Cerebrovascular Duplex Imaging Flashcards
difference between ICA and ECA
ICA:
larger, more lateral, no branches, low resistance
what is the technique to differentiate ECA from ICA
temporal tap
tapping on temporal artery can result in oscillation in the ECA spectrum
describe proximal to stenosis profile
flow may / may not be disturbed or dampened depending upon severity and precisely where the sample is obtained
describe stenosis profile
spectral broadening and elevated frequencies/velocities
describe post stenosis profile
turbulence (flow reversals, eddy currents, vortices)
PSV for stenosis greater than 50%
125 cm/s
EDV for stenosis greater than 80%
140 cm/s
What would cause an over estimation of disease
Inappropriate/inaccurate Doppler angle of insonation
Increased cardiac output
Compensatory flow
What would cause under estimation of disease
Inappropriate/inaccurate Doppler angle of insonation
Poor technique - miss the highest velocity jet
Altered cardiac output, severe LV dysfunction, critically ill patients, left ventricular assist devices
Stenosis in dilatation/prominent carotid bulb
The geometry of the stenosis/lumen, ex: a long smooth stenosis
What is the normal ICA/CCA ratio
<2.0
What is the ICA/CCA ratio for a stenosis of 70% or greater
> 4.0
Name two carotid artery intervention
Endarterectomy, angioplasty with or without stent
Describe endarterectomy
A surgical procedure in which the artery is isolated and opened. Atherosclerotic plaque is removed, often along with the inner lining of an artery. The artery is sutured closed
Describe angioplasty with or without stent
A balloon catheter is passed into the artery and positioned within the stenosis. The balloon is inflamed, opening the artery lumen and then deflated and removed. Often, a metal wire mesh stent is expanded in the area of the stenosis as a scaffold to hold the artery lumen open
