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Vascular > Extracranial Cerebrovascular > Flashcards

Extracranial Cerebrovascular Flashcards

0
Q

What does spectrum analysis sort out?

A

the doppler frequencies FFT - giving us a velocity

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1
Q

What is extracranial?

A

outside the brain

carotid studies

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2
Q

What are we evaluating in spectrum analysis blood flow?

A

pulsatile

flow is slower at the periphery

vessels are not straight

vessels are not uniform

distorted by pathology

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3
Q

What is the proper doppler angle?

A

60 degrees or less to acquire accurate frequency and velocity information

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4
Q

What is a doppler spectrum

A

graph of doppler frequencies generated by moving blood

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5
Q

When do you have broad systolic peak and forward flow throughout diastole?

A

CCA, ICA, vertebral, renal and celiac

low peripheral resistance

entire waveform above or below baseline

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6
Q

When do you get tall, narrow sharp systolic peaks reversed or absent flow through diastole?

A

extremity artieries, ECA, SMA (fasting)

high peripheral resistance

Arterial flow

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7
Q

What varies depending on location, physiology and pathology alteration, status of cardiac function?

A

Pulsatility

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8
Q

When does flow velocity accelerate rapidly?

A

in systole

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9
Q

What might cause acceleration to be slowed?

A

severe arterial obstruction flow

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10
Q

What causes disturbed flow?

A

widening of the wave form

vascular disease

normal tortuous vessels

prominent area -bulb

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11
Q

What happens with arterial obstruction?

A

increase velocity

disturbed flow post stenotic

proximal pulsatility changes

distal pulsatility changes

indirect effects - collateralization

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12
Q

What is Poiseuille’s Law?

A

a statement of physics

the VELOCITY of the steady flow of a fluid through a narrow TUBE varies DIRECTLY as the PRESSURE and the 4th power of the RADIUS of the tube and INVERSELY as the LENGTH of the tube and the coefficient of VISCOSITY.

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13
Q

what law states: because volume flow is porportional to the 4th power of the radius, even small changes in radius can result in large changes in flow?

A

Poiseuille’s Law

calculates VOLUME FLOW

Radius is most important because its to the 4th power

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14
Q

According to Poiseuille’s Law what happens to flow rate when pressure, diameter, length and viscoisty is INCREASED?

A

increase pressure, increase flow rate

increase diameter, increase flow rate

increase length, decrease flow rate

increase viscosity, decrease flow rate

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15
Q

How does Bernoulli’s principle relate velocity and pressure?

A

they are inversely related

high velocity, low pressure

low velocity, high pressure

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16
Q

With Bernoulli’s principle if you have a stenosis, what happens to the pressure and velocity AT the stenotic segment, prox to stenosis and distal to stenosis?

A

Stenotic segment - pressure decreases, velocity increases

prox - pressure increase

distal - pressure increase

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17
Q

Flow moves along the path of _________resistance

A

least

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18
Q

What is a hallmark of high resistance vascular beds?

A

diastolic flow reversal

it doesn’t need a constant flow, it can hesitate….flow reversal

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19
Q

What is an ischemic stroke?

A

interruptions of blood flow to the brain

80% - ruptured intracraninal blood vessel

20% intracranial hemorrhage

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20
Q

What are two ways the blood flow gets interrupted to the brain causing a stroke?

A

Thrombus lodges in a cerebral artery

thrombus in the carotid artery breaks off and travels to a cerebral artery in the brain

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21
Q

What is responsible for more than 50% of all strokes?

A

extracranial carotid artery disease

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22
Q

What is the third leading cause of death in the USA?

A

Stroke (cerebrovascular diseases) 137,119

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23
Q

What can detect potential causes of stroke?

A

carotid imaging

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24
Q

What is the definition of stroke or CVA?

A

permanent ischemic deficit (permanent damage)

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25
Q

What is the definition of TIA (transient ischemic accident)

A

temporary - reversible ischemic neurologic deficit

resolves in <24 hr (usually less than one hour)(lasts 1-30 min until full recovery)

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26
Q

What is the definition of RIND?

A

reversible ischemic neurologic deficit

resolves in >24 hrs (up to three weeks for complete restoration of function)

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27
Q

What is the leading cause of permanent disability?

A

strokes

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28
Q

What is the best treatment for stroke?

A

prevention

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29
Q

What is a thrombotic stroke?

A

clot in the artery in the brain

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30
Q

what is an embolic stroke?

A

piece of a clot is carried to the brain ( or anywhere)

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31
Q

What is a hemorrhagic stroke?

A

blood vessel in the brain breaks

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32
Q

What are the non-modifiable risk factors for stroke?

A

age - risk increases with age

sex - males

race - higher in african american

previous stroke

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33
Q

What are the modifiable or controllable risk factors for stroke?

A

hypertension

atrial fibrillation

cardiac disease

diabetes mellitus

elevated cholestrol

smoking

sedentary lifestyle

obesity

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34
Q

What are the warning signs for stroke?

A

sudden numbness or weakness

sudden confusion, trouble speaking

sudden vision issues

sudden trouble walking, dizziness or loss of balance

sudden headache

35
Q

What does weakness/numbness of one side indicate?

A

disease on the contralateral carotid

36
Q

if you have ocular symptoms where is disease indicated?

A

the same side - ipsilateral

37
Q

What are some things you can ask people to do if you suspect a stroke?

A

smile

talk

raise both arms

stick out tongue

38
Q

What is FAST?

A

Face

Arm

Speech

Time

39
Q

Can a stroke be asymptomatic?

A

yes

check for bruit if you have a risk factor but no symptoms

40
Q

What is Amaurosis fugax?

