Vascular Ultrasound Imaging & Doppler Chronic Venous Examination - SD

Introduction

Hello, my name is Ann Marie Kapinsky
and I'm from the Northeast Vascular Imaging Group
in Albany, New York.
And I'm going to present
to you today the chronic venous duplex
ultrasound examination.
We're going to examine the ultrasound requirements
for the chronic venous insufficiency examination.
Today I'm going to take you through the areas that need
to be evaluated as well as,
talk about diagnostic criteria
and some of the variations in terms of treatment
for chronic venous disease.

Patient Examples and Importance

If you don't work at a dedicated vein center,
you may never encounter a patient like this one here.
This is a patient with a venous stasis ulcer
and we could see it's really red and weepy and bloody.
We can see the discoloration on the skin as well.
And this certainly is the end result
of chronic venous disease.
Something we wanna prevent
because it does have pretty severe debilitating effects
for the patient and their lifestyle.
Most of us have encountered these type patients
with pretty severe varicose veins.
Now we can offer a lot more treatment options for them.
And what we'll go through is exactly what we can do
for diagnostic options.

Prevalence of Venous Disease

Why do we see so many patients with venous disease?
Unfortunately in the United States, about a third
of all American women have some level of varicose veins.
Only about 19 to 20% of men have varicose veins.
However, when we get over the age of 65,
varicose veins are present in about half of us,
and that's a pretty high percentage for any type of disease.
So we will see a lot of these patients in our departments
and laboratories doing the math.
About 6 million Americans we'll present
with skin changes alone that are consistent
with chronic venous insufficiency
and about a half a million Americans have
venous stasis ulcers.
This is a pretty widespread phenomenon.
So we will see these patients a great deal.

Performing the Venous Insufficiency Examination

Assessing Valves

How do we perform the venous
insufficiency examination?
It all comes down to really looking at the valves
and assessing whether
or not the valve is functioning in,
in this image up here we see a valve open down here.
We can see pressure applied to the back of the valve.
The valve is now closed
and this is exactly what we wanna be able to
reproduce at various levels in the limb
to make sure the valves are open or closed.

Hemodynamics and Hydrostatic Pressure

Now you've probably seen this schematic a number of times
before this was borrowed from a earlier article
by David Sumner where he talked about hemodynamics.
And I put this in to illustrate the fact that
we need hydrostatic pressure here to help us generate
pressure against those valves if we're supine,
we use the heart as a reference point
for all pressure measurements in the human body.
And if we're supine, the venous pressure is about zero.
So if we stand up here,
we add hydrostatic pressure
because we've created the effect of gravity due to the fact
that the veins down at the ankle
are set distance away from the heart in
and about a six foot individual, give or take.
That pressure gradient is now 100, give
or take millimeters of mercury.
So if we were supine, the pressure at the heart is zero,
the pressure at the ankle's about 15,
obviously blood flows down a pressure gradient.
So it goes from 15 to maybe about five or 10 to about two
or three back to zero.
But now we've added a hundred millimeters
of mercury when we've stood that patient up.
So we've got about a sevenfold increase in venous pressure,
which is great and helps us do our job to push
pressure against the valves
and see if we can make them not work.

Illustrations of Hydrostatic Pressure

This cartoon borrowed online here just illustrates again the
effects of hydrostatic pressure.
The surface of the water is the reference point in this
illustration, just as if the surface
of an ocean is a reference point for a deep sea diver.
And we can see the pressure near the top
of the barrel here is not so far
'cause the water doesn't stream out so far,
but lower down in the barrel.
As we've increased that distance
and increased the effect of gravity on pressing down on
that column of fluid,
we've actually got higher pressure at the lower barrel
and we can see this stream of water go further.

This is a another slide that I've shown before in the past
and it illustrates the effect of
of hydrostatic pressure as well.
Here's a styrofoam cup we have in the center,
our favorite sharpie marker along the bottom,
and these two objects are actually also styrofoam cups.
They were tied to the outside of a deep sea vessel
and brought down to about 25 a hundred meters,
which is about 8,000 feet, give or take.
The pressure of that weight of the ocean on
that styrofoam cup
actually squeezed out all the air from the cup
and collapsed it down.
So that's a pretty phenomenal effect of hydrostatic pressure
and we wanna do something like
that when we examine our patients.
We have to maximize venous pressure.

Patient Positioning and Ergonomics

Really the ideal position is standing.
If you can get good results standing,
you know you've done the best thing
you can do for your patient.
Now sometimes some patients are not in shape to stand
for long periods of time,
so we can do them in a reverse trendelenberg position.
It's okay, but if you have any doubt, we have
to stand the patient up.
Certainly we wanna observe proper body mechanics.
A height adjustable bed is essential.
We wanna position, so we're scanning either right at our
side here or in front of us.
We don't wanna reach behind us if we are scanning down the
leg, we wanna step back, move the equipment back
with us and follow along.

