Full Interview With Dr. Paul Wang

Full Interview With Dr. Paul Wang

Paul J. Wang, MD, Professor of Medicine, Stanford Hospital & Clinics, talks about 3-D printing for hearts.
We're talking about moving heart surgery to a whole new level right now. It's 
going to be more precise and give doctors a better idea. Is this what 3-D 
printing will do?
Dr. Wang: I'm very excited about what 3-D printing can do. It can revolutionize
 what we do today in terms of medical device innovation and finding new 
therapies and strategies to treat heart rhythm problems. It enables us to be 
able to take a concept and translate it into a workable model that we can use 
for testing. We are trying to design a new tool; we want to really test it on 
the bench. We really don't have a 3-D capability to do that at the present 
time. This allows us to take a real heart size model with its complexity of 
structure and to use the design that we've made and then to see whether the 
physical and mechanical constraints are adequate to operate within that 
environment. So, that's something that we would have to do experimentally 
before we get to patients. Then, eventually we can figure out whether that will
 work in patients. 
 
Was the before model like a hard model or what was it?
Dr. Wang: Prior to having realistic models we couldn't tailor it to the 
dimensions of the patient, the types of heart disease, etc. We have that 
potential at the present time. It allows us to be able to have the real 
dimensions and real detail in terms of structure.
 
When you talk about experimental devices, what kind are you talking about, 
catheters or valves?
Dr. Wang: The full range of different therapeutics and diagnostic capabilities 
are all suitable to using 3-D printing and 3-D printed models. That could be 
catheters or it could be artificial valves, valves that you introduce through 
catheters, or other devices that you might implant in the heart.
 
Do you see using this before every heart surgery? 
Dr. Wang:  There may be a lot of circumstances where we will actually tailor 
what we do to the actual structure of the heart. We're not there at the present
 time, but that is a potential for the future. Also, we could design tools that
 would be able to be used in a specific set of conditions in certain 
structures.
 
What are these 3-D hearts made out of?
Dr. Wang: They could be made of a variety of circumstances and indeed that's 
really where some of the biggest innovations are. Currently we use a relatively
 easy to use hard material, hard plastic material. In the future, they'll be 
much more textured, they'll have other capabilities. There are structural 
elements that can be used to grow cells on, things that will get incorporated 
into and dissolve over time. So, those are things for the future that are being
 developed now.
 
When you look at these 3-D printers, there's no blood, no heart beating so can 
it be that close to the real thing?
Dr. Wang: Sure. There are definite limitations. It is not going to show you the
 ability of the muscle that contract and that kind of thing. At the present 
time, that's certainly the kinds of models that we use. If you can look at the 
complexity, the detail of what we have is extraordinary. I've never seen 
anything like this in some kind of model that we can use. As I mentioned 
before, what is really important to us in designing new devices is the relative
 dimensions and positioning of different parts of the heart, whether it be 
valve leaflets or different muscles. It's very hard to get that from an image 
that you might see on a screen and when you can actually put a device inside 
the heart and see how it behaves, that gives you a whole other set of 
confidence it's likely to work in a human.
 
Is every heart different?
Dr. Wang: Every heart is clearly different and they have very different 
dimensions and relationships. When we consider that, we take account of those 
and make adjustments based on what the characteristics are. That is part of our
 daily practice, to make those adjustments. We don't have that same ability 
when we're designing a device. The device generally is going to be fixed in its
 dimensions. We have to be able to account for a lot of those variations ahead 
of time and to be able to see what the capabilities are.
 
Right now you are looking at scans to do all this?
Dr. Wang: Currently we use data predominately from imaging scans that we have. 
In the future we can do a lot of other things, obviously. We also use the 
ability of computer assisted drawing programs, which are used for architecture 
and other engineering design programs that can allow us to position within the 
heart devices that we've made.
 
With this 3-D printer, you take that information from the same scans. Is that 
how you get this?
Dr. Wang:  We certainly can start with a scan itself and then generate the 
heart, but also what we'll do is take mechanical drawings and actually create a
 model of the device we're creating. Then we can merge the two to see whether 
they fit, whether the dimensions are correct, and how they'll interact with 
each other. It is really an important, exciting way in which we're able to 
advance technology that we couldn't do before.
 
