Ultrasound Evaluation of Complications - Post Arterial Interventions - HD

Introduction

Hi, I'm Nevita here from Phoenix, Arizona.

The lecture today is on ultrasound evaluation of complications related to vascular interventions.

There are many ways ultrasound can help not only in diagnosis, but also in treatment.

Let's go ahead and look at the lecture.

For this lecture we will limit ourselves to lower limb evaluations, especially related to catheterization.

I have no relevant financial relationships.

Vascular Complications Overview

The vascular complications are mostly divided into the post catheterization complications like pseudo aneurysms or AV fistulas.

You can also get acute ischemic limb as a result of the intervention after you put a stent within the aorta.

Ultrasound has a role to look for endoleak and obviously we can also look for dissection of vascular structures.

For the purpose of this lecture, we will concentrate on the top two.

Pseudoaneurysm

Definition

What is a pseudo ansm?

A pseudo ansm is a contained rupture, a sort of a little disruption in the three layers of the arterial wall.

And with pulsation blood tracks out into the perivascular space, it always maintains communication with the artery, and therefore we can always show internal flow within the pseudos lumen.

The flow is sort of contained by the surrounding tissues and thus makes it look like a sac like structure.

Etiology

The etiology can be patient or procedural dependent.

If you use allergic catheter than the chance for complications are also higher.

Also depends on the time spent and the complexity of the intervention.

The longer you are and more complex your intervention then more likely to cause some damage to the artery itself.

It can also happen if there's a simultaneous artery and vein catheterization.

Patient is on anticoagulation, usually older patients at a higher risk of getting a pseudo andSo, poor compression after the procedure, and low or distal puncture site, in which case the puncture did not happen with the common femoral artery, but much more distally, obese and large body habitous patients.

Obviously the complication rates are higher and patients with hypertension have a tendency to have propensity to develop the pseudonym.

Natural History

What is the natural history once you've made a pseudonym?

Now, small pseudonyms, often thrombo spontaneously.

There is a couple of good articles that say if they're less than 3%, then majority of them would eventually thrombus at an average of about 23 day range.

But the spontaneous thrombosis becomes a little bit unlikely.

The patient is anticoagulated or the pseudonym develops a chronic fibrous wall.

If the pseudonym is really small, maybe less than one centimeters, then sometimes you can just follow them to resolution and treat only if they persist or start enlarging.

Complications

Among the complications of pseudonym, rupture is obviously the most commonest complication.

Distal isch may happen dependent on mass effect created by the pseudonym on the vascular structures, sometimes skin ischemia and necrosis, deep vein thrombosis.

If there is a large mass effect on the adjacent vein, they could get sobriety infection also.

Sonographic Diagnosis

How do we make the sonographic diagnosis?

The primary findings obviously are you're gonna look at a fluid collection, which has internal flow on color doppler and obviously shows ility.

There may be a variable amount of patent lumen and thro, and the location is usually superficial to the arteries because that's the trajectory of the intervention.

The secondary finding you look for is a neck connecting the pseudo aneurysm and the artery.

And if you sample this neck, you can always show two andro flow pattern in the neck by spectral doppler.

Or if you're doing a color doppler, you can again show a change in color flow pattern.

Now, grayscale duplex doppler has a pretty good sensitivity and specificity for diagnosing pseudo aneurysm, but the limitations again, are large body hepatitis patients with patients with large amount of edema, soft tissue edema, or they have infiltrating hemorrhage.

A large hematoma makes it very difficult to penetrate and look deep down.

Slow flow sometimes makes it very difficult to document the flow in the neck and into the pseudo sm.

False positive rates are rare.

You can get full by enlarged lymph nodes or inguinal hernias.

Here's a good illustration which shows a very short neck pseudo aneurysm rising from the femoral artery.

And there's a second illustration which shows a large neck.

And sometimes this is important, especially if you are planning some sort of ultrasound gut intervention to close the pseudo aneurysm.

