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MIDS 237 > Ch 11 Extracranial Duplex > Flashcards

Ch 11 Extracranial Duplex Flashcards

1
Q

What is a bruit?

A

-An abnormal “blowing” or “swishing” sound heard with a stethoscope while auscultating over an artery
-Due to vibrations transmitted through a stenotic artery

(bruits are a sign of arterial disease, although not all stenoses have bruits)

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2
Q

Where are baroreceptors assisting in reflex BP control located?

A

In the carotid bulb

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3
Q

Primary goal of performing a carotid exam?

A

To identify pt’s who are at risk for stroke due to atherosclerosis

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4
Q

Treatment for atherosclerosis?

A

-Carotid endarterectomy (CEA)
-Stenting
-Aggressive medical management of modifiable RFs

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5
Q

Secondary goal of performing a carotid exam?

A

To document progressive disease in pt’s who are already known to be at risk or have recurrent stenosis after intervention

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6
Q

List major indications for a duplex scan of the carotid + vertebral arteries?

A

-Asymptomatic neck bruit
-Hemispheric cerebral or ocular TIAs
-History of stroke
-Screening prior to major cardiac, vascular, or other srugery
-Follow up after carotid endarterectomy or stenting

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7
Q

List 3 symptoms of cerebrovascular disease?

A

-Emboli (travels to brain)

-Reduction of flow, due to high grade stenoses (stenosis in ICA does not typically cause symptoms due to circle of willis)

-Arterial thrombosis (carotid artery thrombosis is rare)

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8
Q

How long do symptoms from a TIA + RIND typically last?

A

TIA: minutes to a few hours, but NOT longer than 24 hours

RIND: b/w 24-72 hours

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9
Q

List symptoms of a TIA + RIND?

A

TIA (transient ischemic attack):
-mini stroke
-paralysis or numbness (paresthesia) of face, arm + leg only on 1 side of the body
-difficulty speaking (aphasia)
-symptoms occur on the side of the body OPPOSITE to the affected carotid artery + cerebral hemisphere

RIND (reversible ischemic neurologic deficit):
-same symptoms as a TIA

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10
Q

What is amaurosis fugax?

A

-TIA of the eye
-Painless temp loss of vision in 1 or both eyes
-Causes transient monocular blindness on the SAME side as the responsible carotid artery

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11
Q

What is a cerebrovascular accident?

A

-Stroke
-Permanent neurologic deficits
-Vertebrobasilar arterial insufficiency symptoms include dizziness, diplopia + ataxis
-Carotid circulation symptoms include paralysis or paresthesia of face, arm + leg on ONE side of body

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12
Q

Pt’s who had a TIA, RIND or AF are at an increase risk for what?

A

Stroke

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13
Q

List history questions we should obtain prior to a carotid exam?

A

-Hypertension
-Hypercholesterolemia (high cholesterol)
-Diabetes
-Heart attack, angina
-Relevant vascular surgery
-TIA’s or CVA’s
-Stroke like symptoms

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14
Q

How far should the pt turn their head away for a carotid exam?

A

30-45 degrees from midline

(common pitfall: rotating head too far, as this causes the SCM to tighten + make imaging harder)

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15
Q

Where is plaque m/c found?

A

-CCA bifurcation/bulb (distal CCA)
-Prox ICA
-Prox ECA

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16
Q

What should we set our CD scale to for this exam?

A

20-40 cm/s

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17
Q

Benefits of using CD + power doppler?

A

CD: rapid identification of flow disturbances

PD: detecting very low flow velocities, including “string sign” flow

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18
Q

How should we adjust our CD gains in order to know where to sample with PW?

A

Turn scale up until there is a few pixels of aliasing, this is highest velocity + we want to sample here

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19
Q

How can we perform a temporal tap?

A

-Palpate the pulse in the superficial artery anterior to the ear, then tap on the artery while insonating flow in the ECA
-An artifact from tapping should appear on waveform (looks like spikes in diastolic flow)

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20
Q

What does flow separation (recirculation) look like in the bulb?