A

transient vision loss

41
Q

what is hemiparesis?

A

paralysis

42
Q

what is dysarthria?

A

speech difficulty

43
Q

what is aphasia?

A

inability to communicate (not making any sense)

44
Q

What is dysphagia?

A

difficulty swallowing

45
Q

what is ataxia?

A

what is gait disturbances

46
Q

what is diplopia?

A

double vision

47
Q

what is vertigo?

A

sensation of moving objects

48
Q

What is another name for the brachocephalic?

A

innominate artery

49
Q

What vessels come off of the aortic arch?

A

brachiocephalic

Left common carotid

left subclavian

50
Q

where does the aorta branch out of?

A

left ventricle

51
Q

the innominate or brachiocephalic artery divides into the _______

A

Rt CCA

Rt Subclavian - gives rise to the Rt. vertebral

52
Q

Which CCA is longer, left or right/

A

left is longer

53
Q

the left subclavian gives rise to what?

A

the lt vertebral

see slide 48

54
Q

What are variants of the aortic arch?

A

L CCA forms a common origin with the innominate artery

L vertebral artery arising from the arch

R subclavian artery arises from the arch distal to the Lt

Lt innominate may exist

left innominant may exist

55
Q

What vessels are enclosed in connective tissue called the carotid sheath?

A

carotid artery

jugular vein

vagus nerve

56
Q

where is the common carotid artery found?

A

anterolaterally in the neck

medial to the jugular vein

lateral to the trachea

lateral to the thyroid gland

57
Q

where does the vagus nerve lie in relation to the artery and vein?

A

between

58
Q

does the common carotid artery branch?

A

no it terminates at the bifurcation of the ICA and the ECA

59
Q

Where is the external carotid artery found?

A

originates at the mid cervical level

60
Q

What kind of waveform does the ECA have?

A

high resistance, low diastolic with a notch

usually the smaller vessel

61
Q

What are the identifying characteristics of the ECA?

A

smaller than ICA in diameter

usually the anteriomedial vessel

the ICA frequently has a mild dilatation at its origin termed the carotid bulb, the ECA has no bulb

cervical portion has branches, the ICA rarely has cervical branches

doppler signals normally more resistive in the ECA

response to temporal percussions (tapping in front of the ear makes the waveform vibrate)

62
Q

what is the first and most important branch off of the ECA?

A

superior thyroid

63
Q

What may form when significant disease is present in the ICA?

A

collateral pathways

64
Q

What does the ECA supply?

A

face

scalp

tongue

neck

runs medially and anteriorly to ICA

65
Q

Where does the ICA arise from?

A

the CCA birfucation

66
Q

where does the ICA enter the skull?

A

enters base of skull through petrous bone

67
Q

which is the larger of the CCA terminal branches?

A

ICA

68
Q

What is an unseen branch of the ICA?

A

opthalmic artery

69
Q

what does the ICA supply?

A

brain

eye

forehead

part of the nose

70
Q

What is the bulb?

A

where the ICA and ECA branch

includes distal CCA, proximal ECA and ICA

may be curved or tortuous

71
Q

Where does the ICA terminate?

A

at the circle of Willis

distributes to the low resistance vascular bed

see slide 78

72
Q

What are the differences between ICA and ECA

A

ICA: ECA:

lat/posterior med/anterior

no branches in neck branches early in neck

low resistance waveform high resistance waveform

no response/temp tap alterations waveform w/t tap

73
Q

What is the standard patient position for carotid scanning?

A

supine, head turned slightly (patient on your rt side)

vascular lab approach: patient upside down

no matter patient position, picture should be the same

74
Q

What are you looking for when scanning a carotid?

A

location of stenosis

extent of plaque and patency of the distal ICA

presence tortuosity or kinking vessels

plaque characteristics (smooth, irregular etc)

75
Q

What transducer do you use for carotid?

A

high frequency linear array 7-10MHZ

color with red being artery

angle correct

color display small

doppler parallel to vessel walls

76
Q

What needs to be adjusted throughout the carotid exam?

A

PRF or scale

wall filter

color box/gain

77
Q

What is the spectral waveform of the CCA?

A

demonstrates high and low resistance flow from ICA and ECA

CCA doppler signal will display + doppler shift throughout cardiac cycle

color flow pattern will have continuous color throughout cardiac cycle

78
Q

What is the boundary layer separation?

A

normal flow disturbance

detected as a transient reversal of blood flow along posterior wall of the bulb

sample volumes for ICA should start just distal to this area

79
Q

What is the vertebral artery?

A

branch of the subclavian

feeds cerebral part of the brain

80
Q

what are the segments of the vertebral artery?

A

extravertebral - evaluated during carotid exam

intervertebral

horizontal

intracranial

81
Q

the subclavian artery blockage will cause reverse flow in ______

A

vertebral artery

82
Q

What creates a 20mm hg difference in blood pressure between the two arms?

A

a subclavian artery blockage which causes the vertebral artery flow to go the wrong way

83
Q

What is a subclavian steal?

A

reversal of vertebral artery blood flow direction secondary to a sig obstruction prox to the orgin of the vertebral artery in the ipsilateral subclavian or innominate artery

a phenomenon

84
Q

What is the normal carotid doppler of the CCA?

A

sharp upstroke

clear doppler window

diastolic flow

85
Q

Why will the color pattern of the ICA have continuous color throughout the cardiac cycle?

A

due to low peripheral resistance of the brain

86
Q

Why does the ECA demonstrate a more pulsatile doppler signal?

A

because it supplies blood to skin, and muscular bed of scalp of face

has faster slope to peak systole and near zero in diastole

normal color flow pattern will reflect higher resistance of scalp/face

Vascular (6 decks)

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