Doppler Assessment of the Neonatal Abdomen - HD

Introduction

Hi, I am Brian Coley from Cincinnati Children's Hospital Medical Center, and I'll be talking about doppler of the neonatal abdomen.

Doppler ultrasound is an incredibly valuable tool that adds physiologic information to the usual anatomic information that we get from ultrasound.

During the next 40 minutes or so, we're gonna talk about the applications in the child, in the liver, kidney, bowel, and in the great vessels.

Understanding the Physics

Before we get started, you're gonna have to understand a little bit about physics.

While that can create some anxiety in people, I think there's some very simple principles that'll get you through this and help you to understand the power of doppler and help you interpret the information you see during your scanning.

The doppler equation is this, and we are solving for v the velocity of what we're interrogating, which in clinical practice is the movement of red blood cells most often.

The doppler shift is what we measure with our machine, the incident frequency we know from our machine that we preset.

The angle of insonation is measured when we do an angle correction, and the speed of sound is presumed to be 1,540 meters per second.

Knowing those variables in that one constant, we can measure the velocity of moving blood within a vessel.

Hemodynamics and Laminar Flow

Flow in most blood vessels is laminar.

That is, it's all going in the same direction.

Blood is also viscous, and what that means is there are shear stresses, meaning that it's stickier at the edges of the wall than it is in the center.

When you have laminar flow with viscous blood, you get this parabolic velocity profile where you have near zero velocities at the edge, so-called boundary layer.

Where your mean velocity are roughly half of the maximum velocity at the center of the vessel.

The great thing about doppler is that it actually, the images actually fit with what we know about hemodynamics.

Here's a cross-sectional image of my common carotid artery, and you can see this parabolic velocity profile with slower flow around the edges, and then higher velocities in the center of the vessel, just like you would expect if you did a cross section through this level right here.

The other thing you can do on pulse Doppler examinations is look at the laminar flow profile.

With a narrow gate sampling just a small part of the velocity profile, you can see that that's exactly what I have.

The pulse doppler waveform is nothing more than velocity versus time.

With a narrow gate, I get a very narrow band of velocities in my doppler waveform.

If I open the gate up to encompass the entire width of the vessel, you can see I now get faster flowing velocities at the center, and I get slower velocities at the edge of the vessel.

Again, just what would be predicted by hemodynamics.

Poiseuille's Law

Poiseuille's law tells us that essentially flow is related to pressure.

The more pressure you have upstream, the greater flow you're going to have in a vessel.

Now, there are lots of other determinants about this including vessel radius and vessel length and fluid viscosity.

This also assumes steady flow in a rigid tube.

However, it's still applicable in the simplistic view of hemodynamics and how flowing blood behaves.

Bernoulli's Principle

Another thing to know about is bernoulli's principle, which basically states that flow is constant flow is always depicted as the letter Q and it's equal to velocity times the cross-sectional area.

You see in this simple model of going through a stenosis, if flow is constant at all these areas, but the cross-sectional area decreases, then we know the velocity must increase to keep flow constant.

In practical life, we've all experienced this by putting our finger over the end of a garden hose and having the velocity of the water coming out get higher because we close off a little bit of the end of the hose.

If we look at the total energy in the system by this top line here, that's composed of both kinetic energy and pressure energy.

If the kinetic energy is going up when we cross the lumen down, our pressure energy gets less.

When we take our finger off the end of the hose, everything comes back to the way it was before.

Importantly, this assumes that laminar flow is maintained.

Hemodynamics in vivo is a lot more complicated than steady flow in a rigid tube.

Blood flow is not just a difference between pressures, it's really a difference in fluid energy.

There's pressure energy, there's kinetic energy, there's potential energy with gravity, there's inertial energy in all systems, and there's viscous energy which is usually negative.

Because of Sir Isaac Newton, no matter what the system, we know that energy is conserved.

Here's what happens really with Bernoulli's principle in reality.

As you move through a stenosis, the energy goes up, but you never quite come back to where you were.

There's always a little bit of energy loss, and that depends upon the shape of the stenosis, the length, the viscosity, the fluid, the inertial and viscous losses.

But laminar flow may still be maintained.