A

-Small area of flow reversal, typically along the outer wall of the bulb on the opposite side to the flow divider
-No need to sample this, this is normal in the bulb
-As plaque forms + fills in the bulb, the flow separation will disappear

(small area of blue flow, instead of red)

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21
Q

Which part of the ICA is often hard to see + tortuous?

A

Distal

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22
Q

We must evaluate the distal ICA in pt’s at risk for ___ ___?

A

Fibromuscular dysplasia

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23
Q

How to angle probe to get the vertebral artery?

A

Identify CCA then slide/angle probe posteriorly to find it

(it is located b/w the TRV processes of the cervical vertebrae)

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24
Q

An abnormal vertebral artery waveform may indicate what?

A

Significant stenosis of the ipsilateral (same side) prox subclavian artery

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25
Q

How to angle probe to get the subclavian artery?

A

Place probe at base of neck + angle inferiorly

(place SVB as proximal as possible, then sweep distally to obtain highest PSV + most laminar waveform)

26
Q

SF of the intimal-medial + adventitial layer?

A

Intimal-medial:
-Clearly visible as a thin gray/white line on the innermost part of the wall + is uniform throughout the length of the vessel

Adventitial:
-Visible outside the intimal-medial layer as a brighter white than adjacent tissues

27
Q

List 3 carotid pathologies?

A

-Plaque
-Intraluminal defects
-Iatrogenic injury

28
Q

SF of homogeneous + heterogeneous plaque?

A

Homo:
-Uniform appearance + low echogenicity
-Be sure gains aren’t set too low

Hetero:
-Mixed + brighter echogenicity
-Shadowing due to areas of calcium

29
Q

What are intraluminal defects?

A

-Disruption of intima with blood from the lumen, blood flows b/w the layers of the vessel wall
-Separation of layers is called arterial dissection

30
Q

What does arterial dissection create?

A

A second false lumen within the vessel

(reverberation can mimic this, use CD)

31
Q

Why do intimal dissections occur?

A

Spontaneously or due to trauma

32
Q

What is iatrogenic injury?

A

-Any adverse pt condition that is caused inadvertently by a health care provider during a medical procedure or intervention
-Uncommon

(ex. iatrogenic injury to CCA from catheter interventions or venous line placement)

33
Q

Why does the CCA typically have a low resistance pattern with forward flow?

A

B/c 70% of the normal CCA flow passes through the ICA, so it takes on similar characteristics as it

34
Q

Is flow separation in the bulb normal?

A

Yes! Occurs along outer wall farthest from the ECCA. The waveform shows flow above + below baseline.

(correlates with min or no plaque in bulb)

35
Q

How does a normal vertebral artery waveform appear?

A

-Same as ICA, with a low resistance pattern + forward flow
-Normal PSV is from 30-50 cm/s

36
Q

How does a normal brachiocephalic artery waveform appear?

A

Higher resistance flow pattern, it has a triphasic waveform when normal:
-Arm (high resistance)
-Face (high resistance)
-Brain (low resistance)

37
Q

How would a pre-stenotic waveform appear?

A

-If there are abundant collateral vessels it may appear normal
-If collateral flow is limited + the stenosis is severe, it will appear high resistance with lower/absent diastolic flow

38
Q

How would a stenotic waveform appear?

A

High velocity jet

39
Q

How would a post-stenotic waveform appear?

A

-Turbulence will be present distal to the stenosis, causing spectral broadening
-Waveform will be dampened, with decreased flow velocity, delayed acceleration + have a rounded peak (tardus-parvus pattern)

40
Q

What is the “steal” phenomenon?

A

-A situation where 1 vascular bed draws blood away/steals from another
-Occurs when 2 runoff beds with different resistances are supplied by a limited source of inflow

41
Q

What is subclavian steal?

A

-Severe stenosis of the subclavian artery (or RT BCA) prox to the origin of the vertebral artery

42
Q

3 stages of a steal waveform?

