Usefulness of Echocardiography in Clinical Decision Making - SD

Introduction

Hi, my name is Paul Grabber.
I'm a cardiologist at Baylor University Medical Center in Dallas, Texas.
And I'm gonna talk today about the clinical utility of echocardiography.
It's a broad subject,
but I'm gonna focus on some of the major issues
that we use echo for every day in clinical decision making.

Usefulness of Echocardiography in Clinical Decision Making

Let's talk a little bit about the usefulness
of echocardiography and clinical decision making.
I wanna begin by just giving a rough outline of
what we're gonna talk about, and we'll start out talking
about echocardiography and chest pain
and coronary artery disease,
and then we'll move to valvular heart disease,
and we'll talk about some miscellaneous
cardiac problems.

Echocardiography in Chest Pain and Coronary Artery Disease

Now, one of the most
common reasons why echocardiography is obtained in a patient
is for chest pain.
In fact, it's estimated that about 70%
of the echocardiograms we do are
to evaluate left ventricular function in patients
with either chest pain
or known coronary artery disease or heart failure.
And the things that come about
as possible causes of chest pain for which
echo can be useful is a myocardial infarction
or ischemia, aortic stenosis, mitral valve prolapse,
hypertrophic cardiomyopathy, pulmonary embolus,
pericarditis, aortic dissection.
All of those things can cause chest pain
and can be identified by echocardiography.
But as I said, the most important reason
for doing echo is to evaluate wall motion.
And here's an example of a patient with
a serious wall motion abnormality from an anterior
myocardial infarction.
And what you can see here is the septal region.
Of the left ventricle is akinetic, and it's very bright
and it's very thin.
And so this is usually an full thickness
or transmural myocardial infarction, as you can see here.
Sometimes we use contrast
to help us see the images.
If you look at the panel on the left, you'll see
that there is a four chamber view,
and the wall motion looks completely normal,
septum the apex and the lateral wall all are moving well.
And then we administer a
contrast agent in this patient.
And let me click on this right panel here.
And what you'll see is that in this very same patient,
the wall motion looked normal before contrast,
and afterwards, you can see the apex bulging outwardly.
This is apical dyskinesis from a prior myocardial infarction
from a distal LAD occlusion.
So oftentimes contrast not only makes the images prettier,
but makes diagnoses that we were unable to previously see.
And we did a study on that, and
published it some years ago
where we put people in a magnet, did a gated MRI
to assess wall motion,
and then looked at 2D Echo without contrast
and with contrast in the same patient,
all the images were read blindly.
And what you see here is that there was concordance
between MRI
and ECHO in 76% of patients,
with a lot of patients having uninterpretable
segments
because of just not being able to see them.
And then after contrast, the concordance improved to 91%,
meaning that if you could see the segment
after contrast that you diagnosed it correctly.
So contrast should be used probably more often.
In the same study, we looked at measurement
of ejection fraction.
And this was really somewhat surprising.
Before given the contrast agent, the limits of agreement
for assessment of LVEF are roughly plus
or minus 20%.
That means if we said the ejection fraction was 50%,
it could be 95% confident that it was between
30 and 70%.
That's not really good enough.
But after contrast, as shown on the right,
these confidence intervals narrow down to plus or minus 10%.
And now we have data that with 3D echo and
contrast, we can get ejection fraction to within plus
or minus 5%.
And that's very important for clinical medicine.
We can also see perfusion imaging.
On the left, you can see that
the contrast microbubbles are throughout the myocardium.
This is at rest,
there's clear perfusion of the myocardium.
And then at right on the right image
after adenosine, you'll notice
that there's a subendocardial defect
or a black spot out at the apex indicating that
this is an abnormal stress,
myocardial perfusion echocardiogram.
We did this also with a different technique
where we use high power, high amplitude doppler,
which gives us a color signal.
And on the left panel, you can see
at the top you see a defect at rest and
after adenosine in the inferior wall,
which corresponds nicely to a fixed defect on
SPECT thallium imaging.
And on the right you see good perfusion
in the echo image at the top at rest.
But after stress, you'll see that the
septum becomes black
and it's thin out by the apex, again, corresponding
to an abnormal reversible defect on SPECT testing.
There was a study of a number of
comparing a number of studies
that were looking at SPECT versus MCE against angiography.
And you can see here that actually the sensitivity
and specificity of contrast echo is a little
bit better than SPECT.
Meta-analysis shown in this slide again shows that
MCE is a little bit
or MPE myocardial perfusion echo on this slide.
It's a little bit more accurate than SPECT
when compared to angiography.
So we now use contrast with a stress echo to try
to improve our sensitivity and specificity.