When you come out on the other side of a stenosis, you still have enough energy to perfuse whatever downstream organ you're concerned about.

Reynolds Number

Here's one last concept, it's his Reynolds number.

Reynolds number has to do with the loss of laminar flow into turbulent flow, and that's really proportional to velocity.

When we have below Reynolds number for a fluid, Poiseuille's law remains in effect.

The more pressure, the more flow, but there reaches a point where the more pressure you apply, you're not going to get any more flow through that tube because of turbulence.

What happens in that case when you have a critical enough stenosis, remember as we go through a stenosis, the velocity increases.

As the velocity increases, the Reynolds number goes up, and eventually you'll lose laminar flow to turbulence.

Once that happened, the energy losses increased dramatically.

At that point, you no longer have enough energy within the system to perfuse the downstream tissues.

That's when we have a significant or critical stenosis.

When we're measuring velocities through a stenosis, really what we're doing, this is a proxy for are we going to have enough energy downstream to perfuse the organ that we're interested in arterial waveform?

Sometimes give people problems, but really I think it's pretty simple.

It's just velocity versus time.

It depends upon local conditions.

It depends upon proximal and upstream conditions as well as distal or downstream conditions.

But there's only a certain number of measurements you can have.

There's a peak systolic velocity, there's an end diastolic velocity, and then there's some measure between the two.

I like to use acceleration time.

Really that's all there is.

Once you sort of appreciate that and what these different conditions are that can lead to changes, your doppler examination will become much more clearer to you.

Peak systolic velocity really is related to volume, flow and stenosis.

Here is my superior mesenteric artery fasting, and then after a large breakfast, and you can see that there's been vasodilatation of my splenic bed, the peak systolic velocities have essentially doubled.

There's also an increase in diastolic flow as the splenic circulation is dilated.

Diastolic flow really has a lot to do with the impedance, especially downstream.

Here's a typical phasic waveform from a superficial femoral artery pre-exercise.

Then after running up and down six flights of stairs, you can see again there's been downstream vasodilatation.

As the muscular arterials have dilated, the end diastolic velocity has increased.

We no longer have that sharp reversal flow.

You can also see that the peak systolic velocity has increased as well.

Acceleration time is due to stenosis and impedance, although there are some phenomena if you're downstream from a arteriovenous fistula, you can always see this.

In general though, you'll see a delay of the systolic upstroke, the change from end diastolic velocity to peak systolic velocity to tell you that there's something amiss.

While we're mainly talking about arteries, we do look at venous waveforms.

These are isolated from arterial pulsation.

Normally they're slower flow, and since it is slower flow turbulence is less common since that's related to velocity.

Clearly venous waveforms in venous flow are very sensitive to downstream pressures.

Doppler Angle Considerations

A brief digression before we get into some clinical examples.

There is this notion that you have to measure your doppler velocity is an angle of less than 60 degrees.

That gets ingrained in people so much that they think it has to be at 60 degrees.

Let me just say that you can measure doppler angle or you can angle correct at any sort of doppler interrogation.

The problem is though the 60 degree thing is relevant because as you get towards 60 degree, the potential for error in your measurement goes up greatly.

The physics works no matter what the angle, but small errors in your angle correction have very little impact up to about 60 degrees.

Once you get above 60 degrees, small errors in your angle really start to have demonstrable effects in your quantitative data.

That's the relevance of 60 degrees.

Whenever you're doing these studies, always remember what medications the patient may be on.

Always be cognizant that shunts in cardiac disease can also impact what you're looking at.

Here is an example from a patient after liver transplantation at a very unusual waveform in the hepatic artery, immediately post-op, but was on high dose epinephrine was very vasoconstricted and really had a much more normal waveform as he got better over the next few hours and they were able to wean him off the epinephrine.

Similarly, these are some abnormal waveforms.

In the top one you have delayed systolic upstroke, a very abnormal looking waveform.

This was in a young child with aortic coarctation and the sort of a tardus parvus waveform within the common abdominal aorta.

This last one, you see this abnormal reversal flow in diastole, and that's someone with a patent ductus arteriosus that because of the rapid runoff into the low pressure pulmonary circulation is not able to maintain positive diastolic pressures.

There's another example.

