Ultrasound of Vascular Emergencies - SD

Introduction

My name is Dr. Ed Bluth. I'm chairman emeritus of the Department of Radiology of the Oxford Health System in New Orleans, Louisiana.

And I'm going to talk today about ultrasound of vascular emergencies.

I'm going to be talking about ultrasound of vascular emergencies.

There are five major groupings of vascular emergencies, which I'm going to discuss in this lecture, including deep venous thrombosis, torsion, pulsitile vascular masses, acute changes in neurologic symptoms, and unusual vascular problems.

These are all situations of patients who present to the emergency room and patients who are asked to assess and evaluate.

Deep Venous Thrombosis

Overview

Starting first with deep venous thrombosis, we're gonna be discussing both the lower and upper extremity abnormalities.

Acute DVT affects more than 20 million individuals in the United States, and is therefore a very common problem.

It occurs in both sedimentary outpatients and inpatients.

We have several predisposing factors, including a prolonged congestive heart failure, surgical intervention, including pelvic and lower abdominal surgery.

In particular, patients who have coagulopathies and patients who have paraplegia.

The important reason for the diagnosis of acute DVT is to identify patients who will have pulmonary embolism.

Now, it's important to appreciate the fact that everyone who has a DVT does not develop a pulmonary embolism, but if you do not treat the DVT successfully, then in 50% of the time, a PE is likely to occur.

And since, in most case, in 30% of cases, the outcome of pulmonary embolism is death.

This is a very important diagnosis to identify.

The majority of DVT occur in the lower extremity, but there is now an increasing incidence in upper extremity DVT as we'll discuss shortly.

Normal Vein Criteria

Now, the normal veins, both the upper and lower extremity veins have respiratory ity, have spontaneous flow, have augmentation, or compressible have flow in one direction, and are generally and coic taking these important criteria.

Respiratory ity for one, that refers to the venous flow changes during a respiratory cycle.

So with inspiration, there's an increase in intraabdominal pressure causing compression of the inferior vena cava and decrease in the doppler flow signal.

And with expiration, this increase in visualized flow.

So as a result of that, you can see there's inspiration expiration.

We're asking the patient to hold their breath.

Augmentation relates to the increased velocity of flow post either Val Salva maneuver or post distal compression.

The normal veins can increase 50 to 200% to on a Val Salva maneuver.

And as we see in this patient who initially is having quiet breathing, we're asking the patient to do a Val Salva maneuver.

And after that, the velocity of the vein has augmented compared to the previous portion of the previous time of the patient doing their examination.

We can also change and demonstrate augmentation by compressing at the ankles and better visualizing the cafes when they're not necessarily visualized with just simply color and gray scale.

The most important criteria to identify and look for in veins as transverse compression.

The arteries do not compress the veins completely collapse on transverse compression.

With acute DVT, the veins, as you could see here, don't compress.

Here we're seeing an expanded hypo vein with loss of compressibility.

Important also to appreciate is that as an indirect sign, there's a loss of respiratory ity.

We'll refer to that later on in the lecture.

Lower Extremity DVT

The lower extremities demonstrate the parameters we just discussed.

The veins we normally assess include the common femoral, deep femoral, superficial profunda, femoral, common femoral posterior tibial, anterior t tubulin, and peroneal veins with transverse compression.

In a patient who has acute DVT, the vessel remains hyper expanded, and is anti coic.

The a CR standards at the present time require only assessment of common femoral, superficial femoral and popal veins.

But when there is focal calf pain, this generally requires a complete assessment of that particular area.

And the caffeines.

The important issue of isolated caffeines is that in 80% of isolated thrombi, they will resolve spontaneously.

In only 20% will they extend approximately commonly.

However, patients who have s will also have an associated higher venous thrombus in one of the upper vessels as well.

So therefore, since patients who will have a negative ultrasound, if the caffeines are not completely assessed and they remain symptomatic or repeat, ultrasound is advised to be certain that that patient is not fit into that 20% to pro who propagate proximally.

This is an example of early DVT.

Here we're seeing residual th we're seeing a thrombus just at the level of one of the valves, and you can appreciate that as that valve, as that thrombus begins to regress, that the valves can be destroyed, leading ultimately to venous incompetence.

