Peripheral Arterial Sonography - HD

Introduction

Hi, I'm John Rito.
I'm professor of radiology at the Hofstra Northwell School
of Medicine and Vice Chair of Radiology
for the Northwell Health System.
Today I'll be talking about peripheral arterial sonography.
In this presentation, I will discuss the techniques
and protocols for the duplex examination
of the peripheral arteries.
We will review the diagnostic criteria for arterial stenosis
and occlusion, and I'll discuss the evaluation
of pseudo aneurysm and arterial venous fistula.

Diagnostic Tests for Peripheral Arteries

There are multiple diagnostic tests that we utilize
to evaluate the peripheral arteries.
They include the indirect tests such
as the ankle brachial index,
and of course we will focus on the value
of ultrasound in these evaluations.
We can also employ magnetic resonance angiography,
multi detector CT angiography,
and of course algo standard arteriography.
The indirect tests include the ankle brachial index.
We also use segmental pressure measurements
and pulse volume recordings.
I will show some examples of these tests
as we review cases during this session.
I also evaluate doppler wave forms routinely
during our investigations
and sometimes we will employ treadmill exercise testing
for our patients who present with a history of claudication
and normal baseline studies.
These indirect tests are useful for screening
and to demonstrate the level of disease.

Example of Indirect Tests

Here's an example of one of our indirect tests.
You can see the ankle brachial index on the right is within
the normal range, but there is an abnormal ankle.
Brachial index on the left is 0.61.
If we review the segmental pressure measurements,
we can see there's a significant decrease in pressure
at the femoral popliteal level,
and there is also a decrease in the amplitude
of the pulse volume recordings at that level,
particularly noticeable when we compare it
to the normal right side.
From this information, we can tell that there is
a significant lesion at the left femoral popliteal level,

Doppler Imaging Protocols

so there are different doppler imaging protocols
that we can use in our evaluations.
Sometimes we will do a screening evaluation from the
abdominal aorta down the lower extremity,
or we may focus on the detail level of interest
that was identified from our our indirect tests.
For these evaluations, we will use grayscale, color doppler
and pulse doppler.
During our evaluations, grayscale allows us to evaluate
for the presence of plaque.
The color doppler modality allows us to identify areas
of narrowing and aliasing so
that we can place the puls dola sample
at those arterial segments
and determine sites of flow disturbance
and significant stenosis.
For the lower extremity arterial mapping,
we typically begin at the level of the abdominal aorta
and bring the transducer through the common
and external iliac arteries through the common
and superficial femoral arteries down
to the popliteal artery
and trifurcation branches to the ankle.
We typically will use a five megahertz linear transducer
and we will change the range from three to 10 megahertz.
Depending on the depth of the vessels of interest,
we will optimize the gray scale
and the color doppler parameters.
We also adjust the pulse repetition frequency so
that we can detect hemodynamic disturbances
in the flow pattern
and we will perform pulse staler in regions of abnormal flow
or color aliasing.

Normal Peripheral Arterial Waveform

It's important to recognize the normal peripheral
arterial waveform.
The normal peripheral arterial waveform is phasic.
We have an initial high velocity forward flow component
that occurs with ventricular systole.
As the ventricle contracts, it sends a bolus
of blood down the lower extremity giving us this high
velocity flow component.
Then we see an early diastolic reverse flow component,
and this is related to peripheral resistance.
And then finally we'll see a late diastolic flow component,
and this is thought to do to elastic recoil
as the vessel snaps back into place further propelling the
red blood cells down the lower
extremity In.
In addition to observing the phasic appearance
of normal arterial flow, we will look
for the narrow systolic window or area under the curve.
In a normal vessel, all the red blood cells are moving at
approximately the same velocity at any given point in time,
and that provides this very clean,
crisp waveform appearance.
And of course, we're going to look at the velocity range.
Normal velocities, as you'll see, run between 60
and a hundred centimeters per second
no matter where we sample in the upper lower extremity
peripheral arteries, we expect to see aphasic waveform
in patients at rest.
For example, in the distal abdominal aorta pictured in the
top image we see a phasic waveform,
and of course in the subclavian artery we also see this high
resistant phasic flow pattern, systole and then diastole.
As I mentioned, normal peak systolic velocities will range
from 60 to a hundred centimeters per second.
You can see that the velocities will decrease
as we move down the lower extremity.
The femoral arteries have a velocity range
of approximately 80 to a hundred centimeters per second.
The velocity range is 60
to 80 centimeters per second in the popliteal arteries
and about 40 to 60 centimeters per second
in the tibial arteries.
It is important to analyze the waveforms when we perform
our arterial examinations.
The things that we look for are, again, the waveform shape,
is it phasic or not the peak systolic velocity range
and the spectral window.