Could you explain to me how you get to a heart like that?
Dr. Wang: We take the data set from the image and then have to refine it so 
that you actually only get the area that you're interested in. Essentially the 
blood pool is invisible in terms of looking at the heart model. We only get the
 structure of the heart. So, there's a process. It currently is very laborious.
 It would be hard for us to say with every patient that we see to create a 
picture of their heart and print because it's so laborious to get it to that 
state. In the future, that will become streamlined and we'll be able to have 
that capability.
 
How long does it take to create a heart like that?
Dr. Wang:  The actual printing is relatively fast. It can be done in a matter 
of hours. So, we would leave it overnight, we can even get a complex model 
overnight. The tedious part is actually teasing out the parts of the image as 
precisely as possible, so that we can get rid of the extraneous information 
that we don't want printed. That's probably the most tedious part currently.
 
What's that made of right now?
Dr. Wang: It is a special hard plastic that is one of the most commonly used 
substances in 3-D printing.
 
Just looking at this, I would think that this would be instrumental in 
education.  Would it be?
Dr. Wang: Absolutely. I think we have a whole host of different applications in
 3-D printing that we have not even tried. One of the other aspects is to be 
able to have them understand how different tools can be constructed. In the 
past, for example, we might create a diagram and you would say, okay well let's
 see if that might work. Now, overnight we can get the parts and see whether in
 fact that will function. You will be able to really test whether your own 
design concept can really be translated into effective practice.
 
Have you used this yet in practice?
Dr. Wang: We use it mainly in device innovations. We do this all the time. So, 
in the past if we wanted to create something on a very small scale to generate 
a working apparatus, I would go to a machinist and give them the 
specifications. Then, maybe I'd have it two or three months later. Here we can 
simply go to the computer on one of these assisted drawing programs and then we
 can actually create it. It basically pops out and we get to work with it the 
next day. It allows us to iterate in a very fast way so that over a series of 
days we can then see whether the concept that we've then adjusted and altered 
would produce the outcome that we want. It might have taken months or even a 
year in the past to be able to get to that point. We have a real ability to 
accelerate the pace of innovation and that's one of the most exciting things 
about 3-D imaging. 
 
As a surgeon, do you have a device that may not work as well as this?
Dr. Wang: Well, certainly we always go through an iteration process any time we
 develop a new tool and so that's going to involve many, many steps of testing 
for safety really to make sure it's effective. We want to do the best we can 
before we get to patients. We want to be able to solve the problems and 
understand better what the constraints are. The more we have the ability to 
3-Dimensonally deal with those mechanical and structural elements and 
characteristics of the tools we're designing the better, in my opinion. We'll 
get so much farther along in terms of designing.
 
So what's next for this?
Dr. Wang: I think we are looking at new materials that we need to use for 
designing hearts, but also for tools that we make. So we're in the medical 
innovation device program and we're trying to create new designs and new 
therapies for people. To have a greater range of tissue, properties, and 
materials that we use, that's really the next step for us. There are a variety 
of different ways that people will start to use artificial tissues. 
 
What do you mean by artificial tissues? Would you print this out of artificial 
tissue then?
Dr. Wang: We are not doing this work currently, but others are and there are 
several avenues in which they're proceeding. One is that they're actually 
creating a so called scaffold, much as you would do for a shell of a house. You
 are able to then have cells grow on that structure to provide a certain 
structural element for it. 
 
Is that the same as 3-D printing then?
Dr. Wang: Well, we would 3-D print the scaffold or the structure in which it 
would sit and the tissues then grow to conform that area.
 
What's this mean for everyday people?
Dr. Wang: I think 3-D printing is going to be a revolution in terms of what we 
do in medicine, what we do in all parts of our life. So, I think the ability to
 transform what we think conceptually whether it is on a page or now a screen 
to be able to see it and hold it and work with it is really just an extension 
of what we do in real life. The ability to have an object that you can hold and
 work with is really something that we're very familiar with as humans. In 
fact, if you could argue while working on a screen it's kind of artificial; 
this is getting back to what I think people are mainly used to working with. 
We've just never been able to do it very effectively before. We could only deal
 with pictures of things, copies of things that are on a screen or in a book. 
Now, we can actually have a real life model that we can make.
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