Here's looking at the hepatic vasculature.

The main portal vein has sort of two, not two and fro flow, but you have cessation of flow down to zero intermittently.

Hepatic arterial flow is normal.

You look at the middle hepatic vein there, you have markedly abnormal flow.

Whenever you see something like this, you should think about cardiac disease.

In this particular population, this is this child's chest x-ray.

This is tricuspid atresia with an intact septum and very high right-sided venous pressures.

Liver Applications for Doppler

Let's talk about some liver applications for Doppler.

Certainly we've gotten a lot better.

This was the first published radiograph of live patient in North America.

Not much to say about the abdomen in that child, but ultrasound gives us a tremendous window into the abdomen and particularly into the liver.

When we're talking about liver disease, we're often looking at flow, direct indications of abnormality, meaning alterations of portal vein and hepatic artery flow and size.

There are many different ratios and many different things you can look at.

Some people believe these more than others.

I happen to like the hepatic arterial to portal vein velocity, but there are many other indices that can potentially help you.

Then looking at secondary indications such as portosystemic collaterals or splenomegaly portal hypertension happens when there's increased hepatic impedance.

This can cause a reversal flow during expiration when thoracic pressure increases.

There are normal measurements for adults.

Given the varying sizes of children, it's not so easy to have a simple cutoff in kids.

The size of the portal vein can also be impacted by any other portal systemic shunts.

But certainly when you start seeing an enlarged portal vein and two and fro flow like this, you can certainly suggest that there's portal hypertension.

Present cavernous transformation is fairly common, whether this is due to umbilical venous catheters shortly after birth, a lot of times is idiopathic.

But you'll have this sort of abnormal serpiginous channels within the porta.

Often they'll reconstitute very normal looking intrahepatic portal vein branches, but suffices to say that these recanalize branches are not enough to handle the splanchnic blood flow.

This will give increased hepatic and vascular impedance.

Certainly when you have severe portal hypertension end stage liver disease, again, here's very low velocity two and fro flow, velocity much less than the normal 20 centimeters per second in children.

Here we have elevated peak systolic velocity up to approximately two meters per second.

Children are more hyperdynamic than adults, but still a hepatic arterial velocity over one meter per second is abnormal.

Again, if you look at the hepatic arterial to portal vein velocity, this is certainly much greater than three, which is very abnormal in this child with short gut and TPN induced liver failure.

You can barely get any flow within the portal vein.

What we can get is hepatofugal.

Similarly in the hepatic artery, like the last case, there's elevated systolic velocity, but also look and see that there's abnormal diastolic flow and in fact reversal of flow in diastole.

That indicates a very stiff liver causing high impedance in this low end diastolic flow.

Indirect findings looking for portosystemic collaterals.

If you look in the region of the GE junction, here's aorta, this is the lesser omentum, and you can see multiple tortuous channels that turn out to be venous channels on color doppler.

These are your esophageal varices.

You can see recanalization of the umbilical vein, and you can also see occasionally spontaneous lienorenal shunts all attempts at the portal system to find lower pressure outlets.

Now, there is a lot of hope that there'd be liver tumors would be characterizable by Doppler alone, and that just unfortunately really isn't the case.

However, you can still get a fair amount of information looking at the vascularity of tumors.

Look at the portal vein for patency and to try to get evidence of hepatic venous shunting.

I think there's certainly excellent evidence that there's tumor characterization in adults possible with ultrasound contrast, with specific enhancement patterns.

These same rules should apply to kids, but there just really isn't enough experience yet in the pediatric literature.

This is a child who presented with a large heterogeneous mass, which was highly vascular, also had a very high alpha fetoprotein, and this ended up being a hepatoblastoma.

Here's a child with multiple masses within the liver.

Some of these look like they have a central scar within them.

They do appear to be vascular.

This would be a terrific case for ultrasound contrast.

However, in this particular child, got a CT scan with immediate and delayed images, you can see the typical fat pattern filling in of infantile hepatic hemangiomas.

Doppler can be a useful thing in these particular children.

You do have abnormal AV communications in these abnormal masses that's gonna give you decreased impedance and increased hepatic arterial flow like you can see here in this very large celiac axis and common hepatic artery.

