Duplex/color flow imaging UE and LE Flashcards Preview

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Flashcards in Duplex/color flow imaging UE and LE Deck (28):
1

Combination of real time B-mode imaging and Doppler spectral analysis

Duplex scanning

2

Doppler info is displayed on image after evaluated for phase and its frequency content.

Doppler color flow imaging

3

Sample size for acquiring pulsed doppler is usually?

1-1.5mm

4

Uncommon for arteries in the upper extremities to become stenotic. Main use is evaluation of?

Dialysis access grafts

5

Auscultate the access for bruit and/or palpate for a thrill (vibration). A patent ______, as well as a stenotic one can produce a thrill.

Dialysis access

6

Evaluate dialysis access grafts as follows:

a) inflow artery
b) arterial anastomosis
c) continue through the body of the graft
d) observe for aneurysm, puncture sites, peri-graft fluid
e) observe color flow changes, turbulence
f) venous anastomosis
g) outflow vein

7

UE dialysis access Brescia-Cimino fistula assessment sites include?

Inflow artery, anastomosis, and outflow vein
Straight, looped, synthetic grafts

8

Normal peak systolic velocities vary widely with _____ changes. Doppler signal quality is usually triphasic.

Skin temperature

9

If a > 50% diameter reduction is present, observe for characteristics of the?

Stenosis profile
post stenosis turbulence

10

What aneurysms can form in response to using the palm as a hammer?

ulnar artery

11

What aneurysms are associated with embolization to the digits?

Subclavian

12

Peak systolic velocities and end diastolic velocities vary as to the type of access; normally both are elevated. Low PSV obtained in access graft could indicate arterial _____ problems.

inflow

13

Most common sites for stenosis in hemodialysis access?

venous anastomosis and outflow vein

14

Large blood volumes shunted from artery to lower resistant venous circulation, can increase venous return resulting in?

CHF

15

In what situation is the distal arterial blood flow reversed into the lower resistant venous circulation and can cause pain on exertion, pallor and coolness of the skin distal to the shunt?

steal syndrome

16

Doppler equation for LE duplex/color flow imaging?

Df= 2 Fo V Cos theta/ c
Df- doppler shift freq
Fo- carrier freq
c- speed of US through soft tissue (1540 m/s)
V- velocity of moving reflectors
Cos theta- Angle
2 represents two doppler shifts

17

What do the two Doppler shifts represent in the LE doppler equation?

- RBC is first an observer of a stationary ultrasound field
- Then acts as a wave source when the waves scatter from its surface

18

Equation for velocity

V= c Df/ 2 Fo Cos theta

19

When solving for velocity, what increases its nonlinear influence as the angle becomes closer to 90 degrees?

Doppler angle theta

20

If there is a > 50 % diameter reduction is suspected what should be obtained?

Pre-stenotic PSV
PSV in stenosis
Post-stenotic turbulence signals

21

What is important to know about bypass grafts?

type, location, and age

22

Reversed saphenous vein graft (RSVG)

- Small end is now prox
- Large end is distal
- Vein valves stay open due to arterial flow pressure
- Branches are ligated

23

In-situ vein graft

- GVS stays in place
- Small end is distal
- Large end is prox
- Prior to surgery, valves broken up with special instrument, branches ligated

24

Vein bypass graft evaluation includes observation of gray scale, color flow, and PSV's of the following?

- Inflow artery
- Prox anastomosis
- Entire length of the vein bypass graft
- Distal anastomosis
- Outflow artery
- Also check for branches that could form AV fistulas, valves, and/or other abnormalities

25

Synthetic bypass graft evaluation include observation of gray scale, color image, PSV's of the following:

- inflow artery
- prox anastomosis
- mid graft
- distal anastomosis
- outflow artery

26

Compare stenotic PSV to pre-stenotic PSV:

2:1 ratio = > 50% diameter reduction
4:1 ratio = > 75% diameter reduction
>400 cm/s PSV = 75% diameter reduction
Never accept the value of numbers alone; post-stenotic turbulence should be present

27

Retrograde flow in the native artery may be evident at the distal anastomosis of a RSVG, which provides an additional source of collateral flow. Retrograde flow results from a?

pressure gradient

28

Compare results with previous studies and observe for changes such as?

- Decreased of 30 cm/s in any graft segment
- Reduced PSV's in smallest graft diameter that were greater previously
-Change from triphasic to biphasic
- Decreased in ABI of >0.15
- AV fistula