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Genuine question: why is an artificial heart such a hard thing to make? At least from a lay-person's perspective, it's just some pumps and valves, which we've g

Genuine question: why is an artificial heart such a hard thing to make? At least from a lay-person's perspective, it's just some pumps and valves, which we've gotten pretty good at making. Obviously I'm wrong about that because there really isn't a permanent artificial heart yet, but it's something I have wondered for awhile.

bufferoverflow 5y ago
There are artificial hearts, and people survived for years on them. The record is 7 years, I think. They aren't cheap, $100K to $300K for the first year, depending on the device. Then it's around $18K/year to maintain. I don't know why they are that expensive.
- iancmceachern 5y ago
  And LVADs too, folks have lived over a decade on those. Tens of thousands have been implanted.
bobbylarrybobby 5y ago
In addition to soft flexible machinery being somewhat difficult to manufacture, you would also have to hook it up to the brain. Not exactly an easy feat.
- FinanceAnon 5y ago
  Why would you need to hook it up to the brain? I am assuming to respond to signals, for example stressed -> beat faster? But what would happen if you didn't have this automatic response? Let's say the heartbeat could be controlled by an algorithm or an app - for example if you lie down, it slows down automatically or if you expect to do some exercise, you can turn it up.
  - jensensbutton 5y ago
    I'm fairly certain you don't want your heart controlled by an app on your phone.
    - tux3 5y ago
      An open source app in and of itself would be a little scary, but I can't imagine the startup making your connected artificial heart posting an "incredible journey" blog. Or having to learn from Hacker News that Google is dropping support for your organs.
    - quickthrower2 5y ago
      Ransomware would be brutal
  - jessriedel 5y ago
    You don't need to hook it up the brain. Transplanted hearts are generally not innervated. https://academic.oup.com/eurheartj/article/39/20/1799/2900507 https://academic.oup.com/eurheartj/article/39/20/1799/290050... As a result, they do not correctly respond to higher demand by beating faster, but this is a deficiency that is considered acceptable. Heart transplant recipients aren't routinely running marathons.
jacobn 5y ago
See "total artificial heart": https://en.wikipedia.org/wiki/Artificial_heart https://en.wikipedia.org/wiki/Artificial_heart Layperson speculation: hard to power 24/7 without an external power source, it must connect seamlessly to the blood stream (can't have it disconnect from the aorta after five weeks), and the surfaces exposed to the blood must not cause blood clots (so careful at the seams).
- Blikkentrekker 5y ago
  It does make me wonder how the transplanted pig heart or any transplanted heart connects so seamlessly. The issue simply heals and grows together with the foreign tissue?
  - iancmceachern 5y ago
    They use a common medical technique called anastomosis. Basically they just sew the two arteries/vessels together with suture and the blood and tissue seals it as any other cut or nick in the body. Sometimes they use "bioglue" but its not strictly needed, just a timesaver.
    - Blikkentrekker 5y ago
      And the pig tissue then connects with the human tissue and eventually heals to form a connected vessel? or it never grows together but it is sealed with a blood cloth?
      - iancmceachern 5y ago
        Exactly, the former.
        Blikkentrekker 5y ago
        So say I carve a wound onto my skin, and then put live skin with a sufficient tissue match onto it and connect the blood vessels so that the new live skin does not die; then the live skin graft and my own damaged skin will hen heal into each other and form a connected totality?
toss1 5y ago
It has been done, as mentioned by other comments. My recollection is that aside from power & control, the hardest problem is clotting. The natural heart apparently causes the blood to flow in a way that there is no pooling or stagnation, whereas almost any fixed-shape chamber apparently has locations where the fluid will stagnate, and with blood, that will cause clots in a very short time. When those clots get loose, they can then go to the lungs and cause a pulmonary embolism, or to the brain and cause a stroke, both of which are very bad and often fatal. So, getting a mechanism that won't do that even once in years of continuous operation is ... nontrivial. EDIT - this is what I recall reading, but I'm not a biomed, I'd like to see a more detailed description from someone in the field.
- sitic 5y ago
  This was indeed the case for the early total artificial hearts implants (Jarvik-7), https://youtu.be/0Xn5u-LzsW8 https://youtu.be/0Xn5u-LzsW8 is a nice short documentary about it
- iancmceachern 5y ago
  Indeed, but they've done it. Check out LVADs like the Heartmate 3 and Heartmate 2.