You can look at the hepatic veins.

Here's the normal right hepatic vein draining an area that doesn't have any lesions within it, and you can see the elevated flow in the middle hepatic vein draining the hemangioma.

One thing that doppler can be very useful for is in these children with diffuse hemangiomatosis or multiple infantile hemangiomas, is you can monitor the impact of therapy.

These children, now, the preferred therapy is propranolol, and this is to help both the cardiac function, but it also seems to actually shrink these abnormal arteriovenous communicators within the vascular anomalies.

At the start of therapy, you can see extremely high velocity flow of 3.8 meters per second with elevated diastolic flow and a followup examination your oncologist may want to know, well, is our treatment getting better?

If you look at the liver still, it's like, well, who knows?

There's still innumerable hepatic masses.

But if you look at this point at the hepatic artery, get an angle corrected waveform, you can see that now the velocity is 130 or 1.3 meters per second.

That indicates that yes, in fact therapy is working, those arteriovenous shunts are closing off.

We no longer have the elevated systolic velocity.

You can tell them, even though you can't tell with gray scale, that things are getting better.

Physiologically you can tell that yes, the therapy is working and the child should do well.

Just remember that not all vascular lesions in a child are hemangiomas.

This was a child. We happen to find this incidental 2.4 centimeter mass during pyloric stenosis examination.

Maybe it's a little bit vascular.

This child went on to MRI and you can see a hypo intensity T1 and hyperintensity T2 lesion with an elevated alpha-fetoprotein.

This child had a very small hepatoblastoma.

Okay, Other things to look for, please look for the presence of thrombus within the IVC.

This is one from a umbilical venous catheter, which is fairly typical.

Another thing we see fairly commonly is umbilical vein catheter injuries.

This happens when the catheters don't quite make it through their course into the hepatic veins and IVC.

They may get stuck along the way and with infusions of TPN or pressors that you can actually get little perforations in the liver parenchyma in cisterns of this fluid.

This can be somewhat concerning if you're not familiar with it.

People can be worried that these are masses.

In fact, these will go away on their own.

They seldom need any treatment on their own.

They can calcify, but again, these are very typical along the course of the ductus venosus, as you would expect the umbilical vein catheter to go dopplers, very good for looking for the occasional congenital shunt.

Here you can see hepatic vein coming right into the portal vein.

These are not very common, but they can cause some failure or even encephalopathy.

Occasionally, you can pick up total anomalous pulmonary venous return.

Here's a child who has a very large portal vein.

We weren't exactly sure why.

As we scan through, we could see that there was this anomalous vessel that was coming into the portal vein.

It looked like it was from above the diaphragm color doppler picture, and tells us that blood flow is coming from the thorax into the portal vein.

We were fortunate enough to have an umbilical venous catheter that actually follows the course of this total anomalous pulmonary venous return into the anomalous vein from the portal vein.

Doppler Applications in the Adrenal Gland and Kidney

So briefly talk about some doppler applications within the adrenal gland.

And kidney Adrenal hemorrhage is very common in children, especially after difficult deliveries, there is sometimes concern about whether an observed mass could be a hemorrhage or whether it could be a adrenal neuroblastoma.

If people are willing to wait, you can certainly see the initial solid appearing mass at birth, over time becomes more cystic.

Clearly a hematoma will not have any flow within it, whereas an adrenal neuroblastoma like this case will have some low level flow and maybe some areas of increased echogenicity from calcification.

When looking at doppler evaluation of the kidney, you have to know that the normal arterial resistive index varies over time.

A preterm with a resistive index of 0.9 can be absolutely normal.

Somewhere over the course of the first few months of life, the resistive index starts to drop and becomes more like that of the older child and adult, veins again have minor variability and it's rather remarkable where we've come.

Here's not so very long ago, this was the best we could do with evaluating the renal artery.

Today we're able to get beautiful images and actually make some meaningful diagnoses for our clinical colleagues.

Renal Vein Thrombosis

Renal vein thrombosis is probably occurs more commonly than we think.

There are multiple causes, including dehydration, shock nephrotic syndrome, and on ultrasound you'll get a big swollen kidney with decreased cortical medullary differentiation.

