Chapter 12

Question 1

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

Answer 1

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

Question 2

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

Answer 2

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

Question 3

what is patient positioning for LE duplex?

Answer 3

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

Question 4

what is the doppler shift freq formula?

Answer 4

Df=2 Fo V Cos
___________
c

Question 5

what does the number 2 represent in the formula?

Answer 5

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

Question 6

what is the speed of tissue?

Answer 6

1540 m/sec

Question 7

what is the formula for velocity?

Answer 7

v=c Df
______
2 Fo Cos

Question 8

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

Answer 8

true

Question 9

what is Cos of 90?

Answer 9

0

Question 10

What is COS of 60?

Answer 10

0.5

Question 11

What is Cos of 0?

Answer 11

1

Question 12

what is a source of error when solving for velocity?

Answer 12

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

Question 13

what is the ideal doppler angle?

Answer 13

60

Question 14

what is the ideal place to put the angle correct?

Answer 14

parallel to vessel walls and centerstream

Question 15

what will cause for you to change your doppler angle?

Answer 15

vessel tortuosity and other conditions

Question 16

what are still usable angles?

Answer 16

45-60

Question 17

which angles are not reliable?

Answer 17

doppler angle >60 degrees

Question 18

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

Answer 18

direct

Question 19

what probe freq to use for LE?

Answer 19

7 or 5

Question 20

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

Answer 20

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

Question 21

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

Answer 21

TRI BI or Monophasic

Question 22

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

Answer 22

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

Question 23

what should you know about bypass grafts?

Answer 23

type, location and age

Question 24

what are types of syntheic grafts?

Answer 24

e.g Gortex
RSVG
in- situ vein graft

Question 25

how does the revered saphenous vein graft work?

Answer 25

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

Question 26

how does the in-situ vein graft work?

Answer 26

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

Question 27

T/F protocols for bypass grafts are combined with ABIs

Answer 27

true

Question 28

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

Answer 28

false

Question 29

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

Answer 29

true

Question 30

what is the vein bypass graft evaluation consists of?

Answer 30

gray scale, color flow and PSV

Question 31

what is the area of evaluation for vein bypass grafts?

Answer 31

``` 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 ```

Question 32

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

Answer 32

``` inflow artery, prox anastomosis mid graft distal anastomosis outflow artery ```

Question 33

what is the normal doppler pattern for LE arterial?

Answer 33

triphasic | some can be biphasic

Question 34

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

Answer 34

true

Question 35

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

Answer 35

true

Question 36

what does a 2:1 ratio indicate?

Answer 36

>50% diameter reduction

Question 37

what does a 4:1 ratio indicate?

Answer 37

>75% diameter reduction

Question 38

what does a >400cm/s PSV indicate?

Answer 38

>75% diameter reduction

Question 39

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

Answer 39

false

Question 40

what will a waveform look like prestenois?

Answer 40

monophasic and dampended

Question 41

what will a waveform look like at stenosis?

Answer 41

highest PSVs documented

Question 42

when will turbulance be evident?

Answer 42

to a > 50% stenosis | and post stenosis

Question 43

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

Answer 43

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

Question 44

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

Answer 44

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

Question 45

why should anastomotic sites be evaluated well?

Answer 45

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

Question 46

what does intraoperative monitoring consists of?

Answer 46

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)