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Vascular 1 > Lesson 17 - Carotid Tech Difficult > Flashcards

Lesson 17 - Carotid Tech Difficult Flashcards

1
Q

What method is used to measure plaque is <60% stenosis?

why?

A

2-D

No hemodynamic effects when <60%

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2
Q

How does color doppler help with clacification?

A
  • Provides visualization of flow
  1. around hypoechoic plaque (see it going around)
  2. Jets and direction (velocity highest in stenosis)
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3
Q

What information does spectral doppler provide about flow?

A
  • Velocity (PSV, EDV)
  • Flow characteristics: resistance, evidence of proximal or distal obstruction
  • Spectral broadening
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4
Q

What do you look at when low cardiac output or proximal stenosis makes the charts inaccurate?

A

Compare CCA & ICA velocity

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5
Q

What are the 2 methods for determining % stenosis?

A
  1. Hemodynamic criteria
  2. 2D
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6
Q

What do standardized velocity charts assume that can cause problems if they are not true?

What criteria should be used in the place?

A
  • normal cardiac output
  • no proximal stenosis
  • short stenotic segment
  • ICA/CCA Ratio
  • Ratio = stenosis/proximal
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7
Q

How does the velocity ratio evaluate stenosis?

A

Same as lower extremity

  • 2 x increase = 50% Stenosis

*Reference chart for further breakdown

*Remember: Ratio is for abnormal = poor cardiac output or proximal stenosis

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8
Q

Describe the waveforms of the CCA, ICA and ECA when there is stenosis of the proximal CCA

A

ICA, ECA, CCA = tardus parvus

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9
Q

There is stenosis in the proximal CCA: How might this effect the velocity in an ICA stenosis?

A

ICA stenosis may not reach target velocity on chart

*use ratio, compare to other side (proximal stenosis affects everything up the vessel)

(tardus parvus CCA, ICA and ECA)

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10
Q

Waveforms in the ____________ artieries appear ____________ as a result of poor cardiac output

A
  • CCA, ICA, ECA, Vertebral
  • tardus parvus
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11
Q

Poor cardiac output creates __________ waveforms in the ICA, ECA, CCA, Vertebral on the _____________ side

A

Tardus parvus

right & left (bilateral)

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12
Q

Which velocities are used to calculate the ICA/CCA ratio?

A

ICA = highest stenotic PSV

CCA = PSV of distal CCA (2cm proximal to bulb)

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13
Q

Is an ICA/CCA ratio helpful if no stenosis is visable?

A

No, only applicaple if stenosis is seen

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14
Q

Name the progession phases of stenosis (4)

A

< 50% - no hemodynamic changes

>50% - increase in velocity

Near occlusion - velocity decreases

Occlusion - no flow

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15
Q

What is the “string sign” on angio?

A

trickle flow

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16
Q

Ischemic changes due to decreased flow is a result of ___________

A

Stenosis

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17
Q

A stenosis can turn to total occlusion from (2)

A

Intraplaque hemorrhage

Thrombus

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18
Q

Trickle flow occurs __________ to ____________

A

distal

high-grade stenosis

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19
Q

Velocity in a high grade stenosis can appear 2 ways, name them

A

1) abnormally high
2) very low - doesn’t match what you would expect from the 2D appearance

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20
Q

To image trickle flow with doppler, doppler must be as sensitive as possible. What machine settings will help achieve this?

A
  • Proper angle
  • gain up
  • scale down (<10cm/s)
  • color scale down (<10cm/s)
  • doppler filter as low as possible
  • power doppler
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21
Q

Why is it important to locate trickle flow?

A

Trickle flow means the artery is not occluded. If there is trickle flow an endarterectomy can be done, but not if vessle is occluded. Makes a huge difference!!

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22
Q

ICA occlusion occurs secondary to ________ (2)

A

atherosclerosis

thrombus

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23
Q

What kind of plaque puts the ICA at a higher risk for occlusion?

A

ulcerative plaque

24
Q

Define Ischemic

A

A decrease in the blood supply to a bodily organ, tissue, or part caused by constriction or obstruction of the blood vessels.

25
Q

Define Arteriosclerosis

A

Hardening of the arteries, also called atherosclerosis, is a common disorder. It occurs when fat, cholesterol, and other substances build up in the walls of arteries and form hard structures called plaques.

26
Q

What are the symptoms of ICA occlusion

A

Asymptomatic or stroke symptomes

27
Q

What happens to the ECA when there is occlusion in the ICA?

A

Internalized ECA = low resistance

*looks like ICA - low resistance waveform.
internalized and tapped so it’s the ECA

28
Q

What happens to the CCA flow with ICA occlusion?