Complications of Acute Myocardial Infarction

Now, echo is also very useful for evaluating complications
of acute myocardial infarction,
and those include mural thrombus aneurysm
or pseudoaneurysm, mitral regurgitation,
ventricular septal defect, and even RV infarction.
Here's an example of a mural thrombus,
and as you look at these echoes, you'll
notice here two large thrombi in the apex as we zoom up on them,
on the right, you see them here,
two large mural thrombi in the apex of this person
with an anterior myocardial infarction.
LV pseudoaneurysm is a real problem
because it requires urgent surgery.
It's estimated there's about 500,000
ST elevation myocardial infarctions every year in the US,
and about one to 6% have LV rupture.
Now, many of those patients die
before even getting to the hospital.
But if they form a pseudoaneurysm,
rather than dying immediately,
they're still at risk of death.
And treatment is immediate surgery.
Echo without contrast is only about 26% sensitive
for detecting pseudoaneurysm.
And that's from a large study by Francis et al.
Looking at all the literature on this topic
yet contrast echo is diagnostic for this.
And it turns out if only 1% of pseudoaneurysms
that would be about 5,000 patients a year
had contrast, it would
potentially be life threatening in about 75%
of those or over 3,700 patients.
Here's an example of that
that we saw recently in our hospital in Dallas.
63-year-old lady presented with a stroke,
and her EKG showed ST segment elevation in V three
through V six with T-wave inversions, all suggesting
that this lady had had an anterior myocardial infarction,
probably at home somewhere in the past two, three
or five days, somewhere in that range.
And a transthoracic echo was ordered to assess LV function
and the possible presence of thrombus in the heart,
which could have accounted for her stroke.
And what you can see is
after contrast, there's actually no evidence of any thrombus
at the apex here.
And you can see that right here.
It looks fine,
but the image was angled
and you could see a LV pseudoaneurysm right here,
a small narrow neck with contrast extending
outside the left ventricular cavity.
And this patient had to go to emergency surgery
and have this corrected.
Here's another cause of acute chest pain that occurs
occasionally.
And what you can see here is a flap in the ascending aorta shown right here.
And on a short axis view, you can see it
again right here.
There's flow here in the true lumen,
and the false lumen is here.
So this is an acute aortic dissection,
rapidly diagnosed at the bedside with echocardiography.
Some other situations include this one patient
who presented with chest pain
and an inferior myocardial infarction
was profoundly hypotensive.
And this patient turned out
to have was a ruptured papillary muscle.
And that seen here, this
appears to be a mass,
but this is actually a papillary muscle that is
moving freely because it's ruptured.
The patient had acute mitral regurgitation
after an inferior MI
and was sent to surgery to have this corrected.

