What makes you to be able to tell from the detailed
analysis of just one heartbeat? We are about to find out. You are listening
to ReachMD XM 157, The Channel For Medical Professionals. Welcome to Advances
in Medical Imaging. I am Dr. Jason Birnholz, diagnostic ultrasound consultant
in Oak Brook Illinois, your host and with me today is Dr. Mani Vannan. Dr. Vannan
is a professor of Clinical Internal Medicine at the Ohio State University
College of Medicine, Joseph M. Ryan Chair in Cardiovascular Medicine and
Director of Cardiovascular Imaging at the Ross Heart Hospital at the Ohio State
University. Today we are discussing something brand new, High-Speed Volumetric
Dr. Vannan, thank you very much for joining our program.
It's my pleasure.
I wonder if we might put the new advances and
echocardiography in context by a little review of the history of
Sure. In the last 30 to 35 years, echocardiography has seen
a revolution in the real sense of the word at the very beginning when we did
echocardiography, we relied on spikes. Literally spikes of ultrasound waves
coming back to the transducer after impinging on the target and those were
called A Mode echos amplitude mode echos. Since those early years when we were
looking at the spikes to diagnose cardiac disease, we have come a long way over
the last decade two-dimensional echocardiography has become the bread and
butter of clinical echocardiography. It has become very sophisticated. It is
the bedrock of almost every clinical decision we make in cardiovascular
medicine. It looks at anatomy. It looks at physiology in a manner that no
other technology can do, especially a portable technology, such as echocardiography.
In the last ten years, there has been a big task to try and bring 3-dimensional
echocardiography into the clinical setting and what we have seen are a very
systematic advance in technology so that today we are in the brink, I think of
actually implementing in the Clinical Arena 3D echocardiography in a meaningful
way. So I think echocardiography is truly seen in evolution and a revolution
imaging technology, almost like no other imaging modality in cardiovascular
Well 3D, approaches of 3D has been around for some years.
What's new now?
You are right, 3D has been around for about 10 years now.
The fundamental problem with 3D or fundamental problems I should say with 3D
have been two things over the last ten years and that is at the acquisition and
meaning the image acquisition and so that when you put a transducer on the
chest of a patient and you are trying to get 3 dimensional picture of the
heart. The technology has not been sophisticated enough for us to allow that
to do it almost instantaneously. We have relied on putting the transducer on
the chest and then waiting for about 4 or 5 or 6 heartbeat before you can get
the entire volume of the heart and then we build the 3D volume, which is
somewhat tedious. It's certainly a vast advance over 2D echo, but it is still
tedious because one of the attractions of echocardiography as being that it is
real time. Every heartbeat is recorded in real time and it happens. When you
do this 4 beat or 6 beat capture for 3D, you are essentially negating the
technique of its fundamental advantage, which is realtime because you are now
building the volume overflow to 6 heartbeats instead of every heartbeat. Very
similar to MRI and CT scan to this day because both those techniques are all
based on multiple heartbeat cycles and then put together as a single
heartbeat. The second problem with 3D echo has been that having acquired the
volume albeit over 4 or 6 heartbeats, you then don’t have a very intuitive way
of getting meaningful numbers, data, and information out of the 3D volume.
There is a whole host of information in the 3D volume of the heart. The heart
is a beating organ. It not only has anatomical features, but it is a
profoundly sophisticated physiological structure. To get all of that in 3D and
not have an intuitive way of looking at the data in an efficient manner has
been the second impediment in implementing 3D echo successfully in clinical practice.
Well, I have heard that new technique referred to as echo in
a heartbeat perhaps somewhat sensible is a single heartbeat that you are
analyzing very thoroughly and adequate sampling or do you in practice tend to
look at a lot of different beats?
The new techniques are, you know, so called echo in a
heartbeat is more than a cliche. It sounds very attractive, but in
performance, it has to match up to that cliche and it does. For the first
time, I think we have the ability when you put a transducer on the chest, in a
heart cycle if there were 800 millisecond in our heart cycle; every millisecond
is accounted for in a true 3D image. It is not a 2D image, but it is a true 3D
image, so we are able to get volume image throughout the cardiac cycle so that
now whatever happens between the consecutive millisecond if captured in 3D
volume, you don’t lose information and is realtime. So it is truly an
advance. So all you need is a single heartbeat virtually to get the entire
volume of the heart. So the practical implication of that would be in an ideal
world, you put a transducer on the chest in a single heartbeat, you get the
entire heart information and you take the transducer off the chest. That may
be somewhat of an exaggeration because in a clinical setting, the patients are
sometime not that cooperative to get everything in one heartbeat. So you can
acquire 2 or 3 heartbeats, but every heartbeat has entire information. So you
can then choice which of those heartbeats that you would like to use, if one of
them has got a little bit of artifact then you could use the other one etc. So
it’s a distinct advantage over the previous technology.
Well I guess that means if you are in some sort of full
screening mode you can do an awful lot of patients per day with one instrument.