A

Externalized CCA

29
Q

What are the treatment options for ICA occlusion?

A

1) Acute occlusion - direct endovascular thrombolysis (clot dissolving medications through a catheter)
2) Surgical revascularization via urgent carotid endarterectomy
3) Thrombectomy, or EC-IC (brain) bypass
4) Do nothing if found in a chronic pt

30
Q

Define Thrombectomy

A

surgical removal of a clot from a blood vessel

31
Q

Describe an externalized CCA

A

caused by ICA occlusion

high resistance (should not be)

dampened

32
Q

Describe a CCA and ICA “thump”

A

When the regular flow hits the obstruction and causes the vessle to shift up and down <————>

(opposite direction of pusling)

33
Q

Describe an Internalized ECA

A

Low resistance (should be high), looks like ICA

34
Q

How do you confirm the identity of the ECA?

A

Cervical branches (ICA does not have them)

Temporal tap

35
Q

Should doppler sensitivity be high, low, or in the middle, when determining occlusion?

A

The doppler should be set as sensitive as possible to be SURE there is NO flow!!!

DO NOT MISS FLOW and report as occluded when it is not!

36
Q

How do you increase the sensitivity of the doppler?

A
  • Steer the beam correctly
  • Increase gain
  • Decrease scale/PRF
  • Decrease filter
  • High frequency transducer
  • Power doppler (color doppler energy)
37
Q

If you do not see a waveform, what can you do to the spectral scale?

A

decrease

38
Q

CCA occlusion occurs secondary to ___________

A

atherosclerosis & thrombis

39
Q

What kind of plaque puts someone at risk for CCA occlusion ?

A

ulcertive plaque

40
Q

What are symptoms of CCA occlusion?

A
  • Asymptomatic
  • stroke symptoms
  • Reversed ECA
  • Internalized ECA
  • contralateral or vertebral velocities may increase to compensate
41
Q

What occurs in the ECA with CCA occlusion?

A

Reversed flow

Internalized flow

42
Q

What other vessels may experience increased velocites when there is CCA occlusion?

Why?

A

Contralateral CCA or Vertebrals

to compensate for the lack of flow in the occluded CCA

43
Q

Summarizes the goals and steps to identify and characterize the stenosis

A
  1. Identify plaque
  2. characterize
  3. map the stenosis (proximal, jet, distal)
  4. PSV, EDV ( look at chart)
  5. compare ICA/CCA ratio
  6. compare to the other side
  7. velocities should be congruent with 2D appearance (if not, there may be low cardiac output, proximal stenosis, long segment, near occlusion/trickle flow)
44
Q

What can cause CCA velocities to be higher than expected when no stenosis is present?

A

compensatory flow from contralateral vessel, or vertebral obstruction

45
Q

Why does reversal of flow occur?

A

compensation for obstruction in another vessel

46
Q

When will flow reversal of the Left CCA occur?

A

only if arch anomaly with Left CCA and Left Subclavian trunk

47
Q

Which vessels can reverse bilaterally?

A

ECA

Vertebrals

48
Q

Which CCA would be more likely to show flow reversal?

A

Right CCA (branches off brachiocephalic)

49
Q

what is this an example of ?

why is this method used?

A

high ratio - long stenotic segment

Standardized charts assume normal cardiac output, no proximal stenosis, short stenotic segment:
ICA velocity lower than expected b/c long stenosis
CCA velocity is low due to low cardiac output (CHF or AS) or proximal stenosis

ICA velocity will not increase to target levels on chart

Use ratio to evaluate for amount of velocity increase:
Same theory as LE arterial with 2x increase=50% stenosed, etc. *compensates for low inaccurate flow

50
Q

what can cause velocities to be lower than expected?

A

Low cardiac output
Proximal stenosis
Long segment
Near occlusion – trickle flow

51
Q

Which of the following describes the finding of this exam?

left mid CCA stenosis > 70%

left CCA proximal stenosis

left ICA occlusion

right mid CCA stenosis > 70%

A

left mid CCA stenosis > 70%

52
Q

What is the left ICA:CCA ratio?

0

  1. 76
  2. 0
  3. 3
A

1

53
Q

What is the likely degree of stenosis of this left ICA?

<50%

50-69%

>70% but < near total occlusion

near occlusion

A

near occlusion

54
Q

What is demonstrated on this exam?

occluded ICA

retrograde ECA

stenosis of proximal CCA with tardus parvus waveform

internalized ECA

A

occluded ICA

55
Q

What is demonstrated on this exam?

stenosis of proximal CCA with tardus parvus waveform

retrograde ECA

internalized ECA

stenosis of mid CCA

A

internalized ECA

Vascular 1 (3 decks)

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