves have few.
high; low
___ is a type of velocimetry that uses individual frequencies displayed by the FFT method
spectral analysis
In spectral analysis, the horizontal x axis represents___
time
In spectral analysis, the vertical y axis represents___
frequency shifts
the advantage of spectral analysis is that it is ___
free of the analog recording drawbacks
For doppler waveform analysis, use an ___ frequency probe
8 - 10 MHz
an upper extremity arterial doppler velocity wave form exam includes ____ arteries
subclavian, axillary, brachial at elbow antecubital fossa, radial thumb side at wrist, ulnar at wrist
a lower extremity arterial doppler velocity wave form exam includes ___ arteries
CFA, SFA popliteal, PTA medial malleolus, DPA top of foot, and peroneal if necessary at lateral malleolus
A qualitatively normal wave form is __ while abnormal wave forms may be __ or __
triphasic, biphasic, monophasic
a ____ signal is often obtained proximal to an obstruction, with no diastolic flow.
monophasic/dampened pulsatile
Distal to an obstruction, the signal is _____
monophasic, more steady
___ can appear similar to flow distal to a stenosis
well collateralized occlusion
when there is vasodilation of distal vessels assoc with a proximal obstruction __ occurs
reduction in the pulsatility causing the signals to have lower resistant (steady) flow quality
Normal Doppler waveform Post exercise will have what type of appearance
pre exercise wave form qualities are maintained and/or augmented
*no reverse component
Remember that, usually just segmental pressures obtained post exercise describes
Abnormal Doppler waveform Post exercise will have what type of appearance
*slow upstroke with more rounded peak
*slow downstroke
no reverse component
absent doppler signals that may suggest occlusion or pre-occlusive vessel is known as___.
string sign
analog doppler is not capable of protraying velocities of less than ____.
6 cm/sec
Quantitative interpretation is used with___
spectral analysis
qualitative interpretation is used with__
continuous wave
___ helps to differentiate inflow (aorto-iliac) disease from outflow (S femoral) disease
acceleration time
___ is based on the principle that proximal arterial obstruction results in a slowing of the time interval between the onset of systole to the point of maximum peak.
acceleration time
an acceleration time of greater than____ suggests presence of proximal iliac disease
133 m/sec
PI = P1 - P2/ mean frequency
Pulsatility index equation
what are some of the drawbacks of using Analog vs Spectral analysis for obtaining doppler waveform analysis
noise high velocities underestimated
less sensitivity low velocities overestimated

spectral analysis free of many of the analog recording drawbacks
how do you obtain the calibration of doppler waveform on the analog system
most equipment does a self calibration when the system is activated
The circuitry in analog _____
zero crossing frequency meter
how many times the input signal crosses through zero (the baseline) w/n a time span
spectral analysis display ___ on the horizontal axis
time
spectral analysis display ___ on the vertical axis
frequency shifts
List some the potential source of technical error when performing doppler waveform analysis
*******Incorrect angle of incidence
Improper probe position
inadvertent probe motion
Inadequate amount of gel
Excessive pressure on the Probe tip
Insufficient period of rest before testing