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RVT Review > Chapter 12 > Flashcards

Chapter 12 Flashcards

1
Q

what are capabilities of duplex/color flow imaging (LE)?

A

determine presence/absence of >50% diameter reduction or occulsions
determine presence/ absence of aneurysms
follow up by pass grafts
to localize the stenotic lesion prior to balloon angioplasty

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2
Q

what are limiations of duplex/color flow imaging (LE)?

A

presence of dressings, skin staples, sutures, open wounds
incisional tenderness, hematomas
obesity- difficult to image vessels
calcific shadowing from diabetes and/or atherosclerosis

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3
Q

what is patient positioning for LE duplex?

A

supine with head on pillow
extremity positioned close to the examiner
pts hips minimally rotated externally, knee flexed
prone or LLD may be required for pop artery

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4
Q

what is the doppler shift freq formula?

A

Df=2 Fo V Cos
___________
c

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5
Q

what does the number 2 represent in the formula?

A

two doppler shifts
red blood cell is first an observer of a stationary US field
then acts as a wave source when the waves scatter from its surface

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6
Q

what is the speed of tissue?

A

1540 m/sec

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7
Q

what is the formula for velocity?

A

v=c Df
______
2 Fo Cos

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8
Q

T/F the doppler shift must be known in order to calculate for velocity

A

true

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9
Q

what is Cos of 90?

A

0

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10
Q

What is COS of 60?

A

0.5

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11
Q

What is Cos of 0?

A

1

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12
Q

what is a source of error when solving for velocity?

A

the doppler angle theta which increases its nonlinear influence as the angle becomes closer to 90 degrees

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13
Q

what is the ideal doppler angle?

A

60

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14
Q

what is the ideal place to put the angle correct?

A

parallel to vessel walls and centerstream

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15
Q

what will cause for you to change your doppler angle?

A

vessel tortuosity and other conditions

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16
Q

what are still usable angles?

A

45-60

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17
Q

which angles are not reliable?

A

doppler angle >60 degrees

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18
Q

what is the relationship between the doppler freq and the freq of the transducer

A

direct

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19
Q

what probe freq to use for LE?

A

7 or 5

20
Q

which arteries are you going to image with a LE duplex?

A 
distal external iliac artery 
CFA
CFA bif (SFA and DFA)
SFA (p-d)
pop a (p-d)
trifurcation 
   -ATA
  -PTA
   -peroneal
21
Q

which words do you use to describe a LE doppler signals?

A

TRI BI or Monophasic

22
Q

if a >50% diameter reduction is suspected what should you obtain?

A

pre- stenotic PSV (approaching the stenosis)
PSV (highest) at stenosis
post- stenosis

23
Q

what should you know about bypass grafts?

A

type, location and age

24
Q

what are types of syntheic grafts?

A

e.g Gortex
RSVG
in- situ vein graft

25
Q

how does the revered saphenous vein graft work?

A

small end is now proximal
large end is distal
vein valves stay open due to arterial flow pressure
branches are ligated

26
Q

how does the in-situ vein graft work?

A

GSV stays in place
small end is distal
large end is prox
prior to surgery, valves broken up with special instrument, branches ligated

27
Q

T/F protocols for bypass grafts are combined with ABIs

A

true

28
Q

T/F protocols for by pass grafts can be combined with segmental pressures

A

false

29
Q

T/F protocols for by pass grafts can be combined with PVR

A

true

30
Q

what is the vein bypass graft evaluation consists of?

A

gray scale, color flow and PSV

31
Q

what is the area of evaluation for vein bypass grafts?

A 
inflow artery
proximal anastomosis
entire length of the vein bypass graft 
distal anastomosis 
outflow artery 
also check for branches that could form AVF valves, and or other abnormalities
32
Q

what is the area of evaluation for a synthetic bypass graft?

A 
inflow artery, 
prox anastomosis
mid graft
distal anastomosis 
outflow artery
33
Q

what is the normal doppler pattern for LE arterial?

A

triphasic

some can be biphasic

34
Q

T/F a waveform going from triphasic to biphasic can be a significant finding?

A

true

35
Q

T/F you want to compare stenotic PSV to prestenotic PSV

A

true

36
Q

what does a 2:1 ratio indicate?

A

> 50% diameter reduction

37
Q

what does a 4:1 ratio indicate?

A

> 75% diameter reduction

38
Q

what does a >400cm/s PSV indicate?

A

> 75% diameter reduction

39
Q

T/F you shouldnt worry about the waveforms quality when numbers are abnormal

A

false

40
Q

what will a waveform look like prestenois?

A

monophasic and dampended

41
Q

what will a waveform look like at stenosis?

A

highest PSVs documented

42
Q

when will turbulance be evident?

A

to a > 50% stenosis

and post stenosis

43
Q

where will retrograde flow in the native artery be evident with a graft?

A

distal nastomosis of a RSVG, which provides an additional source of collateral flow
-retrograde flow results from a pressure gradient

44
Q

what are some changes to be aware of with a graft?

A

a decrease of 30cm/s in any graft segment
reduced PSV in smallest graft diameter that were greater prev
change from tri to biphasic signals
decrease in ABI >0.15
observe for post complications such as AVF ,valve cusp

45
Q

why should anastomotic sites be evaluated well?

A

higher chance for aneurysms, pseudo aneurysms and or stenosis
observe for graft occlusions in synthetic grafts

46
Q

what does intraoperative monitoring consists of?

A

B mode imaging
checking patency of anastomotic sites
evaluating for stenosis or turbulent area that can occur in vein of bypass grafts (e.g valve cusp sites or suspected branch sites)

RVT Review (30 decks)

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