Now essentially what is happening is when blood is flowing through the femoral artery, then it finds the neck and comes out into the enclosed sac space where the leak has taken place.

It has nowhere else to go, so it gets back into the artery, and then there's further propagation.

But if you look at the wave formula obtained from the neck of the pseudo ansm, the waveform has two distinct phases.

One, obviously is the systole when the blood is being pushed into the sac, and then there's the diastole when the blood is actually coming out of the sac.

And it's important to distinguish between pan diastolic reversal versus the normal early diastolic reversal.

This is an excellent demonstration of pan diastolic reversal.

The blood went into the sac and almost entire blood came out during the diastole until the heart actually again went into systole and pushed the blood into the sac.

So this is a classic to and fro flow as would be seen in the neck of the pseudonym.

Now against that is this other type of flow pattern, which is normal phasic flow in the artery.

And you can see here clearly that you have a systole in which the blood is obviously going antegrade, but then you have a early diastolic reversal with the third phasic component of the vascular flow.

This early diastolic reversal should not be confused for reversal seen in the neck of the pseudonym.

Repair Methods

Compression Repair

There are many ways to repair a pseudonym.

One of the initial ways that was very popular was the compression repair of pseudonym.

It was relatively simple compress over the neck with the transducer until the pseudonym flow decreases.

Usually you have to maintain compression 10 to 20 minutes.

And when you released it, you slowly released it and checked the flow.

If the flow was persisting, you again increase the pressure.

And the problem with this type of methodology was that you had to do multiple attempts and total compression time was somewhat limited by the patient's comfort and by the operator's tolerance.

The results were fairly successful.

According to literature, almost 63 to 83% of the pseudonyms were successfully closed.

If the pseudonym was larger and patient was an anticoagulation, then sometimes the success rate was relatively lower.

Very low chance of complications.

Pain was a common complaint and could be really severe and that may preclude the treatment because you may not be able to press as hard as you would like.

Operator fatigue does have a roll over peer time.

Illustrative Case: Compression Technique

Okay, let's look at one of the illustrative cases where the compression technique really worked.

A 45-year-old male comes with right leg persistent swelling and bruery after the arterial catheterization for repair of a cerebral aneurysm.

So in this case you can see that there is a pretty short neck pseudo aneurysm arising from the femoral artery, but seems like this is very admirable for compression.

So the compression technique was used in this instance and after 20 minutes you can see that the complete thrombosis of the pseudonym is noted no flow on color doppler within the aneurysm.

Thrombin Injection

Over a period of time thrombin injection of pseudonym became really popular and literature.

There are many successful articles regarding the methodology.

Basically what do we do?

We take thrombin injection and if you use human thrombin, it comes in a concentration of 1000 units per mil.

And to have precise control on how much you inject, usually we use a tubercle and syringe of one mil and a 25 gauge needle.

The needle is inserted into the pseudo ansm with tip away from the neck and incrementally you inject about 52 200 units and look for the closure.

Sequential injections are done until there is complete thrombosis.

Many times you might thrombo one component of the pseudo aneurysm in which case needle repositioning is necessary.

Illustrative Case: Thrombin Injection 1

Here's an illustrative case.

We have a 72-year-old female whose status post left femoral artery puncture for lower extremity artery angioplasty.

She develops the pseudo andm.

Here you can see the vessels way deep down there.

There's some infiltrative hemorrhage on the top and some DM up there.

This is the sac of the pseudo aneurysm and this is the neck of the pseudo aneurysm.

If you sample the neck, you get the classic two and fro flow pattern as you would expect.

So after the injection, we cut the patient back in 24 hours to look for resolution and there was complete thrombosis of the pseudo aneurysm.

Illustrative Case: Thrombin Injection 2

Another case, again, we have a pretty good leg neck you can see good to for movement within the neck of the pseudo aneurysm.

The needle under ultrasound guidance is posted while into the lumen and thrombin is injected and complete closure is demonstrated.