Categories of Disease

Let's review the categories of disease.
The first category is mild
or minimal disease, which is characterized as one
to 19% diameter reduction.
With a mild stenosis, we have a mild
increase in the spectral broadening,
and you can see mild fill in of the spectral envelope.
On this example from the popliteal artery, we have up
to a 29% increase in the beak systolic velocity compared
to the normal proximal segment.
So in these cases, we will take a sample from the area
of abnormality and then we will compare that velocity
to the velocity in the normal proximal segment.
Typically a couple of centimeters upstream.
Notice that with mild lesion, we
maintain our normal phasic appearance
With a moderate lesion, which is described as 20
to 49% diameter or reduction.
We will see an increase in the degree of spectral broadening
or fill in of the spectral window.
We will have up to a 99% increase in the peak systolic
velocity compared to the normal proximal segment.
In this example, we see
that there's a stenosis in the superficial femoral art.
The peak cysto velocity is 166 centimeters per second,
which is less than double the peak velocity in the
normal proximal segment.
So the ratio with a moderate lesion is less than two to one.
Notice our reverse flow component is intact,
which is an important finding
because as we proceed into the significant disease category,
which is described as 50 to 99% diameter reduction,
we see a change in the waveform shape.
There is a loss of the reverse flow component
with a significant stenosis,
and in addition, there's typically
marked spectral broadening.
When we look at the velocity range,
we see there's greater than a hundred percent increase in
the peak systolic velocity compared to the normal segment.
Here is an example of a severe stenosis in the right
superficial femoral artery.
Notice the change of con color on the color doppler display.
We see aliasing at the side of the stenosis.
We use the identification of the aliasing segment
to place the sample volume
and move it through the area to capture
the highest peak cysto velocity in this case,
almost 450 centimeters per second.
So we can further define significant stenosis
as 50 to 75% stenosis when the ratio is greater than two
to one and greater than 75% stenosis when the
ratio is greater than four to one.
That is the peak systolic velocity within the stenosis
compared to the proximal segment.
Recognize that as we move the sample volume
through the abnormal segment into the post zoonotic area,
we will see characteristic findings
of post zoonotic turbulence, which confirm the presence
of a flow reducing lesion.
Obviously, if we have an area of occlusion,
there'll be absence of flow in that occluded segment.
In most cases, we will see a higher resistance waveform in
the patent segment proximal to the occlusion.
There's typically little or no flow in diastole
because the red blood cells have nowhere to go when they
come up against an obstruction.
This pattern can obviously change.
If there is collateralization in the area distal
to the occluded segment, we may see a low resistance
pattern, and this is due to the fact
that there's vasodilatation Due To ischemia
of the extremity, so we would expect to see a TTUs pattern
with lots of diastolic flow.
Collateral flow will typically have this appearance.
Collaterals that supply ischemic tissue typically have a low
velocity monophasic pattern
that is flow only in one direction.
It loses its phasic character.
We typically see a a delayed rise to peak systole.
It's the TARDIS parvis appearance.
Low velocity in this case,
less than 20 centimeters per second,
and as I mentioned, this low resistance pattern is related
to the degree of ischemia.

Case Reviews

Let's review a few cases.
This is a case of a 49-year-old diabetic patient is a smoker
with a history of prior myocardial infarction
with one block claudication.
When we look at the indirect studies, we know
that there's an abnormal ankle brachial index on the left.
We also notice there's a decrease in pressure
and a decrease in the amplitude at the
pulse volume recordings.
Let's take a closer look.
Notice here we have a significant pressure reduction
as we proceed down.
The thigh pressure goes from 164
to 96 millimeters of mercury.
We also notice a significant reduction in amplitude in the
pulse volume recordings,
which is particularly noticeable when you compare it
to the contralateral right side.
This tells us that there's a significant lesion along this
femoral popliteal segment
so we can tailor our duplex examination to that region.
Here's our first sample in this patient.
We're looking at the left common femoral artery.
We notice there's a fairly homogeneous color pattern.
The peak systolic velocity is about 86 centimeters per
second, and we have a normal phasic waveform.
As we proceed into the left superficial femoral artery,
we start to see that there's black, there's narrowing,
and there's aliasing In this segment,
the peak systolic velocity increases
to 256 centimeters per second.
As we proceed distally,
we noticed there is a significant decrease in the velocity
in the popliteal segment.
Now it's approximately 36 centimeters per second.
We've lost our phasic appearance.
We have a low velocity, low resistance
TARDIS parvis waveform confirming that we have
a pressure reducing stenosis,

