Duplex / color Flow imaging (LE) Flashcards

1
Q

Calcific shadowing

A

Limitations

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2
Q

Df= 2 Fo V Cos 0
c

A

The Doppler equation

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3
Q

Df

A

Doppler shift

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4
Q

Fo

A

Carrier Frequency

Transducer frequency directly related to doppler frequency

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5
Q

V

A

Velocity of moving reflectors

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6
Q

Cos 0

A

Angle

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7
Q

c

A

Speed of ultrasound through soft tissue

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8
Q

Speed of ultrasound through soft tissue is

A

1540 m/sec

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9
Q

The number is 2 represents

A

two Doppler shifts (in and out)

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10
Q

Ideal Doppler angle for vascular exams is

A

60 degrees

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11
Q

Not reliable Doppler angle is

A

> 60 degrees

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12
Q

For native arteries you scan with what type of probe

A

7 - 5 MHz frequency linear array

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13
Q

If a > 50% diameter reduction is suspected obtain

A

Pre- stenotic PSV

PSV (highest) in stenosis

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14
Q

GSV - taken out

Small end is now Proximal

Large end is distal

Vein valves stay open due to arterial flow pressure

Branches are ligated (tributraies are cut off)

A

Reversed saphenous vein graft (RSVG)

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15
Q

GSV stays in place

Small end is distal ‘

Large end is proximal

Prior to surgery, valves broken up with special instrument; branches ligated

A

In - situ Vein graft

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16
Q

Inflow artery

Proximal 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

A

Vein bypass graft evaluation

17
Q

Inflow artery

Proximal anastomosis

mid graft

Distal anastomosis

Outflow artery

A

Synthetic bypass graft evaluation

18
Q

Doppler signals are triphasic

Some patients may have biphasic flow without any disease

A

Normal

19
Q

2:1 ratio =

A

> 50% diameter reduction

20
Q

4:1 ratio =

A

> 75% diameter reduction

21
Q

> 400 cm/sec PSV =

A

75 percent diameter reduction

22
Q

Pre - stenotic Doppler spectra

A

(monophasic) and dampened

23
Q

Doppler spectra obtained AT the stenosis

A

Highest PSVs documented

24
Q

Post stenotic turbulence and decreased PSVs

A

> 50% stenosis

25
Q

Lower resistance flow patterns may normally be expected.
Some retrograde flow in the native artery may be evident at the distal anastomosis of RSVG, which proves and additional source of collateral flow. (retrograde flow results from a pressure gradient)

A

Normal

26
Q

Decrease in ABI of > 0.15

Observes for post-complications such as: AV fistula (can siphon off graft flow); valve cusp

Insitu only- if tributary is not ligated

A

Abnormal findings

27
Q

Anastomosis sites should be evaluated well for aneurysm and/or stenosis

Can loosely apply the previous data to determine whether a > 50% diameter reduction exists

Observe for graft occlusions

A

Synthetic grafts

28
Q

In general velocities stented arteries may have elevated peak systolic velocities

Greatly elevvated peak systolic velocities are abnormal and suggests hemodynamically significant diameter reduction

A

Post endovascular intervention

29
Q

Gray scale is most important

Used for checking patency of the anastomotic sites

Evaluate any suspicious stenotic or turbulent areas that can occur in vein bypass grafts

Use highest frequency imaging transducer available

A

Intraoperative monitoring