- [Steve] So hold on. This is my heart, is it?
- [Steve] Exactly.
- I am on my way to get an MRI scan of my heart.
Not because there's something wrong with it,
but because I know someone who can do something
really interesting with the data.
This video is paid for by Dassault Systems.
So after half an hour in a very loud magnet,
I've got one of these.
I don't know what I was expecting the results to look like,
but really, it boils down to
a series of black and white images,
some white pixels, some black pixels,
but mostly some shade of gray in between.
Here, for example, is a slice roughly
through the middle of my heart.
You can see the left ventricle there,
and the right ventricle,
but actually a series of images
were taken at different positions.
So we can sweep through my heart, look past the valves,
and into the atriums, or is it atria? Who knows?
Scans were also taken at time intervals,
so you can see my heart pumping.
But what if you wanted to take those grayscale 2D pixels
and turn them into a 3D model?
Well, you need to do something called edge detection,
and it's something we, as humans, can do quite easily.
Look, here's the edge of the heart.
You can tell it's the edge of the heart,
because, well, you're doing some object recognition there,
but also there's a big contrast
between these pixels and these pixels.
You can teach a computer to do that, as well.
This video isn't about that.
Instead I'll just show you the result.
Here, thanks to Dassault Systems, is a 3D model of my heart.
Wait, what is that? Some sort of lump?
Oh gosh, I'm going to worry about this lump now.
Should I show it to a doctor?
I don't know. If only I knew a good heart doctor.
Oh, of course. Rohin.
I can ask him.
(phone rings)
- Hey Steve, how's it going?
- [Steve] Hey, Rohin.
Yeah, I've just got a question.
Do you know any to get heart doctors?
What if we wanted to animate the heart?
Well, we could use some animation software
to move bits of it around.
But what if we wanted to simulate the way
the heart behaves under different conditions?
Like, what if we want to simulate how my heart behaves
when I'm 80, with the addition of a pacemaker, for example?
Well, to do that, we need to map out not just
the position of all that muscle tissue,
but other properties that go with it,
like stiffness, electrical conductivity.
With all that information applied to this 3D model,
perhaps we could send a virtual signal to the heart
and see if it will pump.
- Sounds like a good idea,
but how do you go about building a heart?
There's tons of knowledge out there.
Instead of all of us working in isolation,
I pitched this idea to the experts in each domain,
that if they would just share the piece of the puzzle
that they understood,
that I would take the responsibility to put it together.
And within one year, we actually had
a fully working human heart.
- [Steve] That was Steve Levine from Dassault systems.
How do you bring these disparate professionals together?
The people who understand the electrical side of the heart,
people who understand the mechanical side of the heart,
people who understand the fluid dynamics
of the blood in the heart.
Like, how'd you get them together on a technical level?
Well, there's one method that can pull information together
from these different disparate disciplines.
It's called the finite element method.
You may have heard of the finite element method before.
It's that thing that tells you whether a bridge
is safe or not,
and finite element analysis is that.
But it has the potential to be so much more.
Let's take a look at that bridge example, actually.
Like if I wanted to figure out what's the maximum weight
I can apply to this bridge before it breaks.
Well, if the bridge was simple,
like it was made of two rods bolted at each bank
and joined together in the middle,
I could apply a weight in the middle.
And if we assume that the rods are somewhat elastic,
they will lengthen until the restoring force
matches the weight of the mass that we applied.
So then, it's a simple case of just balancing the forces,
and doing a bit of trigonometry to work out
what's the stress in those rods.
But this bridge isn't made of rods.
It's made of stones and cement.
It doesn't have these discrete parts
that we can easily analyze.
The opposite of discrete is continuous.
It's a continuous medium.
The forces at every single point in the bridge
need to be analyzed,
and there are infinitely many points
in a continuous medium, an impossible calculation.
What do we do?
The first step is called discretization.
You have a continuous medium,
and you're going to create a model that is discrete.
It has a finite number of parts.
So, great, now you can just solve the problem
at each one of those nodes.
Except it's not that simple,
because each node influences the neighboring nodes,
and those nodes influence their neighbors as well.
You have to solve these problems simultaneously.
you might know from your past experience
with simultaneous equations,
that if you have, for example, two unknowns,
you need at least two equations.
Or if you have three unknowns,
you need three simultaneous equations.
But if you have a thousand nodes in your mesh,
and each node has three degrees of freedom,
then you have 3000 unknowns,
and you need 3000 simultaneous equations,
each one having 3000 terms in it.
Actually you can simplify things quite a bit,
because a lot of the terms ended up being zero.
But the point is it's still a huge undertaking.