Here's a fairly typical case.

The classic triad is an abdominal mass and hematuria, along with hypertension.

Here's a normal appearing right kidney.

Here's a left kidney, which is still within normal limits in size, but certainly is very bulbous.

You have poor cortico medullary differentiation.

You can get these little echogenic lines going through the parenchyma, which some people think are actually thrombi in intrarenal vessels and doppler can really help you out here.

Here's the normal kidney, which has a normal resistive index, normal renal venous flow, and look at what's happening in the other kidney.

There is, because of the thrombosis, this kidney is swollen, it's tense.

There's very high intrarenal impedance, and so you've got very poor diastolic flow, actually reversal of diastolic flow and very poor outflow in the renal veins.

The reason I made the comment that it probably happens more often than we think is that here's the doppler on this child the very next day.

Now, certainly the gray scale appearance of this kidney is not normal and it's probably not ever going to be normal, but the doppler doesn't look too bad.

You've got some recanalization, you've got some good flow coming out of the vein, and you've got normal diastolic flow going into the kidney.

Depending on when you happen to do the examination, you may not find the classic Doppler findings.

Here's just over time.

Another patient, normal left sided kidney abnormal looking right kidney with poor cortical medullary differentiation.

Again, similar findings with the Doppler evaluation.

This is a neonate.

So again, that would be low diastolic flow for you and I, but normal for this child.

But again, look over at the affected kidney.

Very high intravascular impedance, reversal of diastolic flow.

Late findings are variable.

There's an excellent paper by the group at Toronto, sick kids.

You can see some, some kidneys will escape and look fairly normal.

Others will shrivel up and become this little fibrotic remnant.

This one happened to have multiple little intravascular calcifications.

If you really look around carefully, you will almost always find a remnant of an IVC thrombus.

In this case, it's always calcified.

If you have an abnormal kidney, and you're not sure what's happened to it, if you don't have any earlier scanning, look around for this.

'cause odds are, this means it had a renal vein thrombosis.

Renal Arterial Hypertension

Renal arterial hypertension is uncommon in neonates, but it does occur in neonates in younger children.

It can happen because of umbilical arterial catheters, but like other causes of renal arterial hypertension in kids fibromuscular dysplasia is really the most common cause.

You can see it after renal vein thrombosis or in children who have coarctation of the aorta.

Not to get into the controversy over whether ultrasound should be a good screening test.

The ultrasound specificity is very good.

So when you find an abnormality, you can be very confident you've got an abnormality.

What's unclear is what the sensitivity is because, with fibromuscular dysplasia, you can just have segmental renal disease.

You don't have to have main renal artery disease, and you can have accessory renal arteries that you may not necessarily interrogate.

Criteria for renal arterial hypertension from the American College of Radiology and elevated peak systolic velocity in adults, people use 1.8 or two meters per second.

Again, in children that's a little more difficult since they tend to be hyperdynamic and normal velocity measurements really don't apply.

Certainly if you have a delayed acceleration time of greater than 70 milliseconds, you can still use the renal artery to aortic peak systolic velocity ratio of greater than 3.5.

As you get very critical stenosis, you will get downstream vaso dilatation and elevated diastolic flow, so your resistive index will drop, although I don't find that particularly useful for me, practically speaking.

An absent early systolic peak is actually very useful.

Just as for terms of a visualization of the waveform.

Just some examples, this, these are some older children, certainly not neonates, but this was a young man who had significant hypertension.

You can see normal waveform on the right.

A little bit of delayed systolic upstroke, normal on the left.

A little bit of delayed systolic upstroke on the right, elevated diastolic flow.

This is a variant of fibromuscular dysplasia with a little bit of a web here, had a significant gradient that went away after angioplasty.

As did his hypertension. Another older patient.

This is a 15-year-old girl who was having a sports physical and was found to be hypertensive.

There are delayed systolic upstrokes within both main renal arteries that indicates there's some sort of a proximal stenosis since it would be essentially unheard of for an otherwise healthy girl.

To have main renal artery disease, you need to keep looking farther upstream.

We know there's a problem. So when you have a problem in the main renal arteries, you always have to look at the aorta.

