
The 50-year quest to build a mechanical heart - fisherjeff
http://www.theverge.com/2015/11/4/9665902/artificial-heart-transplant-cedars-sinai-clinical-trials
======
sithadmin
I find myself consistently in awe of the accomplishments that engineers
working on implantable medical devices manage to yield. This is not only
because of the remarkable impact that these devices often have on a patient's
quality of life, but also because of the seemingly insurmountable number of
hurdles that must be overcome to bring a functional product to market.

For moral and regulatory reasons, these engineers cannot depend on large trial
groups, the ability to rapidly iterate designs, run A/B trials, or exact much
control over the quality and consistency of their sample subjects. And to top
it all off, the nuances of human body systems are still very much 'black
boxes' (in spite of our considerable and rapid advances in the field). From a
business perspective, many of these efforts are viewed as nearly untouchable
due to the levels of risk involved.

Yet, things like the artificial hearts mentioned in this article still manage
to get developed. They're not perfect, but they're damn impressive.

~~~
mmmBacon
I worked on wearable sensing technology over the last couple years. Coming
from a pure EE/Physics type background it was a real eye-opener to deal with
the variability in human physiology. Even in the simplest sensors, it's nearly
impossible to account for all the variability one encounters in the entirety
of human population. Basically you always have a percentage of the population
that your device just won't work on.

I can only imagine the difficulty in building a device like an artificial
heart. The fact that these artificial hearts work at all for any length of
time is really a marvel of modern engineering and science.

------
erobbins
I remember watching the first Jarvik 7 transplant on PBS as a kid, thinking
that by the time I was an adult it would be a routine procedure and how
amazing that was.

Reality kicked in of course. It's always surprised me that an artificial heart
is so difficult to perfect. The heart is probably the simplest organ in the
body, yet the devil is in the details.

~~~
SeanDav
Simple yes, it is just a pump - but it has to be 100% reliable, every time,
all the time, no downtime, for 70+ years. Just a few seconds of malfunction in
all that time and you are likely dead. Amazing bit of kit - I am quite
attached to mine.

~~~
trhway
>but it has to be 100% reliable, every time, all the time, no downtime, for
70+ years.

this is why it looks kind of yesterday to me (like many things in the other
highly regulated industry - aviation - too) - why 100% requirement for one
device? How about "horizontal scaling" \- have 2 of them or 3 smaller and less
reliable ones. Once one failed - that is a signal to promptly go in for the
"service".

Replicating biology is a start, yet machinery has different advantages and
disadvantages, so mechanical heart doesn't have to be a mechanical copy of the
biological one. For example one can imagine having smaller helper pumps
installed on all the big arteries, like near the groin for legs and near
armpits for arms - that would improve the circulation and decrease the
physical load on central arteries and overall energy consumption compare to
the original biological schema of one central pump.

~~~
mikeash
There are a couple of problems with that approach.

One is that if you're going to have three-way redundancy, then each one has to
be one-third the size to still fit, which adds to the engineering challenge
and may well make reliability worse.

Another is that not all failures can be fixed with redundancy. If one of your
redundant hearts stops pumping, that's fine. But if it fails by, say, dumping
all your blood into your chest cavity, then adding redundant hearts increases
your chance of death, rather than decreasing it.

Since you mentioned airplanes, making sure redundancy reduces rather than
increasing risk is a big issue. For example, single-engine airplanes are prone
to crashes due to engine failure. The solution is to add a second engine and
you're much safer, right? Except that twin-engine planes can be very
challenging to fly with a dead engine, and if you're not very careful with
design and training, you'll end up with an airplane with two engines that
crashes if _either_ engine fails, greatly increasing the probability of a
failure rather than decreasing it.

~~~
trhway
>Since you mentioned airplanes, making sure redundancy reduces rather than
increasing risk is a big issue. For example, single-engine airplanes are prone
to crashes due to engine failure. The solution is to add a second engine and
you're much safer, right?

that is the same thinking that has been in the aviation for the last 100
years. Why 2? Put 8 electrical ones driven from 2 generators from 2
ICE/turbines. In such approach no component have to be of an "air-worthy"
level of reliability (and associated cost/price), just a regular "consumer
auto" reliability level would easily do.

>But if it fails by, say, dumping all your blood into your chest cavity, then
adding redundant hearts increases your chance of death, rather than decreasing
it.

that is a good point. I'd say that abnormal flow can be detected, and with 2
hearts the option of shutting down the one where abnormal flow is detected is
really a feasible option, while it is definitely not in the case of just one
heart.

~~~
mikeash
Now you have even more things that can go wrong. You can't just pile on extra
equipment, declare it to achieve reliability through redundancy, and have it
be so. Even if you do achieve reliability, what does it cost? Your solution
would probably be unbelievably expensive and inefficient, since you've added a
huge amount of weight and drag.