On the other end of the spectrum is this patient who has a large amount of thrombus dis bending completely, the common femoral greatest, superficial femoral vein and the profundo femoral here in both sagittal and transverse dimensions.

As I said, we evaluate the venous structures, both directly with gray scale and with color, and also doer spectrum analysis, looking for asymmetry here.

If we look on the right side, there is a loss of respiratory ity compared to the normal left side.

Putting the two sides together again, loss of respiratory ity on the right compared to the better respiratory ity we're seeing on the left side, and that demonstrates that proximal to the A area that we are visualizing there is acute venous thrombus in that iliac vein.

Another example of asymmetry is these two images.

This is the right and left sides of the popal veins, and we see there's loss of respiratory ity on the left side compared to the right side, even though we have good augmentation.

Again, looking at it more closely, we can see the loss of respiratory physicality on the left compared to the right, and that tells us that there is a proximal abnormality, which we have not yet visualized.

It's a partially occluding thrombus in the poile vein because we still have good augmentation indicating it's not completely occluding the vessel lumen proximal.

Isolated Calf Vein Thrombosis

What about isolated caffeine thrombosis?

Again, the incidence, as I stated in asymptomatic patients, is high up to 88%.

Upward propagation occurs, however, only in around 20%.

So calf clot is unlikely to lead to significant pulmonary emboli.

It's important also to appreciate the fact that if the initial examination is normal in 2% of patients' abnormalities are evident on serial testing.

So even if an examination is completely normal, we may have missed one of the duplicated caffeines, which one may not have been visualized and the thrombus may have propagated approximately.

It's very important to realize that if a patient has unilateral symptoms, is it appropriate or inappropriate to do a bilateral examination?

If a patient has DVT on an affected side in five to 22% of the patients, the unaffected limb or the asymptomatic limb will have an associated DVT as well.

In contrast to that, if the symptomatic leg is negative, clot will occur in less than 1% of patients who are asy on the asymptomatic side.

So, as a result of this, if most people still do a bilateral examination, but if you want, if you were stretched for time, if the symptomatic leg is negative, then you don't necessarily have to do the contralateral side.

An example is this one.

We're seeing acute venous thrombosis involving the superficial femoral and popal vessels on the right side, and this was the symptomatic side.

And when we looked at the left side, we saw extensive DVT in the left common femoral vein.

Bilateral Symptoms

What about patients who have bilateral symptoms?

In most patients who have bilateral symptoms, cardiac disease or peripheral vascular is a dominant cause.

Others have said that we still need to do bilateral examinations because there's a significant incidence in DVT, and this is probably related to the fact that these patients also have additional risk factors.

It's pointed out by John Cronin, how accurate are we in DVT assessment?

In the Fmpo area, the sensitivity is 99% and the accuracy is 98%.

And for isolated caffeine thrombosis, the accuracy decreases.

The false negative rate is, again, 18%.

So what does that mean?

In particular, the true negative rate for our assessments is 96%, but that means that the false negative rate cannot be, is at approximately 4%.

Meaning, again, that if the examination is negative, it doesn't mean if the patient is sym remains symptomatic, that you should not perform the examination.

Again, you may have a patient who has one of these false negative examinations, and we are not a hundred percent in any of these assessments.

So in summary, with regard to the upper, the lower extremities, if a patient has unilateral swelling, the most common diagnosis will be acute DVT.

Less commonly, you'll find some other abnormalities at around 10% of the time, including ruptured VA cysts and musculoskeletal injuries.

If the patient has bilateral acute symptoms, most commonly it'll be congestive failure, but less commonly, but not insignificant.

It will be patients who have bilateral DVT.

Upper Extremity DVT

Let's move on to the upper extremities.

Do the in incidents appears to be increasing with increased use of central venous catheters and PICC lines.

Also, other risk factors include pacemaker wires as well as underlying malignancy and hypercoagulable states.

Why do the vessels we should be assessing?

These include irregular veins, cephalic veins, axillary and subclavian veins, as well as the internal jugulars.

It's important to appreciate that the axillary and subclavian veins are usually anterior to the arteries, and that's a way to be certain that you're looking at the correct vessel.

Veins usually are touching the arteries.

Compression should occur also with using the linear a transducer, the same way that you attempt to compress the veins in the lower extremities.