There are many different approaches to solving that problem.
But one option is simply to take a guess
at how much and in what direction
did each one of those nodes in your mesh move.
You then plug that guess into the simultaneous equations
and see if they were right.
If they weren't, then you tweak them a little bit,
and see if it got you any closer.
In other words, you iterate towards the right solution.
That's all very well for a bridge,
but how do we make this work for a heart?
Well, there's a few things you have to do.
The first thing is you add data
to each one of those nodes in your mesh.
So, as well as the stiffness of your heart
at each one of those points,
you're also interested in electrical conductivity.
And how much does the muscle distort, and in what directions
when you apply a voltage.
With all these additional properties,
you can now not only apply a force to the heart,
like we did with the bridge,
but you can also apply a voltage to see what happens.
And so look; here is Dassault Systems'
simulation of my heart,
when a repeated electrical signal is applied.
How cool is that?
By the way, the calculations become much harder,
simply by adding a time element to it.
Like when we were analyzing the bridge,
the bridge was in equilibrium,
but now we've got this dynamic model
where you need to consider acceleration
and damping forces and things like that.
In fact, a complete heartbeat might take eight hours
of computation time,
though they are looking at artificial intelligence,
trained on a massive library of simulated hearts
to see if they can get important results more quickly.
It's all good fun to see a simulation of my heart,
but these models are actually being used with real patients.
For example, patients that have a blockage.
- And so if somebody has a blockage,
we can introduce that blockage,
and see how that actually affects their tissue.
A doctor can say,
"Okay, well that's where our limitations are.
Here's how I should fix it."
Surgeons working with children usually
are seeing unique cases.
Once they open the child, they see what's happening.
They have maybe 10 minutes to decide,
which will affect the child's entire life.
It's staggering when you think of it,
the pressure they feel,
and you can see that when they look in your eyes
and say, "Anything you can do."
I can't sleep the night before that surgery,
knowing what will happen.
You know, these surgeons are brilliant
at visualizing what's happening.
If you enable them to do the actual surgery
on the virtual patient first,
when they get in there, "I've seen this before.
I know what to expect. I know what to do,"
and they can execute.
And so we're actually doing this and saving lives.
- [Steve] This model is also useful
when you're investigating medical devices
like stents or artificial valves.
Like, imagine you're developing
a new type of artificial valve and you want
to bring it to market.
To do that, you have to test it on human hearts,
and that's a long and dangerous process.
But imagine if you could first test it
on hundreds or thousands of virtual hearts.
You recreate your device in a computer,
you add it to the model and you apply
finite element analysis to the whole thing,
to see how it behaves.
Eventually, you have to test on human hearts
as validation of the virtual research,
but by that point, it's safer and it will be quicker.
I also asked Steve about the way doctors interact
with these models.
- We actually have been working with a holographic tablet,
and you can actually just interact with the holograph
floating right in front of you.
The doctors can figure out what the right surgery is.
They can then show it to the entire staff.
The surgeon normally has it in their head.
And then they can show the family.
They say, "See, this is where the hole is
in your son's heart, and we're going to put a patch,
and here's how it's going to fix."
A company take the output of our simulations,
and they use that as the input into their printing process,
and they change the material properties of the print,
so that its deflection matches what we predict.
So you can print ...
It actually feels and moves just like the real object.
So if you have, for example, a calcification in an artery,
it'll be hard in that area and then softer in other areas
and you can actually feel that.
- And that would be really useful for a surgeon.
You can even use the model to explore drug interactions,
for example, beta blockers.
They block electrical signals.
So all you have to do is change those variables
related to electrical signals at the nodes in your model
and see how the heartbeat changes.
- [Steve] We can tell you what will happen
to the blood flow in that heart based on
what that drug is doing inside the cell.
- [Steve] Something interesting happens when
loads of practitioners and researchers
are working with the same model.
- So we now have over 150 hospitals, research organizations,
universities in 24 countries, all using the same model.
So someone's introducing heart disease.
Someone is putting in a valve problem,
and they're all sharing the results
so that the heart model just gets better and better
and better.
We've been so successful,
now, all the other communities are starting to nucleate.
So we now have a living brain community.
We have a living lung community.
I've come to realize that, with the proper motivation,
people really do want to come together
to solve society's problems.
Give them the vehicle to work together,
they'll rise to the occasion.
- Thank you to Dassault Systems
for all their help on this video.
The YouTube algorithm thinks you'll enjoy this video next.
That's interesting, isn't it?
Thanks also to my patrons on Patreon there.
That's it for this video.
Don't forget to subscribe if you're not already,
and I'll see you next time.