Valvular Heart Disease

Now I'm gonna switch gears
and talk about valvular heart disease for a moment.
Valvular heart disease is quite common.
And this is a slide that shows the epidemiology
of valvular heart disease,
predominantly left sided valvular lesions.
Now, a lot of people think of aortic stenosis
as being very common in the elderly,
but as this slide shows,
mitral regurgitation shown here is actually more
common than aortic stenosis shown here
and occurs in over 10% of patients above the age
of 75 aortic stenosis is also quite common,
and both these lesions are really readily identified
and characterized by echocardiography.
This slide from Catherine Otto's paper in the New
England Journal shows the progression of aortic stenosis,
which in most people is very similar to atherosclerosis
of the coronary arteries.
You start off with a mild degree
of thickening of the leaflets.
As that progresses over time, they still open well,
but eventually the atherosclerotic lesions
restrict opening of the three aortic cusps
and eventually in the late stages become severe aortic stenosis.
This can all be measured
by looking at the Doppler velocity across the aortic valve
as shown here, which
is typically about one meter per second,
but can increase to over four meters per second
with severe aortic stenosis.
Again, as illustrated here,
this is the left ventricle.
Here's the aortic valve.
The flow through the aortic valve will accelerate
as a pressure gradient develops between the LV and the AO.
And that pressure gradient is shown here in the shaded bar between the left ventricular pressure here
and the aortic pressure here.
And as that pressure gradient that gives the heart murmur,
the characteristic diamond shaped systolic murmur,
and that gives the increased velocity
that we can detect on echocardiography.
Now, as you know, using Doppler
to measure a velocity is very angle dependent.
Here's an example of a patient
with a two meter per second jet coming through the aortic
valve along here.
And if we angle our Doppler beam precisely with the jet,
we'll measure a two meter jet if we're off a little bit,
and you can see this angle here
of about 20 degrees,
then we'll measure 1.88 meters per second instead of two.
And if we're off by
a significant amount here, like say 60 degrees off,
we'll actually measure 1.0.
So it's very important to align the Doppler beam
with the jet, and that takes some time
and requires multiple windows.
So what we typically do is we measure from the apex
from a standard apical view,
we roll the patient on their right side
and measure from the right sternal border shown here.
And we also do suprasternal notch Doppler.
In this particular patient,
the right sternal border measurement was 4.7 meters per
second, which was the highest and
therefore the most accurate.
It turns out this simple measure
of Doppler velocity is very important in predicting
outcomes in patient with aortic stenosis.
So if you have a velocity
of more than four meters per second,
you have a very high likelihood of either dying
or requiring valve surgery over the next few months.
If the velocity is less than three,
that likelihood is very much diminished, and between three
and four is somewhere in between.
And so for this reason,
a velocity over four meters per second is now considered
severe aortic stenosis according to the guidelines.
We can also measure
the aortic valve area using the continuity equation.
And what we do here is we measure velocity of the aortic
stenosis jet by continuous wave Doppler,
as we've just discussed, and we measure the velocity just
proximal to the aortic valve in the LV
outflow tract shown here.
And then we measure the diameter
of the LV outflow tract off 2D echo
and convert that to an area by the pi R squared formula.
And therefore, the aortic valve area is equal
to the velocity or the velocity time integral in the LVOT
times the area of the LVOT divided by the velocity
or velocity time integral across the aortic valve.
And this has proven to be very accurate
and is also a reference standard
for measuring aortic stenosis.
As you may know, we're now able to repair
aortic valves by implanting
a percutaneous aortic valve prosthesis.
This is the Edwards Sapien valve.
This is the Medtronic CoreValve.
These are the two valves that are approved in Europe
and in clinical trials here in the US.
Actually recently, the Edwards valve was approved
for use in high risk patients in the US
and that was based on
data from the PARTNER trial shown here where you have
a survival curve for untreated patients
with high risk aortic stenosis that's
shown here in yellow and after TAVR
or transcatheter valve implant here.
And of note, the mortality was reduced at one year from 50%
to 30% with a number needed
to treat a five patients to save one life.
This is not only statistically significant,
but it was really a profoundly positive trial.
And we are gonna see more
and more patients in the future treated
with percutaneous approaches.