And if you can compress the veins as you frequently can't, media in the medial component of the subclavian veins, you could try using the sniffing maneuver, which will cause the subclavian vein to decrease or using the Valsalva maneuver and causing the subclavian vein to increase in size.

Here's an example of subclavian vein an artery, and we are compressing the vein with direct pressure using linear A transducer.

An example of acute DVT in the upper extremity.

Frequently, these can be a little more echogenic than they are in the lower extremity, and who we're seeing flow surrounding the acute DVT in the subclavian vein, in a jugular vein, both sag transverse and sagal projection, we're seeing acute DVT, which did not compress.

Here is a an example of a Hickman catheter, which we visualized in subclavian vein and could see the acute venous thrombosis touching and immediately adjacent to this catheter.

We also wanna look for symmetry in the rest of the spectrum analysis pattern in these patients to be certain that we're not missing proximal thrombus.

We, as we've pointed out in the lower extremities, another course also of a asymmetry in the subclavian veins particularly is imaging of collateral vessel when you haven't visualized the subclavian invaded all.

Here's an example again, of asymmetry, loss of respiratory VA in the right could add to the left.

This would suggest that there could be a proximal thrombus on the right or more commonly as we see or occurring.

In this case, this actually represents a collateral vessel rather than subclavian vessel, which a technologist originally thought.

Torsion

Moving on to another cause of vascular emergencies, that includes torsion, and we are talking about both torsion of the testes and ovaries.

Testicular Torsion

Testicular caution occur.

Torsion occurs most commonly in infants and adolescent boys, and the clinical symptoms include triad or pain, swelling and ery ous abnormalities on the scrotum itself without any history of trauma.

Usually the effect of testis enlarged and in 10% early of patients with early torsion, the examination is completely normal.

The ultrasound findings are decreased, asymmetric or absent blood flow.

The findings are relate to the degree of torsion of the vessels.

If it's a 540 degrees, at least in this complete arterial and venous occlusion, if it's less than 360 degrees, you can get venous occlusion and may still have arterial flow, but with some dampening and loss of dia diastolic component.

Sometimes you may have complete detorsion and you may have both arterial and venous flow.

Another abnormality to look for with ultrasound is the spiral twist or the torsion knot, which you can frequently visualize cranial to the testis itself.

This an example of both the right left testes.

The right is obviously larger than the left side, and this is the patient to had torsion another patient.

On the right side, we're seeing lack of vascular flow on the right compared to the left.

And I would recommend always starting with the asymptomatic side.

So you could set up the color and do spectrum analysis, and then you should expect to see normal flow on the symptomatic side.

So here's an example of torsion on the right, again, some examples of a torsion knot.

The increased abnormality superior to the testis itself, which needs to be separated from the epidermis.

And one of the keys to that is the lack of color enhancement in the epidermis in a in con in patients with a torsion knot in contrast to patients who have epididimitis and have increased flow in the epidermis.

Ovarian Torsion

Ovarian torsion also is caused by complete or incomplete rotation of the pedicle.

This results in compromised venous lymphatic drainage leading to edema and congestion of the parenchyma, and ultimately loss of arterial flow.

This occurs in normal ovaries as well as abdo ovaries, which have a preexisting cysts or benign masses.

It also occurs in patients who have enlarged ovaries in pregnancy frequently with corpus lium cyst.

And the clinical symptoms are the patients who present with pain, nausea, and vomiting.

And most commonly it occurs on the right.

The ovary is large.

On ultrasound, there are multiple follicles.

Frequently there's several.

Sometimes it'll simply be a cyst, and there sometimes it's free fluid in the cul-de-sac using co flow doppler, which is very important.

There's absent flow in the effect side or asymmetric flow.

You may have arterial flow and absent venous flow as well.

And frequently you'll be able to see the vascular pedicle.

And again, look for symmetry, symmetry in the Doppler spectrum analysis pattern.

Here we have torsion on the right in an enlarged right ovary compared to the left ovary.

Here we have another patient with abnormal flow pattern on the right compared to normal arterial and normal venous flow.

On the left, again, you see dampening on this right ovary.

Pulsatile Vascular Masses

Another cause of emergencies that are sent to us are patients with pulsitile abdominal masses, and these include aortic aneurysms as well as groin masses.