The thinking from the last 100 years of aviation has resulted in by far the
safest means of transportation ever devised, with a fatality rate so low that
it can no longer be reliably measured. Calling something "the same thinking"
as that is high praise! If you think you have a better way to do it, it's
certainly possible, but you have an _extremely_ high bar to clear.

~~~
trhway
>Even if you do achieve reliability, what does it cost? Your solution would
probably be unbelievably expensive and inefficient, since you've added a huge
amount of weight and drag.

well, i did these calculations some years ago when i was looking at the cost
of heavy low powered, ages in technology behind, engines like Lycoming. Cost
of "horizontally scaled" solution is lower. Efficiency and reliability is
higher. Weight for equivalent power may be a little bit larger, yet it is well
balanced by the efficiency, ie. the lesser fuel consumption.

>The thinking from the last 100 years of aviation has resulted in by far the
safest means of transportation ever devised

at the high level - definitely. But we aren't talking reliability of one huge
heart for 200 patients - the cost here would allow to engineer 10 nines
reliability. We're talking small individual devices. To compare - small
aviation (included in the "General Aviation" below) is completely different -
the GA is ~10 times more dangerous than driving :

[http://www.meretrix.com/~harry/flying/notes/safetyvsdriving....](http://www.meretrix.com/~harry/flying/notes/safetyvsdriving.html)

" For GA, there were 11.2 fatal accidents and 19.7 fatalities per million
hours of flying.

For motor vehicles, there were 1.32 fatal accidents and 1.47 fatalities per
100M miles. "

and that after much more pilot training, after much more technical attention
to the hardware and no 70+ year old "grannies" pilots :) . The technological
state of small aviation, i.e. lack of technological progress for the last half
a century at least, is bordering a shame of our civilization

~~~
mikeash
GA is a totally different world, to be sure. I don't see that it's shameful,
though. It's just not that important overall, so there's not much money in it.
Medevac helicopters and things like that are pretty nice, but stuff like small
Cessnas have few practical uses. And I say this as a hobby pilot who flies
things with absolutely zero practical use.

I'm curious about your solution. How do you fit 8 electric motors to a GA
aircraft? Where do they all go? Do they share props, or do they each have
their own?

~~~
trhway
in general each motor have their own prop. The 2 motors per prop is just an
obvious way to increase redundancy in any other schema, and it works nice in
the sense that electric motors are very easily share the same shaft.

The most obvious way to place more props is the one which even NASA recently
recognized benefits of (like increased lift) -
[http://www.nasa.gov/centers/armstrong/Features/leaptech.html](http://www.nasa.gov/centers/armstrong/Features/leaptech.html)
. Yet that is just a start. Many props driven by smaller electric engines open
a lot of other design possibilities - like easy tilting which easily brings us
to VTOL - [http://nextbigfuture.com/2014/08/nasa-research-shows-
hybrid-...](http://nextbigfuture.com/2014/08/nasa-research-shows-hybrid-
electric.html). Again NASA is very simplistic and primitive in their approach.
The multi-wing designs along the Scaled Composites' ones may be more suitable
here especially if cross-bred with typical octo-copter. The smaller props also
open the possibility of ducts where is a bigger duct for one big prop is
subject to very high loads and as result is very heavy and expensive and
pretty much non-starter as a result. Ducting improves trust at low speed and
decrease noise - both are big advantages for smaller planes.

~~~
mikeash
I'd be really surprised if that approach worked well for normal aircraft.
Small propellors are less efficient than large ones, and you're putting
virtually the entire wing in prop wash, which is going to screw up the
airflow. I'm sure the approach _works_ , but I don't see it working _well_
compared to the more typical solutions with one or two engines on small
aircraft.

I also don't see how this design makes VTOL easy. That design involves
rotating the entire wing by 90 degrees to transition between horizontal and
vertical flight. That's a _huge_ complication over conventional aircraft where
the wing structure is fixed. I can see how it might be a better approach if
you already need VTOL, but if you're content with using a runway then using
this design is going to massively complicate everything.