That’s right. I in this age in our preliminary experience
now, what we have done, is to put the transducer on 2 separate locations on the
chest and that’s all it takes and that is compared to the 2D echocardiograms
that we do now as a standard practice where we get multiple standard views of
the heart because it is 2 dimensional echo and you need to cover the entire
heart in multiple views, where as with this new technology one should be able
to put the transducer in 2 separate locations and if you have 2 very good
heartbeat information you have done virtually in a matter of a couple of
minutes or 3 minutes at the most.
If you are just joining us, you are listening to Advances
in Medical Imaging on ReachMD XM 157, the channel for medical professionals. I
am Dr. Jason Birnholz and I am speaking with Dr. Mani Vannan. We are
discussing a high-speed volumetric echocardiography.
Now Dr. Vannan, have you taken the machine off to a Coronary
Care Unit and looked at some acutely ill patients?
We haven't taken the machine physically to a Coronary Care
Unit only because the machine has been in a preliminary state of development,
so we housed it in a room, but we did have a very sick patients come down to
the echo lab, who are extraordinarily short of breath and in these patients, it
is usually we spent 15-20 minutes patients on oxygen etc., where we try and get
us much information as we can. We have done a few patients now with this new
technology and I recall at least one patient whose example I show now who was
extremely short of breath and has severe heart failure and we got entire heart
information, not only the structure i.e. the anatomy we also got flow information,
valve leak information with color Doppler, all in a matter of literally a
minute and a half. That’s all it took us to get the entire heart information
and that was a big relief for the patient who just could not lie down flat,
just could not stay still etc. So that to me is the telling example of how far
we have come in terms of doing 3D even in very sick patients.
Lets move to the people who are not quite so compromised.
Have you tried doing any stress echos with this new technique?
We have not tried the stress echos yet, but it is a very
intuitive application of this technology. When we do a stress echo generally
if we were to do a treadmill stress test for example, the challenge we have is
at the peak exercise when the patient is ready to come off the treadmill
because he or she is exhausted or has chest pain or short of breath or has got
leg pain, the patient comes off the treadmill and we literally have the patient
jump on to a couch and lie in the correct position for echocardiogram and then
we have to acquire the entire heartbeat or heart information as quickly as
possible , preferably within the first minute because the heart rate is coming
down all the time . That’s being a challenge in stress echocardiography. I
think we have done very well with 2D echo, but with this technology, I would
see that we put the transducer on the chest on two different locations and you
should be done in literally two heartbeats and you have the entire heart
information and then you can clearly not spend a whole lot of time trying to
chase the heartbeat because it is coming down all the time after a stress
test. We could it a really very close to the peak heart rate, which would be a
true stress test.
Well, I take it down that you are going way beyond global
measures like ejection fraction and looking at much more specifically at how
heart is contracting.
That’s right and I think the advantage of doing imaging in
one heartbeat in a truly volumetric fashion is that when you are measuring
anything in the left ventricle, which is the main pumping chamber of the heart
and you what to measure the ejection fracture or you want to measure left
ventricular volume or you want to measure mechanical function such as the
muscle function, such as strain or strain rate of the muscle, all of this are
based on the predication that what you are measuring is at every heartbeat
because all these indices change every heartbeat, especially in patients who
are sick. So if you are looking a normal it may be acceptable not desirable,
but may be acceptable to look at the data or number that is derived from
multiple heart cycles in a 3D echo, but when you are looking at abnormal hearts
or patients with heart disease, it is not acceptable and not desirable to get
these numbers from multiple heartbeats. So doing it in one heartbeat means now
we have a real reliable method of looking and believing those numbers that we
get out of 3D echo because these are numbers for every heartbeat and even if
they change every heartbeat, the numbers will reflect that change truly.
Now, instead of situation of trying to diagnose a problem or
even grade it, what about using this technique for monitoring therapy?
Absolutely. I mean a simple example of that would be
ejection fraction. One of the big issues with echocardiography and measuring
ejection fraction as an index of efficacy or lack of efficacy of a therapy has
been that 2 dimensional ejection fraction is variable between 2 days in the
same patient for no other reason then the fact that we cannot reproduce the
exact plane of imaging of the heart, with the currently the technology where
you have to get multiple heart cycles to build the volume. The same problem
exists because you now holding for 4 or 6 heartbeat cycles to do it, with the single
heartbeat, it is far more reliable and reproducible in terms of looking at
ejection fraction as an index of accessing a specific therapy, efficacy, or
lack thereof. So I think we are on to using echocardiography in a meaningful
way to direct therapy or change therapy in patients.
My thanks to Dr. Mani Vannan, who has been our guest and we
have been discussing high-speed volumetric echocardiography.
Dr. Vannan, this has been really fascinating. Thank you so
much for joining us.
I am Dr. Jason Birnholz. You have been listening to
Advances in Medical Imaging on ReachMD XM 157, The Channel for Medical
Professionals. Be sure to visit our website at www.reachmd.com now featuring podcast
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