Illustrative Case: Thrombin Injection 3

Another illustrative case, we have a 69-year-old male with a complicated medical history, which includes peripheral vascular disease and this patient now reports painful swelling in the right groin after failed left popal artery recanalization.

So in this case you can see there is a fairly large pseudo aneurysm and shows very good flow with some perivascular tissue vibration.

And a neck is demonstrated with color doppler thrombin injection is done and complete occlusion is demonstrated immediately after about one cc of thrombin.

A little flow is noted in the neck and usually I won't worry if the flow is still noted in the neck region.

They usually close off with time.

However, in this instance, the patient comes back in 24 hours and the lumen is opened up again with good flow sometimes with large pseudo aneurysm.

This is an expected result.

So you again do the same procedure and inject thrombin, which is what we did in this case.

And after the second injection, there was again, no flow within the pseudo.

After 24 hours, again, we saw the patient and this time the thrombin worked completely and the pseudonym remained blocked.

So if you have to inject a couple of times, that's okay.

It is a known expected course.

Contraindications for Thrombin Injection

What are the contraindications of thrombin?

Now, if you have a wide neck or a short neck, you would be hesitant to use thrombin.

And how do you define a wide neck or a short neck?

This is often asked to me by my residents and there really is not a good answer In literature.

There are reports which say that if the neck is between 0.3 to eight millimeters, then it's too short, but it's really difficult to accurately measure neck and define it as wide.

I usually just look at the pseudonym and try to make educated guess whether this is large enough to have some potential for some sort of complication secondary to thrombin injection.

If you have a combined pseudos and a AV fistula, now that would be a co contraindication to injecting because if you have a fistulas connection to the pseudo ansm, then you are obviously increasing the chance for a pulmonary embolism.

Now here's a pretty obvious case of a pretty large wide neck there arising from the artery, partially thrombo, pseudo andm.

This is one of those cases I would hesitate to inject thrombin.

Another Case in which in the longitudinal way, in the longitudinal section, the pseudonym does not appear to be as dangerous as you would expect and thrombin was injected in this instance successfully.

Here's another case. You can see that there is a rent in the interior wall of the artery with a pretty wide necked pseudo.

And again, this is one of those that you would not wanna inject.

Complications of Thrombin Injection

What are the complications of trauma injection?

Distal embolization is one of the most worrisome complication.

And obviously you avoid it by trying to not inject pseudonyms, which have those wide short necks.

I would not inject if I'm not sure where the needle is.

So you have to be absolutely certain where the needle is because if you're not seeing the needle tip, you might be in some other component of the pseudonym or of the neck or of the artery itself.

Avoid injecting the necks themselves, and sort of the anatomy really well because if you deal with multiloculated, pseudo ANMs, I would usually go for the loculation closest to the neck.

If you take care of that, the distal loculation are automatically thrombosed.

Sometimes you have very large pseudonym which are multi compartment and might have associated arterial rans or lacerations.

Those are the ones which may fail to thrombus.

Very rarely. You might deal with complications related to hemorrhage.

Hematoma causing pressure on the vein leading to DVT, and allergy.

Closure Devices

Now, one of the things that has been used recently is closure devices.

The closure devices eliminate the need for prolonged art TL compression and they reduce the subsequent interval of bedrest.

There are usually two types of devices.

One is a collagen hemo hemostatic puncture closure device and the second one is a suture mediated device.

Illustrative Case: Closure Device

Okay, here's a illustrative case.

We have a 59-year-old woman who status post right groin assessment for a cardiac authorization.

In October, 2006, she had angioplasty done and had a drug eluting stand put in, but then since she presents to the outpatient service with bruie in the right groin access area, and she also had exertional right lower extremity paraesthesia and numbness.

So we see this little echogenic line in the vessel itself and gets really confusing 'cause we're not able to decide if there's this some kind of a focal dissection of the intima itself or is this something we should be worried about.