Mitral Regurgitation

Mitral regurgitation, this is a 72-year-old man with
class three heart failure as an absent S1,
grade three over six holosystolic murmur in an
S3 gallop, and he has cardiomegaly on chest x-ray
and sinus rhythm on EKG.
His echo showed a end diastolic diameter of 5.7,
which is the upper limit of normal,
a left ventricular end systolic diameter of 4.3,
which is elevated a flail anterior leaflet
with severe mitral regurgitation
and an ejection fraction of 55%.
And here you can see the flail leaflet.
This is a transesophageal echocardiogram right over here.
And you can see the mitral regurgitation jet
going right here through
from the left ventricle to the left atrium.
In this still frame here,
you can see a large proximal convergence zone,
and we use a method called PISA
to actually calculate the flow rate across the mitral valve.
I'm not gonna go into the details of how that's done,
but it's very good at
assessing the actual mitral valve flow rate in the mitral
valve regurgitant orifice area.
And here on the right you can see systolic flow reversal in
the left upper pulmonary vein.
So flow is going backwards
during systole into the pulmonary vein,
which is a very specific finding
for severe mitral regurgitation.
And we use 3D Echo now routinely to assess these patients.
And what you can see right here is a flail anterior leaflet.
This is what's called the A1 scallop
or the lateral portion of the anterior leaflet.
And you can even see a little torn
chord right at the end of that.
And so this patient is
a dilemma.
What would you do? Would you schedule an annual clinic follow up,
start them on vasodilators, do a mitral valve replacement,
do a mitral valve repair, or ask for help?
Well, this is a patient that should get a
mitral valve repair.
We should always repair the valve whenever we can.
And this is the repair that was done.
This is a schematic diagram of our patient,
and basically the surgeon cut out the flail portion
with a little triangular resection here, sewed
that back together, and then put in a ring
underneath it, which is not shown here,
and corrected their mitral regurgitation.
This is a slide from the Mayo Clinic showing that
if you get a mitral valve repair shown here,
your survival is restored to completely normal
expected survival, whereas if you get a replacement,
your survival is diminished.
So we now do mitral valve repairs instead
of replacements whenever we can.
An echo is critical to the decision about whether
or not we can repair the valve.
This is the same patient I just showed you
after a mitral valve repair,
and you can see that there's no residual mitral
regurgitation and is left ventricular size actually
shrunk and became better.
Interestingly, we can also do percutaneous mitral valve
repair now and selected patients.
This is the MitraClip device.
It's been approved in Europe since 2008,
but is not yet approved in the United States.
This device is placed percutaneously
through the femoral vein
and comes down to the mitral valve
and basically pins the anterior
and posterior leaflet together, making sort of a
ski mask opening of the mitral valve and diastole,
but is designed to eliminate
or at least reduce mitral regurgitation.
Here's an example of how that looks.
This is actually the device coming down here
and aiming right at the mitral regurgitation.
So let me show you a case.
This is a patient of mine, a 46-year-old lady
who was in a car accident and fractured her tibia.
She had undergone multiple operations.
In fact, I think it was 18 operations
because she had osteoarthritis.
And at one point her doctors
were thinking about amputating her foot,
but eventually got her healed
and she was unable to walk for 18 months after she got up
and started rehabbing
and walking around, she noticed severe shortness of breath.
And it turned out that she had probably torn a chord
to her mitral valve during the car accident
and had a flail posterior leaflet
because she was so tired of having multiple operations.
She declined mitral valve repair
and elected to have the MitraClip operation done.
So here's an echocardiogram.
It's actually a TEE done
before the clip showing the flail posterior
leaflet seen right here.
And you can see that that looks quite flail.
She had severe mitral regurgitation
as shown here on this echocardiogram.
And again, we determined
after looking at these images that we could do
a mitral clip operation.
This confirms that her mitral regurgitation was severe
by this very large proximal flow convergence zone.
And so we took her to the cath lab
and we put a catheter in her right femoral vein
and advanced up to the right atrium, which is shown here.
And then we guide our transseptal puncture right here in the
arrow on the posterior
and superior aspect of the atrial septum
because we want to get away from the aorta
and go posterior enough
to come down on top of the mitral valve.
So part of this procedure involves accurately positioning
the transseptal puncture under echo guidance.
Then we place the tip of the catheter in the left atrium,
shown here by the blue arrow, again, away from the aorta,
and nice and centrally in the left atrium.
We then bring our device down on top
of the mitral valve in two different planes.
Here you can see the catheter here positioned centrally
in a what we call a mid commissural view,
and again, centrally in an apical long axis view
where you have the flail leaflet here
and the normal anterior leaflet here.
And again, our desire here is to put these two
leaflets together.
So we open the clip,
and you can see it open here in this position.
This is a long axis view.
The aortic valve is here, anterior mitral leaflet here,
and the flail posterior leaflet here.
And then we look at a 3D image to make sure
that we've oriented this in a proper alignment
and it's not properly aligned.
So here's the coaptation of the mitral valve.
Here you can see that the clip is angled about 45 degrees.
We want it to be perfectly parallel to mitral closure.
So at this point, we rotate the clip
counterclockwise and then re-look.
And now we're nicely perpendicular
to the closure line exactly where we want to be.
And so at this point, we deploy the clip
by pulling it back and capturing both leaflets.
And we look very carefully shown by the arrow to see
that this posterior flail leaflet is going over the
clip and inserted down into it and
properly pinched.
And the same for the anterior leaflet.
It's a very important part of the procedure.
And then we've seen
that we've almost completely eliminated her mitral
regurgitation afterwards.
So we do have the opportunity
to do these percutaneous mitral valve repairs,
and they're done under echo guidance.
This is from the EVEREST II trial,
which was published last year in the New England Journal,
a randomized trial of the mitral clip versus surgery.
And what was interesting in that is
that you could really see that there didn't seem to be much
of a difference between the clip
and surgery in three situations here, which was basically older folks,
folks with depressed ejection fractions
and functional mitral regurgitation
that is the mitral regurgitation was due
to left ventricular dysfunction.

