MOCK Midterm Flashcards
What must be known for the US to convert the Doppler frequency shift to a velocity?
Doppler angle
Using 60 degrees for your Doppler angle improves (2)
Reliability of velocity
Consistency throughout exam and from one exam to the next
Describe the levels of pulsatility with the vessel: Subclavian A ICA ECA CCA Vertebral
Subclavian A: High pulsatility ICA: Low pulsatility ECA: Mod pulsatility CCA: Mod pulsatility Vertebral: Low pulsatility
SCA waveform
High pulsatility, high resistance
Little/no EDV
T/F poor cardiac activity profoundly affects flow in cerebrovascular system
True
What parameter is used to assess stenosis in patients with heart condition?
Ratio NOT velocities
T/F pressure will decrease following a hemodynamically significant stenosis
True
In the event of SSS, what happens? (3)
Ipsilateral vertebral flow is reversed
Damped flow distal to stenosis, tardus parvus waveform
Ipsilateral brachial pressure decreased (>20 mmHg)
Contralateral brachial pressure not affected
T/F the RT and LT brachial pressures must differ by 20 mmHg to be considered significant in SSS
What does the waveform look like at 20 mmHg vs. 40 mmHg
True
At 20 mmHg vertebral artery waveform is bidirectional
At 40 mmHg VA waveform retrograde flow
The opthalmic artery may be a source of collateral flow in which circumstance?
What direction of flow will be visualized in the OA?
What feeds the opthalmic artery?
ICA high grade stenosis/occlusion
Retrograde OA flow
ECA feeds the OA
What parameters are useful in grading a stenosis? (3)
PSV
EDV
ICA/CCA Ratio
T/F colour Doppler is not affected by the colour box angle
False
Steer box in the same direction as the angle
T/F Internalization of the ECA occurs in the event of ICA occlusion
True
A high grade stenosis occurs when the lumen diameter is significantly reduced
True
T/F Tardus parvus waveform indicates a hemodynamically significant prox stenosis
True
What describes a stroke?
Motor/sensory deficit lasting > 24hr
Major cause of vascular disease
Atherosclerosis
ICA symptoms include (3)
Paralysis on contralateral side
Decreased level of consciousness
Amaurosis fugax
(NOT ataxia)
What neurological symptom is related to atherosclerosis disease in the posterior circulation
Vertigo
Continuous wave Doppler can be used in all the following (3)
Peri-orbital
Extracranial arteries
Trans cranial arteries
(NOT ocular pneumoplethysmography)
What is the most utilized of the Doppler criteria for estimation of percentage diameter stenosis?
PSV
What artifact is encountered with pulsed Doppler in a hemodynamically significant stenosis/
Aliasing
Aliasing occurs when _________
How may it be corrected? (5)
Frequencies exceed the Nyquist limit (1/2 PRF)
Corrected: Change probe position Decrease depth Increase PRF Increase Dop angle Lower frequency
3 advantages of power Doppler
Defining occlusive vessels (detection slow flow)
Independent of angle
No aliasing
Tunica media can be described as
Layer of muscle and elastic tissue
Variable plaque morphology can be described as
Heterogenous with anechoic areas
The cerebrovascular vessels arise from the
Aortic arch
Branches of the subclavian artery include (4)
Vertebral
Internal thoracic
Thyrocervical & costocervical trunk
Dorsal scapular
ICA spectral analysis description (3)
Rapid increase velocity during systole
Clear window
Continuous antegrade flow during diastole
Term that describes flow in normal carotid artery
Laminar/parabolic