A lot of people ask how do we do this
with a patient standing and how do we get through this exam?
Here we have our technologists sitting on this step stool
here and she's leaning forward.
Her back is bent, her neck is cocked here to the side
and she's examining the mid thigh area in this this subject.
However, this is totally gonna wind up with
her needing a massage if nothing else
because she's gonna produce a lot of strain on her neck
and shoulder and back.
We've changed from this stool to a step stool.
She's lower down so she's at a better position here
to examine the thigh.
We've moved the equipment down in front
and lower, so now she's much more ergonomically adjusted
so she can complete the exam.
When you're through with examining the thigh portion
of the leg when you have to go to the knee
and lower, then you can move the bed up,
have the patient dangle their leg over the side, go back
to a regular task chair
or stool, adjust the equipment again
so it's at the proper height
and you can complete the evaluation of the calf area.

Hemodynamics of Normal and Abnormal Flow

Now in terms of hemodynamics, this illustration shows
how normal blood flow happens in the lower extremity.
We have a deep venous system here
and the superficial venous system here
and they're connected in between by perforating veins.
If we take a step
and contract our calf muscles, blood heads north back up
to the heart, and when we relax,
these valves close both in the superficial
and deep system to prevent blood from falling back down.
So that blood fills the venous system only coming over from
the arterial side of the circuit.

Now when we see patients with varicose veins,
what happens is we still take a step, everything heads north
to the heart, but when we relax,
some blood comes over from the arterial side,
but some blood falls back down
because now we have incompetent valves
along the saphenofemoral junction
and within the superficial system.
So this prevents the blood from step moving only in one direction
and actually moves in a retrograde fashion filling these veins.
The increase in volume results in an increase in pressure,
the veins dilate, they become tortuous
and we see the classic presentation of varicose veins.

Now the worst case scenario is
where we have not only incompetent superficial valves,
but we now have incompetence of the perforator valves
and maybe some level of obstruction within the deep system,
some sort of latent chronic DVT that we don't know about.
So what happens is we take a step
and some blood goes up, some blood goes out,
the incompetent perforator,
some goes down the incompetent deep system,
and when we relax you can see some blood flows down,
some comes in and it's all this very circular
motion of flow.
So we can't empty the calf properly, we never reduce
that volume and that pressure
and it sets us up for
what can eventually become chronic venous
insufficiency with ulceration.

Detecting Chronic Venous Insufficiency

So in the ultrasound departments
or vascular labs, our job is to detect
and detect chronic venous
insufficiency in these patients.
When we evaluate for venous insufficiency, we have
to figure out what kind of pathology is involved.
Is it strictly reflux? Is there some DVT present?
Is it a combination of both? And what anatomy is involved?
Is it the superficial deep perforating veins,
proximal distal?
All those questions have to be answered by ultrasound.

Again, here's a patient with a venous stasis ulcer ulcer
and you can see the marked pigmentation
and the varicosities in their leg.
Now a complete protocol will involve all three areas.
Sometimes clinicians have seen the patient
before, they know what's going on
and they can focus you in on a particular segment.
But in terms of the deep system, we'll evaluate for DVT
as well as look for reflux within the common femoral,
femoral and popliteal veins.
We don't usually include the tibial level veins
because there's really not too much that can be done
for those vessels in terms of correcting
that valvular incompetence.
So many people choose not to scan those.
We also look at the superficial system,
but there we really need to evaluate the entire length
of the grate and small saphenous veins
and also perforating veins.
And in this kind of a patient here, many
of the perforators involved will be in the
region of the ulcer.

Ultrasound Flow Profiles and Criteria

This ultrasound image just shows a normal
venous flow profile.
We can see flow and then no flow.
We see tiny little bit of retrograde flow here
and that's normal because
as flow comes up towards the heart, the valves open
and we need just a little bit of back pressure to engage
and close those valves.
So this tiny little bit of amount
must be less than half a second
and that's normal valve closure phenomenon.

In this example here we can see this portion
of the flow profile is act actually retrograde flow.
We can see we're angled up towards the heart.
So flow's moving in this direction.
Back down the leg, it's going
to present a positive doppler shift
and that's what we see here.
This is about a four second sweep total.
So this is about two and a half seconds worth of reflux.

Deep System Evaluation

As I said, with the deep system, we're gonna look
through the whole femoral vein, stopping
and taking images along the way.
We wanna see flow and then no flow.
This is a little bit of augmentation, no retrograde flow, so
that's a nice competent femoral vein.
We can continue all the way down.
We can use our color to help guide us,
particularly in the deeper vessels.
And again that we wanna confirm what's going on
with our spectral doppler.
The last level of the deep system, as I mentioned,
would be the popliteal vein.
And we can see that here, the popliteal vein, again,
nice normal phasic flow with no retrograde flow.