Color Flow Findings in Peripheral Arterial Investigations

So there are important color flow findings
that we should look for in our peripheral
arterial investigations.
We use the pulse repetition frequency
to help us identify a focal color change at
the site of the stenosis.
This allows us to place the sample volume
to get the highest peak systolic velocity.
We look for color brewery artifacts to also tell us
where there is a significant flow disturbance.
These are perivascular tissue vibrations due
to high velocity flow and tissue vibration.
We will also see a color mosaic pattern
in the post knot area due to turbulence.
Let's take a look at some color aliasing.
In this example, we have a significant stenosis in the
posterior tibial artery.
Notice the focal color change
that occurs within the tightest part of the stenosis.
This is obviously where we wanna place the sample volume,
move it through this area
to get the highest peak systolic velocity.
When we do so, we see the peak systolic velocity is over 350
centimeters per second,
and this is the velocity we will use
to characterize the lesion as a high grade stenosis.
Here's an example of a color bruie artifact.
Notice that in systole we see the scintillating pattern
of color that washes over the soft tissues
at the side of the stenosis.
This is a very helpful artifact
that allows the investigator to identify the area
of high velocity flow
and be able to place the sample volume
to get the highest peak STI velocity.
Notice that these color disturbance occurs
during peak systole.
Here's a case of arterial occlusion involving the
superficial femoral artery.
As we discussed before, we have an area of
absent flow in the occluded segment.
In this particular case,
we see a prominent collateral arising from the distal aspect
of the superficial femoral artery above the occlusion.
This is well seen on the magnetic resonance angiogram.
We can see there is a abrupt occlusion
of the superficial femoral artery at the site
noted on the ultrasound exam
and the prominent collateral that is going
to feed the lower extremity.

