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30 Cards in this Set
- Front
- Back
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how to calculate resistive index
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peak systole - end diastolic flow / peak systolic flow
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what causes the dip below the baseline that can be seen in nml high resistance arteries
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elastic recoil of arterial wall seen in early diastole
transient flow reversal occurs b/c there is high resistance to fwd flow so there is transient reversal of flow from passive reoil |
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what does a triphasic arterial wave look like
example |
first phase - above baseline
2nd phase - below baseline 3rd phase - above baseline seen in extremitie s |
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what is aliasing
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causes high frequency components to wrap around from the positive extreme of hte scale to the negative extreme (or vice versa)
the color appearance can switch as well |
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when can aliasing be useful
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can identify areas of high flow velocity
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what causes aliasing
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pulse repetition frequency is too low --> artifactually negative frequency shift information
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appearance of aliasing
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1st: truncation of systolic peaks with wrap-around of peaks below baseline
eventually, there can be multiple wrap arounds and becomes non-arterial in appearance |
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how to decrease aliasing
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shift to a lower frequency probe
scan at a large doppler angle scan so that the probe is closer to the BV |
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describe relationship between ECA and ICA
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ECA is anterior and medial
ICA is lateral and posterior |
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ddx for hypoechoic mass in testis
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malignancy
infarct focal atrophy focal orchitis hematoma abscess sarcoid contusion |
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which testicular tumor more commonly has calcs
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germ cell tumor
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what is parvus et tardus and when do you see it
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very distal to the stenosis
will see delayed upstroke and prolonged downstroke |
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describe post-stenotic turbulence
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when there is doppler waveform signal to and from the transducer
has a very jagged appearance |
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what can cause baseline carotid velocity to be decreased (artificially)
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aortic stenosis, decreased CO, occult proximal stenosis
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what can cause the carotid art velocity to be overestimated
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high grade stenosis on contralateral side
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peak systolic velocity indicating >70% çarotid stenosis
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230 cm/s
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diastolic velocity indicating >70% carotid stenosis
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>100 cm/s
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where is most common location for ICA stenosis
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first 2-3 cm
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what does total occlusion of ICA lead to in CCA
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"externalization of CCA" b/c all the blood flow goes to CCA
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describe blood flow pattern if there is complete occlusion of CCA
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flow from contralateral ECA across head and neck to supply ipsilateral ICA via retrograde flow through ipsilateral ECA -->flow through ICA across CCA bifurcation
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what does reversed flow in vertebral arteries indicate
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stenosis/occlusion at origin of subclavian or brachiocephalic vein
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how is blood flow maintained in a subclavian steal syndrome
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contralateral carotid and vertebral artery blood flow crosses through COW and basilar artery --> retrograde flow in the vert artery that is affected
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define pseudoaneurysm
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hematoma that maintains an internal area of extravascular bl flow via a patent neck (usually in the groin, in communication with fem artery)
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how to dx pseudoaneurysm on US
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look for swirlying/yin-yang in lumen of pseudoaneurysm
flow in the neck shows systolic flow into aneurysm and diastolic flow out of aneurysm (in sequence) |
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how to tx pseudoaneurysm
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thrombin injection under US
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define pseudoaneurysm
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hematoma that maintains an internal area of extravascular bl flow via a patent neck (usually in the groin, in communication with fem artery)
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how to dx pseudoaneurysm on US
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look for swirlying/yin-yang in lumen of pseudoaneurysm
flow in the neck shows systolic flow into aneurysm and diastolic flow out of aneurysm (in sequence) |
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how to tx pseudoaneurysm
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thrombin injection under US
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branches of the renal arteroes
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segmental arteries (travel from hilum to renal sinus)
--> interlobar and arcuate arteries |
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abnormalities assoc with renal art stenosis
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focal areas of aliasing
localized perivascualr tissue vibration peak systolic velocity >200 cm/s velocity:peak aortic velocity ratio >3.5 |