When we looked at the aorta, same sort of waveform markedly delayed systolic upstrokes.

Again, this tells you there is still a problem more proximally, and the most common thing is going to be an aortic coarctation.

That's in fact what this child had Here is another child.

This is a 14 month old that had significant hypertension.

Looking at the intrarenal waveforms, it's hard to even know whether this is arterial or venous.

I will tell you that is an arterial waveform.

Little arterial peaks incredibly delayed systolic upstroke.

We did not find the accessory renal artery, but on the arteriogram there is in fact this lower pole artery, which is what we were measuring, and a selective injection.

You can see a classic beaded appearance of fibromuscular dysplasia in this 14 month old.

Doppler Applications in the Bowel

Let's talk a little bit about looking at the bowel in the young child.

I'm gonna draw heavily on the work from doctors Pelman and Danon from Hospital for Sick children in Toronto.

I highly recommend this paper.

This is looking about what happens in necrotizing enterocolitis.

This is a devastating disease that affects neonates.

Its ischemic injury of bowel, and you can tell a lot with the ultrasound and doppler evaluation about the disease of necrotizing enterocolitis before you can find things on plain radiographs.

A case from our practice, a child who was not doing well had suspected NEC, had normal radiographs, but as we did the ultrasound, certainly there's this abnormal echogenic fluid throughout the abdomen.

This markedly hyper echoic bowel probably representing mucosal hemorrhage.

You can see the small bowel mucosa here, with ultrasound examination with color doppler.

This was a little less perfused than we thought.

This is something you really have to get used to with whatever your own equipment is and define your own standards for normal.

As we looked around a little bit further, as in this child, we could actually find the area of bowel discontinuity and leaking of enteric contents into the peritoneal cavity.

Going back to the work by doctors Pelman and Danon.

Here's a lovely ultrasound pathology correlation from their paper showing hyperemic bowel around a loop of bowel, which is hypoperfused, probably has some small areas of intraluminal pneumatosis.

At pathologic examination, you here's the abnormal bowel with pneumatosis surrounded by hyper perfused bowel.

Another case in our practice, again, you can see pneumatosis intestinalis in the wall, non-dependent portions of the GI tract, along with some complicated ascites.

If you're worried about that and you want to check and see, look for portal vein air, put your doppler cursor over the portal vein and look for these abnormal spikes.

Okay, anytime a little bit of a bubble goes through, that's gonna give you this spike.

As we looked further, as time went on, we could certainly come up with a lot of portal vein gas within this liver.

Just because you see this doesn't mean they have necrotizing enterocolitis if they have a low umbilical venous catheter, and there's a little bit of bubble in whatever they're flushing.

You can also get little dots of portal vein gas.

You can get the artifacts and you interrogate the portal vein.

Know what lines you have, know what's going on with the child.

But, doppler is a very sensitive way to look for portal vein gas.

Central and Peripheral Vessels

Just a little bit about the central and peripheral vessels, because I think this is a underutilized area of doppler in children.

We're typically looking for thrombus, we're looking for stenosis and occlusions.

It's important to know that even if you can't see the occlusion or the stenosis, indirect signs are very useful.

It's also very important to know that like with other areas of doppler in the central peripheral vessels, just because you have flow doesn't mean that its normal.

Very common to have little bits of IVC clot, particularly at the ends of catheters.

These are very common.

The more you look, the more you'll see.

They may not always need treatment or the lines removed, but it's a good place to look.

Like we talked about before, when there's renal vein thrombus, it's very common for that thrombus to propagate down into the inferior vena cava.

It may not be occlusive.

But as I said before, you almost always have a little remnant of IVC clot or calcification after these events.

You may see very slow flow downstream from a thrombus up here in the upper part of the IVC.

Doesn't happen very often, but you can get thrombi or little fibrin webs.

It can come off umbilical venous catheters, which is what this was.

This was not a dissection, but in this case went into the superior mesenteric artery.

Fortunately, this did not cause any intestinal ischemia.

The central veins are very easy to evaluate in kids.

When you do, you should always see reflected cardiac and respiratory activity.

This is a normal jugular vein in about a 12-year-old.

It also works the same as if it was a 12 month old.

Sometimes you'll see these little incompetent valves in the distal part of the jugular vein.