Important Pulse Doppler Findings in Peripheral Arterial Disease

Important pulse dola findings in peripheral arterial disease
include elevated peak systolic velocities
within the stenosis.
There'll be loss of diastolic reversal in the stenosis.
That's because the red blood cells cannot reverse when
there's a pressure reducing state.
Those red blood cells get sucked
through the stenosis into the post stenotic area.
Blood flow can only be in one direction
through a high grade stenosis.
We could also see evidence
of a bruery artifact on the pulse doppler spectrum,
and of course, we will look for evidence
of tardis parvis waveforms in the post stenotic area distal
to a high grade stenosis.
Here's an example of a patient that presented with leg pain.
Again, note on the color display we have plaque
narrowing, aliasing,
and of course a color brew artifact alerting us to the
location of the lesion in the common femoral artery.
We're gonna place our sample volume
and drag it across this segment
to capture the highest peak systolic velocity.
When we do so, we see
that the velocity is over 400 centimeters per second.
Also notice that during peak systole we have this artifact
right at the baseline.
Notice that it occurs at the highest point in the velocity,
and this is a bruery artifact.
The bruery artifact is a low frequency artifact
that is seen on both sides of the baseline
because brews have no direction.
As we proceed down the lower extremity, we'll see
that the velocity decreases
to 91 centimeters per second in the
superficial femoral artery.
Notice now we have a low resistance wave form
flow only in one direction in systole and diastole,
and then we move into the mid portion
of the superficial femoral artery
and the velocity increases
to about 180 centimeters per second, indicating
that we have a second stenosis,
so we have tandem lesions.
In this case, we see a lesion in the common femoral artery
and a second lesion in the superficial femoral artery.
And as you would expect,
as we move into the popliteal artery, you'll see now
that we have low velocity, low resistance waveform
with a TARDIS appearance, a slow rise to peak systole, sort
of a TP appearance is characteristic of a, of a patient
that has a significant proximal lesion.
In this case, two lesions that we have identified,
and the velocity is approximately 30 centimeters per second.
Our next patient presents with rest pain,
had abnormal indirect studies and pulse volume recordings.
Our first sample is from the common femoral artery.
Notice here that the velocity is only 37
centimeters per second.
We have an abnormal waveform and that it is not phasic.
One thing I want you to recognize
that it has a rapid systolic upstroke.
The upstroke is perpendicular to the baseline,
meaning the inflow should be normal.
Let's take a look at another waveform.
Let's move down into the superficial femoral
artery and what do we notice?
We have a further decrease in the peak systolic velocity.
We went from 37 to 14 centimeters per second.
Notice also that the waveform has changed.
Now it's even higher resistance.
There's no flow in diastole,
so we maintain our rapid systolic upstrokes suggesting the
inflow is normal, but very high resistance
suggesting there's outflow obstruction.
So where do you think the lesion is?
Would it be in the external iliac artery,
common femoral artery, superficial femoral artery,
or popliteal artery?
Well, by analyzing these waveforms, you should be able
to tell that the inflow is should be normal as we have
that rapid systolic ups throw.
So a lesion in the external iliac
and common femoral artery would not be correct.
When we get into the superficial femoral artery, you notice
that we have decreasing velocities,
increasing resistance indicating we're getting closer
to the level of disease.
So the appropriate answers would be either the distal
superficial femoral artery or the popal artery.
Let's see what we find as we move into the
mid to distal portion of the superficial femoral artery.
We see there is evidence of occlusion
and what we find are multiple collateral vessels running
through the tissue in the vascular bed.
So we have a superficial femoral artery occlusion accounting
for the low velocities
and high resistance in the waveforms that we visualize.
As we proceed inferiorly into the popliteal artery,
you'll notice that the popliteal artery is occluded.
It's the a calcified wall,
no flow seen in the popliteal artery on the color display.
And we confirm that
by placing the sample volume within the vessel,
and we notice that there is no flow on the spectral trace.
So we have a long occlusion
of the superficial femoral artery extending into
the popliteal artery.
And this was confirmed on the magnetic resonance angiogram.
Notice that at the levels of the abdominal
or an iliac vessels,
although there is mild disease there,
the vessels are patent.
When we extend the exam into the extremities,
we see there is a abrupt termination
of flow in the proximal superficial femoral artery.
As we predicted from the duplex exam,
we see collateral vessels running through the tissue
and the occlusion extending through the popliteal artery.
Our next patient is a 70-year-old
with one block claudication.
We're starting this examination at the level
of the external iliac artery.
The vessel has a normal diameter, a normal flow pattern,
and a peak systolic velocity of 78 centimeters per second.
Notice the phasic appearance.
Then we move into the common femoral artery,
still have normal caliber vessel, normal color flow pattern.
Peak velocity within the normal range is 86 centimeters per
second and aphasic appearance.
As we move into the superficial femoral artery, we see
that there is marked narrowing.
There's plaque and a peak systolic velocity at the site
of narrowing is almost 290 centimeters per second.
So clearly we have a significant stenosis at this location.
Let's keep going. As we move into the distal portion
of the superficial femoral artery,
the peak systolic velocity decreases from 288
to 88 centimeters per second notice.
Now we have a low resistance flow pattern likely due
to ischemia in the distal extremity.
Interestingly, we start to see collaterals
arising from the superficial femoral artery.
And the reason that we see these collaterals is
as we move into the popliteal artery,
we see there's evidence of occlusion.
So another example of patient with multiple lesions,
we have a lesion in the superficial femoral
and occlusion of the popliteal artery,
so we would expect there to be marked changes
in the distal vessels of the calf.
And this is demonstrated by this sample
taken from the distal left popliteal artery
where we have low velocity flow less than 40 centimeters per
second, and a TARDIS parvis wave form.
As we move into the dorsalis,
we can see here low velocity flow less than 20 centimeters
per second, and marked TARDIS parvis changes indicating
significant proximal disease.
And these changes were noted on the indirect studies
that were performed prior to the study.
You can see here from on the left side
that there is a decrease in pressure at both the
femoral popliteal
and popliteal tibial levels, decreased pressures,
decreased amplitude,
and you can see as we proceed down into the metatarsal
and tar and digit levels markedly reduce flow compared
to the contralateral side.
Now here's a sample taken from the popliteal artery.
You can see the vessel is enlarged,
the diameter is 2.4 centimeters per second.
What's the diagnosis? Oh, I think that's fairly obvious.
We're looking at a popliteal artery aneurysm.