bufferoverflow 5y ago

There are artificial hearts, and people survived for years on them. The record is 7 years, I think. They aren't cheap, $100K to $300K for the first year, depending on the device. Then it's around $18K/year to maintain. I don't know why they are that expensive.

iancmceachern 5y ago
And LVADs too, folks have lived over a decade on those. Tens of thousands have been implanted.

bobbylarrybobby 5y ago

In addition to soft flexible machinery being somewhat difficult to manufacture, you would also have to hook it up to the brain. Not exactly an easy feat.

FinanceAnon 5y ago
Why would you need to hook it up to the brain? I am assuming to respond to signals, for example stressed -> beat faster? But what would happen if you didn't have this automatic response? Let's say the heartbeat could be controlled by an algorithm or an app - for example if you lie down, it slows down automatically or if you expect to do some exercise, you can turn it up.
- jensensbutton 5y ago
  I'm fairly certain you don't want your heart controlled by an app on your phone.
  - tux3 5y ago
    An open source app in and of itself would be a little scary, but I can't imagine the startup making your connected artificial heart posting an "incredible journey" blog. Or having to learn from Hacker News that Google is dropping support for your organs.
  - quickthrower2 5y ago
    Ransomware would be brutal
- jessriedel 5y ago
  You don't need to hook it up the brain. Transplanted hearts are generally not innervated. https://academic.oup.com/eurheartj/article/39/20/1799/2900507 https://academic.oup.com/eurheartj/article/39/20/1799/290050... As a result, they do not correctly respond to higher demand by beating faster, but this is a deficiency that is considered acceptable. Heart transplant recipients aren't routinely running marathons.

jacobn 5y ago

See "total artificial heart": https://en.wikipedia.org/wiki/Artificial_heart https://en.wikipedia.org/wiki/Artificial_heart Layperson speculation: hard to power 24/7 without an external power source, it must connect seamlessly to the blood stream (can't have it disconnect from the aorta after five weeks), and the surfaces exposed to the blood must not cause blood clots (so careful at the seams).

Blikkentrekker 5y ago
It does make me wonder how the transplanted pig heart or any transplanted heart connects so seamlessly. The issue simply heals and grows together with the foreign tissue?
- iancmceachern 5y ago
  They use a common medical technique called anastomosis. Basically they just sew the two arteries/vessels together with suture and the blood and tissue seals it as any other cut or nick in the body. Sometimes they use "bioglue" but its not strictly needed, just a timesaver.
  - Blikkentrekker 5y ago
    And the pig tissue then connects with the human tissue and eventually heals to form a connected vessel? or it never grows together but it is sealed with a blood cloth?
    - iancmceachern 5y ago
      Exactly, the former.
      - Blikkentrekker 5y ago
        So say I carve a wound onto my skin, and then put live skin with a sufficient tissue match onto it and connect the blood vessels so that the new live skin does not die; then the live skin graft and my own damaged skin will hen heal into each other and form a connected totality?

toss1 5y ago

It has been done, as mentioned by other comments. My recollection is that aside from power & control, the hardest problem is clotting. The natural heart apparently causes the blood to flow in a way that there is no pooling or stagnation, whereas almost any fixed-shape chamber apparently has locations where the fluid will stagnate, and with blood, that will cause clots in a very short time. When those clots get loose, they can then go to the lungs and cause a pulmonary embolism, or to the brain and cause a stroke, both of which are very bad and often fatal. So, getting a mechanism that won't do that even once in years of continuous operation is ... nontrivial. EDIT - this is what I recall reading, but I'm not a biomed, I'd like to see a more detailed description from someone in the field.

sitic 5y ago
This was indeed the case for the early total artificial hearts implants (Jarvik-7), https://youtu.be/0Xn5u-LzsW8 https://youtu.be/0Xn5u-LzsW8 is a nice short documentary about it
iancmceachern 5y ago
Indeed, but they've done it. Check out LVADs like the Heartmate 3 and Heartmate 2.