So when we look back to the history, turns out that this was one of the closure devices that used a suture for closure.

And what we were looking at was just the suture material, prolene suture.

You can see it sort of diagonally going through that whole vessel.

So this is something to keep in mind if you are trying to follow up cases who've had these type of devices used for closure Hematoma.

Other Complications

Hematoma

Many times you can have this complication so you're not dealing with a pseudo aneurysm.

However, there was a bleed which sort of got walled off itself, may or may not be related to the artery itself, but nevertheless, it does form a large hematoma.

It's not uncommon. Most of them do resolve.

You have to watch for femoral nerve compression, which if it occurs, patient might present with paraesthesia.

It takes weeks to months to resolve if the puncture site was above the inguinal ligament in the common femoral artery.

And the chance for forming a hematoma that extends into retroperitoneum is much higher.

And that is when you might require a CT scan to evaluate the extent of the hemorrhage.

This is how infiltrative hemorrhage looks is really very difficult to make out.

This is not a well-defined hematoma.

You know that there was a bleed in the soft tissues.

Makes it very difficult by ultrasound to even look at the vessels.

Deep down, these are the arteries.

Sometimes you have to just put the spectral doppler and confirm that's an artery, but it may be suboptimal to rule out a pseudonym that might be hidden over there.

These are patients you need to get back in 24 hours and you might see them better if there's high suspicion and you can give contrast.

You can even get a CT scan to look for a pseudonym.

These are well-defined hematomas.

You can see they can cause some sort of mass effect on the vein.

And so watch for deep vein thrombosis in such cases because of extrinsic pressure.

AV Fistula

AV fistula. The another type of complication we deal with with relation to catheterization procedures in the groin.

This is an abnormal collection connection between the artery and the venous system that bypasses the normal capillary beds.

Obviously hydrogen incidents is fairly low and duplex ultrasound is the current diagnostic test for choice.

The complication with large AV fistulas is that you can learn up with high output cardiac failure.

Sonographic signs, we look for focal region of aliasing and persistent turbulent pulse trial flow at the site of the fistula throughout the cardiac cycle.

There is pulsitile venous flow because it's connected now to an artery and you might demonstrate a focal area of extravascular tissue vibration on color doppler.

This is how extravascular tissue vibration looks on color. Doppler a mosaic of colors around that vessel.

This is often the first sign which helps you to focus narrowly onto this area and evaluate for AV fistula.

When you put a pulse doppler, you invariably get high peak systolic velocity and high diastolic flow through this small narrow communication channel between an artery and a vein.

This one was even visible on gray scale. That is a rarity.

Normally it's very difficult to make out the fistula on the gray scale itself on color dopplar.

Focal aliasing allows you to choose a spot where you would like to calculate the velocities and find out the flow waveform dynamics.

And in this image you can see the velocities are pretty high.

And again, large amount of diastolic flow is flowing through the AV fistula.

Acute Arterial Occlusion

Some of the other major complications can be acute arterial occlusion, can be because of embolism or thrombosis, sometimes dissection.

Secondary trauma patients will come with severe limbic leukemia symptoms, pain paraesthesia, loss of peripheral pulses, skin may be cool and there could be palor or synosis distal to the obstruction site.

And basically with ultrasound, when you look for here is a local common femoral artery that is completely thrombus and occluded after a procedure.

This is a different case.

This is a popple artery and this is secondary embolism.

There is a complete occlusion of the populated artery itself.

Conclusion

In conclusion, small pseudonyms and AV fistulas may resolve spontaneously and you can wait and watch for that to happen.

Follow up these cases over a couple of weeks.

If you are planning to inject, define the neck of the aneurysm accurately.

Have a good understanding of where the aneurysm is rising from.

You may have to use different transducers to accurately identify the deeper vessels.

And when you do the injection, you must know where the needle is before injecting.

Post procedure, careful monitoring, at least we advocate patients should be admitted for 24 hours and scan again the next day to look for complete closure.

Thank you very much.