Finally, none of this appears to address the question of catastrophic failures
versus benign ones. This design will greatly improve safety in the case where
a motor just stops producing power. But for failure modes where, say, the
motor catches fire or the prop comes apart, you've greatly increased the
chances of a major problem.

~~~
trhway
> Small propellors are less efficient than large ones,

not really - they are about of the same efficiency for the same power load.

> and you're putting virtually the entire wing in prop wash, which is going to
> screw up the airflow.

this is the idea here. Increased airflow for the wing means increased lift. Of
course you need to make sure that it is good quality airflow. If you notice -
the NASA uses kind of fans instead of props.

>I also don't see how this design makes VTOL easy. That design involves
rotating the entire wing by 90 degrees to transition between horizontal and
vertical flight.

rotating wing is just this NASA design and it isn't the best one. VTOL is a
big theme. I'd just mention that [technically] successful VTOLs have been -
CL-84, XV-15/V-22, X-22, XV-5 - and looking at them one can get an idea how a
good number (4 minimum, 8 better) of well controlled prop+engine units would
make for a good VTOL.

>But for failure modes where, say, the motor catches fire or the prop comes
apart, you've greatly increased the chances of a major problem.

electric motor isn't an issue. A main generator unit - having at least 2 of
them - can be easily immediately shutdown and flooded with fire-suppressor
gas. Smaller props present less a danger and if in ducts that would be even
less dangerous.

------
Mz
Excerpts:

 _" This doesn’t only take from your body, it takes from your mind, spirit,
and soul," De La Cruz says._

And:

 _Perhaps the biggest moral conundrum, though, has nothing to do with living
with a mechanical heart, but dying with one. Unlike biological hearts,
artificial ones can pump blood throughout the body and oxygen to the brain
when the rest of the body breaks down. Death is dragged out — and may require
the machine be shut off. "I’ve had patients where the liver and kidney failed,
the skin turned yellow and died, and the only thing working normally was the
brain," Arabia says._

I find stuff like this incredibly disturbing. I always find myself wondering
why doctors don't spend more time on helping people keep their own organs
functioning instead of on this kind of stuff. I find this very scary.
"Resistance is futile. You will be assimilated."...because we are only going
to offer you something Frankensteinian like this and not offer better options
for healing the tissues you were born with.

I have a condition that accounts for a high percentage of lung transplants. So
this stuff hits rather close to home for me.

~~~
mikeash
Why not work on both preserving existing organs _and_ replacing them when they
can't be kept going? Not everything can be fixed. A _ton_ of medical research
is put into preserving the function of the original organs, but people will
still sometimes have them fail. When that happens, isn't it good that an
artificial replacement is an option, rather than it just being a guaranteed
death?

~~~
Mz
You are talking to someone who used to have a hole in one lung, with a
condition where doctors wait for infection to eat your lungs up and then list
you for transplant. At one time, I was on 8 or 9 presciption drugs and I spent
3.5 years in constant, excruciating, please-kill-me-now pain. I reached a
point where the _only_ thing I wanted was to hurt less and doctors were not
offering me that. My pulmonologist told me "People like you don't get well.
Symptom management is the name of the game."

So I began pursuing alternative treatments because doctors had no hope to give
me. I did whatever reduced my pain, during a time when I was routinely
hallucinating conversations with The Grim Reaper. And when I hallucinated that
he peered down into my face, saw something he had not seen before and turned
his black steed to leave, I ran screaming after him "Take me with you!" I knew
the death watch was over and I would live. I also knew I faced a long, hard,
torturous recovery. It was a journey I had no desire to make.

I think there are things worse than death. And I also very much fear two
things: 1) That every minute put into researching heroics like artificial
hearts is a minute taken away from researching something more humane and 2)
the extremely high value we place on just making sure no one dies, and quality
of life be damned, gives patients like me a very grim future, even if we get
the best available care and do everything "right" (according to our doctors).

That answer is not intended as dramatics or as anything screechy. It is just
honest commentary on my actual experiences that my views grow out of. Your
question is a very reasonable one. I think my concerns are equally reasonable.
I am aware few people will side with me on this. (Perhaps none, in fact.)

~~~
Gibbon1
I have a friend that worked as a pediatric nurse in a cardiac ward. One of the
reasons she quit was the grim feeling that she was often just enabling
suffering. One of her patients was an infant they should have just let die.
But they cut him open and fixed things and he lived another 6 weeks in torment
and it was her job to make it last.

My grandmother when she was dying mentioned feeling annoyed that government
would spend a few hundred a day on worthless treatments for old old lady on
deaths door when kids were going hungry.

~~~
Mz
When one of my relatives was in ICU, there was an elderly woman in the same
ICU ward that repeatedly had to have dramatic life-saving intervention. A
relative of mine commented on the fact that the entire family knew this
elderly patient was not going home alive, so they were merely dragging out her
death torturously, not extending her life.

Sometimes, it is more humane to just let them die already.

Thank you for commenting.

------
lujim
A bit stressful to read but amazing. I can't imagine having to endure
surgeries where there is a relatively large risk that you won't wake up. If
you do wake up there can be malfunctions in the device that can flip you off
like a light switch. One patient remarked "I have never felt so good" then a
short time later died due to a motor malfunction.

------
brc
The article only briefly mentions it, but the future looks like pulse less
continuous flow hearts. This one [http://bivacor.com](http://bivacor.com) uses
magnetic levitation to eliminate wear surfaces and needs no external air pump
like the ones in the article.

~~~
esturk
I'd heard about this a few years back but there's been no progress since about
any clinical trials. Since the articles mentions SynCardia as the only
artificial heart company approved by the FDA, I'm guessing the BiVACOR is
still not ready?

------
zachrose
Would it be possible to temporarily power your own artificial heart with
skeletal muscle? For example, by turning a crank attached to an artificial
heart?

~~~
sithadmin
Seems like it could be, given proper controls to ensure relatively regular
pumping action (gearbox?). Pneumatic systems could probably be operated with a
bellows of sorts.

~~~
ethbro
... I think I just read the beginning of the best steampunk story ever.