That's normal. But as you get down further into superior vena cava, and as you look at the internal jugular waveform, this looks very much like an hepatic venous waveform.

You are seeing right atrial activity.

When you don't see that, that's gotta be abnormal.

You have to think about that.

This is a child which we didn't figure out for a very long time, but had multiple medical problems, as a newborn had refractory ascites, and we got multiple images that looked like this.

One day, a very perceptive sonographer said, Hey, that's going the wrong direction.

Because all the previous evaluators said, Hey, we've got flow in the inferior vena cava, we have flow in the hepatic veins.

Everything must be fine. Yes, there was flow, but no one paid attention to direction of it.

It was abnormal when we looked at the hepatic veins that were very dampened, we are not getting any sort of right atrial activity.

When we finally went to other imaging evaluations, we found that in fact there was an IVC web right here, which is a very difficult place to evaluate with doppler.

Not just saying flow, therefore normal.

It's like, no, there was flow but going the wrong way.

This works very well in other places.

This was a young child about a year of age who had a heart transplant and facial swelling.

Looking at the brachiocephalic veins, yes, there is activity, this is respiratory activity.

The conclusion was the vessels are patent.

Well, yes, the vessels are patent, but the waveforms are dampened.

We are not seeing normal right atrial activity in the superior vena cava.

Again, this child went on to other cross-sectional imaging and there was a significant stenosis at the caval anastomosis.

Even though we couldn't see this just by looking at the indirect signs, you knew there was a problem between where you were and the right atrium.

Occasionally, ultrasound can be helpful in figuring out azygos continuation.

This is a child that had some difficulty getting vascular access from below.

You can see the aorta.

We don't have a normal IVC, but we do have a very large azygos, which you can follow up on multiple projections here.

You can see we did not have a normal IVC, we had normal hepatic veins.

Sonographer, wondering if this is a large azygos vein and turning on color doppler and actually measuring it.

You can see yes, in fact that's what that was.

Peripheral arteries should typically have this appearance.

The muscular arteries at rest have a very high impedance and give you this typical phasic waveform after cardiac catheterization.

This young child had a slightly cool leg and the official interpretation was the right common femoral artery was patent.

While that's true, when we went back and looked at the other side, 'cause symmetry is your friend, you can see that there is a markedly delayed upstroke, especially compared to the other side that indicates that there's a proximal problem.

There's elevated diastolic flow that indicates there's downstream vasodilatation.

You don't have the reversal flow like you do in the normal leg.

This is a very typical appearance for a right iliac artery occlusion and collateral reconstitution.

This child had swelling and actually a palpable thrill over a groin after another cardiac catheterization procedure.

Here we can see the left common femoral vein has a very noisy waveform.

Here's the artery, which has incredibly high diastolic flow.

You can actually, as we work our way through, you can actually see the connection between the two.

Aneurysms

Very briefly about aneurysms.

True aneurysms are very uncommon.

The pediatric population, true aneurysms contain all vessel layers.

Layers that can be seen with trauma, but are often seen with arteritis or connective tissue disease.

Pseudo aneurysms are much more common and these are usually a contained leak caused by trauma.

Usually iatrogenic either an arterial line or a catheterization procedure.

Here is an uncommon true aneurysm of the radial artery with normal walls around it.

This is going back to another case.

This is the child we showed earlier that has renal vein thrombosis, has an IVC clot.

This child was receiving heparin injections and developed a lump over the thigh where they were getting injections.

When we scan in that area, here's the lump, but we noticed another abnormality.

When we looked at that in real time, things are sort of swirling around in it.

You can see that there's a feeding vessel with a little jet.

We put doppler.

You have the typical two and fro waveform, very classic for a pseudo aneurysm.

Conclusion

In conclusion, that was a very brief and quick tour through a lots of different things you can do with doppler in the young child's abdomen.

Dopplers a very useful tool and with a little bit of understanding, it's not that hard or complicated.

If you learn a little bit about the physics and the hemodynamics, you can figure out the predictable alterations that allow you to apply this to clinical physiology and it really will improve your diagnosis, both in terms of sensitivity and specificity for these young patients.

Thank you for your time.