Popliteal Artery Aneurysm and Entrapment Syndrome

The popliteal artery aneurysm is the most common peripheral
arterial aneurysm.
And the second most common that we may see,
it has a strong male preponderance
and is typically identified as a pulsatile mass,
which can be bilateral in 50 to 70% of patients,
and about 40%
of patients will have a concomitant
abdominal aortic aneurysm.
Another popliteal artery lesion
that you should know about is the
popliteal entrapment syndrome.
Popliteal artery entrapment syndrome refers
to symptomatic compression
or occlusion of the popliteal artery due
to an abnormal relationship with the medial head
of the gastric anemia muscle
or less commonly with the popliteus muscle.
Here I'm showing an example
of popliteal entrapment on magnetic resonance angiography.
As it's easy to demonstrate, this can also be
identified on the duplex study.
Our next case is that of a 60-year-old with left arm pain,
and it's important to recognize every once in a while you're
gonna get some very strange waveforms
and it's important to take some time
to evaluate the waveforms and and get
and get a thorough look at the extremity to try
to figure out what's going on.
Now this initial waveform obtained from the left sup from
the left subclavian artery looks relatively normal.
Looks like we, it has aphasic appearance,
but recognize that the velocity is on the low side.
It's only 46 centimeters per second.
As we proceed into the axillary artery, now we start
to see some strange waveforms.
Now notice when we look at the axillary artery on the
colored display, it appears almost completely
thrombo at this level.
We see a little bit of flow along the periphery
of the vessel, and we see a strange looking
monophasic waveform flow only in one direction completely
filled in under the spectral window.
So what could this be due to?
See the velocity is about 90 centimeters per second.
And addition, if we take a second waveform,
we see almost a two
and fro plat pattern also arising from the periphery of this
almost completely occluded axillary vessel.
And as we pursue down into the brachial artery, we can see
that there's a low velocity tardis waveform.
And how do we put this all together? Look at the velocity.
In this case, it's only nine centimeters per second.
That's very low velocity flow.
So because we have this constellation of waveforms, we need
to go back and take a look at the entire vessel,
and we can appreciate that.
What we, what's going on here is
that we have an axillary artery occlusion,
and we can see from the distal end
of the subclavian we have these collaterals coming off
and these collaterals reconstitute the distal axillary
and brachial arteries.
And some of those strange wave forms
that we were seeing were coming from the collaterals, some
that were delivering blood flow to the distal vessel,
giving us a low resistance waveform
and some not quite getting there, giving us that sort
of high resistance to andro waveform.
So in order to interpret some of these strange waveforms,
we really need to take a look at the entire upper extremity.

Pseudoaneurysms

Let's shift gears here and talk about pseudo aneurysm.
As we know, pseudo aneurysms
or vascular masses connected to the femoral artery
by a track or a neck,
they can result from a hole in the arterial wall,
which allows the escape of blood Under pressure,
blood is typically confined by the surrounding soft tissues
and hematoma, and we typically see these
after an arterial puncture for a diagnostic
or a therapeutic procedure.
Less commonly these may arise from other forms
of trauma or infection.
The duplex and cauli flow findings associated
with pseudo aneurysm includes swirling color flow
that occurs within the pseudo aneurysm sac,
so-called yin yang pattern.
We look for a track
or a neck that communicates
between the pseudo aneurysm cavity and the feeding artery.
We will see a two and fro flow pattern when we place the
sample volume in the neck.
And this is due to the fact
that a high velocity jet enters the pseudo aneurysm cavity
during systole, and then there is a reversal
of flow back into the artery during diastole due
to a change in the pressure that occurs within the sac.
Notice the change of color that occurs
with systole and diastole.
That is the color correlate of the two
and fro flow that we see on the spectral trace.
So when we place the sample volume in the neck
of the pseudo aneurysm, we see the two
and fro flow pattern flow goes into the sector in systole,
and then this continuous reversal
of flow back into the artery during diastole.
There are different types of treatment that can be offered
for pseudo aneurysm.
When pseudo aneurysms are small, typically a centimeter
or less, they may spontaneously thrombosis
and may not need to have an intervention.
Surgical repairs typically reserved
for those pseudo aneurysms that are growing
or don't have a visible neck.
Ultrasound guided compression repair used
to be the noninvasive standard for the treatment
of pseudo aneurysms, which has subsequently been replaced
by thrombin injections.
Of course, when pseudo aneurysms occur in unusual places
such as in the axillary subclavian vessels, different types
of interventional procedures may be performed
to treat pseudo aneurysms such as balloon occlusion.
As I mentioned, thrombin repair
of pseudo aneurysms has sensual replaced compression repair.
It is the non-operative alternative.
And for these types of procedures,
we employ a 22 gauge needle,
which IMP is placed into the pseudo aneurysm cavity.
Under ultrasound guidance, a small amount
of thrombin is then injected directly into the cavity
as we observe immediate thrombosis of the pseudo aneurysm.
And this has proven to be a fast, fast
and effective treatment for pseudo aneurysm.
Here's an example of one of our cases of thrombin repair.
You can see a well-defined pseudo aneurysm arising from the
common femoral artery.
The neck is is can be seen between the femoral artery
and the pseudo aneurysm.
And following thrombin injection, you can see
that the pseudo aneurysm has been converted into a hematoma.