Ultrasound, of course, is not the procedure of choice for patients with rupturing.

A abdominal aortic aneurysms CT is the required study that needs to be done.

But frequently we're asked to assess patients who have a pulsitile mass to determine if there is an aortic aneurysm present.

Again, remember, you are to measure the aorta accurately.

You need to be perpendicular to long axis of the vessel and measure the outer to outer lumen.

Here's an example of an aortic aneurysm, which will measuring the outer to outer lumen.

And again, ultrasound is a very accurate assessment of aortic aneurysms.

Similarly, we can assess popal pulsitile masses.

This is an example of a popal artery aneurysm, and by definition, these are vessels that have diameter of greater than one centimeter color flow doppler is very valuable in the assessment of differentiating pseudo aneurysm from a hematoma in the common femoral artery or the femoral artery.

The classic pattern is a yin yang pattern, which most people are familiar with.

The good example here of this patient who had a cardiac catheterization and had a pulsatile mass.

And you're seeing with color flow doppler the yin yang pattern within the aneurysm.

Here we see the ingress and ingress of flow causing that yin yang pattern.

Again, be very careful, don't have just tunnel vision.

Here we're seeing a patient who has a definitely a pseudo aneurysm classic yin yang pattern, but also had acute DVT in the superficial femoral vein, which was non-compressible.

So again, you can get more than one problem, and be well aware that ultrasound is capable of assessing both these abnormalities.

Acute Changes in Neurologic Symptoms

Moving on another cause of vascular emergencies or change in neurologic symptoms.

And this relates to the identifying most commonly heterogeneous plaque in a patient who is having a TIA tore to digress for a moment, there are two different types of plaque.

One is fibrous collagenous plaque, which is stable, and the second is plaque, which contains intra plaque hemorrhage and is thought to be unstable or vulnerable.

There are two methods of assessment of the international system, which divides plaque into four different types of characteristics and the heterogeneous homogeneous pattern, which is useful and most frequently used in the United States.

The heterogeneous pattern overlaps the type one and type two type of plaques, and the type three and type four international system plaques fit into the homogeneous pattern category.

Now, why is characterization so important?

It's because, again, the heterogeneous type of plaque appears to be the vulnerable plaque, the type that will break down and embolize more.

And when patients present with the TIA, they may be undergoing that process.

This was demonstrated very clearly in a patient in a study done by a Nickis who followed patients who had been, had their plaque classified and followed them with ct.

All these patients had greater than a 50% stenosis, and the type one plaque, which is heterogeneous, had 66% incidence of CT infarction compared to patients who had type four plaque, which was homogeneous and had a 10.5 in incidents of CT infarction.

So one of these different types of plaques look like homogeneous plaque is uniform, has low echoes, and again, it is less than 50% lucin.

Here's an example with a pathologic specimen.

Here's the residual lumen.

Here's the carotid bulb.

It is homogeneous, has a few small lucid areas, and pathologically there was just fibrous collagenous plaque, no evidence of inter plaque hemorrhage.

Another example, a sagittal and transverse image in both methodologies need to be used in order to classify plaque.

You could see that we have relatively uniform plaque with any any degree of lucency within it.

This is homogeneous type four plaque.

In this transverse image and sagal image, we see a very small residual lumen on this transverse image, but with some areas of lucency, but small areas of lucency relative to the volume of the plaque itself.

And this is type three homogeneous plaque.

Again, it's important to emphasize plaque characterization can only be done in gray scale and you cannot classify plaque using color or power.

Heterogeneous plaque looks differently.

Most importantly, it has more than 50% lucency and it can either have a smooth or an irregular surface.

You are seeing considerable hypo coic plaque in this area with an irregular margin, and you can appreciate that there's more than 50% of this volume is sonocent.

Here's another example, internal and external carotid arteries has a residual lumin of the internal carotid artery marked off, and here is the outer margin, which is completely sonocent.

This would therefore be type one heterogeneous plaque.

And there's pathologic specimen.

You could see the large amount of intra plaque hemorrhage, which was visualized in this endarterectomy specimen in another patient.

Here you could see the residual lumen on this power doppler image, but again, you must classify it with gray scale and you could see that's large amounts of heterogeneous plaque.