A

Stage 1: Latent or Hesitant
-Antegrade flow with a deep flow reversal notch

Stage 2: Alternating or Bidirectional
-When the deep notch extends below the baseline

Stage 3: Complete
-A progressing stenosis where the ratio of antegrade + retrograde flow is altered
or
-A complete steal where the flow is entirely retrograde

43
Q

How does string flow appear on b-mode, CD + spectral doppler?

A

B-Mode: extensive plaque, often with shadowing

CD: severely narrowed lumen (power doppler may show small lumen)

Spectral doppler: non-specific. Variable velocity + possibly decreased diastolic flow in ipsilateral CCA

44
Q

What is the “string sign” or “trickle flow”?

A

-Low velocity flow with a somewhat resistive waveform
-Occurs before complete occlusion of vessel
-M/c found in a severely diseased ICA where only a small string like lumen remains

45
Q

How can we differentiate b/w the string sign + complete occlusion?

A

CT angiography is useful to confirm occlusions

(note: direct intervention is not possible once the ICA has been fully occluded)

46
Q

What is a choke lesion?

A

A severe distal CCA obstruction with continued patency of the carotid bifurcation

47
Q

What happens when there is stenosis in the CCA?

A

-It will affect the ICA + ECA too
-Flow may reverse in the ECA to help supply the ICA

48
Q

How does an ICA stenosis waveform appear?

A

-Highly resistive
-Decreased or no end diastolic flow
-Blunted appearance

49
Q

How does a stenosis or occlusion in the ICA affect the CCA?

A

Stenosis: highly resistive + blunted flow in ICA will be reflected in CCA waveform

Occlusion: CCA waveform will take on features of the patent ECA

50
Q

How does a prox ECA stenosis waveform appear?

A

-Focal velocity increase
-Post stenotic turbulence, due to spectral broadening
-Dampened waveform distally

51
Q

Is complete ECA occlusion common?

A

No, b/c it has multiple branches + abundant collateral pathways

52
Q

Besides with a stenosis, when would there be a diffuse increase in ECA velocity?

A

When the ipsilateral ICA is completely occluded (due to collateral pathways via the circle of willis)

53
Q

How does a vertebral artery stenosis waveform appear?

A

-Dampened distally
-Delayed acceleration
-Rounded peal
-Post stenotic turbulence

(typically occur at origin of vessel from subclavian)

54
Q

How would waveforms appear if the pt has a low CO + poor EF?

A

Dampened with delayed acceleration in every artery, yet no stenosis or turbulence seen

55
Q

How would waveforms appear if the pt has Ao valvular disease + hypertrophic obstructive cardiomyopathy?

A

It will have 2 prominent systolic peaks separated by a mid-systolic retraction known as “pulsus bisferiens”

56
Q

How would waveforms appear if the pt has a cardiac arrhythmia?

A

Standard velocity criteria may not apply + the waveform contour is altered

57
Q

How would waveforms appear if the pt has a cardiac assist device?

A

-Can be unrecognizable as arterial flow
-They are used when pt’s have heart failure (ex. a LVAD + IABP)

58
Q

How to calculate ICA/CCA ratio?

A

-Pick the highest PSV from the stenotic site for ICA value

-Pick the PSV in a normal mid-distal CCA segment for the CCA value

59
Q

In what scenario would the ICA/CCA ratio not be valid?

A

In presence of significant CCA disease

60
Q

How can CCA + ECA stenoses be diagnosed?

A

By a focal increase in PSV followed by post-stenotic turbulence

(PSV of >200 cm/s indicates suspicion for a 50-99% stenosis)

61
Q

When there is a significant stenosis at the origin of the CCA, the more distal CCA waveforms will appear ___?

A

Dampened with low PSV + slow systolic acceleration

62
Q

How can we identify a vertebray artery stenosis of >50%?

A
  1. Velocity ratio:
    -Max PSV in prox vertebral / PSV in normal distal vertebral = >2.2
  2. Focal vertebral artery PSV of >150 cm/s

MIDS 237 (23 decks)

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