Vascular Lab Flashcards
Axial resolution relationship to frequency
Linear; dependent on US freq transducer and depth of structure of interest
Recommended measurement of Abdom aorta
A-P; outer wall to outer wall
Characteristics of arterial waveform with proximal stenosis/obstruction
Delayed systolic upstroke; decrease in overall amplitude
Characteristic of arterial waveform in presence of stenosis/obstruction distally
Diminished diastolic flow
Characteristic of arterial waveform in presence of high grade stenosis
Increased PSV; turbulent flow; when stenosis severe, elevation of EDV
Duplex US findings of cystic adventitial dz
Extra-luminal compression of pop artery; anechoic/hypoechoic w/o color flow; possibly elevated velocity beyond stenosis
What is the stereotypical signal for perforator veins on duplex US?
To-and-fro flow
Duplex findings indicating hemodynamically significant restenosis of iliac stent
Localized elevated velocities >200cm/sec w/ turbulent flow; peak velocity ratios > 2.0; monophonic femoral waveforms; add’l physiologic data incl. ABI decrease by at least 0.15, return of claudication
TcPO2 sufficient to support wound healing
> 40 mmHg
Ankle, toe pressures representing critical limb ischemia
Ankle pressure
Duplex US findings w pop art entrapment
Loss of pedal pulse, tri-phasic waveform with active plantar flexion
Dx maneuver to help dx MAL w duplex
Evaluate inspiratory and expiratory PSV’s of celiac artery; PSV increases w/ expiration
Define relationship btwn Doppler freq shift and transmitted US freq
Linear
Define relationship between US amplitude and transmitted frequency
Amplitude is strength or POWER of the sound wave and is INDEPENDENT of frequency
Define PRF
of pulses that occur in 1 sec.; NOT related to transmitted US freq, nor will it change w/ the transducer frequency
Contraindications to US guided thrombin injection of femoral PSA
LE ischemia, infection at access site, AVFistula, pregnancy
Complications of US guided thrombin injection
Intra-arterial thrombosis (
Indications for open surgical repair of femoral PSA
Contraindications to non op mgmt (peripheral ischemia, infection, surgical graft, lg supra-Inguinal PSA) OR presence of complications (rapid enlargement, skin necrosis, distal embolization, rupture)
Define renal resistive index (RRI) and its utility
Percentage reduction ED flow; marker of downstream impedance; values
Describe spectral waveform found in presence of proximal stenosis
Damped or blunted, low velocity spectra, notched waveform
Minimum BP cuff width for LE segmental Doppler pressures
At least 20% greater than diameter of the limb
Normal high thigh pressures with 4 cuff technique? 3 cuff technique?
1.4; 1.0
Duplex US Dx criteria for >60 % stenosis of renal artery
PSV > 200cm/sec; AND renal-aortic-ratio > 3.5; supra renal aorta must not be aneurysmal, and PSV must be at least 45cm/sec
Restenosis/occlusion rate post CEA; CAS
Equal; approx 6 %
Arteries examined in the teams-temporal window
MCA; ACA; PCA; terminal ICA
Depths of arteries in trans-temporal window
MCA 30-60mm antegrade flow
Term ICA 55-65mm bidirectional
ACA 60-80mm retrograde
PCA 60-70mm antegrade
Velocities indicating vasospasm on transcranial Doppler
Mean velocity 60cm/sec
MCA >120cm/sec
ACA >130cm/sec
PCA >110cm/sec
Define relations between frequency shift and the propagation speed of US in the tissue
Inverse; it is proportional to the freq of transmitted US (transmitter freq), speed of RBC’s, cosine of Doppler angle (max at 0 degr, min at 99 degr)