Here this is type two because there are are some there's both homogeneous and there is both low level uniform echoes and big focus on lucid areas of plaque.

Again, this is appreciated in the sagal image of the same patient.

Here is a residual lumen.

We see the outlines of where the plaque must be, but we classify it with gray scale alone, and we see the large areas of sonar lucency within the plaque.

More than 50% of the volume, but not completely a hundred percent.

And this therefore is type two heterogeneous plaque.

So in summary, the characterization pattern consists primarily of the degree of, so lucency heterogeneous plaque is more than 50%.

Sonocent calcifications can occur in both surface, can only can be either smooth or irregular with heterogeneous plaque.

Now, why is this important?

Again, it's important because the heterogeneous plaque is a independent risk factor for vascular emergencies and stroke independent.

The two independent risk factors are degree of stenosis and degree of sonar licensing.

And so it's my recommendation that patients with TIAs be sent to assess the plaque, both the volume of the plaque as well as the degree of heterogenetic.

The second cause of vascular emergencies with related to changing neural symptoms relates to patients with secondary signs of who have cerebral infarction.

Here is a patient with a very narrowed internal carotid artery.

We're seeing the residual lumen, which is very narrowed.

When we look at the spectrum of the internal carotid of the internal carotid, we see low velocities, which correlates with a high degree of stenosis greater than 95%.

We see low velocities in the common as well as the internal carotid artery.

And we see dampening not only is the common, which would go along with a very tight stenosis, the internal carotid artery, but also in the internal carotid artery itself completely.

This indicates to us that there not only is there a significant stenosis in the carotid bulb itself that we've visualized, and these are the velocities which were present in this patient, peak velocity of the internal of 69 and the systolic ratio of two of 2.6.

But also this tells us since there is dampening and no diastolic flow in the internal carotid artery, that there is this distal stenosis.

As we see here in this CTA moving on, there are some unusual vascular emergencies.

Unusual Vascular Problems

We are frequently sent, frequently we're sent to assess patients who have ascites from the emergency room to identify if they have blood chiari syndrome or some other vascular abnormalities.

And occasionally patients with abdominal pain also who they don't think have aortic aneurysms.

Here we're seeing a patient with a large amount of ascites, and we're seeing in fact that this patient has reverse flow in the portal vein.

And when we assess this patient more carefully, not only with the reverse flow in the portal vein, but also there was thrombus in all the hepatic veins, although there was a patent inferior vena caver.

And this was an example of a patient with body Chiari syndrome.

This was a 30 5-year-old lady who we later identified to have a hypercoagulable state and ultimately had to go on to a liver transplant.

But this is how she presented with acute onset of ascites and ultimately and acute diagnosis of Bud Chiari syndrome.

Dissection of the aorta is most commonly idiopathic, although some causes can occur with maran syndrome, pregnancy, and focal stenosis, hypertension and bicuspid or aortic valve patients.

Typically it begins in the thorax and extends all the way into the abdomen and relates to a defect in the intima.

And sometimes we also see blood flow in both the falls and true lumen of the vessel.

Here's an example of an aortic dissection.

We can see the flap, which was fluttering on real time, although we did not see bidirectional flow in the aorta with color flow itself.

Another example in another patient here is the intimal flap in this aorta and again in transversely in this vessel as well.

Conclusion

So in summary, we've gone through a large number of vascular emergencies.

We've looked discussed deep venous thrombosis, torsion, pulsitile vascular masses, acute changes in neurologic symptoms, and unusual vascular problems.

In conclusion, ultrasound is a useful tool to evaluating vascular emergencies.

The most commonly requested procedure is the upper and lower extremity DVT studies and in around 10% of these patients, ultrasound is valuable, is we're also gonna identify another cause such as a ruptured ba cysts, aneurysms, lymphoma, or he hematomas torsion of the ovaries and testes can be accurately diagnosed with ultrasound.

And you must use dola spectrum analysis to evaluate for both arterial and venous flow.

You certainly can't look at the color flow alone and know that there's arterial and venous flow.

Patients with TIAs can be sent to evaluate for the presence of unstable heterogeneous plaque, and it's something I would recommend.

And pulsitile masses can be accurately assessed with.

Ultrasound and pseudo aneurysms have a characteristic yin yang pattern, which is visualized.