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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

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 11y ago
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 11y ago
  >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.
  - Kalium 11y ago
    I should think that emulating biology does the best job of cutting back on extra difficulties introduced by trying to outsmart biology.
  - mikeash 11y ago
    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 11y ago
      >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 11y ago
        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.

SeanDav 11y ago

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 11y ago
>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.
- Kalium 11y ago
  I should think that emulating biology does the best job of cutting back on extra difficulties introduced by trying to outsmart biology.
- mikeash 11y ago
  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 11y ago
    >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 11y ago
      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.