Mitral Stenosis

Mitral stenosis is a common problem worldwide.
We don't see as much in the US as we used to,
but it's pathognomonic seen on echo
as this hockey stick deformity
of the anterior mitral leaflet that's shown here.
Let me go back
and see if I can get that to show you right here.
The anterior leaflet has a hockey stick deformity.
It's thin through most of the leaflet,
but very thick at the tips.
And this is pretty pathognomonic for mitral stenosis.
We can actually measure that by coming
to a short axis view, cutting right across here
through the short axis view and plan the area.
And that's what's done here.
You can see the we've zoomed up the picture.
We can actually measure the area of the mitral valve here
and get a mitral valve area.
When doing that. It's important
to be right at the true orifice.
So the mitral valve is shaped somewhat like a cone.
And if you measure back here at the base
or at the mid portion, you'll get a falsely
high mitral valve area.
So you have to orient the imaging plane right
through the tip of the cone as shown here.
And then you'll get the true mitral valve
area by planimetry.
One caveat to this is if the patient has had a prior
mitral commissurotomy, this does not appear
to be an accurate technique.
We can also measure the mitral valve gradient
with continuous wave Doppler,
and that's pretty simple to do from an apical view.
And here you see the velocity across the mitral valve.
And by doing a planimetry of this,
we can get a mean gradient, so we can get both mean gradient
and valve area.

Miscellaneous Cardiac Problems

Now we also look at masses with echocardiography.
This is a case of a left atrial myxoma.
Sometimes this can be confused
for a vegetation on the mitral valve,
but the trick here is to note that it's actually attached
to the atrial septum, which confirms
that it's a left atrial myxoma.
And this patient had this corrected by surgery.
And then of course, there are all kinds of unusual things
that we see with echocardiography.
This is another patient I saw who's 41 years old
and had an ASD closure performed
percutaneously three years ago.
She had originally presented with
paroxysmal supraventricular tachycardia, had an RF ablation
for that and was incidentally found
to have an ostium secundum ASD.
And that was repaired percutaneously.
But now she presents with severe chest pain, gasping
and feeling of impending doom.
She actually feels like she's about to die.
So we did an echocardiogram on her.
And there's a very subtle finding on here
that many people might not notice.
But if you look in the ascending aorta, there's an abnormal
mass right here.
And it looks somewhat like the dissection
that I showed you earlier,
but it doesn't have this undulating flap.
Instead, it looks more mass like.
And so doing some further imaging on it, we could see
that in fact there was a connection
between the aorta shown here
and the right atrium shown here.
She has a fistula,
and what's happened is that the
closure device has eroded into the aorta
and created a connection between the aorta
and the right atrium, which is why she has this feeling
of impending doom.
So we did a surgical excision of this.
Here's a picture from the surgery,
and you can actually see the hole between the aorta
and the right atrium shown by this white arrow.
And the left arrow shows the edge of the
Amplatzer closure device,
which looks somewhat like a saw blade
and is actually cut through here on full excision of this.
You can see that even though this was put in three years
ago, tissue ingrowth has not completely
covered the prosthesis.
And this sharp edge of it moving up against the aorta
with each heartbeat over the years caused
it to erode through.

Conclusion

So basically those are some just interesting cases
that I wanted to show you to illustrate
how important echo is
to us every day in making clinical decisions about our
patients and in guiding therapy.
And I think you'll see in the future,
it's even more important as we use it
to guide novel percutaneous surgical approaches.
Thank you very much.