Arteriovenous Fistulas

Next, let's talk about arteriovenous fistula.
These also occur secondary to femoral artery punctures
or other types of penetrating trauma.
These are seen less commonly than pseudo aneurysms.
Typically, they occur between the common
or deep femoral artery and the common femoral vein.
And when these communications are large,
they may result in ischemia or congestive heart failure.
In this particular case, we can see this communication
that exists between the artery and vein.
We appreciate this arc
or this track that communicates between
the artery and the vein.
When we place the sample volume into the fistula,
we typically see high velocity low resistance flow.
Because the artery is
filling a low pressure system here,
the peak cysto velocity is almost 300
centimeters per second.
Notice the continuous forward flow that occurs
through systole
and diastole, which is markedly different from
that higher resistance to andro flow pattern
that we saw earlier.
With pseudo aneurysm, the color
and pulse dolar findings seen with arterio venous fistula,
we see continuous blood flow between the artery and vein.
Persistent forward flow on the waveforms obtained
during pulse dolar sampling
a color brewery artifact is not uncommon that it is seen
during systole from perivascular tissue vibration.
And again, the communication is typically seen in diastole.
Here we have two images, one in systole, one in diastole.
During cyst during systole, we see the the noise,
the color brew, and if we freeze
and move into diastole, we can better see the communication
identified as alias in between the artery and the vein.
One of the ways that we can document the presence
of an arterial venous fistula is
by demonstrating high velocity
low resistance flow on the arterial side
and an arterialized flow pattern on the venous side.
Here's another example.
Here is my rainbow fistula from the artery to the vein.
Notice on the arterial side, we have loss
of the phasic pattern.
We will low resistance pattern,
and when we move the sample volume into the venous side,
we see it has become arterialized.
Let me finish up by showing you
a couple of interesting cases.
This was a 74-year-old status post groin cat catheterization
and presented with a pulau groin mass.
Here we see an outpouching from the femoral
artery on gray scale.
When we turn the color on,
we can see there's a small communication that occurs
between the artery and this mass.
When we look at it with power doppler,
we can see this communication very nicely,
and I think most of us looking at these color images would
assume it is a pseudo aneurysm.
Trouble is that when we sample this neck,
we get this high velocity low resistance pattern,
which is not consistent with a pseudo aneurysm,
but more consistent with an arterial venous fistula.
So how do we reconcile this difference?
Well, we keep looking
and as we scan around the area, we can appreciate
that not only does we have this out patching
and this small collection,
but the communication between this area
and the the draining vein.
So we in fact have an arterial venous fistula,
which is the reason why we have this high
velocity low resistance pattern.
These are important findings
because if we would try to treat this with thrombin, we risk
injecting thrombin into the venous system.
So the case is an 85-year-old with a pulsitile groin mass.
And again, similar findings in that we see what looks like
a pulsatile groin mass arising from the femoral artery.
Again, I think just from looking from the at the color flow
image, one might assume that we have a pseudo aneurysm.
When we sample the apparent neck.
Again, we get this very low resistance pattern.
We don't see a two
and fro flow pattern that we would expect if it
were a pseudo aneurysm.
So something is not quite right
and requires us to take a closer look.
So going back into the room,
let's take another look at the patient.
And notice here on the color display, we sort of have a rain
of color that proceeds from the superficial tissue.
It's just raining down across the soft tissues
and wonder what this artifact could be coming from.
As we sample around the tissues, again,
we have a low resistance pattern,
so we should be thinking about arterial venous fistula,
although we can't find that, that communication yet.
So we work a little bit harder
and then we can identify
that we have this large arterial venous fistula extending
from the artery all the way around to the draining vein,
which is why we have this low resistance pattern
because what we have here is an extensive
arterial venous fistula.

Conclusion

So in conclusion, there are a number of different tests
that we can use to evaluate the peripheral arterial system.
We find the indirect tests are extremely helpful.
They serve as a screening examination
and allow us to focus on an area of interest for our pulse.
DOLA studies, duplex
and cholo doppler are very valuable
to characterize focal lesions, monitor disease progression,
direct appropriate intervention,
assess therapeutic response,
and help identify complications of treatment.
Thank you.