Now I put in this slide to remind us that we really need
to adjust the equipment in with reflux studies.
We really wanna set the doppler scale
or PRF such that when we augment, we produce aliasing
as illustrated here.
And then after we produce that augmentation,
we see this long, low level, low venous,
doppler flow profile here, which is indicative of reflux.
Sometimes these velocities are very, very low,
so we really need to adjust the system appropriately.

Now, some folks use just manual compression,
squeezing the limb in order to augment flow, pushing
that flow past the transducer weighting,
listening and looking.
However, some folks don't like that.
And years ago, Dr. Paul Van Belin,
when he was at the University of Washington,
published this paper which said, you know,
squeezing is good, but let's try to standardize it.
So he said, let's put some various cuffs on the limb,
inflate them to certain pressures, greater pressures
as we move distally in the leg to account for
that hydrostatic pressure, which increases distally.
Let's inflate the pressure
and then rapidly deflate it and look and listen.
So this is a standardized way to augment
and look for reflux.
Some folks do this and find that it works very well for them.

Superficial System Evaluation

Now what about the superficial system?
That's really what clinically we can see a lot
of varicose veins in these patients.
We'll start at the saphenofemoral junction,
which is illustrated here.
Here's the great saphenous vein emptying into
the common femoral vein.
Color coded in blue flow is going all the way
back up towards the heart.
So that's normal antegrade flow.

In this slide here we see two examples.
We have the patient Val Salva, which is obviously something
that some folks have difficulty with.
So it's important before you start your venous examination
to have them practice doing that.
Val Salva maneuver, we have them Val Salva.
We see virtually no color flow, just a little blip here,
but this is a competent saphenofemoral junction
as compared to this example.
On the lower right we have the Val Salva
and we see the orange reddish color here,
which is indicating flow towards the transducer,
which is reflux Color is great
and color can rapidly identify reflux,
but I would recommend
that we actually still do spectral doppler as well,
putting in our spectrum and looking at
and being able to measure the reflux time.
All the equipment can do this.

In this example, our reflux time is almost three seconds.
Most folks have gotten away with trying
to grade severity of reflux saying
that maybe a half a second to one second is mild
and then one to two is moderate
and greater than two is severe.
Pretty much nobody uses those kind of systems anymore.
And in general, folks use a half a second of reflux
as being significant.
Some folks will use one second,
particularly in the deep system.

This slide illustrates the normal anatomy
of the great saphenous vein.
It's usually encompassed in a fascial boundary.
We can see this bright white line here, which is fascia
and this white line underneath it.
So it's sort of wrapped here.
And if you look at this, it kind
of looks like a little eyeball looking at us here.
Here's the eye staring at us
and here's the eyelids.
That is the normal planar arrangement of the
of the great saphenous vein.
However, there are numerous tributaries, secondary branches
that will move up and out of this plane.
They can have venous insufficiency
and need treatment as well.
So it's important to identify
tributaries versus the main trunk.
And the main trunk usually lies in this fascial plane.

The other thing I note here is vein diameter.
In this case it's 7.4 millimeters.
This used to be important in determining the size
of catheters that some physicians use
for ablation procedures.
However, it's not quite as important,
but some insurance companies want that information.
So you may still be required to measure vein diameter
in the superficial system if people are undergoing ablation
techniques, which we'll talk about in a minute.

Here is just another example.
Again, we're angled in on this very kind
of flat segment of the great saphenous vein.
We've got our gain up a little bit so we can try
to see low flow
and when you just have to be careful
that you don't over gain too much
and confuse what the real signal is versus
what the over gain signal is.

Now many examples I've put in the angle,
correct feature on the equipment even
though it's a venous study.
And basically we don't care about the absolute veloc,
we care about the direction.
However, this really promotes us to use a good angle.
If we see it, we try to keep to 60 degrees
because if we get too far off 60, we're just going
to decrease the doppler signals
so significantly that'll make our job a lot harder.
And this example here, I've turned the angle off
so you can see we don't have an angle correction,
but if we were getting too far off 60, we would not be able
to pick up this signal as well as we are here.

Perforators

Okay, what about perforators?
While perforators are small veins
that connect the do the deep in superficial systems,
sometimes they directly communicate
with the deep systems such as the popliteal perineals,
posterior tubes or femoral vein that are straight shot
through to those named veins.
And sometimes they're actually just vessels
that connect into various muscular tributaries
or even the so veins, but they all have valves
and they all have should have flow only in one direction.

This slide shows some common locations
for perforating veins, usually in the middle thigh,
upper calf, lower calf, some are branches
straight off the main trunk of the great or small saphenous
and sometimes the perforators come off of branches.
So there's a lot of variability clinically
in patients with ulcers.
We see usually three to five
that are relevant in those patients.

