RPVI-Lower arterial duplex Flashcards
what are pitfall in LED?
edema
obese
low outflow
calcified
imaging pop at trifurcation
tandem lesions
what is normal waveform?
fast upstroke reversal in early diastole forward in late diastole high resistance flow which is normal PSV gradually decrease distally
What does a biphasic waveform look like
reversal in early diastole but no forward flow in late diastole
what does mono phasic look like
slow upstroke and no early diastole reversal
What are stenotic effects to the waveform at the site os stenosis
early D flow reversal decreases and disappears with severity
S acceleration time slowed
S peak is rounded and reduced (tarsus and parvus)
decreased PSV
turbulent flow
dampened
What are average velocities for the LE vessels?
CFA 114 SFA P 90 SFA D 90 POP A 70 PTA 40-50
How to we define stenosis
compare one set to another
if is doubles then 50% stenosis or greater
2-4 cm prox to stenosis then at stenosis
What features represent normal LE flow?
PSV 70-100 cm/s
triphasic
What features represent 20-49% LE flow?
> 30% increase in psv
triphasic
> 50%
> 100% increase in psv
monophasic/turbulent beyond stenosisl
> 75%?h
> 400cm/s or quadruple
monophasic/high velocity
What is a hemodyn signif stenosis? what does is cause?
50%
vasod and collateral formation
not necessarily cause symptoms
What is different about flow in stents?
may have increased velocities b/c smaller diameters and lack of normal arterial elasticity
what is appropriate bypass surveillance?
within 7 d
1month
3-6 months x 1 year
then 1-2 year
do this to increase patency. primary assisted patency
where do you sample the bypass
sample every 2-3 cm of the graft
what is the bypass graft stenosis criteria?
PSV sten/ PSV 2-4 cm prox
ratio >2 >50% stenosis
ratio >3 >75%
ratio >4 surgical intervention
EDV >100-120c,/sec severe stenosis
What are normal velocities in bypass?
70-100cm/s
<45 should be monitored this is better predictor in ptfe then vein
What are signs that graft is at increased risk?
triphasic-monophasic
PSV400 cm/sec
ratio >3.5
what defines an aneurysm in LE?
50% increase in size from normal segment
What is plethysmography?
indirect measurement of volume changes in the extremities. ABI is air. PVR
photo is for digits ppg
what is a normal PVR or ppg?
sharp upstroke with dicrotic notch
what happens to pvr or ppg with disease
loss of dicrotic notch
delayed upstroke
rounded waveforms
what are limitations to CW
can't determine depth less sensitive then PW can't determine direction calcification can effect room temp can effect
what size should BP cuff be
> 20% then limb diameter
narrow is falsely elevated
wide falsely low pressures
what are abi criteria?
> 0.9 normal
0.4-0.9 mil to mod disease (0.70)
<0.4 severe
what is the margin of error for ABI?
0.15
what is a normal high thigh /brachial index?
> 1.2
0.8-1.2 inflow/prox dz
<0.8 inflow occlusion/severe stenosis
what is normal changes between segmental pressure?
<20mmhg
what are some abi artifacts?
cuff mismatch
non-compressible vessels
patient movement
improper angle
post exercise testing?
pressures after exercise every 2-3 minutes
post exercise changes, how long until return to normal for single level dz? multilevel
2-6 min
10 min
what are normal post exercise changes? abnormal
increase in pressures
decreas in pressures
what if patient not able to exercise? what does single level, multilevel look like?
do reactive hyperemia.
occlude vessels for 3-5 mins with cuff
normal limb may also have a drop
single 50%
when do we do toe pressure?
if non compressible ankle
abnormal ankle level waveforms
non-healing ulcers
diabetic
what is a ppg that will still likely heal ulcer
> 50 hhmg more
what is normal TBI?
> 0.7 normal
0.4-0.69 mil-mod
0.2-0.39 severe
<0.2 critical
what is tcpO2?
what abnormal
measure amount of o2 diffusing from the skin
>35-40 good
10-35 intermediate
<10 poor
what is normal worst brachial index? finger brachial index?
<0.9
<0.7 abnormal
what stress manoeuvres can you perform in UE testing for TOS?
rest–90 degree arms-overhead raise
military position-then turn head right and left
any position that the have symptoms
how do you perform an allens test
ppg on 2 and 5th digits
asses rest, compression, after release
how do you test for raynauds?
baseline
ppg after ice water for 2-5 minutes
what are normal AVF hemodynamics?
low resistance, high flow, can be monophasic
how to measure AVF
native artery prox to AVF native artery distal to AVF anastomosis evaluate outflow superficial vein first 10cm of draining vein for branches
what is the ideal fistula
> 4mm vein
mean volume >500ml.min
600 for grafts
depth less then 5mm
what are criteria for avf stenosis for artery
PSV at stenosis, then 2cm prox
3:1 ratio = >50%
what are criteria for avf stenosis for draining vein/graft narrowing?
2:1 velocity ratio = >50%
what is criteria at venous anastomoso
2: 1 > 50%
3: 1 > 75% stenosis
What is arterial steal in an avf?
retrograde flow in the native artery distal to anastomosis
because blood flow to area of least resistance
gentle compression of avf shows a return of ante grade flow
