CVTE 103 Carotid Flashcards
Rotating:
turning the beam around its axis.
Angling:
sweeping the beam across its axis
Usually in short
Rocking
the beam along its axis.
Sliding:
moving the probe across the skin.
There are only four basic kinds of probe movement—four things you can do with the ultrasound beam to alter your image.
Angling Rotating Rocking Sliding
Don’t let your elbow
stick out to the side. Just let it drop relaxed from the shoulder. This keeps you from bending at the wrist into the “carpal tunnel position”.
The brain is perfused by …
the two carotid and two vertebral arteries
The ophthalmic arteries arise just…
proximal to the circle of Willis.
The internal carotid arteries perfuse
the eyes
The external carotid arteries perfuse
the face and scalp.
ophthalmic artery branches from
ICA just proximal to the circle of Willis and the brain.
Common carotid artery arises from
the aortic arch on the left, from the innominate bifurcation on the right.
The CCA bifurcates into
internal carotid and external carotid arteries at about the level of the laryngeal prominence (Adam’s apple).
Transverse divides things into
superior and inferior.
The right carotid artery is the first branch off of the aorta. The first branch off of the aorta is the innominate and it bifurcates into
the right subclavian and the right common coratid artery.
The left common carotid artery comes off of
the aorta.
Most strokes are caused by
atheromatous plaque at the carotid bifurcation.
Other possible causes of stroke include
hemorrhagic stroke and embolic activity from the heart.
Superficial temporal artery and the temporal artery can provide
collateral circulation if the ICA is blocked.
The superficial temporal artery is the superior part of the ECA.
The superior thyroid is just a landmark to find
the ECA
Superficial is
on the top next to the surface
Deep is
farther down than superficial
Medial is to the
right on the right, to the left on the left.
Transverse procedure:
Start low in the neck, bumping the clavicle.
Keep the CCA centered and move distally to the bifurcation.
Identify the branches, then go as far distally as possible in the ICA.
Orientation in sagittal:
Feet are always to the right of the screen.
Move toward feet; tissue should come into the screen from the right.
(From transverse, rotate clockwise.)
How do you keep the walls clear?
Angle and rotate, rotate and angle.
Identifying the branches:
ICA is usually
ECA is usually
ICA: the larger one, and usually the lateral one.
ECA: smaller and medial.
Approaches on the neck:
Anterior
Lateral
Posterior
These refer to the position of the probe relative to the principal landmark on the neck:
the sternocleidomastoid muscle:
It makes a good acoustic window, so we stay conscious of using it for good image quality.
You must progressively lay the probe _________ to keep aiming at the artery as you move from anterior to lateral and posterior approaches.
back
The best approaches:
- Start
- Then
Default to
Start anterior low in the neck to get as far proximal as possible.
Then move quickly to a lateral approach— almost always best image quality (using the SCM muscle as a window).
lateral, anterolateral, and posterolateral approaches unless the anatomy dictates otherwise.
Most common error in carotid performance test year after year:
Stuck anterior. Usually makes for a fuzzy image. And usually the result of tension.
Image problems and how to fix:
Transverse: Artery not centered.
Fix by rocking the beam to move it to the center of the field of view. (Or maybe just a small scoot of the probe face.)
Image problems and how to fix:
Sagittal problems: Ends closed off.
Fix by rotating to line up with the artery. (Sometimes it’s just one end—then rotate that end.)
Image problems and how to fix:
Sagittal problems: Walls fuzzing out.
Not sending beam through largest diameter of artery.
Image problems and how to fix:
Sagittal problems: Artery not level.
Fix by rocking the beam to level it. (A bit more pressure on the deeper end of the artery…)
Controls on scanner
Depth
Set so that there’s clearance under vessels, but not so deep that there’s a lot underneath. 4 cm is almost always good for most carotid patients.
Controls on scanner
Gain
This is the amount of amplification of the return echoes. Master gain is overall amplification.
Controls on scanner
TGC:
Time gain compensation Controls gain at different depths, to compensate for loss of echo strength (attenuation) at deeper structures.
Controls on scanner
TCG
The TGCs usually need to be pulled down in the near field (to keep it from being too bright), and boosted in the far field (to keep it from being too dark).
TRY TO EVEN OUT THE GRAY SCALE THROUGHOUT THE FIELD
Sagittal is divided into
Left and right
long axis or longitudinal