This slide here is just taken from an anatomy
textbook showing again the level they all have names.
These are the Dodds perforators, the Boyd Perforator right
around just below the knee.
The c***s perforators are very important in the lower calf.
They all have names. It might be nice to know the names.
It's much more important to know where they're at
and if they're working well or not.

We're gonna use ultrasound
to identify the perforators one of two ways.
We're either gonna follow the great saphenous
or the small saphenous
and look for branches
that trail down in a way deep in the image.
Or we're gonna look at the deep veins
and look for branches that come up
and connect into the superficial system.
We'll use color imaging
or spectral doppler again to determine flow direction.
We can use some compression techniques to augment flow back
and forth, and we'll wanna look
for flow in the wrong direction.
Again, that lasts more than half a second here.

We have a good color image of a perforating vein here.
We don't really see the great saphenous too well
because we're sort of off plane,
but we can see the pathway of this perforating vein
and it's color coded in blue.
So we know flow is going away from us as compared
to this vessel, which is color coded in red.
And it's coming up.
The flow is coming up towards this great
saphenous sitting up here.
So this is retrograde flow
and this is an incompetent perforator.

We have to be careful because the perforating veins do have
a small companion artery
and you can see that flashing at times
and it might confuse you.
But again, the veins usually have lower flow states,
more continuous color appearance to them.

Many of us also choose
to measure the diameter of the perforator.
We usually try to measure that about where it cuts
through the fascia.
Sometimes some physicians will elect
to ligate perforators based on size,
even if we can't determine insufficiency by ultrasound.

In this example, this calf perforator is almost four
millimeters, so it's likely to be incompetent
when we're evaluating perforators.
If someone's going to have a perforator ligation,
we'll mark the skin right where the perforator
penetrates the fascia.
As I said, we also record the diameter
and we'll make a note if there's a lot of wandering going
around or if the vein comes off obliquely.
Those things are important again when we're planning
interventions such as a ligation
or vein ablation procedure.

This paper was almost 10 years old,
but published in JVS several years ago
and talked about again the size of the perforator,
that once you get up three and a half
or close to four millimeters in the calf,
that vein is likely
to be incompetent even if you can't generate
incompetence on ultrasound.
And once we get above four close
to five millimeters in the thigh,
that vein is incompetent as well.

Ablation Procedures

Now during ablation, what are we gonna do differently?
Well, we're gonna mark the great saphenous vein on the skin
as an access site for entry into the vein,
usually in the lower thigh or knee or upper calf area.
And using our ultrasound, we're going to guide the insertion
of the guide wire and the devices into the saphenous vein.
We try to get a little bit away from the saphenofemoral
junction because we wanna leave the superficial epigastric
vein intact.

In this slide we can see
that tumescent anesthesia has been injected.
We can see the very echoes area of the fluid kind
of looking like edema.
It does two things.
It first acts as anesthesia
and then secondly also acts as a heat sink
to prevent any damage from the skin.
We can see as well here
that the catheters in place in the saphenous vein
and this fluid has actually compressed the vein around
the catheter.

Post-Ablation Assessment

After we've done ablation,
folks usually follow their patients, certainly an early
post procedure Ultrasound evaluation is essential
to rule out the presence
of venous thrombosis in the deep system.
Some folks just do that one scan
and never follow the patients again.
Other folks choose to serially monitor their patients.
That's gonna be a matter of departmental policy.

What we wanna see is post ablation,
that there's echogenic material within the vein
that there's no color flow within the vein.
And over time this vein will become a tre and shrink down
and basically look like a fibrous cord.
And in some individuals we may not be able to detect it.

Here is an image of a vein that's post ablation.
This has all been ablated, it's fibrotic, not thrombotic.
They don't like us to use that word.
Following an ablation procedure,
we can see the common femoral vein here
and a little bit of flow still through
that saphenofemoral junction, which is essentially coming
through the superficial epigastric vein.

This is what we don't wanna see.
We don't wanna see thrombus here extending down
through the saphenofemoral junction.
This is obviously a potential problem for embolic
disease and pulmonary embolism.

This image shows a very, very thin
fibrous cord where we can barely make out
what was the great saphenous vein
post vein ablation treatment.

Conclusion

So to conclude, venous ultrasound is certainly a very good
tool to evaluate patients for venous insufficiency.
Spectral doppler will rapidly identify venous reflux.
We're gonna use criteria of greater than half a second
to indicate that valvular insufficiency
color is a great tool.
It rapidly identifies the direction of flow.
If we're dealing with perforators, we may wanna mark
on the skin where the perforator penetrates the fascia
to aid in the treatment of these perforators.
And we're not only going to use ultrasound to diagnose
venous insufficiency,
but we're also going to use ultrasound during treatments,
treatment procedures such as vein ablation
and also to assess status post procedure.
Thank you very much.