Chapter 12 Duplex/ Color Flow Imaging Lower Extremity Flashcards

1
Q

What is the Doppler equation

A

Df= 2 Fo V Cos 0 / C

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2
Q

What is the speed of ultrasound through soft tissue

A

1540 m/sec

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3
Q

What is the ideal Doppler angle for vascular exams

A

60 degrees center stream parallel to walls

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4
Q

If the transducer frequency is decreased what happens to the Doppler waveform size

A

Decreases

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5
Q

What type of transducer should be used

A

7 or 5 MHz linear array

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6
Q

If a 50% diameter reduction is suspected you obtain what 2 things

A

1) pre stenotic PSV
2) PSV highest in stenosis

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7
Q

If the small end is now prox, large end is distal, vein valves stay open due to arterial flow pressure and branches are ligated this is a sign of

A

Reversed saphenous vein graft

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8
Q

If the GSV stays in place, small end is distal, large end is proximal this is a sign of

A

In Situ vein graft

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9
Q

A 2:1 ratio is what percentage of diameter reduction

A

> 50%

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10
Q

A 4:1 ratio of what percentage is diameter reduction

A

> 75%

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11
Q

If it’s greater than 400 cm/sec PSV what is the diameter reduction

A

> 75%

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12
Q

Retrograde flow in a bypass graft results from a

A

Pressure gradient

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